Enantioselective Decarboxylative Alkylation Reactions: Catalyst Development, Substrate Scope, and Mechanistic Studies

Science.gov (United States)

Behenna, Douglas C.; Mohr, Justin T.; Sherden, Nathaniel H.; Marinescu, Smaranda C.; Harned, Andrew M.; Tani, Kousuke; Seto, Masaki; Ma, Sandy; Novák, Zoltán; Krout, Michael R.; McFadden, Ryan M.; Roizen, Jennifer L.; Enquist, John A.; White, David E.; Levine, Samantha R.; Petrova, Krastina V.; Iwashita, Akihiko; Virgil, Scott C.; Stoltz, Brian M.

2012-01-01

α-Quaternary ketones are accessed through novel enantioselective alkylations of allyl and propargyl electrophiles by unstabilized prochiral enolate nucleophiles in the presence of palladium complexes with various phosphinooxazoline (PHOX) ligands. Excellent yields and high enantiomeric excesses are obtained from three classes of enolate precursors: enol carbonates, enol silanes, and racemic β-ketoesters. Each of these substrate classes functions with nearly identical efficiency in terms of yield and enantioselectivity. Catalyst discovery and development, the optimization of reaction conditions, the exploration of reaction scope, and applications in target-directed synthesis are reported. Experimental observations suggest that these alkylation reactions occur through an unusual inner-sphere mechanism involving binding of the prochiral enolate nucleophile directly to the palladium center. PMID:22083969

Enantioselective Decarboxylative Alkylation Reactions: Catalyst Development, Substrate Scope, and Mechanistic Studies

KAUST Repository

Behenna, Douglas C.; Mohr, Justin T.; Sherden, Nathaniel H.; Marinescu, Smaranda C.; Harned, Andrew M.; Tani, Kousuke; Seto, Masaki; Ma, Sandy; Nová k, Zoltá n; Krout, Michael R.; McFadden, Ryan M.; Roizen, Jennifer L.; Enquist, John A.; White, David E.; Levine, Samantha R.; Petrova, Krastina V.; Iwashita, Akihiko; Virgil, Scott C.; Stoltz, Brian M.

2011-01-01

α-Quaternary ketones are accessed through novel enantioselective alkylations of allyl and propargyl electrophiles by unstabilized prochiral enolate nucleophiles in the presence of palladium complexes with various phosphinooxazoline (PHOX) ligands. Excellent yields and high enantiomeric excesses are obtained from three classes of enolate precursor: enol carbonates, enol silanes, and racemic β-ketoesters. Each of these substrate classes functions with nearly identical efficiency in terms of yield and enantioselectivity. Catalyst discovery and development, the optimization of reaction conditions, the exploration of reaction scope, and applications in target-directed synthesis are reported. Experimental observations suggest that these alkylation reactions occur through an unusual inner-sphere mechanism involving binding of the prochiral enolate nucleophile directly to the palladium center.

Enantioselective Decarboxylative Alkylation Reactions: Catalyst Development, Substrate Scope, and Mechanistic Studies

KAUST Repository

Behenna, Douglas C.

2011-11-14

α-Quaternary ketones are accessed through novel enantioselective alkylations of allyl and propargyl electrophiles by unstabilized prochiral enolate nucleophiles in the presence of palladium complexes with various phosphinooxazoline (PHOX) ligands. Excellent yields and high enantiomeric excesses are obtained from three classes of enolate precursor: enol carbonates, enol silanes, and racemic β-ketoesters. Each of these substrate classes functions with nearly identical efficiency in terms of yield and enantioselectivity. Catalyst discovery and development, the optimization of reaction conditions, the exploration of reaction scope, and applications in target-directed synthesis are reported. Experimental observations suggest that these alkylation reactions occur through an unusual inner-sphere mechanism involving binding of the prochiral enolate nucleophile directly to the palladium center.

Construction of an Asymmetric Quaternary Carbon Center via Allylation of Hydrazones

International Nuclear Information System (INIS)

Kim, Jin Bum; Satyender, Apuri; Jang, Doo Ok

2013-01-01

Asymmetric indium-mediated allylation of imine derivatives bearing a chiral auxiliary is a reliable strategy for the synthesis of chiral homoallylic amines. Various techniques for indium-mediated stereoselective allylation of imines bearing a chiral auxiliary have been reported. In 1997 Loh and co-workers reported indium-mediated allylation with imines derived from L-valine methyl ester. Since then, many forms of indium-mediated allylation bearing a chiral auxiliary have been reported, including imines derived from (S)-valinol, (R)-phenylglycinol, uracil, (R)-phenylglycinol methyl ester, N-tert-butanesufinamide, and (1R,2S)-1-amino-2-indanol. However, the synthesis of chiral auxiliaries often involves a laborious multi-step synthesis with expensive reagents. Therefore, the development of readily accessible chiral auxiliaries for asymmetric indium-mediated all-ylation is in high demand

Lewis base catalyzed enantioselective allylic hydroxylation of Morita-Baylis-Hillman carbonates with water

KAUST Repository

Zhu, Bo

2011-08-19

A Lewis base catalyzed allylic hydroxylation of Morita-Baylis-Hillman (MBH) carbonates has been developed. Various chiral MBH alcohols can be synthesized in high yields (up to 99%) and excellent enantioselectivities (up to 94% ee). This is the first report using water as a nucleophile in asymmetric organocatalysis. The nucleophilic role of water has been verified using 18O-labeling experiments. © 2011 American Chemical Society.

The nature of resonance in allyl ions and radical.

Science.gov (United States)

Linares, Mathieu; Humbel, Stéphane; Braïda, Benoît

2008-12-18

A recent valence bond scheme based on Lewis structures, the valence bond BOND (VBB) method (BOND: Breathing Orbitals Naturally Delocalized) method (Linares, M.; Braida, B.; Humbel, S. J. Phys. Chem. A 2006, 110, 2505-2509), is applied to explore the nature of resonance in allyl systems. Whereas allyl radical is correctly described by the resonance between the two traditional Lewis structures, a third "long-bonded" structure, which apparently creates a pi bond between the two distant carbon atoms, appears to plays an important role in allyl ions description. The similar vertical resonance energy (VRE) for both allyl ions is rather moderate (approximately 37 kcal/mol) in the two-structure description but is significantly enhanced when the long-bonded structure is included into the VBB wave function (by up to 20 kcal/mol). The allyl radical is much less resonant and is correctly described by the traditional two-structure picture. The development of VBB Lewis structures into "pure" valence bond determinants enlightens the role of the third structure in the description of allyl ions. The existence of a long bond between the two distant carbon atoms is clearly ruled out. Charge equilibration effect is shown to be a minor factor. The third structure is finally attributed to one- and three-electron bonding character revealed in the pi systems of the cation and anion, respectively. This makes these systems two surprising examples of odd electron bonding within a singlet state. Last, the two-structure description of allyl radical is improved by addition of missing ionic structures.

Direct asymmetric allylic alkenylation of N-itaconimides with Morita-Baylis-Hillman carbonates

KAUST Repository

Yang, Wenguo

2012-08-03

The asymmetric allylic alkenylation of Morita-Baylis-Hillman (MBH) carbonates with N-itaconimides as nucleophiles has been developed using a commercially available Cinchona alkaloid catalyst. A variety of multifunctional chiral α-methylene-β-maleimide esters were attained in moderate to excellent yields (up to 99%) and good to excellent enantioselectivities (up to 91% ee). The origin of the regio- and stereoselectivity was verified by DFT methods. Calculated geometries and relative energies of various transition states strongly support the observed regio- and enantioselectivity. © 2012 American Chemical Society.

Alkylation of enolate anions formation of enol ethers

NARCIS (Netherlands)

Heiszwolf, G.J.; Kloosterziel, H.

1970-01-01

The alkylation of ambident enolate anions-obtained from aliphatic ketones (and one particular type of aldehyde)-was studied using various solvents, bases, alkylating agents and substrates. Alkylation with a reactive alkylating agent (dialkyl sulfates, triethyloxonium fluoroborate) in an aprotic

Catalytic allylic oxidation of internal alkenes to a multifunctional chiral building block

Science.gov (United States)

Bayeh, Liela; Le, Phong Q.; Tambar, Uttam K.

2017-07-01

The stereoselective oxidation of hydrocarbons is one of the most notable advances in synthetic chemistry over the past fifty years. Inspired by nature, enantioselective dihydroxylations, epoxidations and other oxidations of unsaturated hydrocarbons have been developed. More recently, the catalytic enantioselective allylic carbon-hydrogen oxidation of alkenes has streamlined the production of pharmaceuticals, natural products, fine chemicals and other functional materials. Allylic functionalization provides a direct path to chiral building blocks with a newly formed stereocentre from petrochemical feedstocks while preserving the olefin functionality as a handle for further chemical elaboration. Various metal-based catalysts have been discovered for the enantioselective allylic carbon-hydrogen oxidation of simple alkenes with cyclic or terminal double bonds. However, a general and selective allylic oxidation using the more common internal alkenes remains elusive. Here we report the enantioselective, regioselective and E/Z-selective allylic oxidation of unactivated internal alkenes via a catalytic hetero-ene reaction with a chalcogen-based oxidant. Our method enables non-symmetric internal alkenes to be selectively converted into allylic functionalized products with high stereoselectivity and regioselectivity. Stereospecific transformations of the resulting multifunctional chiral building blocks highlight the potential for rapidly converting internal alkenes into a broad range of enantioenriched structures that can be used in the synthesis of complex target molecules.

Tsuji-Trost N-allylation with allylic acetates using cellulose-Pd catalyst

Science.gov (United States)

Allylic amines are synthesized using heterogeneous cellulose-Pd catalyst via N-allylation of amines; aliphatic and benzyl amines undergo facile reaction with substituted and unsubstituted allyl acetates in high yields.

Preconditioning with subneurotoxic allyl nitrile: protection against allyl nitrile neurotoxicity.

Science.gov (United States)

Tanii, H; Higashi, T; Saijoh, K

2010-02-01

High-dose cruciferous allyl nitrile can induce behavioral abnormalities in rodents, while repeated exposure to allyl nitrile at subneurotoxic levels can increase phase 2 detoxification enzymes in many tissues, although the brain has not been investigated yet. In the present study, we examined the effect of 5 days repeated exposure to subneurotoxic allyl nitrile (0-400 micromol/kg/day) on the brain. Elevated glutathione S-transferase activity was recorded in the striatum, hippocampus, medulla oblongata plus pons, and cortex. Enhancement of quinone reductase activity was observed in the medulla oblongata plus pons, hippocampus, and cortex. In the medulla oblongata plus pons, elevated glutathione levels were recorded. Following repeated subneurotoxic allyl nitrile exposure (0-400 micromol/kg/day), mice were administered a high-dose allyl nitrile (1.2 mmol/kg) which alone led to appearance of behavioral abnormalities. Compared with the 0 micromol/kg/day group, animals in the 200 and 400 micromol/kg/day pre-treatment groups exhibited decreased behavioral abnormalities and elevated GABA-positive cell counts in the substantia nigra pars reticulata and the interpeduncular nucleus. These data suggest that repeated exposure to subneurotoxic levels of allyl nitrile can induce phase 2 enzymes in the brain, which together with induction in other tissues, may contribute to protection against allyl nitrile neurotoxicity. Copyright 2009 Elsevier Ltd. All rights reserved.

Z-Selective iridium-catalyzed cross-coupling of allylic carbonates and α-diazo esters† †Electronic supplementary information (ESI) available: Full procedures, computational details and characterization data. See DOI: 10.1039/c7sc04283c

Science.gov (United States)

Thomas, Bryce N.; Moon, Patrick J.; Yin, Shengkang; Brown, Alex

2017-01-01

A well-defined Ir–allyl complex catalyzes the Z-selective cross-coupling of allyl carbonates with α-aryl diazo esters. The process overrides the large thermodynamic preference for E-products typically observed in metal-mediated coupling reactions to enable the synthesis of Z,E-dieneoates in good yield with selectivities consistently approaching or greater than 90 : 10. This transformation represents the first productive merger of Ir–carbene and Ir–allyl species, which are commonly encountered intermediates in allylation and cyclopropanation/E–H insertion catalysis. Potentially reactive functional groups (aryl halides, ketones, nitriles, olefins, amines) are tolerated owing to the mildness of reaction conditions. Kinetic analysis of the reaction suggests oxidative addition of the allyl carbonate to an Ir-species is rate-determining. Mechanistic studies uncovered a pathway for catalyst activation mediated by NEt3. PMID:29629093

Bicyclic enol cyclocarbamates inhibit penicillin-binding proteins

NARCIS (Netherlands)

Dockerty, Paul; Edens, Jerre G; Tol, Menno B; Morales Angeles, Danae; Domenech Pena, Arnau; Liu, Yun; Hirsch, Anna K H; Veening, Jan-Willem; Scheffers, Dirk-Jan; Witte, Martin D

2017-01-01

Natural products form attractive leads for the development of chemical probes and drugs. The antibacterial lipopeptide Brabantamide A contains an unusual enol cyclocarbamate and we used this scaffold as inspiration for the synthesis of a panel of enol cyclocarbamate containing compounds. By

Neutron radiographic characteristics of MA-ND type (allyl-diglycol-carbonate) nuclear track detectors

Energy Technology Data Exchange (ETDEWEB)

Ilic, R.; Rant, J.; Humar, M.; Somogyi, G.; Hunyadi, I.

1986-01-01

Neutron radiographic properties of recently developed new nuclear track detectors (MA-ND/..cap alpha.., MA-ND/p and MA-ND/p1), manufactured from allyl diglycol carbonate, were studied. It was found that the quality of radiographic image has an optimum at a removed layer thickness of about 0.8 ..mu..m. The image obtained under this condition is characterized by high detection sensitivity to neutrons (approx. 8.10/sup -3/ tracks/nsub(th) when using B converter) and by excellent inherent unsharpness (approx. 5 ..mu..m) as well as high image contrast (maximum value of net optical density is approx. 1.4).

Total Synthesis of Marine Cyclic Enol-Phosphotriester Salinipostin Compounds

Science.gov (United States)

Zhao, Mingliang; Wei, Xianfeng; Liu, Xuemeng; Dong, Xueyang; Yu, Rilei; Wan, Shengbiao; Jiang, Tao

2018-06-01

Due to their structural diversity and variety of biological activities, marine natural products have been the subject of extensive study. These compounds, especially phospholipid polycyclic aromatic hydrocarbons, have a wide range of pharmacological applications, including embedded DNA and central nervous system, anti-tumor, anti-virus, anti-parasite, anti-bacterial, and antithrombotic effects. Unfortunately, the insufficient drug sources have limited the development of these compounds. In this study, we isolated salinpostin compounds from a fermentation solution of marine-derived Salinospora sp., which has a common bicyclic enol-phosphotriester core framework, as well as potent and selective antimalarial activities against P. falciparum with EC50 = 50 nmol L-1. The chemical synthesis of these compounds in greater quantities is necessary for their use in bioactivity studies. Thus we explored a short route with high yields and mild reaction conditions, which can generate combinatorial libraries for drug discovery and lead optimization. We developed a new total synthesis method for six cyclic enol-phosphotriester salinipotin compounds and their diastereomers. For the total synthesis of cyclipostin P, we prepared cyclic enol-phosphotriester salinipostin compounds in 10 steps from a readily accessible starting material, 1,3-dihydroxyacetone, and obtained an overall yield of 1.29%. We fully characterized these compounds by proton nuclear magnetic resonance (1H-NMR), carbon-13 NMR (13C-NMR), and high-resolution mass spectrometry (HRMS) analyses, and found they coincide absolutely with the same compounds reported previously.

Solid radiation curable polyene compositions containing liquid polythiols and solid styrene-allyl copolymer based polyenes

International Nuclear Information System (INIS)

Morgan, C.R.

1977-01-01

Novel styrene-allyl alcohol copolymer based solid polyene compositions which when mixed with liquid polythiols can form solid curable polyene-polythiol systems are claimed. These solid polyenes, containing at least two reactive carbon-to-carbon unsaturated bonds, are urethane or ester derivatives of styrene-allyl alcohol copolymers. The solid polyenes are prepared by treating the hydroxyl groups of a styrene-allyl alcohol copolymer with a reactive unsaturated isocyanate, e.g., allyl isocyanate or a reactive unsaturated carboxylic acid, e.g., acrylic acid. Upon exposure to a free radical generator, e.g., actinic radiation, the solid polyene-polythiol compositions cure to solid, insoluble, chemically resistant, cross-linked polythioether products. Since the solid polyene-liquid polythiol composition can be cured in a solid state, such a curable system finds particular use in preparation of coatings, imaged surfaces such as photoresists, particularly solder-resistant photoresists, printing plates, etc

Thermal studies on unirradiated and γ-irradiated polymer of allyl diglycol carbonate

International Nuclear Information System (INIS)

Kalsi, P.C.; Pandey, A.K.; Iyer, R.H.; Singh Mudher, K.D.

1995-01-01

The thermal decomposition of unirradiated and γ-irradiated (5.93-15.5 MRad dose range) allyl diglycol carbonate polymer (trade name, CR-39) was studied by thermogravimetry (TG) and differential thermal analysis (DTA). These studies indicate four main decomposition steps in CR-39 polymer in air. Assessment of the influence of radiation dose on the above range shows that while the 5.93 MRad γ-irradiated polymer CR-39 degrades in three steps, the 15.5 MRad γ-irradiated polymer degrades in only two steps. The kinetics of the different stages of degradation were also evaluated from the TG curves. Irradiation enhances the decomposition rate and the effect increases further with increasing radiation dose. The activation energy values calculated for all the decomposition stages decrease on irradiation

Regiospecific decarboxylative allylation of nitriles

Science.gov (United States)

Recio, Antonio; Tunge, Jon A.

2009-01-01

Palladium-catalyzed decarboxylative α-allylation of nitriles readily occurs using Pd2(dba)3 and rac-BINAP. This catalyst mixture also allows the highly regiospecific α-allylation of nitriles in the presence of much more acidic α-protons. Thus, the reported method provides access to compounds that are not readily available via base-mediated allylation chemistries. Lastly, mechanistic investigations indicate that there is a competition between C- and N-allylation of an intermediate nitrile-stabilized anion and that N-allylation is followed by a rapid [3,3]-sigmatropic rearrangement. PMID:19921827

Regio- and Enantioselective N-Allylations of Imidazole, Benzimidazole, and Purine Heterocycles Catalyzed by Single-Component Metallacyclic Iridium Complexes

Science.gov (United States)

Stanley, Levi M.

2010-01-01

Highly regio- and enantioselective iridium-catalyzed N-allylations of benzimidazoles, imidazoles, and purines have been developed. N-Allylated benzimidazoles and imidazoles were isolated in high yields (up to 97%) with high branched-to-linear selectivity (up to 99:1) and enantioselectivity (up to 98% ee) from the reactions of benzimidazole and imidazole nucleophiles with unsymmetrical allylic carbonates in the presence of single component, ethylene-bound, metallacyclic iridium catalysts. N-Allylated purines were also obtained in high yields (up to 91%) with high N9:N7 selectivity (up to 96:4), high branched-to-linear selectivity (98:2), and high enantioselectivity (up to 98% ee) under similar conditions. The reactions encompass a range of benzimidazole, imidazole, and purine nucleophiles, as well as a variety of unsymmetrical aryl, heteroaryl, and aliphatic allylic carbonates. Competition experiments between common amine nucleophiles and the heterocyclic nitrogen nucleophiles studied in this work illustrate the effect of nucleophile pKa on the rate of iridium-catalyzed N-allylation reactions. Kinetic studies on the allylation of benzimidazole catalyzed by metallacyclic iridium-phosphoramidite complexes, in combination with studies on the deactivation of these catalysts in the presence of heterocyclic nucleophiles, provide insight into the effects of the structure of the phosphoramidite ligands on the stability of the metallacyclic catalysts. The data obtained from these studies has led to the development of N-allylations of benzimidazoles and imidazoles in the absence of an exogenous base. PMID:19480431

Enantioselective functionalization of allylic C-H bonds following a strategy of functionalization and diversification.

Science.gov (United States)

Sharma, Ankit; Hartwig, John F

2013-11-27

We report the enantioselective functionalization of allylic C-H bonds in terminal alkenes by a strategy involving the installation of a temporary functional group at the terminal carbon atom by C-H bond functionalization, followed by the catalytic diversification of this intermediate with a broad scope of reagents. The method consists of a one-pot sequence of palladium-catalyzed allylic C-H bond oxidation under neutral conditions to form linear allyl benzoates, followed by iridium-catalyzed allylic substitution. This overall transformation forms a variety of chiral products containing a new C-N, C-O, C-S, or C-C bond at the allylic position in good yield with a high branched-to-linear selectivity and excellent enantioselectivity (ee ≤97%). The broad scope of the overall process results from separating the oxidation and functionalization steps; by doing so, the scope of nucleophile encompasses those sensitive to direct oxidative functionalization. The high enantioselectivity of the overall process is achieved by developing an allylic oxidation that occurs without acid to form the linear isomer with high selectivity. These allylic functionalization processes are amenable to an iterative sequence leading to (1,n)-functionalized products with catalyst-controlled diastereo- and enantioselectivity. The utility of the method in the synthesis of biologically active molecules has been demonstrated.

Allyl nitrile: Toxicity and health effects.

Science.gov (United States)

Tanii, Hideji

2017-03-28

Allyl nitrile (3-butenenitrile) occurs naturally in the environment, in particular, in cruciferous vegetables, indicating a possible daily intake of the compound. There is no report on actual health effects of allyl nitrile in humans, although it is possible that individuals in the environment are at a risk of exposure to allyl nitrile. However, little is known about its quantitative assessment for the environment and bioactivity in the body. This study provides a review of previous accumulated studies on allyl nitrile. Published literature on allyl nitrile was examined for findings on toxicity, metabolism, risk of various cancers, generation, intake estimates, and low-dose effects in the body. High doses of allyl nitrile produce toxicity characterized by behavioral abnormalities, which are considered to be produced by an active metabolite, 3,4-epoxybutyronitrile. Cruciferous vegetables have been shown to have a potential role in reducing various cancers. Hydrolysis of the glucosinolate sinigrin, rich in cruciferous vegetables, results in the generation of allyl nitrile. An intake of allyl nitrile is estimated at 0.12 μmol/kg body weight in Japan. Repeated exposure to low doses of allyl nitrile upregulates antioxidant/phase II enzymes in various tissues; this may contribute to a reduction in neurotoxicity and skin inflammation. These high and low doses are far more than the intake estimate. Allyl nitrile in the environment is a compound with diverse bioactivities in the body, characterized by inducing behavioral abnormalities at high doses and some antioxidant/phase II enzymes at low doses.

Pressure Dependent Product Formation in the Photochemically Initiated Allyl + Allyl Reaction

Directory of Open Access Journals (Sweden)

Thomas Zeuch

2013-11-01

Full Text Available Photochemically driven reactions involving unsaturated radicals produce a thick global layer of organic haze on Titan, Saturn’s largest moon. The allyl radical self-reaction is an example for this type of chemistry and was examined at room temperature from an experimental and kinetic modelling perspective. The experiments were performed in a static reactor with a volume of 5 L under wall free conditions. The allyl radicals were produced from laser flash photolysis of three different precursors allyl bromide (C3H5Br, allyl chloride (C3H5Cl, and 1,5-hexadiene (CH2CH(CH22CHCH2 at 193 nm. Stable products were identified by their characteristic vibrational modes and quantified using FTIR spectroscopy. In addition to the (re- combination pathway C3H5+C3H5 → C6H10 we found at low pressures around 1 mbar the highest final product yields for allene and propene for the precursor C3H5Br. A kinetic analysis indicates that the end product formation is influenced by specific reaction kinetics of photochemically activated allyl radicals. Above 10 mbar the (re- combination pathway becomes dominant. These findings exemplify the specificities of reaction kinetics involving chemically activated species, which for certain conditions cannot be simply deduced from combustion kinetics or atmospheric chemistry on Earth.

ION EXCHANGE SUBSTANCES BY SAPONIFICATION OF ALLYL PHOSPHATE POLYMERS

Science.gov (United States)

Kennedy, J.

1959-04-14

An ion exchange resin having a relatively high adsorption capacity tor uranyl ion as compared with many common cations is reported. The resin comprises an alphyl-allyl hydrogen phosphate polymer, the alphyl group being either allyl or a lower alkyl group having up to 5 carbon atoins. The resin is prepared by polymerizing compounds such as alkyl-diallyl phosphate and triallyl phosphate in the presence of a free radical generating substance and then partially hydrolyzing the resulting polymer to cause partial replacement of organic radicals by cations. A preferred free radical gencrating agent is dibenzoyl peroxide. The partial hydrolysis is brought about by refluxing the polymer with concentrated aqueous NaOH for three or four hours.

Compound list: allyl alcohol [Open TG-GATEs

Lifescience Database Archive (English)

Full Text Available allyl alcohol AA 00010 ftp://ftp.biosciencedbc.jp/archive/open-tggates/LATEST/Human/in_vitro/allyl_alcohol....Human.in_vitro.Liver.zip ftp://ftp.biosciencedbc.jp/archive/open-tggates/LATEST/Rat/in_vitro/allyl_alcohol...dbc.jp/archive/open-tggates/LATEST/Rat/in_vivo/Liver/Repeat/allyl_alcohol.Rat.in_vivo.Liver.Repeat.zip ftp:/.../ftp.biosciencedbc.jp/archive/open-tggates/LATEST/Rat/in_vivo/Kidney/Single/allyl_alcohol.Rat.in_vivo.Kidney....Single.zip ftp://ftp.biosciencedbc.jp/archive/open-tggates/LATEST/Rat/in_vivo/Kidney/Repeat/allyl_alcohol.Rat.in_vivo.Kidney.Repeat.zip ...

Gold-catalyzed alkylation of silyl enol ethers with ortho-alkynylbenzoic acid esters

Directory of Open Access Journals (Sweden)

Yoshinori Yamamoto

2011-05-01

Full Text Available Unprecedented alkylation of silyl enol ethers has been developed by the use of ortho-alkynylbenzoic acid alkyl esters as alkylating agents in the presence of a gold catalyst. The reaction probably proceeds through the gold-induced in situ construction of leaving groups and subsequent nucleophilic attack on the silyl enol ethers. The generated leaving compound abstracts a proton to regenerate the silyl enol ether structure.

Design of the passive personal dosimeter for miners using an allyl diglycol carbonate plastic. Phase 1

International Nuclear Information System (INIS)

1983-12-01

The report summarizes the results of the feasibility study on the design and development of a passive personal dosimeter incorporating an allyl diglycol carbonate plastic (CR39) detector, for use by uranium miners. Based upon the feasibility study, a passive personal dosimeter using a capacitor-type electrostatic enhancement device has been designed. Preliminary tests indicate that the prototype could be used in the mine environment to differentiate radon and thoron daughters with a detection efficiency comparable to that of a typical active device. Further study is required, however, into the possible influence in the mine environment of local variations in charged fraction, upon the calibration of this dosimeter

Synthesis of Chromane Derivatives via Indium-mediated Intramolecular Allenylation and Allylation to Imines

International Nuclear Information System (INIS)

Kang, Han Young; Yu, Yeon Kwon

2004-01-01

The results of preparing chromans by intramolecular allylation are shown in Table 2. The results indicated that the indium-mediated allylation was not as efficient as the allenylation. About 10-20% decrease in yields was observed. As mentioned above, in each case only a single isomer was observed, and the stereochemistry of the product was determined as cis by analysis of 1 H NMR and NOE spectra. There are, however, still some limitations in these transformations. Especially, in the case of allylation mixtures of cis and trans isomers are always produced in about 2 : 1 ratio (cis/trans). The ratio was not improved under the various reaction conditions we attempted. Since the indium-mediated addition to carbonyl groups has been successful, it occurred to us that it would be worthwhile to test the addition to carbon-nitrogen double bonds, that is, imine groups. We wish to report here the results of the investigations on allylation and allenylation to C=N bond to provide the chromane structures. The whole transformations

Highly Stereoselective Gold-Catalyzed Coupling of Diazo Reagents and Fluorinated Enol Silyl Ethers to Tetrasubstituted Alkenes.

Science.gov (United States)

Liao, Fu-Min; Cao, Zhong-Yan; Yu, Jin-Sheng; Zhou, Jian

2017-02-20

We report a highly stereoselective synthesis of all-carbon or fluorinated tetrasubstituted alkenes from diazo reagents and fluorinated enol silyl ethers, using C-F bond as a synthetic handle. Cationic Au I catalysis plays a key role in this reaction. Remarkable fluorine effects on the reactivity and selectivity was also observed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermal aromatic Claisen rearrangement and Strecker reaction of alkyl(allyl-aryl ethers under green reaction conditions: Efficient and clean preparation of ortho-allyl phenols (naphthols and alkyl(allyloxyarene-based γ-amino nitriles

Directory of Open Access Journals (Sweden)

Kheila N. Silgado-Gómez

2017-11-01

Full Text Available Chemical transformations of 13 diverse allyl(alkyl-aryl ethers, easily prepared using Williamson reaction of different hydroxyarenes and allyl bromide and alkyl (n-butyl, n-octyl bromides, were studied. Thermal aromatic Claisen rearrangement of allyl-aryl ethers to obtain ortho-allyl phenols (naphthols employing propylene carbonate as a nontoxic and biodegradable solvent was described for the first time. The use of this green solvent allowed to enhance notably product yields and reduce significantly the reaction time comparing with the use of 1,2-dichlorobenzene, toxic solvent, which is traditionally employed in this type of Claisen rearrangement. Three-component Strecker reaction of selected alkyl(allyl-aryl ethers with formyl function on aryl fragment and, piperidine and potassium cyanide in the presence of sulfuric acid supported on silica gel (SSA, SiO2-O-SO3H under mild reaction conditions was used in the preparation of new γ-amino nitriles, analogues of alkaloid girgensohnine [2-(4-hydroxyphenyl-2-(piperidin-1-ylacetonitrile], a perspective biological model in the search for new insecticidal agrochemicals against Aedes aegypti. The use of SSA, an inexpensive and reusable solid catalyst, allowed to obtain new series of 2-[4-alkyl(allyloxyphenyl]-2-(piperidin-1-ylacetonitriles in short time at room temperature with good yields.

SYNTHESIS OF ALLYL PHENYL ETHER AND CLAISEN REARRANGEMENT

Directory of Open Access Journals (Sweden)

Gagik Torosyan

2011-12-01

Full Text Available It has been established the possibility for phenol allylation on natural zeolites and them analogs. Here is demonstrated the synthesis of allyl phenol, which has wide industrial applications. The offered method in comparison with the traditional methods has more advantages – higher selectivity, smaller material and power resources consumption. It has been obtained the mixture of allylating phenols (30% in general with allyl phenyl ether (1 with 80% yields. At 600 K is obtained allylphenyl ether, at 700 K beginning the formation of allyl phenols, which is the result of direct C-allylation of the aromatic ring. It has been investigated the possibility of Claisen rearrangement in the same conditions. All of that are established by gas-liquid chromatography and liquid chromatography data.

Intramolecular Hydrogen Bonding in (2-Hydroxybenzoyl)benzoylmethane Enol

DEFF Research Database (Denmark)

Hansen, Bjarke Knud Vilster; Winther, Morten; Spanget-Larsen, Jens

2014-01-01

, and the dienol form of 1,3-dibenzoylacetone. But in these examples the two H-bonds are equivalent, while in the case of OHDBM they are chemically different, involving one enolic and one phenolic hydroxy group. OHDBM is thus an interesting model compound with two competing H-bonds to the same carbonyl group......In the stable enol tautomer of the title compound (OHDBM), one carbonyl group is flanked by two β-hydroxy groups, giving rise to bifold intramolecular H-bonding. A similar situation is found in other β,β'-dihydroxy carbonyl compounds like chrysazin, anthralin, 2,2'-dihydroxybenzophenone...

On the X-ray reflectivity by poly allyl diglycol carbonate (PADC)

International Nuclear Information System (INIS)

Ghazaly, M. El

2011-01-01

X-ray reflectivity via the poly allyl diglycol carbonate (CR-39 polymer sheet) was investigated. X-ray reflectivity was measured for a pristine and a chemically etched CR-39 detector in 6.25N NaOH at (70 ± 0.5) .deg. C for different durations. Far from the spectral peak, the reflectivity of the CR-39 polymer sheet has a wide peak at 2θ = 20.1 .deg. , and its intensity is decreased by increasing the etching time. Moreover, the integrated counts under the peaks, C(t e ), vary linearly as a function of the etching time t e . Data are fitted using a linear function C(t e ) = A+Bt e , with fitting parameters A = (3271 ± 170) and B = (- 960 ± 84). The reflectivity deterioration is attributed to the increase of CR-39 surface's roughness due to the chemical etching. The rocking curves of X-ray reflectivity were measured for a pristine and an etched CR-39 polymer sheet. Specular reflections are observed, as well as Yoneda wings, which broaden and move away from the specular reflections due to the increase in the CR-39 surface's roughness.

Carbocyclization cascades of allyl ketenimines via aza-Claisen rearrangements of N-phosphoryl-N-allyl-ynamides.

Science.gov (United States)

DeKorver, Kyle A; Wang, Xiao-Na; Walton, Mary C; Hsung, Richard P

2012-04-06

A series of carbocyclization cascades of allyl ketenimines initiated through a thermal aza-Claisen rearrangement of N-phosphoryl-N-allyl ynamides is described. Interceptions of the cationic intermediate via Meerwein-Wagner rearrangements and polyene-type cyclizations en route to fused bi- and tricyclic frameworks are featured.

Preparation of Substituted Enol Derivatives From Terminal Alkynes and Their Synthetic Utility

Science.gov (United States)

DeBergh, John R.; Spivey, Kathleen M.; Ready, Joseph M.

2009-01-01

Stereodefined enol derivatives of aldehydes are prepared from terminal alkynes. Specifically, terminal alkynes are known to undergo Cp2ZrCl2-catalyzed methylalumination. Here, we show that the resultant vinylalanes can be oxygenated with peroxyzinc species to generate trisubstituted enolates. Electrophilic trapping with carboxylic anydrides or silyl triflates yields trisubstituted enol esters or silanes, respectively. The tandem carbometalation/oxygenation tolerates free and protected alcohols, heterocycles, olefins and nitriles. Likewise, amination can be accomplished using azodicarboxylates. Stereodefined enol esters can undergo asymmetric dihydroxylation to yield optically-active α-hydroxy aldehydes. Reduction with NaBH4 provides the diols of 1,1-disubstituted olefins in excellent ee. An application of this methodology to the enantioselective synthesis of the insect pheromone frontalin is presented. Finally, α-hydroxy aldehydes are shown to undergo homologation to a terminal alkyne, reductive amination, oxidation and olefination. Preliminary results indicate that tandem carbometalation/amination can be accomplished with azodicarboxylates. In this way, ene-hydrazines are formed in excellent yield. PMID:18517202

Palladium-catalyzed allylation of tautomerizable heterocycles with alkynes.

Science.gov (United States)

Lu, Chuan-Jun; Chen, Dong-Kai; Chen, Hong; Wang, Hong; Jin, Hongwei; Huang, Xifu; Gao, Jianrong

2017-07-21

A method for the allylic amidation of tautomerizable heterocycles was developed by a palladium catalyzed allylation reaction with 100% atom economy. A series of structurally diverse N-allylic substituted heterocycles can be synthesized in good yields with high chemo-, regio-, and stereoselectivities under mild conditions.

Benchmarking Continuum Solvent Models for Keto-Enol Tautomerizations.

Science.gov (United States)

McCann, Billy W; McFarland, Stuart; Acevedo, Orlando

2015-08-13

Experimental free energies of tautomerization, ΔGT, were used to benchmark the gas-phase predictions of 17 different quantum mechanical methods and eight basis sets for seven keto-enol tautomer pairs dominated by their enolic form. The G4 method and M06/6-31+G(d,p) yielded the most accurate results, with mean absolute errors (MAE's) of 0.95 and 0.71 kcal/mol, respectively. Using these two theory levels, the solution-phase ΔGT values for 23 unique tautomer pairs composed of aliphatic ketones, β-dicarbonyls, and heterocycles were computed in multiple protic and aprotic solvents. The continuum solvation models, namely, polarizable continuum model (PCM), polarizable conductor calculation model (CPCM), and universal solvation model (SMD), gave relatively similar MAE's of ∼1.6-1.7 kcal/mol for G4 and ∼1.9-2.0 kcal/mol with M06/6-31+G(d,p). Partitioning the tautomer pairs into their respective molecular types, that is, aliphatic ketones, β-dicarbonyls, and heterocycles, and separating out the aqueous versus nonaqueous results finds G4/PCM utilizing the UA0 cavity to be the overall most accurate combination. Free energies of activation, ΔG(‡), for the base-catalyzed keto-enol interconversion of 2-nitrocyclohexanone were also computed using six bases and five solvents. The M06/6-31+G(d,p) reproduced the ΔG(‡) with MAE's of 1.5 and 1.8 kcal/mol using CPCM and SMD, respectively, for all combinations of base and solvent. That specific enolization was previously proposed to proceed via a concerted mechanism in less polar solvents but shift to a stepwise mechanism in more polar solvents. However, the current calculations suggest that the stepwise mechanism operates in all solvents.

Molecular Mechanics and Quantum Chemistry Based Study of Nickel-N-Allyl Urea and N-Allyl Thiourea Complexes

Directory of Open Access Journals (Sweden)

P. D. Sharma

2009-01-01

Full Text Available Eigenvalue, eigenvector and overlap matrix of nickel halide complex of N-allyl urea and N-allyl thiourea have been evaluated. Our results indicate that ligand field parameters (Dq, B’ and β evaluated earlier by electronic spectra are very close to values evaluated with the help of eigenvalues and eigenvectors. Eigenvector analysis and population analysis shows that in bonding 4s, 4p, and 3dx2-y2, 3dyz orbitals of nickel are involved but the coefficient values differ in different complexes. Out of 4px, 4py, 4pz the involvement of either 4pz or 4py, is noticeable. The theoretically evaluated positions of infrared bands indicate that N-allyl urea is coordinated to nickel through its oxygen and N-allyl thiourea is coordinated to nickel through its sulphur which is in conformity with the experimental results.

Rhodium-Catalyzed Asymmetric N-H Functionalization of Quinazolinones with Allenes and Allylic Carbonates: The First Enantioselective Formal Total Synthesis of (-)-Chaetominine.

Science.gov (United States)

Zhou, Yirong; Breit, Bernhard

2017-12-22

An unprecedented asymmetric N-H functionalization of quinazolinones with allenes and allylic carbonates was successfully achieved by rhodium catalysis with the assistance of chiral bidentate diphosphine ligands. The high efficiency and practicality of this method was demonstrated by a low catalyst loading of 1 mol % as well as excellent chemo-, regio-, and enantioselectivities with broad functional group compatibility. Furthermore, this newly developed strategy was applied as key step in the first enantioselective formal total synthesis of (-)-chaetominine. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

General Allylic C–H Alkylation with Tertiary Nucleophiles

Science.gov (United States)

2015-01-01

A general method for intermolecular allylic C–H alkylation of terminal olefins with tertiary nucleophiles has been accomplished employing palladium(II)/bis(sulfoxide) catalysis. Allylic C–H alkylation furnishes products in good yields (avg. 64%) with excellent regio- and stereoselectivity (>20:1 linear:branched, >20:1 E:Z). For the first time, the olefin scope encompasses unactivated aliphatic olefins as well as activated aromatic/heteroaromatic olefins and 1,4-dienes. The ease of appending allyl moieties onto complex scaffolds is leveraged to enable this mild and selective allylic C–H alkylation to rapidly diversify phenolic natural products. The tertiary nucleophile scope is broad and includes latent functionality for further elaboration (e.g., aliphatic alcohols, α,β-unsaturated esters). The opportunities to effect synthetic streamlining with such general C–H reactivity are illustrated in an allylic C–H alkylation/Diels–Alder reaction cascade: a reactive diene is generated via intermolecular allylic C–H alkylation and approximated to a dienophile contained within the tertiary nucleophile to furnish a common tricyclic core found in the class I galbulimima alkaloids. PMID:24641574

General allylic C-H alkylation with tertiary nucleophiles.

Science.gov (United States)

Howell, Jennifer M; Liu, Wei; Young, Andrew J; White, M Christina

2014-04-16

A general method for intermolecular allylic C-H alkylation of terminal olefins with tertiary nucleophiles has been accomplished employing palladium(II)/bis(sulfoxide) catalysis. Allylic C-H alkylation furnishes products in good yields (avg. 64%) with excellent regio- and stereoselectivity (>20:1 linear:branched, >20:1 E:Z). For the first time, the olefin scope encompasses unactivated aliphatic olefins as well as activated aromatic/heteroaromatic olefins and 1,4-dienes. The ease of appending allyl moieties onto complex scaffolds is leveraged to enable this mild and selective allylic C-H alkylation to rapidly diversify phenolic natural products. The tertiary nucleophile scope is broad and includes latent functionality for further elaboration (e.g., aliphatic alcohols, α,β-unsaturated esters). The opportunities to effect synthetic streamlining with such general C-H reactivity are illustrated in an allylic C-H alkylation/Diels-Alder reaction cascade: a reactive diene is generated via intermolecular allylic C-H alkylation and approximated to a dienophile contained within the tertiary nucleophile to furnish a common tricyclic core found in the class I galbulimima alkaloids.

A catalyst-free addition reaction of zinc amide enolates to N-sulfonyle imines

Energy Technology Data Exchange (ETDEWEB)

Joo, Seong Ryu; Im, Pyeong Won; Kim, Jong Sung; Kim, Seung Hoi [Dept. of Chemistry, Dankook University, Cheonan (Korea, Republic of); Park Soo Youl [Interface Chemistry and Engineering Research Team, Korea Research Institute of Chemical Technology, Daejon (Korea, Republic of)

2016-12-15

Despite the remarkable expansion of the imino-Reformatsky reaction, one interesting aspect is that, to the best of our knowledge, zinc enolates derived solely from α-halo esters have been mainly used in the recent progress. In contrast, a few limited examples have been reported concerning the application of zinc enolates derived from α-halo amide to the imino-Reformatsky reaction. In recent years, Rodriguez-Solla and co-workers reported the addition reaction of samarium enolates derived from both α-halo esters and amides to imines, resulting in the synthe- sis of β-amino esters or amides. In conclusion, we established a potential synthetic proto- col for the preparation of β-amino amides. This work was accomplished by the direct addition of zinc amide enolates to N-sulfonyl imines in the absence of any metal-catalyst under mild conditions. Due to the operational simplicity of the proposed method, it can be further utilized in synthetic organic chemistry. Further studies to elucidate the scope of this approach are currently underway in our laboratory.

A catalyst-free addition reaction of zinc amide enolates to N-sulfonyle imines

International Nuclear Information System (INIS)

Joo, Seong Ryu; Im, Pyeong Won; Kim, Jong Sung; Kim, Seung Hoi; Park Soo Youl

2016-01-01

Despite the remarkable expansion of the imino-Reformatsky reaction, one interesting aspect is that, to the best of our knowledge, zinc enolates derived solely from α-halo esters have been mainly used in the recent progress. In contrast, a few limited examples have been reported concerning the application of zinc enolates derived from α-halo amide to the imino-Reformatsky reaction. In recent years, Rodriguez-Solla and co-workers reported the addition reaction of samarium enolates derived from both α-halo esters and amides to imines, resulting in the synthe- sis of β-amino esters or amides. In conclusion, we established a potential synthetic proto- col for the preparation of β-amino amides. This work was accomplished by the direct addition of zinc amide enolates to N-sulfonyl imines in the absence of any metal-catalyst under mild conditions. Due to the operational simplicity of the proposed method, it can be further utilized in synthetic organic chemistry. Further studies to elucidate the scope of this approach are currently underway in our laboratory

Toward Efficient Palladium-Catalyzed Allylic C-H Alkylation

DEFF Research Database (Denmark)

Jensen, Thomas; Fristrup, Peter

2009-01-01

Recent breakthroughs have proved that direct palladium (II)-catalyzed allylic C-H alkylation can be achieved. This new procedure shows that the inherent requirement for a leaving group in the Tsuji-Trost palladium-catalyzed allylic alkylation can be lifted. These initial reports hold great promise...... for the development of allylic C-H alkylation into a widely applicable methodology, thus providing a means to enhance synthetic efficiency in these reactions....

Two-dimensional NMR studies of allyl palladium complexes of ...

Indian Academy of Sciences (India)

Administrator

h3-Allyl complexes are intermediates in organic synthetic reactions such as allylic alkylation and amination. There is growing interest in understanding the structures of chiral h3-allyl intermediates as this would help to unravel the mechanism of enantioselective C–C bond forming reactions. Two-dimensional NMR study is a.

Cutting thin sheets of allyl diglycol carbonate (CR-39) with a CW CO2, laser

International Nuclear Information System (INIS)

Kukreja, L.M.; Bhawalkar, D.D.; Basu, C.; Goswami, J.N.

1984-01-01

Recent studies have shown that Allyl Diglycol Carbonate, commercially known as CR-39 (the most sensitive among etch track detectors) can detect relativistic oxygen and other heavier nuclei. We are using large sheets of special grade CR-39 (DOP) in our experiment in Space Shuttle-Spacelab-3. As CR-39 is a highly brittle substance, special care is required to cut CR-39 shetts, especially in case of large sheets and circular cuts. A study of cutting of CR-39 sheets using laser light is described in this paper. It has been found that this method is sufficiently fast to handle large number of sheets and also equally safe for big sheets. A maximum speed up to 200 cm/min with a 5 x 10 4 W/cm 2 laser is obtained during the present study. This study also shows that laser cutting does not affect the track properties of CR-39. (orig.)

Lactone Enol Cation-Radicals. Gas-Phase Generation, Structure, Energetics, and Reactivity of the Ionized Enol of Butane-4-Lactone

Czech Academy of Sciences Publication Activity Database

Tureček, F.; Vivekananda, S.; Sadílek, M.; Polášek, Miroslav

2002-01-01

Roč. 37, - (2002), s. 829-839 ISSN 1076-5174 R&D Projects: GA ČR GA203/00/0632 Institutional research plan: CEZ:AV0Z4040901 Keywords : lactone enol ions * dissociation mechanisms * isotope effects Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.781, year: 2002

Catalytic Oxidation of Allylic Alcohols to Methyl Esters

DEFF Research Database (Denmark)

Gallas-Hulin, Agata; Kotni, Rama Krishna; Nielsen, Martin

2017-01-01

Aerobic oxidation of allylic alcohols to methyl esters using gold nanoparticles supported on different metal oxide carriers has been performed successfully under mild conditions (room temperature, 0.1 MPa O2) without significant loss of catalytic activity. The effects of different reaction...... parameters are studied to find the suitable reaction conditions. All catalysts are characterised by XRD, XRF and TEM. Among these catalysts, Au/TiO2 showed the most efficient catalytic activity towards the selective oxidation of allylic alcohols to the corresponding esters. Moreover, the same Au/TiO2...... to synthesize methyl esters from allylic alcohols....

Decarbonylation and hydrogenation reactions of allyl alcohol and acrolein on Pd(110)

Science.gov (United States)

Shekhar, Ratna; Barteau, Mark A.

1994-11-01

Allyl alcohol and acrolein reactions on the Pd(110) surface were investigated using temperature programmed desorption. For both unsaturated oxygenates, three coverage-dependent reaction pathways were observed. At low coverages, allyl alcohol decomposed completely to CO, hydrogen and carbonaceous species on the surface. For θ > 0.15 monolayer, ethylene (and small amounts of ethane) desorbed at ca. 295 K. Near saturation coverages, desorption of propanal was detected at ca. 235 K. The parent molecule, allyl alcohol, desorbed only after exposures sufficient to saturate these channels. Acrolein decomposition spectra were similar to those observed for allyl alcohol decomposition on the clean surface. Additional experiments with allyl alcohol on hydrogen- and deuterium-precoveredPd(110) surfaces demonstrated increased hydrogenation of the C 2-hydrocarbon products along with hydrogenation of allyl alcohol to 1-propanol. However, in contrast to previous results for allyl alcohol on the Pd(111) surface, there was no evidence for C-O scission reactions of any C 3 oxygenate on Pd(110).

Water promoted allylic nucleophilic substitution reactions of (E)-1,3 diphenylallyl acetate

KAUST Repository

Ghorpade, Seema Arun; Sawant, Dinesh N; Makki, Arwa; Sekar, N; Eppinger, Jö rg

2017-01-01

Transition metal free, water based, greener protocol for allylic alkylation, allylic amination, O-allylation of (E)-1,3-diphenylallyl acetate is described. The developed methodology is applicable for a wide range of nucleophiles furnishing excellent yields of corresponding products up to 87% under mild reaction conditions. A Distinct effect of water and base is explored for allylic nucleophilic substitution reactions of (E)-1,3-diphenylallyl acetate.

Water promoted allylic nucleophilic substitution reactions of (E)-1,3 diphenylallyl acetate

KAUST Repository

Ghorpade, Seema Arun

2017-11-30

Transition metal free, water based, greener protocol for allylic alkylation, allylic amination, O-allylation of (E)-1,3-diphenylallyl acetate is described. The developed methodology is applicable for a wide range of nucleophiles furnishing excellent yields of corresponding products up to 87% under mild reaction conditions. A Distinct effect of water and base is explored for allylic nucleophilic substitution reactions of (E)-1,3-diphenylallyl acetate.

Rapid synthesis of polyprenylated acylphloroglucinol analogs via dearomative conjunctive allylic annulation.

Science.gov (United States)

Grenning, Alexander J; Boyce, Jonathan H; Porco, John A

2014-08-20

Polyprenylated acylphloroglucinols (PPAPs) are structurally complex natural products with promising biological activities. Herein, we present a biosynthesis-inspired, diversity-oriented synthesis approach for rapid construction of PPAP analogs via double decarboxylative allylation (DcA) of acylphloroglucinol scaffolds to access allyl-desoxyhumulones followed by dearomative conjunctive allylic alkylation (DCAA).

Reactions of the ionized enol tautomer of acetanilide: elimination of HNCO via a novel rearrangement.

Science.gov (United States)

Heydorn, Lisa N; Carter, Lynn M; Bowen, Richard D; Terlouw, Johan K

2003-01-01

The reactions of ionised acetanilide, C(6)H(5)NH(=O)CH(3)(.+), and its enol, C(6)H(5)NH(OH)=CH(2)(.+), have been studied by a combination of tandem mass spectrometric and computational methods. These two isomeric radical cations have distinct chemistries at low internal energies. The keto tautomer eliminates exclusively CH(2)=C=O to give ionised aniline. In contrast, the enol tautomer loses H-N=C=O, via an unusual skeletal rearrangement, to form predominantly ionised methylene cyclohexadiene. Hydrogen atom loss also occurs from the enol tautomer, with the formation of protonated oxindole. The mechanisms for H-N=C=O and hydrogen atom loss both involve cyclisation; the former proceeds via a spiro transition state formed by attachment of the methylene group to the ipso position, whereas the latter entails the formation of a five-membered ring by attachment to the ortho position. The behaviour of labelled analogues reveals that these two processes have different site selectivities. Hydrogen atom loss involves a reverse critical energy and is subject to an isotope effect. Surprisingly, attempts to promote the enolisation of ionised acetanilide by proton-transport catalysis were unsuccessful. In a reversal of the usual situation for ionised carbonyl compounds, ionised acetanilide is actually more stable than its enol tautomer. The enol tautomer was resistant to proton-transport catalysed ketonisation to ionised acetanilide, possibly because the favoured geometry of the encounter complex with the base molecule is inappropriate for facilitating tautomerisation.

Taxonomía de levaduras de origen enológico por espectrometría de masas

OpenAIRE

Gutiérrez López, Cristina

2016-01-01

Esencialmente, la tesis presentada bajo el título “Taxonomía de levaduras de origen enológico por espectrometría de masas” trata sobre la implementación del proceso de identificación y clasificación taxonómica de levaduras de interés enológico mediante el empleo de la técnica MALDI-TOF MS, como alternativa a la utilización de técnicas clásicas y moleculares. Se ha creado una librería de espectros de masas mediante MALDI-TOF MS con una extensa colección de levaduras aisladas del entorno enológ...

Synthesis of 3-alkyl enol mimics inhibitors of type II dehydroquinase: factors influencing their inhibition potency.

Science.gov (United States)

Blanco, Beatriz; Sedes, Antía; Peón, Antonio; Lamb, Heather; Hawkins, Alastair R; Castedo, Luis; González-Bello, Concepción

2012-05-14

Several 3-alkylaryl mimics of the enol intermediate in the reaction catalyzed by type II dehydroquinase were synthesized to investigate the effect on the inhibition potency of replacing the oxygen atom in the side chain by a carbon atom. The length and the rigidity of the spacer was also studied. The inhibitory properties of the reported compounds against type II dehydroquinase from Mycobacterium tuberculosis and Helicobacter pylori are also reported. The binding modes of these analogs in the active site of both enzymes were studied by molecular docking using GOLD 5.0 and dynamic simulations studies.

Allyl borates: a novel class of polyhomologation initiators

KAUST Repository

Wang, De

2016-12-24

Allyl borates, a new class of monofunctional polyhomologation initiators, are reported. These monofunctional initiators are less sensitive and more effective towards polymethylene-based architectures. As an example, the synthesis of α-vinyl-ω-hydroxypolymethylenes is given. By designing/synthesizing different allylic borate initiators, and using 1H and 11B NMR spectroscopy, the initiation mechanism was elucidated.

Enolate Stabilization by Anion-π Interactions: Deuterium Exchange in Malonate Dilactones on π-Acidic Surfaces.

Science.gov (United States)

Miros, François N; Zhao, Yingjie; Sargsyan, Gevorg; Pupier, Marion; Besnard, Céline; Beuchat, César; Mareda, Jiri; Sakai, Naomi; Matile, Stefan

2016-02-18

Of central importance in chemistry and biology, enolate chemistry is an attractive topic to elaborate on possible contributions of anion-π interactions to catalysis. To demonstrate the existence of such contributions, experimental evidence for the stabilization of not only anions but also anionic intermediates and transition states on π-acidic aromatic surfaces is decisive. To tackle this challenge for enolate chemistry with maximal precision and minimal uncertainty, malonate dilactones are covalently positioned on the π-acidic surface of naphthalenediimides (NDIs). Their presence is directly visible in the upfield shifts of the α-protons in the (1) H NMR spectra. The reactivity of these protons on π-acidic surfaces is measured by hydrogen-deuterium (H-D) exchange for 11 different examples, excluding controls. The velocity of H-D exchange increases with π acidity (NDI core substituents: SO2 R>SOR>H>OR>OR/NR2 >SR>NR2 ). The H-D exchange kinetics vary with the structure of the enolate (malonates>methylmalonates, dilactones>dithiolactones). Moreover, they depend on the distance to the π surface (bridge length: 11-13 atoms). Most importantly, H-D exchange depends strongly on the chirality of the π surface (chiral sulfoxides as core substituents; the crystal structure of the enantiopure (R,R,P)-macrocycle is reported). For maximal π acidity, transition-state stabilizations up to -18.8 kJ mol(-1) are obtained for H-D exchange. The Brønsted acidity of the enols increases strongly with π acidity of the aromatic surface, the lowest measured pKa =10.9 calculates to a ΔpKa =-5.5. Corresponding to the deprotonation of arginine residues in neutral water, considered as "impossible" in biology, the found enolate-π interactions are very important. The strong dependence of enolate stabilization on the unprecedented seven-component π-acidity gradient over almost 1 eV demonstrates quantitatively that such important anion-π activities can be expected only from

Formation of Supported Graphene Oxide: Evidence for Enolate Species.

Science.gov (United States)

Novotny, Zbynek; Nguyen, Manh-Thuong; Netzer, Falko P; Glezakou, Vassiliki-Alexandra; Rousseau, Roger; Dohnálek, Zdenek

2018-04-18

Graphene oxides are promising materials for novel electronic devices or anchoring of the active sites for catalytic applications. Here we focus on understanding the atomic oxygen (AO) binding and mobility on different regions of graphene (Gr) on Ru(0001). Differences in the Gr/Ru lattices result in the superstructure, which offers an array of distinct adsorption sites. We employ scanning tunneling microscopy and density functional theory to map out the chemical identity and stability of prepared AO functionalities in different Gr regions. The AO diffusion is utilized to establish that in the regions that are close to the metal substrate the terminally bonded enolate groups are strongly preferred over bridge-bonded epoxy groups. No oxygen species are observed on the graphene regions that are far from the underlying Ru, indicating their low relative stability. This study provides a clear fundamental basis for understanding the local structural, electronic factors and C-Ru bond strengthening/weakening processes that affect the stability of enolate and epoxy species.

preparation of bicyclic lactones using lewis acids catalyzed ene

African Journals Online (AJOL)

Administrator

The synthesis of the cis-fused bicyclic lactones relies extensively on the Lewis acid ... having an allylic hydrogen (an"ene") and a compound containing an electron .... observed that the lithium enolate obtained from 3-methyl-2(5H)- furanone ...

Palladium-Catalyzed Anti-Markovnikov Oxidation of Allylic Amides to Protected beta-Amino Aldehydes

NARCIS (Netherlands)

Dong, Jiajia; Harvey, Emma C.; Fananas-Mastral, Martin; Browne, Wesley R.; Feringa, Bernard

2014-01-01

A general method for the preparation of N-protected beta-amino aldehydes from allylic amines or linear allylic alcohols is described. Here the Pd(II)-catalyzed oxidation of N-protected allylic amines with benzoquinone is achieved in tBuOH under ambient conditions with excellent selectivity toward

40 CFR 721.7000 - Polymer of disodium maleate, allyl ether, and ethylene oxide.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polymer of disodium maleate, allyl... New Uses for Specific Chemical Substances § 721.7000 Polymer of disodium maleate, allyl ether, and... substance identified generically as a polymer of disodium maleate, allyl ether, and ethylene oxide (P-91...

Supramolecular Influence on Keto-Enol Tautomerism and Thermochromic Properties of o-Hydroxy Schiff Bases

Directory of Open Access Journals (Sweden)

Marija Zbačnik

2016-06-01

Full Text Available This work presents a study on thermo-optical properties of three Schiff bases (imines in the solid state. The Schiff bases were obtained by means of mechanochemical synthesis using monosubstituted o-hydroxy aromatic aldehydes and monosubstituted aromatic amines. The keto-enol tautomerism and proton transfer via intramolecular O∙∙∙N hydrogen bond of the reported compounds was found to be influenced more by supramolecular interactions than by a temperature change. All products were characterised by powder X-ray diffraction (PXRD, FT-IR spectroscopy, thermogravimetric (TG analysis and differential scanning calorimetry (DSC. Molecular and crystal structures of compounds 1, 2 and 3 were determined by single crystal X-ray diffraction (SCXRD. The molecules of 1 appear to be present as the enol-imine, the molecules of 2 as the keto-amine tautomer and the molecules of 3 exhibit keto-enol tautomeric equilibrium in the solid state. An analysis of Cambridge structural database (CSD data on similar imines has been used for structural comparison. This work is licensed under a Creative Commons Attribution 4.0 International License.

Synthesis of 4-substituted tetrahydropyridines by cross-coupling of enol phosphates

DEFF Research Database (Denmark)

Larsen, U.S.; Martiny, L.; Begtrup, M.

2005-01-01

Enol phosphates, synthesized from 4-piperidone, react by palladium catalyzed cross-coupling with arylboronic acids and by iron and palladium catalyzed cross-coupling with Grignard reagents to give 4-substituted tetrahydropyridines. (c) 2005 Elsevier Ltd. All rights reserved....

Practical Stannylation of Allyl Acetates Catalyzed by Nickel with Bu3 SnOMe.

Science.gov (United States)

Komeyama, Kimihiro; Itai, Yuuhei; Takaki, Ken

2016-06-27

A practical and scalable nickel-catalyzed allylic stannylation of allyl acetates with Bu3 SnOMe is described. A variety of acyclic and cyclic allyl acetates, even with base-sensitive moieties, undergoes the stannylation by using NiBr2 /4,4'-di-tert-butylbipyridine (dtbpy)/Mn catalyst system to afford highly functionalized allyl stannanes with excellent regioselectivity and yields. Furthermore, the scope of protocol is also extended by the reaction of propargyl acetates, giving rise to propargyl or allenyl stannanes. Additionally, a unique diastereoselectivity using the nickel catalyst different from the palladium was demonstrated for the stannylation of cyclic allyl acetates. In the reaction, inexpensive and stable nickel complexes, abundant reductant (Mn), and atom-economical stannyl source were used. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oral Administration of (S)-Allyl-l-Cysteine and Aged Garlic Extract to Rats: Determination of Metabolites and Their Pharmacokinetics.

Science.gov (United States)

Park, Taehoon; Oh, Ju-Hee; Lee, Joo Hyun; Park, Sang Cheol; Jang, Young Pyo; Lee, Young-Joo

2017-11-01

( S )-Allyl-l-cysteine is the major bioactive compound in garlic. ( S )-Allyl-l-cysteine is metabolized to ( S )-allyl-l-cysteine sulfoxide, N -acetyl-( S )-allyl-l-cysteine, and N -acetyl-( S )-allyl-l-cysteine sulfoxide after oral administration. An accurate LC-MS/MS method was developed and validated for the simultaneous quantification of ( S )-allyl-l-cysteine and its metabolites in rat plasma, and the feasibility of using it in pharmacokinetic studies was tested. The analytes were quantified by multiple reaction monitoring using an atmospheric pressure ionization mass spectrometer. Because significant quantitative interference was observed between ( S )-allyl-l-cysteine and N -acetyl-( S )-allyl-l-cysteine as a result of the decomposition of N -acetyl-( S )-allyl-l-cysteine at the detector source, chromatographic separation was required to discriminate ( S )-allyl-l-cysteine and its metabolites on a reversed-phase C 18 analytical column with a gradient mobile phase consisting of 0.1% formic acid and acetonitrile. The calibration curves of ( S )-allyl-l-cysteine, ( S )-allyl-l-cysteine sulfoxide, N -acetyl-( S )-allyl-l-cysteine, and N -acetyl-( S )-allyl-l-cysteine sulfoxide were linear over each concentration range, and the lower limits of quantification were 0.1 µg/mL [( S )-allyl-l-cysteine and N -acetyl-( S )-allyl-l-cysteine] and 0.25 µg/mL [( S )-allyl-l-cysteine sulfoxide and N -acetyl-( S )-allyl-l-cysteine sulfoxide]. Acceptable intraday and inter-day precisions and accuracies were obtained at three concentration levels. The method satisfied the regulatory requirements for matrix effects, recovery, and stability. The validated LC-MS/MS method was successfully used to determine the concentration of ( S )-allyl-l-cysteine and its metabolites in rat plasma samples after the administration of ( S )-allyl-l-cysteine or aged garlic extract. Georg Thieme Verlag KG Stuttgart · New York.

Effect of allyl isothiocyanate on developmental toxicity in exposed Xenopus laevis embryos

Directory of Open Access Journals (Sweden)

John Russell Williams

2015-01-01

Full Text Available The pungent natural compound allyl isothiocyanate isolated from the seeds of Cruciferous (Brassica plants such as mustard is reported to exhibit numerous beneficial health-promoting antimicrobial, antifungal, anticarcinogenic, cardioprotective, and neuroprotective properties. Because it is also reported to damage DNA and is toxic to aquatic organisms, the objective of the present study was to determine whether it possesses teratogenic properties. The frog embryo teratogenesis assay-Xenopus (FETAX was used to determine the following measures of developmental toxicity of the allyl isothiocyanate: (a 96-h LC50, defined as the median concentration causing 50% embryo lethality; (b 96-h EC50, defined as the median concentration causing 50% malformations of the surviving embryos; and (c teratogenic malformation index (TI, equal to 96-h LC50/96-h EC50. The quantitative results and the photographs of embryos before and after exposure suggest that allyl isothiocyanate seems to exhibit moderate teratogenic properties. The results also indicate differences in the toxicity of allyl isothiocyanate toward exposed embryos observed in the present study compared to reported adverse effects of allyl isothiocyanate in fish, rodents, and humans. The significance of the results for food safety and possible approaches to protect against adverse effects of allyl isothiocyanate are discussed.

Polymerizations of beta-substituted allylic arsonium ylides with catalytic amounts of organoboron compounds

International Nuclear Information System (INIS)

Mondiere, R.

2004-01-01

My Ph.D. work consisted in the generalization and optimization of a new polymerization reaction involving allylic arsonium ylides and catalytic amounts of various boron compounds. Thus, various β-substituted allylic arsonium salts were produced according to synthetic strategies that depended on the nature of the functional group born by the salt. These salts were converted in situ to the corresponding arsonium ylides which were then treated with boron compounds to yield polymers. Our new method of polymerization afforded either non conjugated polyenes that are functionalized every three atoms of carbon, or statistic copolymers, depending on the nature of the group R born on the β position of the ylide. These new polymers cannot be synthesized by usual methods of polymerization. Initial molar ratios of reactants were found to give molar mass control of the synthesized polymers. This controlled polymerization allowed us to produce several bloc copolymers. All the polymers were characterized by NMR techniques, by size exclusion chromatography and, for some of them, by mass spectrometry. Investigation of their physicochemical properties will need additional experiments. (author)

Theoretical and vibrational spectroscopic approach to keto-enol tautomerism in methyl-2-(4-methoxybenzoyl)-3-(4-methoxyphenyl)-3-oxopropanoylcarbamate

Science.gov (United States)

Arı, Hatice; Özpozan, Talat; Büyükmumcu, Zeki; Kabacalı, Yiğit; Saçmaci, Mustafa

2016-10-01

A carbamate compound having tricarbonyl groups, methyl-2-(4-methoxybenzoyl)-3-(4-methoxyphenyl)-3-oxopropanoylcarbamate (BPOC) was investigated from theoretical and vibrational spectroscopic point of view employing quantum chemical methods. Hybrid Density Functionals (B3LYP, X3LYP and B3PW91) with 6-311 G(d,p) basis set were used for the calculations. Rotational barrier and conformational analyses were performed to find the most stable conformers of keto and enol forms of the molecule. Three transition states for keto-enol tautomerism in gas phase were determined. The results of the calculations show that enol-1 form of BPOC is more stable than keto and enol-2 forms. Hydrogen bonding investigation including Natural bond orbital analysis (NBO) for all the tautomeric structures was employed to compare intra-molecular interactions. The energies of HOMO and LUMO molecular orbitals for all tautomeric forms of BPOC were predicted. Normal Coordinate Analysis (NCA) was carried out for the enol-1 to assign vibrational bands of IR and Raman spectra. The scaling factors were calculated as 0.9721, 0.9697 and 0.9685 for B3LYP, X3LYP and B3PW91 methods, respectively. The correlation graphs of experimental versus calculated vibrational wavenumbers were plotted and X3LYP method gave better frequency agreement than the others.

Enol tautomers of Watson-Crick base pair models are metastable because of nuclear quantum effects.

Science.gov (United States)

Pérez, Alejandro; Tuckerman, Mark E; Hjalmarson, Harold P; von Lilienfeld, O Anatole

2010-08-25

Intermolecular enol tautomers of Watson-Crick base pairs could emerge spontaneously via interbase double proton transfer. It has been hypothesized that their formation could be facilitated by thermal fluctuations and proton tunneling, and possibly be relevant to DNA damage. Theoretical and computational studies, assuming classical nuclei, have confirmed the dynamic stability of these rare tautomers. However, by accounting for nuclear quantum effects explicitly through Car-Parrinello path integral molecular dynamics calculations, we find the tautomeric enol form to be dynamically metastable, with lifetimes too insignificant to be implicated in DNA damage.

Aggregation and Cooperative Effects in the Aldol Reactions of Lithium Enolates

NARCIS (Netherlands)

Larrañaga, O.; de Cózar, A.; Bickelhaupt, F.M.; Zangi, R.; Cossío, F.P.

2013-01-01

Density functional theory and Car-Parrinello molecular dynamics simulations have been carried out for model aldol reactions involving aggregates of lithium enolates derived from acetaldehyde and acetone. Formaldehyde and acetone have been used as electrophiles. It is found that the geometries of the

Zinc Mediated Tandem Fragmentation-Allylation of Methyl 5-Iodopentofuranosides

DEFF Research Database (Denmark)

Hyldtoft, Lene; Madsen, Robert

1999-01-01

In the presence of zinc and allyl bromide methyl 5-iodopentofuranosides undergo a tandem fragmentation alkylation to give functionalized dienes. These can undergo ring-closing olefin metathesis to produce cyclohexenes which on dihydroxylation give quercitols.......In the presence of zinc and allyl bromide methyl 5-iodopentofuranosides undergo a tandem fragmentation alkylation to give functionalized dienes. These can undergo ring-closing olefin metathesis to produce cyclohexenes which on dihydroxylation give quercitols....

SYNTHESIS OF 4-ALLYL-2-METHOXY-6-AMINOPHENOL FROM NATURAL EUGENOL

Directory of Open Access Journals (Sweden)

I Made Sudarma

2010-06-01

Full Text Available The aim of this preliminary research was to synthesize derivatives of eugenol such as 4-allyl-2-methoxy-6-nitrophenol (2 and 4-allyl-2-methoxy-6-aminophenol (3. The result could be used as a reference on the transformation of eugenol to its derivatives. Theoriticaly nitration of eugenol (1 by nitric acid could produced 4-allyl-2-methoxy-6-nitrophenol (2 and followed by reduction could achieved 4-allyl-2-mehtoxy-6-aminophenol (3. The formation of this product was analyzed by analytical thin layer chromatography (TLC and GC-MS. These analysis showed the formation of product (2 and (3 were visible. TLC showed product (1 less polar than eugenol and gave orange colour, and supported by GC-MS which showed molecular ion at m/z 209 due to the presence of -NO2 by replacing one H at 6 position of eugenol. Product (3 was afforded by reduction of (2 with Sn/HCl and tlc analysis showed compound (3 more polar than eugenol (1 and (2 and supported by GC-MS which showed molecular ion at m/z 179 due to the presence of -NH2.   Keywords: Synthesis, 4-allyl-2-methoxy-6-aminophenol, Eugenol

Palladium-Catalyzed Asymmetric Allylic Alkylation of 4-Substituted Isoxazolidin-5-ones: Straightforward Access to β2,2 -Amino Acids.

Science.gov (United States)

Nascimento de Oliveira, Marllon; Arseniyadis, Stellios; Cossy, Janine

2018-04-03

We report here an unprecedented and highly enantioselective palladium-catalyzed allylic alkylation applied to 4-substituted isoxazolidin-5-ones. Ultimately, the process provides a straightforward access to β 2,2 -amino acids bearing an all-carbon quaternary stereogenic center in great yields and a high degree of enantioselectivity. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Conversion of alkyl radicals to allyl radicals in irradiated single crystal mats of polyethylene

International Nuclear Information System (INIS)

Fujimura, T.; Hayakawa, N.; Kuriyama, I.

1978-01-01

The decay of alkyl radicals, the conversion of alkyl radicals to allyl radicals and the trapping of allyl radicals in irradiated single crystal mats of polyethylene have been studied by electron spin resonance (e.s.r.). It has been suggested that in the crystal core alkyl radicals react with trans-vinylene double bonds and are converted into trans-vinylene allyl radicals; at the crystal surface, alkyl radicals react with vinyl end groups and are converted into allyl radicals with vinyl end groups. The decay of radical pairs and the formation of trans-vinylene double bonds are discussed. (author)

Highly Stereoselective Intermolecular Haloetherification and Haloesterification of Allyl Amides

Science.gov (United States)

Soltanzadeh, Bardia; Jaganathan, Arvind; Staples, Richard J.

2016-01-01

An organocatalytic and highly regio-, diastereo-, and enantioselective intermolecular haloetherification and haloesterification reaction of allyl amides is reported. A variety of alkene substituents and substitution patterns are compatible with this chemistry. Notably, electronically unbiased alkene substrates exhibit exquisite regio- and diastereoselectivity for the title transformation. We also demonstrate that the same catalytic system can be used in both chlorination and bromination reactions of allyl amides with a variety of nucleophiles with little or no modification. PMID:26110812

Urinary excretion of N-acetyl-S-allyl-L-cystein upon garlic consumption by human volunteers.

NARCIS (Netherlands)

de Rooij, B.M.; Boogaard, P.J.; Rijksen, D.A.; Commandeur, J.N.M.; Vermeulen, N.P.E.

1996-01-01

N-Acetyl-S-allyl-L-cysteine (allylmercapturic acid, ALMA) was previously detected in urine from humans consuming garlic. Exposure of rats to allyl halides is also known to lead to excretion of ALMA in urine. ALMA is a potential biomarker for exposure assessment of workers exposed to allyl halides.

Synthesis of some fenchyl-substituted alkenes and enol-ethers containing 3-oxyphenyl substituents by the Barton-Kellogg reaction

International Nuclear Information System (INIS)

Ciscato, Luiz Francisco M.L.; Bartoloni, Fernando H.; Baader, Wilhelm Josef; Bastos, Erick L.; Guenther, Wolfgang; Weiss, Dieter; Beckert, Rainer

2010-01-01

The synthesis of one fenchyl-substituted alkene and two enol-ethers, containing 3-oxyphenyl substituents by the Barton-Kellogg reaction is described. The tri-substituted aromatic fenchylalkene 1a was prepared in 53% yield from thiofenchone and a diazoanisole; whereas enol-ethers 1b and 1c were obtained (95 and 75% yield, respectively) using an inverse approach based on diazofenchone and aromatic thionoesters. A mixture of Z and E isomers was obtained in all cases; isomer attribution and quantification has been carried out by analysis of NMR spectroscopic data assisted by theoretical calculations (E/Z ratio: 1a = 0.72, 1b = 2.2, 1c = 1.8). Reaction proceeds with low stereoselectivity leading to the preferential formation of diastereoisomeric olefins and enol-ethers where the aromatic substituent resides at the side of the two fenchyl methyl groups. (author)

Synthesis of some fenchyl-substituted alkenes and enol-ethers containing 3-oxyphenyl substituents by the Barton-Kellogg reaction

Energy Technology Data Exchange (ETDEWEB)

Ciscato, Luiz Francisco M.L.; Bartoloni, Fernando H.; Baader, Wilhelm Josef, E-mail: wjbaader@iq.usp.b [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Quimica. Dept. de Quimica Fundamental; Bastos, Erick L. [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil). Centro de Ciencias Naturais e Humanas; Guenther, Wolfgang; Weiss, Dieter; Beckert, Rainer [Friedrich-Schiller Universitaet Jena (Germany). Institut fuer Organische Chemie und Makromolekulare Chemie

2010-07-01

The synthesis of one fenchyl-substituted alkene and two enol-ethers, containing 3-oxyphenyl substituents by the Barton-Kellogg reaction is described. The tri-substituted aromatic fenchylalkene 1a was prepared in 53% yield from thiofenchone and a diazoanisole; whereas enol-ethers 1b and 1c were obtained (95 and 75% yield, respectively) using an inverse approach based on diazofenchone and aromatic thionoesters. A mixture of Z and E isomers was obtained in all cases; isomer attribution and quantification has been carried out by analysis of NMR spectroscopic data assisted by theoretical calculations (E/Z ratio: 1a = 0.72, 1b = 2.2, 1c = 1.8). Reaction proceeds with low stereoselectivity leading to the preferential formation of diastereoisomeric olefins and enol-ethers where the aromatic substituent resides at the side of the two fenchyl methyl groups. (author)

Derivatization of enolic OH of piroxicam: a comparative study on esters and sulfonates

Energy Technology Data Exchange (ETDEWEB)

Jayaselli, J.; Cheemala, J. Manila Sagar; Geetha Rani, D.P.; Pal, Sarbani [MNR Post Graduate College, Kukatpally, Hyderabad (India). Dept. of Chemistry]. E-mail: sarbani277@yahoo.com

2008-07-01

A number of ester and sulfonate derivatives of piroxicam were prepared via acylation/sulfonation of the enolic OH of piroxicam. All the compounds were evaluated for their chemical stability and cyclooxygenase inhibiting properties. Data suggested that esters could be useful for the development of potential prodrugs. The sulfonate derivatives prepared for the first time were found to be stable. One of them showed a moderately selective COX-2 inhibition over COX-1 and would have lower gastrointestinal side effects than piroxicam due to the masked enolic OH group. A plausible mechanism for the acylation/sulfonation process has been proposed that involves participation of the pyridine moiety of piroxicam. Molecular structure of one of the ester was established for the first time by the crystal structure analysis from X-ray powder data. (author)

Derivatization of enolic OH of piroxicam: a comparative study on esters and sulfonates

International Nuclear Information System (INIS)

Jayaselli, J.; Cheemala, J. Manila Sagar; Geetha Rani, D.P.; Pal, Sarbani

2008-01-01

A number of ester and sulfonate derivatives of piroxicam were prepared via acylation/sulfonation of the enolic OH of piroxicam. All the compounds were evaluated for their chemical stability and cyclooxygenase inhibiting properties. Data suggested that esters could be useful for the development of potential prodrugs. The sulfonate derivatives prepared for the first time were found to be stable. One of them showed a moderately selective COX-2 inhibition over COX-1 and would have lower gastrointestinal side effects than piroxicam due to the masked enolic OH group. A plausible mechanism for the acylation/sulfonation process has been proposed that involves participation of the pyridine moiety of piroxicam. Molecular structure of one of the ester was established for the first time by the crystal structure analysis from X-ray powder data. (author)

Vapor-liquid equilibria of the binary system 1,5-hexadiene + allyl chloride

NARCIS (Netherlands)

Raeissi, S.; Florusse, L.J.; Peters, C.J.

2014-01-01

Knowledge of accurate vapor–liquid equilibrium data for mixtures of allyl chloride and 1,5-hexadiene is important for several industrial purposes. The bubble points of binary mixtures of allyl chloride and 1,5-hexadiene have been measured experimentally using a synthetic method. Measurements were

Enantioconvergent synthesis by sequential asymmetric Horner-Wadsworth-Emmons and palladium-catalyzed allylic substitution reactions

DEFF Research Database (Denmark)

Pedersen, Torben Møller; Hansen, E. Louise; Kane, John

2001-01-01

A new method for enantioconvergent synthesis has been developed. The strategy relies on the combination of an asymmetric Horner-Wadsworth-Emmons (HWE) reaction and a palladium-catalyzed allylic substitution. Different $alpha@-oxygen-substituted, racemic aldehydes were initially transformed by asy...... the allylic stereocenter and the alkene geometry. Thus, a single $gamma@-substituted ester was obtained as the overall product, in high isomeric purity. The method was applied to a synthesis of a subunit of the iejimalides, a group of cytotoxic macrolides.......A new method for enantioconvergent synthesis has been developed. The strategy relies on the combination of an asymmetric Horner-Wadsworth-Emmons (HWE) reaction and a palladium-catalyzed allylic substitution. Different $alpha@-oxygen-substituted, racemic aldehydes were initially transformed...... by asymmetric HWE reactions into mixtures of two major $alpha@,$beta@-unsaturated esters, possessing opposite configurations at their allylic stereocenters as well as opposite alkene geometry. Subsequently, these isomeric mixtures of alkenes could be subjected to palladium-catalyzed allylic substitution...

Predicting Keto-Enol Equilibrium from Combining UV/Visible Absorption Spectroscopy with Quantum Chemical Calculations of Vibronic Structures for Many Excited States. A Case Study on Salicylideneanilines.

Science.gov (United States)

Zutterman, Freddy; Louant, Orian; Mercier, Gabriel; Leyssens, Tom; Champagne, Benoît

2018-06-21

Salicylideneanilines are characterized by a tautomer equilibrium, between an enol and a keto form of different colors, at the origin of their remarkable thermochromic, solvatochromic, and photochromic properties. The enol form is usually the most stable but appropriate choice of substituents and conditions (solvent, crystal, host compound) can displace the equilibrium toward the keto form so that there is a need for fast prediction of the keto:enol abundance ratio. Here we demonstrate the reliability of a combined theoretical-experimental method, based on comparing simulated and measured UV/visible absorption spectra, to determine this keto/enol ratio. The calculations of the excitation energies, oscillator strengths, and vibronic structures of both enol and keto forms are performed for all excited states absorbing in the relevant (visible and near-UV) wavelength range at the time-dependent density functional theory level by accounting for solvent effects using the polarizable continuum model. This approach is illustrated for two salicylideneaniline derivatives, which are present, in solution, under the form of keto-enol mixtures. The results are compared to those of chemometric analysis as well as ab initio predictions of the reaction free enthalpies.

Selective epoxidation of allylic alcohols with a titania-silica aerogel

Energy Technology Data Exchange (ETDEWEB)

Dusi, M.; Mallat, T.; Baiker, A. [Lab. of Technical Chemistry, Swiss Federal Inst. of Technology, ETH-Zentrum, Zuerich (Switzerland)

1998-12-31

An amorphous mesoporous titania-silica aerogel (20 wt%TiO{sub 2} - 80 wt% SiO{sub 2}) and tert.-butylhydroperoxide (TBHP) have been used for the epoxidation of various allylic alcohols. Allylic alcohols possessing an internal double bond were more reactive than those with a terminal C=C bond. Epoxide selectivities could be improved by addition of (basic) zeolite 4 A and NaHCO{sub 3} to the reaction mixture. (orig.)

Ketone deprotonation mediated by mono- and heterobimetallic alkali and alkaline earth metal amide bases: structural characterization of potassium, calcium, and mixed potassium-calcium enolates.

Science.gov (United States)

He, Xuyang; Noll, Bruce C; Beatty, Alicia; Mulvey, Robert E; Henderson, Kenneth W

2004-06-23

Potassium, calcium, and mixed potassium-calcium amide combinations have been shown to be efficient reagents in enolization reactions, and a set of representative intermediate mono- and heterobimetallic enolates have been successfully isolated and crystallographically characterized.

Formation of gas-phase π-allyl radicals from propylene over bismuth oxide and γ-bismuth molybdate catalysts

International Nuclear Information System (INIS)

Martir, W.; Lunsford, J.H.

1981-01-01

Gas-phase π-allyl radicals were produced when propylene reacted over Bi 2 O 3 and γ-bismuth molybdate catalysts at 723 K. The pressure in the catalyst zone was varied between 5 x 10 -3 and 1 torr. The radicals were detected by EPR spectroscopy together with a matrix isolation technique in which argon was used as the diluent. The matrix was formed on a sapphire rod at 12 K which was located 33-cm downstream from the catalyst. Bismuth oxide was more effective in the production of gas-phase allyl radicals than γ-bismuth molybdate. By contrast α-bismuth molybdate was ineffective in forming allyl radicals and MoO 3 acted as a sink for radicals which were produced elsewhere in the system. Comparison of the π-allyl radical and the stable product concentrations over Bi 2 O 3 revealed that gas-phase radical recombination reactions served as a major pathway for the formation of 1,5-hexadiene. Addition of small amounts of gas-phase oxygen increased the concentration of allyl radicals, and at greater oxygen levels allyl peroxy radicals were detected. Because of the effect of temperature on the equilibrium between allyl and allyl peroxy radicals, the latter product must be formed in the cooler part of the system

Radiation initiated copolymerization of allyl alcohol with acrylonitrile

International Nuclear Information System (INIS)

Solpan, Dilek; Guven, Olgun

1996-01-01

Copolymerization of allyl alcohol (AA) with acrylonitrile (AN) initiated by γ-rays has been investigated to determine the respective reactivity ratios. Three different experimental techniques, namely Fourier Transform Infrared (FTIR), Ultraviolet (UV/vis) and elemental analysis (EA) have been used for the determination of copolymer compositions. Fineman-Ross (FR), Kelen-Tudos (KT), Non-Linear Least Square (NLLS) Analysis and Q-e methods have been applied to the three sets of experimental data. It has been concluded that data obtained from elemental analysis as applied to the Non-Linear Least Square approach gave the most reliable reactivity ratios as 2.09 and 0.40 for acrylonitrile and allyl alcohol, respectively. (Author)

Total syntheses of naturally occurring diacetylenic spiroacetal enol ethers.

Science.gov (United States)

Miyakoshi, Naoki; Aburano, Daisuke; Mukai, Chisato

2005-07-22

A highly stereoselective method for constructing a (2E)-methoxymethylidene-1,6-dioxaspiro[4.5]decane skeleton has been developed on the basis of the palladium(II)-catalyzed ring-closing reaction of the 3,4-dioxygenated-9-hydroxy-1-nonyn-5-one derivatives as a crucial step. The newly developed procedures could be successfully applied to the first total synthesis of five diacetylenic spiroacetal enol ether natural products starting from commercially available (R,R)- or (S,S)-diethyl tartrate.

Transient overexpression of adh8a increases allyl alcohol toxicity in zebrafish embryos.

Directory of Open Access Journals (Sweden)

Nils Klüver

Full Text Available Fish embryos are widely used as an alternative model to study toxicity in vertebrates. Due to their complexity, embryos are believed to more resemble an adult organism than in vitro cellular models. However, concerns have been raised with respect to the embryo's metabolic capacity. We recently identified allyl alcohol, an industrial chemical, to be several orders of magnitude less toxic to zebrafish embryo than to adult zebrafish (embryo LC50 = 478 mg/L vs. fish LC50 = 0.28 mg/L. Reports on mammals have indicated that allyl alcohol requires activation by alcohol dehydrogenases (Adh to form the highly reactive and toxic metabolite acrolein, which shows similar toxicity in zebrafish embryos and adults. To identify if a limited metabolic capacity of embryos indeed can explain the low allyl alcohol sensitivity of zebrafish embryos, we compared the mRNA expression levels of Adh isoenzymes (adh5, adh8a, adh8b and adhfe1 during embryo development to that in adult fish. The greatest difference between embryo and adult fish was found for adh8a and adh8b expression. Therefore, we hypothesized that these genes might be required for allyl alcohol activation. Microinjection of adh8a, but not adh8b mRNA led to a significant increase of allyl alcohol toxicity in embryos similar to levels reported for adults (LC50 = 0.42 mg/L in adh8a mRNA-injected embryos. Furthermore, GC/MS analysis of adh8a-injected embryos indicated a significant decline of internal allyl alcohol concentrations from 0.23-58 ng/embryo to levels below the limit of detection (< 4.6 µg/L. Injection of neither adh8b nor gfp mRNA had an impact on internal allyl alcohol levels supporting that the increased allyl alcohol toxicity was mediated by an increase in its metabolization. These results underline the necessity to critically consider metabolic activation in the zebrafish embryo. As demonstrated here, mRNA injection is one useful approach to study the role of candidate enzymes

Computer-Assisted Design and Synthetic Applications of Chiral Enol Borinates: Novel, Highly Enantioselective Aldol Reagents

Directory of Open Access Journals (Sweden)

Gennari Cesare

1998-01-01

Full Text Available We have recently described the development of a quantitative transition state model for the prediction of stereoselectivity in the boron-mediated aldol reaction. This model provides qualitative insights into the factors contributing to the stereochemical outcome of a variety of reactions of synthetic importance. The force field model was used to assist the design and preparation of new chiral boron ligands derived from menthone. The chiral boron enolates were employed in various stereoselective processes, including the addition to chiral aldehydes and the reagent-controlled total synthesis of (3S,4S-statine. The chiral enolates derived from alpha-halo and alpha-oxysubstituted thioacetates were added to aldehydes and imines. Addition to imines leads to the enantioselective synthesis of chiral aziridines, a formal total synthesis of (+-thiamphenicol, and a new highly efficient synthesis of the paclitaxel (taxol® C-13 side-chain and taxol semisynthesis from baccatin III. The stereochemical outcome of the addition to imines was rationalised with the aid of computational studies. Enantioselective addition reactions of the chiral boron enolate derived from thioacetate have successfully been applied to solid phase bound aldehydes to give aldol products in comparable yields and enantioselectivities to the usual solution conditions.

Theoretical Studies of [2,3]-Sigmatropic Rearrangements of Allylic Selenoxides and Selenimides

Directory of Open Access Journals (Sweden)

Sonia Antony

2009-08-01

Full Text Available Density-functional theory is used to model the endo and exo transition states for [2,3]-sigmatropic rearrangement of allylic aryl-selenoxides and -selenimides. The endo transition state is generally preferred for selenoxides if there is no substitution at the 2 position of the allyl group. Based upon the relative energies of the endo and exo transition states, enantioselectivity of rearrangements is expected to be greatest for molecules with substitutions at the 1- or (E-3- position of the allyl group. Ortho substitution of a nitro group on the ancillary selenoxide phenyl ring reduces the activation barriers, increases the difference between the endo and exo activation barriers and shifts the equilibrium toward products.

Gold-catalyzed intermolecular coupling of sulfonylacetylene with allyl ethers: [3,3]- and [1,3]-rearrangements

Directory of Open Access Journals (Sweden)

Jungho Jun

2013-08-01

Full Text Available Gold-catalyzed intermolecular couplings of sulfonylacetylenes with allyl ethers are reported. A cooperative polarization of alkynes both by a gold catalyst and a sulfonyl substituent resulted in an efficient intermolecular tandem carboalkoxylation. Reactions of linear allyl ethers are consistent with the [3,3]-sigmatropic rearrangement mechanism, while those of branched allyl ethers provided [3,3]- and [1,3]-rearrangement products through the formation of a tight ion–dipole pair.

Crystal structure of 4′-allyl-4,5,6,7,2′,7′-hexachlorofluorescein allyl ester unknown solvate

Directory of Open Access Journals (Sweden)

Lili Wang

2018-01-01

Full Text Available In the title compound, 4′-allyl-4,5,6,7,2′,7′-hexachlorofluorescein allyl ester {systematic name: prop-2-en-1-yl 2,3,4,5-tetrachloro-6-[2,7-dichloro-6-hydroxy-3-oxo-4-(prop-2-en-1-yl-3H-xanthen-9-yl]benzoate}, C26H14Cl6O5, accompanied by unknown solvate molecules, the dihedral angle between the xanthene ring system (r.m.s. deviation = 0.046 Å and the pentasubstituted benzene ring is 71.67 (9°. Both allyl groups are disordered over two sets of sites in statistical ratios. The scattering contributions of the disordered solvent molecules (both Ph2O and CHCl3, as identified by NMR were removed with the PLATON SQUEEZE algorithm [Spek (2015. Acta Cryst. C71, 9–18]. In the crystal, tetrameric supramolecular aggregates linked by O—H...O hydrogen bonds occur; these further interact with neighboring aggregates through C—Cl...π interactions arising from the benzene rings, forming infinite two-dimensional sheets. Each C6Cl4 ring shifts in the direction perpendicular to the two-dimensional sheet, exhibiting a helical chain in which every C6Cl4 ring is utilized as both a donor and an acceptor of Cl...π contacts. Thus, these two-dimensional sheets pack in a helical fashion, constructing a three-dimensional network.

Allyl borates: a novel class of polyhomologation initiators

KAUST Repository

Wang, De; Hadjichristidis, Nikolaos

2016-01-01

Allyl borates, a new class of monofunctional polyhomologation initiators, are reported. These monofunctional initiators are less sensitive and more effective towards polymethylene-based architectures. As an example, the synthesis of α

Biosynthetic conversion of thebaine to codeinone. Mechanism of ketone formation from enol ether in vivo

International Nuclear Information System (INIS)

Horn, J.S.; Paul, A.G.; Rapoport, H.

1978-01-01

Biosynthesis of the morphinan alkaloids proceeds by conversion of the enol ether or thebaine to the keto group of neopinone and thence to codeinone. To determine the mechanism of this transformation, [G- 14 C,6- 18 O]thebaine was fed to Papaver somniferum and the codeine and morphine were isolated. Comparison of the 18 O/ 14 C ratios in the codeine and morphine isolated with that of the thebaine fed showed that approximately 34% of the 18 O had been retained. Parallel feedings with [G- 14 C,6- 18 O]-codeinone demonstrated that the loss was due to nonenzymic exchange. Thus, the mechanism of enol ether cleavage in thebaine is established as cleavage of the 6-O-methyl group with retention of the 6-oxygen in the codeinone

Reaction of aryl diazonium tetrafluoro borates with allyl methacrylate in the presence of rhodanide-anion

International Nuclear Information System (INIS)

Grishchuk, B.D.; Baranovskij, V.S.; Simchak, R.V.; Tulajdan, G.N.; Gorbovoj, P.M.

2006-01-01

Reaction of aryl diazonium tetrafluoro borates (I) with allyl ester of methacrylic acid in the water-acetone (1:5) medium is studied by means of IR spectroscopy and 1 H NMR. It is established that (I) reacts with aryl methacrylate in the presence of rhodanide-anion and catalytic quantities of copper salts with the formation of allyl esters of 2-thiocyanato-2-methyl-3-aryl propionic acids with the yield of 32-56%. Allyl fragment of biunsaturated compound shows no reaction under the tested conditions [ru

The stereochemistry of the addition of chlorotitanium enolates of N-acyl oxazolidin-2-ones to 5- and 6- membered N-acyliminium ions

Directory of Open Access Journals (Sweden)

Pilli Ronaldo A.

2001-01-01

Full Text Available The stereoselective addition of chiral and achiral titanium enolates derived from the corresponding N-acyl oxazolidin-2-ones to 5- and 6- membered N-acyliminium ions afforded 2-substituted pyrrolidines in moderate to good diastereoisomeric ratio (5:1 to 14:1 while lower diastereoselection was generally observed in the formation of the corresponding 2-substituted piperidines. The stereochemical outcome was found to be modulated by the nature of the cyclic N-acyliminium ion (5- or 6-membered and of its carbamate and by the N-acyl group in the enolate precursor. The preferential lk approach seems to be dictated mainly by the minimization of non-bonding interactions between the N-acyl group in the chlorotitanium (IV enolate and the carbamate and methylene groups in the cyclic N-acyliminium ion.

The effects of γ-irradiation on the garlic oil contents in garlic bulbs and the radiolysis of allyl trisulfide

International Nuclear Information System (INIS)

Wei Genshuan, Wang Guanghui; Yang Ruipu; Wu Jilan

1995-01-01

The study of the effects of γ-irradiation on the garlic oil contents in the garlic bulbs and the radiolysis of allyl trisulfide and disulfide were carried out. The content of garlic oil in fresh garlic bulbs treated by gamma ray keeps nearly constant as stored for 10 months long. The main components of the garlic oil are allyl trisulfide (about 60%) and allyl disulfide (about 30%). The G values of radiolysis products of allyl disulfide and trisulfide in ethanol system were determined. The results show that allyl trisulfide is a very effective solvated electron scavenger and can oxidize CH 3 C HOH radical into acetaldehyde, which causes that the formation of 2,3-butanediol is extensively inhibited. (author)

The effects of γ-irradiation on garlic oil content in garlic bulbs and on the radiolysis of allyl trisulfide

International Nuclear Information System (INIS)

Wei Genshuan; Wang Guanghui; Yang Ruipu; Wu Jilan

1996-01-01

A study of the effects of γ-irradiation on garlic oil content in garlic bulbs and on the radiolysis of allyl trisufide and disulfide was carried out. The content of garlic oil in fresh garlic bulbs treated by gamma ray keeps nearly constant when stored for 10 months. The main components of garlic oil are allyl trisulfide (about 60%) and allyl disulfide (about 30%). The G values of radiolysis products of allyl disulfide and trisulfide in ethanol system were determined. The results show that allyl trisulfide is a very effective solvated electron scavenger and can oxidize CH 3 C . HOH radical into acetaldehyde, which means that the formation of 2,3-butanediol is extensively inhibited. (author)

An Efficient Synthesis of de novo Imidates via Aza-Claisen Rearrangements of N-Allyl Ynamides

Science.gov (United States)

DeKorver, Kyle A.; North, Troy D.; Hsung, Richard P.

2010-01-01

A novel thermal 3-aza-Claisen rearrangement of N-allyl ynamides for the synthesis of α-allyl imidates is described. Also, a sequential aza-Claisen, Pd-catalyzed Overman rearrangement is described for the synthesis of azapine-2-ones. PMID:21278848

Radiation synthesis and characterization of new hydrogels based on acrylamide copolymers cross-linked with 1-allyl-2-thiourea

Energy Technology Data Exchange (ETDEWEB)

Sahiner, Nurettin [Department of Chemistry, Faculty of Science, Hacettepe University, Beytepe Campus, 0653 Ankara (Turkey); Malci, Savas [Department of Chemistry, Faculty of Science, Hacettepe University, Beytepe Campus, 0653 Ankara (Turkey); Celikbicak, Oemuer [Department of Chemistry, Faculty of Science, Hacettepe University, Beytepe Campus, 0653 Ankara (Turkey); Kantoglu, Oemer [Ankara Nuclear Research Center, Turkish Atomic Energy Authority, 06983 Ankara (Turkey); Salih, Bekir [Department of Chemistry, Faculty of Science, Hacettepe University, Beytepe Campus, 0653 Ankara (Turkey)]. E-mail: bekir@hacettepe.edu.tr

2005-10-01

Poly(acrylamide-1-allyl-2-thiourea) hydrogels, Poly(AA-AT), were synthesized by gamma irradiation using {sup 60}Co {gamma} source in different irradiation dose and at different 1-allyl-2-thiourea content in the monomer mixture. For the characterization of the hydrogels, Fourier transform infrared spectrometer (FT-IR), thermogravimetric analyzer (TGA), elemental analyzer and the swellability of the hydrogels were used. It was noted that 1-allyl-2-thiourea in the synthesized hydrogels was increased by the increasing the content of the 1-allyl-2-thiourea in the irradiation monomer mixture and increasing the radiation dose for the hydrogel synthesis. sis.

La creación de productos turísticos utilizando rutas enológicas

Directory of Open Access Journals (Sweden)

Tomás J. López Guzmán

2008-01-01

Full Text Available Los cambios que se están produciendo en la actividad turística en los últimos años están llevando a la creación de nuevos productos turísticos, destacando los relacionados con las raíces locales y regionales. En este trabajo presentamos un análisis sobre la creación y desarrollo de rutas enológicas como producto turístico en determinadas áreas rurales. Y este análisis lo planteamos desde una triple perspectiva: primera, un estudio en profundidad acerca de qué son las rutas turísticas enológicas y su creación y desarrollo en otros países; segundo, un análisis de cómo se certifican en España las rutas del vino; y tercera, una referencia a una ruta del vino certificada en España, la de Montilla-Moriles en la provincia de Córdoba.

Allylic azides as potential building blocks for the synthesis of nitrogenated compounds

Directory of Open Access Journals (Sweden)

Sá Marcus M.

2003-01-01

Full Text Available The synthetic potential of multifunctional allylic azides and imines in attempted intramolecular cyclizations to nitrogen-containing heterocycles was investigated. Tandem Staudinger/aza-Wittig reaction of (E-3-aryl-2-(azidomethylpropenoates with triphenylphosphine and aldehydes yielded N-allylic imines in good yield. The (E-stereochemistry of C=C and C=N bonds was assigned based on NOESY experiments. AlCl3 mediated formation of 3-carbomethoxyquinoline from methyl (E-2-(azidomethyl-3-phenylpropenoate is also described.

Deconvoluting the memory effect in Pd-catalyzed allylic alkylation; effect of leaving group and added chloride

DEFF Research Database (Denmark)

Fristrup, Peter; Jensen, Thomas; Hoppe, Jakob

2006-01-01

An analysis of product distributions in the Tsuji-Trost reaction indicates that several instances of reported memory effects can be attributed to slow interconversion of the initially formed syn- and anti-[Pd(eta3-allyl)] complexes. Addition of chloride triggers a true memory effect, in which...... the allylic terminus originally bearing the leaving group has a higher reactivity. The latter effect, termed regioretention, can be rationalized by ionization from a palladium complex bearing a chloride ion, forming an unsymmetrically substituted [Pd(eta3-allyl)] complex. DFT calculations verify...

An intramolecular [2 + 2] cycloaddition of ketenimines via palladium-catalyzed rearrangements of N-allyl-ynamides.

Science.gov (United States)

DeKorver, Kyle A; Hsung, Richard P; Song, Wang-Ze; Wang, Xiao-Na; Walton, Mary C

2012-06-15

A cascade of Pd-catalyzed N-to-C allyl transfer-intramolecular ketenimine-[2 + 2] cycloadditions of N-allyl ynamides is described. This tandem sequence is highly stereoselective and the [2 + 2] cycloaddition could be rendered in a crossed or fused manner depending on alkene substitutions, leading to bridged and fused bicycloimines.

The Defense Metabolite, Allyl Glucosinolate, Modulates Arabidopsis thaliana Biomass Dependent upon the Endogenous Glucosinolate Pathway.

Science.gov (United States)

Francisco, Marta; Joseph, Bindu; Caligagan, Hart; Li, Baohua; Corwin, Jason A; Lin, Catherine; Kerwin, Rachel; Burow, Meike; Kliebenstein, Daniel J

2016-01-01

Glucosinolates (GSLs) play an important role in plants as direct mediators of biotic and abiotic stress responses. Recent work is beginning to show that the GSLs can also inducing complex defense and growth networks. However, the physiological significance of these GSL-induced responses and the molecular mechanisms by which GSLs are sensed and/or modulate these responses are not understood. To identify these potential mechanisms within the plant and how they may relate to the endogenous GSLs, we tested the regulatory effect of exogenous allyl GSL application on growth and defense metabolism across sample of Arabidopsis thaliana accessions. We found that application of exogenous allyl GSL had the ability to initiate changes in plant biomass and accumulation of defense metabolites that genetically varied across accessions. This growth effect was related to the allyl GSL side-chain structure. Utilizing this natural variation and mutants in genes within the GSL pathway we could show that the link between allyl GSL and altered growth responses are dependent upon the function of known genes controlling the aliphatic GSL pathway.

Tandem catalytic allylic amination and [2,3]-Stevens rearrangement of tertiary amines.

Science.gov (United States)

Soheili, Arash; Tambar, Uttam K

2011-08-24

We have developed a catalytic allylic amination involving tertiary aminoesters and allylcarbonates, which is the first example of the use of tertiary amines as intermolecular nucleophiles in metal-catalyzed allylic substitution chemistry. This process is employed in a tandem ammonium ylide generation/[2,3]-rearrangement reaction, which formally represents a palladium-catalyzed Stevens rearrangement. Low catalyst loadings and mild reaction conditions are compatible with an unprecedented substrate scope for the ammonium ylide functionality, and products are generated in high yields and diastereoselectivities. Mechanistic studies suggested the reversible formation of an ammonium intermediate.

Anti-Inflammatory and Antioxidant Effects of Repeated Exposure to Cruciferous Allyl Nitrile in Sensitizer-Induced Ear Edema in Mice.

Science.gov (United States)

Tanii, Hideji; Sugitani, Kayo; Saijoh, Kiyofumi

2016-02-29

Skin sensitizers induce allergic reactions through the induction of reactive oxygen species. Allyl nitrile from cruciferous vegetables has been reported to induce antioxidants and phase II detoxification enzymes in various tissues. We assessed the effects of repeated exposure to allyl nitrile on sensitizer-induced allergic reactions. Mice were dosed with allyl nitrile (0-200 µmol/kg), and then received a dermal application of 1 of 3 sensitizers on the left ear or 1 of 2 vehicles on the right ear. Quantitative assessment of edema was carried out by measuring the difference in weight between the portions taken from the right and left ears. We tested enzymes (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and thiobarbituric acid reactive substances (TBARS) in ears. Repeated exposure to allyl nitrile reduced edemas induced by glutaraldehyde and by 2, 4-dinitrochlorobenzene (DNCB), but not by formaldehyde. The repeated exposure decreased levels of TBARS, a marker of oxidative stress, induced by glutaraldehyde and by DNCB, but not by formaldehyde. Allyl nitrile elevated SOD levels for the 3 sensitizers, and CAT levels for formaldehyde and DNCB. Allyl nitrile also increased GPx levels for formaldehyde and DNCB, but not for glutaraldehyde. The reduced edemas were associated with changes in oxidative stress levels and antioxidant enzymes. Repeated exposure to allyl nitrile reduced allergic reactions induced by glutaraldehyde and by DNCB, but not by formaldehyde. This reduction was associated with changes in ROS levels and antioxidant enzyme activities.

Metabolism, excretion, and pharmacokinetics of S-allyl-L-cysteine in rats and dogs.

Science.gov (United States)

Amano, Hirotaka; Kazamori, Daichi; Itoh, Kenji; Kodera, Yukihiro

2015-05-01

The metabolism, excretion, and pharmacokinetics of S-allyl-l-cysteine (SAC), an active key component of garlic supplements, were examined in rats and dogs. A single dose of SAC was administered orally or i.v. to rats (5 mg/kg) and dogs (2 mg/kg). SAC was well absorbed (bioavailability >90%) and its four metabolites-N-acetyl-S-allyl-l-cysteine (NAc-SAC), N-acetyl-S-allyl-l-cysteine sulfoxide (NAc-SACS), S-allyl-l-cysteine sulfoxide (SACS), and l-γ-glutamyl-S-allyl-l-cysteine-were identified in the plasma and/or urine. Renal clearance values (l/h/kg) of SAC indicated its extensive renal reabsorption, which contributed to the long elimination half-life of SAC, especially in dogs (12 hours). The metabolism of SAC to NAc-SAC, principal metabolite of SAC, was studied in vitro and in vivo. Liver and kidney S9 fractions of rats and dogs catalyzed both N-acetylation of SAC and deacetylation of NAc-SAC. After i.v. administration of NAc-SAC, SAC appeared in the plasma and its concentration declined in parallel with that of NAc-SAC. These results suggest that the rate and extent of the formation of NAc-SAC are determined by the N-acetylation and deacetylation activities of liver and kidney. Also, NAc-SACS was detected in the plasma after i.v. administration of either NAc-SAC or SACS, suggesting that NAc-SACS could be formed via both N-acetylation of SACS and S-oxidation of NAc-SAC. In conclusion, this study demonstrated that the pharmacokinetics of SAC in rats and dogs is characterized by its high oral bioavailability, N-acetylation and S-oxidation metabolism, and extensive renal reabsorption, indicating the critical roles of liver and kidney in the elimination of SAC. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

N-Boc Amines to Oxazolidinones via Pd(II)/Bis-sulfoxide/Brønsted Acid Co-Catalyzed Allylic C–H Oxidation

Science.gov (United States)

2015-01-01

A Pd(II)/bis-sulfoxide/Brønsted acid catalyzed allylic C–H oxidation reaction for the synthesis of oxazolidinones from simple N-Boc amines is reported. A range of oxazolidinones are furnished in good yields (avg 63%) and excellent diastereoselectivities (avg 15:1) to furnish products regioisomeric from those previously obtained using allylic C–H amination reactions. Mechanistic studies suggest the role of the phosphoric acid is to furnish a Pd(II)bis-sulfoxide phosphate catalyst that promotes allylic C–H cleavage and π-allylPd functionalization with a weak, aprotic oxygen nucleophile and to assist in catalyst regeneration. PMID:24999765

N-Boc amines to oxazolidinones via Pd(II)/bis-sulfoxide/Brønsted acid co-catalyzed allylic C-H oxidation.

Science.gov (United States)

Osberger, Thomas J; White, M Christina

2014-08-06

A Pd(II)/bis-sulfoxide/Brønsted acid catalyzed allylic C-H oxidation reaction for the synthesis of oxazolidinones from simple N-Boc amines is reported. A range of oxazolidinones are furnished in good yields (avg 63%) and excellent diastereoselectivities (avg 15:1) to furnish products regioisomeric from those previously obtained using allylic C-H amination reactions. Mechanistic studies suggest the role of the phosphoric acid is to furnish a Pd(II)bis-sulfoxide phosphate catalyst that promotes allylic C-H cleavage and π-allylPd functionalization with a weak, aprotic oxygen nucleophile and to assist in catalyst regeneration.

catena-Poly[[bromidocopper(I)]-?-?2,?1-3-(2-allyl-2H-tetra?zol-5-yl)pyridine

OpenAIRE

Wang, Wei

2008-01-01

The title compound, [CuBr(C9H9N5)] n , has been prepared by the solvothermal treatment of CuBr with 3-(2-allyl-2H-tetra?zol-5-yl)pyridine. It is a new homometallic CuI olefin coord?ination polymer in which the CuI atoms are linked by the 3-(2-allyl-2H-tetra?zol-5-yl)pyridine ligands and bonded to one terminal Br atom each. The organic ligand acts as a bidentate ligand connecting two neighboring Cu centers through the N atom of the pyridine ring and the double bond of the allyl group. A three-...

One-Pot Multicomponent Coupling Methods for the Synthesis of Diastereo- and Enantioenriched (Z)-Trisubstituted Allylic Alcohols

Science.gov (United States)

Kerrigan, Michael H.; Jeon, Sang-Jin; Chen, Young K.; Salvi, Luca; Carroll, Patrick J.; Walsh, Patrick J.

2009-01-01

(Z)-Trisubstituted allylic alcohols are widespread structural motifs in natural products and biologically active compounds but are difficult to directly prepare. Introduced herein is a general one-pot multicomponent coupling method for the synthesis of (Z)-α,α,β-trisubstituted allylic alcohols. (Z)-Trisubstituted vinylzinc reagents are formed in situ by initial hydroboration of 1-bromo-1-alkynes. Addition of dialkylzinc reagents induces a 1,2-metallate rearrangement that is followed by a boron-to-zinc transmetallation. The resulting vinylzinc reagents add to a variety of prochiral aldehydes to produce racemic (Z)-trisubstituted allylic alcohols. When enantioenriched aldehyde substrates are employed (Z)-trisubstituted allylic alcohols are isolated with high dr (>20:1 in many cases). For example, vinylation of enantioenriched benzyl protected α- and β-hydroxy propanal derivatives furnished the expected anti-Felkin addition products via chelation control. Surprisingly, silyl protected α-hydroxy aldehydes also afford anti-Felkin addition products. A protocol for the catalytic asymmetric addition of (Z)-trisubstituted vinylzinc reagents to prochiral aldehydes with a (−)-MIB-based catalyst has also been developed. Several additives were investigated as inhibitors of the Lewis acidic alkylzinc halide byproducts, which promote the background reaction to form the racemate. α-Ethyl and α-cyclohexyl (Z)-trisubstituted allylic alcohols can now be synthesized with excellent levels of enantioselectivity in the presence of diamine inhibitors. PMID:19476375

A Green Approach for Allylations of Aldehydes and Ketones: Combining Allylborate, Mechanochemistry and Lanthanide Catalyst

Directory of Open Access Journals (Sweden)

Viviane P. de Souza

2016-11-01

Full Text Available Secondary and tertiary alcohols synthesized via allylation of aldehydes and ketones are important compounds in bioactive natural products and industry, including pharmaceuticals. Development of a mechanochemical method using potassium allyltrifluoroborate salt and water, to successfully perform the allylation of aromatic and aliphatic carbonyl compounds is reported for the first time. By controlling the grinding parameters, the methodology can be selective, namely, very efficient for aldehydes and ineffective for ketones, but by employing lanthanide catalysts, the reactions with ketones can become practically quantitative. The catalyzed reactions can also be performed under mild aqueous stirring conditions. Considering the allylation agent and its by-products, aqueous media, energy efficiency and use of catalyst, the methodology meets most of the green chemistry principles.

Determination of thermodynamic parameters for enolization reaction of malonic and metylmalonic acids by using quartz crystal microbalance

Directory of Open Access Journals (Sweden)

Minoru Yoshimoto

2016-06-01

Full Text Available We investigated the process of a bromination reaction of malonic acid and methylmalonic acid in the Belousov-Zhabotinsky reaction by using a quartz crystal microbalance (QCM. The process involves an enolization reaction as a rate-determining step. We found that, in the step, the variation of Br2 concentration induced an exactly quantitative shift of a resonant frequency of the QCM, based on the change of the surface mass on the QCM and the solution viscosity and density. This new finding enabled us to estimate the reaction rate constants and the thermodynamic parameters of the enolization reaction due to a QCM measurement. The values measured by the QCM were in good agreement with those measured by a UV-spectrophotometer. As a result, we succeeded to develop a new measurement method of a nonlinear chemical reaction.

Chemical Kinetics of Hydrogen Atom Abstraction from Allylic Sites by 3O2; Implications for Combustion Modeling and Simulation.

Science.gov (United States)

Zhou, Chong-Wen; Simmie, John M; Somers, Kieran P; Goldsmith, C Franklin; Curran, Henry J

2017-03-09

Hydrogen atom abstraction from allylic C-H bonds by molecular oxygen plays a very important role in determining the reactivity of fuel molecules having allylic hydrogen atoms. Rate constants for hydrogen atom abstraction by molecular oxygen from molecules with allylic sites have been calculated. A series of molecules with primary, secondary, tertiary, and super secondary allylic hydrogen atoms of alkene, furan, and alkylbenzene families are taken into consideration. Those molecules include propene, 2-butene, isobutene, 2-methylfuran, and toluene containing the primary allylic hydrogen atom; 1-butene, 1-pentene, 2-ethylfuran, ethylbenzene, and n-propylbenzene containing the secondary allylic hydrogen atom; 3-methyl-1-butene, 2-isopropylfuran, and isopropylbenzene containing tertiary allylic hydrogen atom; and 1-4-pentadiene containing super allylic secondary hydrogen atoms. The M06-2X/6-311++G(d,p) level of theory was used to optimize the geometries of all of the reactants, transition states, products and also the hinder rotation treatments for lower frequency modes. The G4 level of theory was used to calculate the electronic single point energies for those species to determine the 0 K barriers to reaction. Conventional transition state theory with Eckart tunnelling corrections was used to calculate the rate constants. The comparison between our calculated rate constants with the available experimental results from the literature shows good agreement for the reactions of propene and isobutene with molecular oxygen. The rate constant for toluene with O 2 is about an order magnitude slower than that experimentally derived from a comprehensive model proposed by Oehlschlaeger and coauthors. The results clearly indicate the need for a more detailed investigation of the combustion kinetics of toluene oxidation and its key pyrolysis and oxidation intermediates. Despite this, our computed barriers and rate constants retain an important internal consistency. Rate constants

On Hydrogen Bonding in the Intramolecularly Chelated Taitomers of Enolic Malondialdehyde and its Mono- and Dithio-Analogues

DEFF Research Database (Denmark)

Carlsen, Lars; Duus, Fritz

1980-01-01

The intramolecular hydrogen bondings in enolic malondialdehyde and it mono- and dithio-analogues have been evaluated by a semiempricial SCF–MO–CNDO method. The calculations predict that the hydrogen bonds play an important part in the stabilities of malondialdehyde and monothiomalondialdehyde...

Cascade synthesis of dihydrobenzofuran via Claisen rearrangement of allyl aryl ethers using FeCl3/MCM-41 catalyst

Directory of Open Access Journals (Sweden)

Sachin S. Sakate

2018-05-01

Full Text Available Dihydrobenzofuran as one of the active ingredients of the naturally occurring motif is synthesized by using in situ generation of ortho allyl phenols. Aryl allyl ethers on reacting with catalytic amounts of non noble metal iron (III chloride supported on MCM-41 under moderate reaction conditions yield dihydrobenzofuran. First step via Claisen rearrangement gives ortho allyl phenol followed by its in situ cyclization to yield dihydrobenzofuran in very good yields. Both Lewis as well as Brønsted acidity of the catalyst as evidenced by Py-FTIR studies was found to catalyze the cascade synthesis of dihydrobenzofuran. The scope of the present strategy was successfully demonstrated for several substrates with varying electronic effects for the synthesis of corresponding dihydrobenzofuran with high yields in a range of 71–86%. Keywords: Claisen rearrangement, Dihydrobenzofuran, Aryl allyl ether, MCM-41, Ferric chloride

Asymmetric allylation of α-ketoester-derived N-benzoylhydrazones promoted by chiral sulfoxides/N-oxides Lewis bases: highly enantioselective synthesis of quaternary α-substituted α-allyl-α-amino acids.

Science.gov (United States)

Reyes-Rangel, Gloria; Bandala, Yamir; García-Flores, Fred; Juaristi, Eusebio

2013-09-01

Chiral sulfoxides/N-oxides (R)-1 and (R,R)-2 are effective chiral promoters in the enantioselective allylation of α-keto ester N-benzoylhydrazone derivatives 3a-g to generate the corresponding N-benzoylhydrazine derivatives 4a-g, with enantiomeric excesses as high as 98%. Representative hydrazine derivatives 4a-b were subsequently treated with SmI2, and the resulting amino esters 5a-b with LiOH to obtain quaternary α-substituted α-allyl α-amino acids 6a-b, whose absolute configuration was assigned as (S), with fundament on chemical correlation and electronic circular dichroism (ECD) data. © 2013 Wiley Periodicals, Inc.

Mechanistic Investigation of Palladium–Catalyzed Allylic C–H Activation

DEFF Research Database (Denmark)

Engelin, Casper Junker; Jensen, Thomas; Rodríguez-Rodríguez, Sergio

2013-01-01

The mechanism for the palladium–catalyzed allylic C–H activation was investigated using a combination of experimental and theoretical methods. A Hammett study revealed a buildup of a partial negative charge in the rate-determining step, while determination of the kinetic isotope effect (KIE...

On the Nature of the Intermediates and the Role of Chloride Ions in Pd-Catalyzed Allylic Alkylations: Added Insight from Density Functional Theory

DEFF Research Database (Denmark)

Fristrup, Peter; Ahlquist, Mårten Sten Gösta; Tanner, David Ackland

2008-01-01

The reactivity of intermediates in palladium-catalyzed allylic alkylation was investigated using DFT (B3LYP) calculations including a PB-SCRF solvation model. In the presence of both phosphine and chloride ligands, the allyl intermediate is in equilibrium between a cationic eta(3)-allylPd complex...

Cobalt-catalyzed hydrogenation of esters to alcohols: unexpected reactivity trend indicates ester enolate intermediacy.

Science.gov (United States)

Srimani, Dipankar; Mukherjee, Arup; Goldberg, Alexander F G; Leitus, Gregory; Diskin-Posner, Yael; Shimon, Linda J W; Ben David, Yehoshoa; Milstein, David

2015-10-12

The atom-efficient and environmentally benign catalytic hydrogenation of carboxylic acid esters to alcohols has been accomplished in recent years mainly with precious-metal-based catalysts, with few exceptions. Presented here is the first cobalt-catalyzed hydrogenation of esters to the corresponding alcohols. Unexpectedly, the evidence indicates the unprecedented involvement of ester enolate intermediates. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of praseodymium allyl iodide complex and its use in piperilene polymerization

International Nuclear Information System (INIS)

Gajlyunas, G.A.; Biktimirov, R.Kh.; Khajrullina, R.M.; Marina, N.G.; Manakov, Yu.B.; Tolstikov, G.A.

1987-01-01

Synthesis, structure and catalytic properties of tetrahydrofuran praseodymium allyl iodine complex (1) are described and studied. Complex 1 is formed during interaction of allyl iodine with metal praseodymium (the molar ratio is 2:1) in THF at room temperature with 97% yield. It represents the solid powder-like substance of the light-brown colour with a pale green shade, being sensitive to moisture and oxygen and decomposing at temperature >120 deg. On the basis of the IR-spectroscopy data the supposition about the dimeric (or n-dimensional) complex structure is made. The complex prepared in combination with tributyl aluminium during piperylene polymerization gives a high-stereoregular and high-molecular polypiperylene

General and Efficient a-Oxygenation of Carbonyl Compounds by TEMPO Induced by Single-Electron-Transfer Oxidation of Their Enolates

Czech Academy of Sciences Publication Activity Database

Dinca, E.; Hartmann, P.; Smrček, Jakub; Dix, I.; Jones, P. G.; Jahn, Ullrich

-, č. 24 (2012), s. 4461-4482 ISSN 1434-193X Institutional support: RVO:61388963 Keywords : carbonyl compounds * oxidation * radicals * electron transfer * enolates Subject RIV: CC - Organic Chemistry Impact factor: 3.344, year: 2012

Enantioselective synthesis of almorexant via iridium-catalysed intramolecular allylic amidation

NARCIS (Netherlands)

Fananas Mastral, Martin; Teichert, Johannes F.; Fernandez-Salas, Jose Antonio; Heijnen, Dorus; Feringa, Ben L.

2013-01-01

An enantioselective synthesis of almorexant, a potent antagonist of human orexin receptors, is presented. The chiral tetrahydroisoquinoline core structure was prepared via iridium-catalysed asymmetric intramolecular allylic amidation. Further key catalytic steps of the synthesis include an oxidative

Allylic chlorination of terpenic olefins using a combination of MoCl{sub 5} and NaOCl

Energy Technology Data Exchange (ETDEWEB)

Boualy, Brahim; Firdoussi, Larbi El; Ali, Mustapha Ait; Karim, Abdellah, E-mail: elfirdoussi@ucam.ac.m [Universite Cadi Ayyad, Marrakech (Morocco). Faculte des Sciences Semlalia. Lab. de Chimie de Coordination

2011-07-01

MoCl{sub 5} is applied as efficient agent in allylic chlorination of terpenic olefins in the presence of NaOCl as chlorine donor. Various terpenes are converted to the corresponding allylic chlorides in moderate to good yield under mild and optimized reaction conditions. Different molybdenum precursors are also studied. Among them, MoO{sub 3} gives good yield, but after a longer reaction time. (author)

Enhanced degradation of spiro-insecticides and their leacher enol derivatives in soil by solarization and biosolarization techniques.

Science.gov (United States)

Fenoll, José; Garrido, Isabel; Vela, Nuria; Ros, Caridad; Navarro, Simón

2017-04-01

The leaching potential of three insecticides (spirodiclofen, spiromesifen, and spirotetramat) was assessed using disturbed soil columns. Small quantities of spirodiclofen and spiromesifen were detected in leachate fraction, while spirotetramat residues were not found in the leachates. In addition, the transformation products (enol derivatives) are relatively more mobile than the parent compounds and may leach into groundwater. Moreover, the use of disinfection soil techniques (solarization and biosolarization) to enhance their degradation rates in soil was investigated. The results show that both practices achieved a reduction in the number of juvenile nematodes, enhancing in a parallel way degradation rates of the insecticides and their enol derivatives as compared with the non-disinfected soil. This behavior can be mainly attributed to the increase in soil temperature and changes in microbial activity. All insecticides showed similar behavior under solarization and biosolarization conditions. As a consequence, both agronomic techniques could be considered as suitable strategies for detoxification of soils polluted with the studied pesticides.

RhII -Catalyzed β-C(sp2 )-H Alkylation of Enol Ethers, Enamides and Enecarbamates with α-Diazo Dicarbonyl Compounds.

Science.gov (United States)

McLarney, Brett D; Cavitt, Marchello A; Donnell, Theodore M; Musaev, Djamaladdin G; France, Stefan

2017-01-23

A Rh II -catalyzed method for intermolecular alkylation of the β-C(sp 2 )-H bond of enol ethers, enamides, and enecarbamates with α-diazo-1,3-dicarbonyl compounds is reported. The products are formed in up to 99 % yield and can be readily derivatized under a variety of conditions. By utilizing a combination of experimental and computational studies, the presumptive addition-elimination reaction mechanism was investigated and found to proceed under thermodynamic control at higher temperature. The acquired fundamental knowledge was translated into a strategic reaction design and yielded the first example of the β-C-H functionalizations of acyclic enol ethers using α-diazo-1,3-dicarbonyl compounds. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Residue evaluation of imidacloprid, spirotetramat, and spirotetramat-enol in/on grapes (Vitis vinifera L.) and soil.

Science.gov (United States)

Mohapatra, Soudamini; Kumar, Sampath; Prakash, G S

2015-10-01

A combination of imidacloprid and spirotetramat effectively controls sucking pests on grapevines. Residues of these insecticides on grapes were evaluated after treatment with spirotetramat 12% + imidacloprid 12% (240 SC) three times at 90 and 180 g a.i. ha(-1). The samples were extracted and purified by QuEChERS method and analyzed by high-performance liquid chromatography with a photodiode array detector (imidacloprid) and gas chromatography mass spectrometry (spirotetramat and its metabolite spirotetramat-enol). Satisfactory results were obtained with ranges of 80.6-98.6% for the recovery, 3.1-10% for the relative standard deviation range, and 9.8-15.6% for the uncertainty. The limits of detection and quantification were 0.015 μg mL(-1) and 0.05 mg kg(-1), respectively. Initial residue concentrations of imidacloprid after the 90 and 180 g a.i. ha(-1) treatments were 0.912 (half-life 11 days) and 1.681 mg kg(-1) (half-life 12.4 days), respectively. For spirotetramat + spirotetramat-enol, the residue concentrations were 1.337 (half-life 5.6 days) and 2.0 mg kg(-1) (half-life 7.6 days) for the 90 and 180 g a.i. ha(-1) treatments, respectively. Spirotetramat degraded faster than spirotetramat-enol. After treatment at 90 g a.i. ha(-1), the initial residues of both insecticides were within European Union maximum residue limits and a 1-day pre-harvest interval (PHI) was adequate for safe consumption of grapes. After treatment at 180 g a.i. ha(-1), the required PHI was 7 day. Therefore, a PHI of 7 day should be used after treatment with imidacloprid and spirotetramat.

Density, excess volume, and excess coefficient of thermal expansion of the binary systems of dimethyl carbonate with butyl methacrylate, allyl methacrylate, styrene, and vinyl acetate at T = (293.15, 303.15, and 313.15) K

International Nuclear Information System (INIS)

Wisniak, Jaime; Cortez, Gladis; Peralta, Rene D.; Infante, Ramiro; Elizalde, Luis E.; Amaro, Tlaloc A.; Garcia, Omar; Soto, Homero

2008-01-01

Densities of the binary systems of dimethyl carbonate with butyl methacrylate, allyl methacrylate, styrene, and vinyl acetate have been measured as a function of the composition at (293.15, 303.15, and 313.15) K at atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube densimeter. The excess molar volumes are negative for the (dimethyl carbonate + vinyl acetate) system and positive for the three other binaries, and become more so as the temperature increases from (293.15 to 313.15) K. The apparent volumes were used to calculate the values of the partial excess molar volumes at infinite dilution. The excess coefficient of thermal expansion is positive for the four binary systems. The calculated excess molar volumes were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. An explanation of the results is offered based on the FT-IR (ATR) spectra of several mixtures of the different systems

Density, excess volume, and excess coefficient of thermal expansion of the binary systems of dimethyl carbonate with butyl methacrylate, allyl methacrylate, styrene, and vinyl acetate at T = (293.15, 303.15, and 313.15) K

Energy Technology Data Exchange (ETDEWEB)

Wisniak, Jaime [Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)], E-mail: wisniak@bgumail.bgu.ac.il; Cortez, Gladis; Peralta, Rene D.; Infante, Ramiro; Elizalde, Luis E. [Centro de Investigacion en Quimica Aplicada, Saltillo 25253, Coahuila (Mexico); Amaro, Tlaloc A.; Garcia, Omar; Soto, Homero [Facultad de Ciencias Quimicas, Universidad Autonoma de Coahuila, Saltillo 25280, Coahuila (Mexico)

2008-12-15

Densities of the binary systems of dimethyl carbonate with butyl methacrylate, allyl methacrylate, styrene, and vinyl acetate have been measured as a function of the composition at (293.15, 303.15, and 313.15) K at atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube densimeter. The excess molar volumes are negative for the (dimethyl carbonate + vinyl acetate) system and positive for the three other binaries, and become more so as the temperature increases from (293.15 to 313.15) K. The apparent volumes were used to calculate the values of the partial excess molar volumes at infinite dilution. The excess coefficient of thermal expansion is positive for the four binary systems. The calculated excess molar volumes were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. An explanation of the results is offered based on the FT-IR (ATR) spectra of several mixtures of the different systems.

A convenient procedure for the synthesis of allyl and benzyl ethers ...

Indian Academy of Sciences (India)

Unknown

Department of Chemistry, Pondicherry University, Pondicherry 605 014, .... organic synthesis we hope that the procedure described in this paper will find ... Allyl bromide (Fluka) and benzyl bromide (E Merck) were freshly distilled before use.

Photodissociaton of allyl-d2 iodide excited at 193 nm: Stability of highly rotationally excited H2CDCH2 radicals to C-D fission

International Nuclear Information System (INIS)

Szpunar, D.E.; Liu, Y.; McCullagh, M.J.; Butler, L.J.; Shu, J.

2003-01-01

The photodissociation of allyl-d2 iodide (H2C=CDCH2I) and the dynamics of the nascent allyl-d2 radical (H2CCDCH2) were studied using photofragment translational spectroscopy. A previous study found the allyl radical stable at internal energies up to 15 kcal/mol higher than the 60 kcal/mol barrier to allene + H formation as the result of a centrifugal barrier. The deuterated allyl radical should then also show a stability to secondary dissociation at internal energies well above the barrier due to centrifugal effects. A comparison in this paper shows the allyl-d2 radical is stable to allene + D formation at energies of 2-3 kcal/mol higher than that of the non-deuterated allyl radical following photolysis of allyl iodide at 193 nm. This is most likely a result of a combination of the slight raising of the barrier from the difference in zero-point levels and a reduction of the impact parameter of the dissociative fragments due to the decrease in frequency of the C-D bending modes, and the refore allene + D product orbital angular momentum. Integrated signal taken at m/e = 40 (allene) and m/e = 41 (allene-d1 and propyne-d3) shows a minor fraction of the allyl-d2 radicals isomerize to the 2-propenyl radical, in qualitative support of earlier conclusions of the domination of direct allene + H formation over isomerization

Dual platinum and pyrrolidine catalysis in the direct alkylation of allylic alcohols: selective synthesis of monoallylation products.

Science.gov (United States)

Shibuya, Ryozo; Lin, Lu; Nakahara, Yasuhito; Mashima, Kazushi; Ohshima, Takashi

2014-04-22

A dual platinum- and pyrrolidine-catalyzed direct allylic alkylation of allylic alcohols with various active methylene compounds to produce products with high monoallylation selectivity was developed. The use of pyrrolidine and acetic acid was essential, not only for preventing undesirable side reactions, but also for obtaining high monoallylation selectivity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemoenzymatic one-pot synthesis in an aqueous medium: combination of metal-catalysed allylic alcohol isomerisation-asymmetric bioamination.

Science.gov (United States)

Ríos-Lombardía, Nicolás; Vidal, Cristian; Cocina, María; Morís, Francisco; García-Álvarez, Joaquín; González-Sabín, Javier

2015-07-11

The ruthenium-catalysed isomerisation of allylic alcohols was coupled, for the first time, with asymmetric bioamination in a one-pot process in an aqueous medium. In the cases involving prochiral ketones, the ω-TA exhibited excellent enantioselectivity, identical to that observed in the single step. As a result, amines were obtained from allylic alcohols with high overall yields and excellent enantiomeric excesses.

Copper-catalyzed decarboxylative trifluoromethylation of allylic bromodifluoroacetates.

Science.gov (United States)

Ambler, Brett R; Altman, Ryan A

2013-11-01

The development of new synthetic fluorination reactions has important implications in medicinal, agricultural, and materials chemistries. Given the prevalence and accessibility of alcohols, methods to convert alcohols to trifluoromethanes are desirable. However, this transformation typically requires four-step processes, specialty chemicals, and/or stoichiometric metals to access the trifluoromethyl-containing product. A two-step copper-catalyzed decarboxylative protocol for converting allylic alcohols to trifluoromethanes is reported. Preliminary mechanistic studies distinguish this reaction from previously reported Cu-mediated reactions.

Vanadium-Catalyzed Enantioselective Desymmetrization of meso-Secondary Allylic Alcohols and Homoallylic Alcohols

OpenAIRE

Li, Zhi; Zhang, Wei; Hisashi Yamamoto, H.

2008-01-01

Vanadium-catalyzed epoxidation has extended substrate scope. In addition to various bis-allylic alcohols, bis-homoallylic alcohols can also be desymmetrized using our Vanadium-Bis-hydroxamic acid complexes.

An XPS study of pulsed plasma polymerised allyl alcohol film growth on polyurethane

Energy Technology Data Exchange (ETDEWEB)

Watkins, Lucy [Department of Chemistry, University of York, Heslington, York YO10 5DD (United Kingdom); Bismarck, Alexander [Department of Chemical Engineering, Polymer and Composite Engineering (PaCE) Group, Imperial College London, London SW7 2AZ (United Kingdom); Lee, Adam F. [Department of Chemistry, University of York, Heslington, York YO10 5DD (United Kingdom); Wilson, Darren [Smith and Nephew Research Centre, York Science Park, Heslington, York YO10 5DF (United Kingdom); Wilson, Karen [Department of Chemistry, University of York, Heslington, York YO10 5DD (United Kingdom)]. E-mail: kw13@york.ac.uk

2006-09-30

The growth of highly functionalised poly allyl alcohol films by pulsed plasma polymerisation of CH{sub 2} =CHCH{sub 2}OH on biomedical grade polyurethane has been followed by X-ray photoelectron spectroscopy (XPS) and contact angle measurements. Film thickness is observed to increase approximately linearly with plasma modification time, suggesting a layer-by-layer growth mode of poly allyl alcohol. Water contact angle measurements reveal the change in the surface free energy of wetting decreases linearly with plasma modification up to the monolayer point after which a constant limiting value of -24 mJ m{sup -2} was attained. Films prepared at 20 W plasma power with a duty cycle of 10 {mu}s:500 {mu}s exhibit a high degree of hydroxyl (-OH) retention with minimal fragmentation of the monomer observed. Increasing the plasma power up to 125 W is found to improve -OH retention at the expense of ether formation generating films close to the monomer stoichiometry. Duty cycle plays an important role in controlling both film composition and thickness, with longer off times increasing -OH retention, while longer on times enhance allyl alcohol film growth.

Enantioselective epoxidation with chiral MN(III)(salen) catalysts: kinetic resolution of aryl-substituted allylic alcohols.

Science.gov (United States)

Adam, W; Humpf, H U; Roschmann, K J; Saha-Möller, C R

2001-08-24

A set of aryl-substituted allylic alcohols rac-2 has been epoxidized by chiral Mn(salen*) complexes 1 as the catalyst and iodosyl benzene (PhIO) as the oxygen source. Whereas one enantiomer of the allylic alcohol 2 is preferentially epoxidized to give the threo- or cis-epoxy alcohol 3 (up to 80% ee) as the main product (dr up to >95:5), the other enantiomer of 2 is enriched (up to 53% ee). In the case of 1,1-dimethyl-1,2-dihydronaphthalen-2-ol (2c), the CH oxidation to the enone 4c proceeds enantioselectively and competes with the epoxidation. The absolute configurations of the allylic alcohols 2 and their epoxides 3 have been determined by chemical correlation or CD spectroscopy. The observed diastereo- and enantioselectivities in the epoxidation reactions are rationalized in terms of a beneficial interplay between the hydroxy-directing effect and the attack along the Katsuki trajectory.

Solvent-controlled regioselective protection of allyl-4,6-benzylidene glucopyranosides

Directory of Open Access Journals (Sweden)

Migaud Marie E

2007-09-01

Full Text Available Abstract We wish to report a simple synthetic procedure, which permits the regiospecific mono-acylation, alkylation and silylation at the 2-position of allyl 4,6-O-benzylidene α-D-glucopyranoside in high yields and which does not require the use of catalysts.

Expression of liver functions following sub-lethal and non-lethal doses of allyl alcohol and acetaminophen in the rat

DEFF Research Database (Denmark)

Tygstrup, N; Jensen, S A; Krog, B

1997-01-01

BACKGROUND/AIMS: To relate severity of intoxication with allyl alcohol and acetaminophen to modulated hepatic gene expression of liver functions and regeneration. METHODS: Rats fasted for 12 h received acetaminophen 3.5 or 5.6 g per kg body weight, or allyl alcohol 100 or 125 microl by gastric tu...

Direct activation of allylic alcohols in palladium catalyzed coupling reactions

NARCIS (Netherlands)

Gümrükçü, Y.

2014-01-01

The direct use of allylic alcohols in substitution reactions without pre-activation of the hydroxyl-group into a better leaving group or the use of additional stoichiometric in situ activators remains challenging due to the poor leaving group ability of the hydroxyl-group. Hence, it is important to

How phenyl makes a difference: mechanistic insights into the ruthenium( ii )-catalysed isomerisation of allylic alcohols

KAUST Repository

Manzini, Simone

2013-10-16

[RuCl(η5-3-phenylindenyl)(PPh3)2] (1) has been shown to be a highly active catalyst for the isomerisation of allylic alcohols to the corresponding ketones. A variety of substrates undergo the transformation, typically with 0.25-0.5 mol% of catalyst at room temperature, outperforming commonly-used complexes such as [RuCl(Cp)(PPh3) 2] and [RuCl(η5-indenyl)(PPh3) 2]. Mechanistic experiments and density functional theory have been employed to investigate the mechanism and understand the effect of catalyst structure on reactivity. These investigations suggest a oxo-π-allyl mechanism is in operation, avoiding intermediate ruthenium hydride complexes and leading to a characteristic 1,3-deuterium shift. Important mechanistic insights from DFT and experiments also allowed for the design of a protocol that expands the scope of the transformation to include primary allylic alcohols. © 2013 The Royal Society of Chemistry.

How phenyl makes a difference: mechanistic insights into the ruthenium( ii )-catalysed isomerisation of allylic alcohols

KAUST Repository

Manzini, Simone; Poater, Albert; Nelson, David J.; Cavallo, Luigi; Nolan, Steven P.

2013-01-01

[RuCl(η5-3-phenylindenyl)(PPh3)2] (1) has been shown to be a highly active catalyst for the isomerisation of allylic alcohols to the corresponding ketones. A variety of substrates undergo the transformation, typically with 0.25-0.5 mol% of catalyst at room temperature, outperforming commonly-used complexes such as [RuCl(Cp)(PPh3) 2] and [RuCl(η5-indenyl)(PPh3) 2]. Mechanistic experiments and density functional theory have been employed to investigate the mechanism and understand the effect of catalyst structure on reactivity. These investigations suggest a oxo-π-allyl mechanism is in operation, avoiding intermediate ruthenium hydride complexes and leading to a characteristic 1,3-deuterium shift. Important mechanistic insights from DFT and experiments also allowed for the design of a protocol that expands the scope of the transformation to include primary allylic alcohols. © 2013 The Royal Society of Chemistry.

Theoretical investigation on hydrogen bond interaction of diketo/keto-enol form uracil and thymine tautomers with intercalators.

Science.gov (United States)

Anithaa, V S; Vijayakumar, S; Sudha, M; Shankar, R

2017-11-06

The interaction of diketo and keto-enol form of thymine and uracil tautomers with acridine (Acr), phenazine (Phen), benzo[c]cinnoline (Ben), 1,10-phenanthroline (1,10-Phe), and 4,7-phenenthroline (4,7-Phe) intercalating drug molecules was studied using density functional theory at B3LYP/6-311++G** and M05-2×/6-311++G** levels of theory. From the interaction energy, it is found that keto-enol form tautomers have stronger interaction with intercalators than diketone form tautomers. On complex formation of thymine and uracil tautomers with benzo[c]cinnoline the drug molecules have high interaction energy values of -20.14 (BenT3) and -20.55 (BenU3) kcal mol -1 , while phenazine has the least interaction energy values of -6.52 (PhenT2) and -6.67 (PhenU2) kcal mol -1 . The closed shell intermolecular type interaction between the molecules with minimum elliptical value of 0.018 and 0.019 a.u at both levels of theory has been found from topological analysis. The benzo[c]cinnoline drug molecule with thymine and uracil tautomers has short range intermolecular N-H…N, C-H…O, and O-H...N hydrogen bonds (H-bonds) resulting in higher stability than other drug molecules. The proper hydrogen bonds N-H..N and O-H..N have the frequency shifted toward the lower side (red shifted) with the elongation in their bond length while the improper hydrogen bond C-H...O has the frequency shifted toward the higher side (blue shifted) of the spectral region with the contraction in their bond length. Further, the charge transfer between proton acceptor and donor along with stability of the bond is studied using natural bond orbital (NBO) analysis. Graphical abstract Hydrogen bond interaction of diketo/keto-enol form uracil and thymine tautomers with intercalators.

Tether-directed synthesis of highly substituted oxasilacycles via an intramolecular allylation employing allylsilanes

Directory of Open Access Journals (Sweden)

Cox Liam R

2007-02-01

Full Text Available Abstract Background Using a silyl tether to unite an aldehyde electrophile and allylsilane nucleophile into a single molecule allows a subsequent Lewis-acid-mediated allylation to proceed in an intramolecular sense and therefore receive all the benefits associated with such processes. However, with the ability to cleave the tether post allylation, a product that is the result of a net intermolecular reaction can be obtained. In the present study, four diastereoisomeric β-silyloxy-α-methyl aldehydes, which contain an allylsilane tethered through the β-carbinol centre, have been prepared, in order to probe how the relative configuration of the two stereogenic centres affects the efficiency and selectivity of the intramolecular allylation. Results Syn-aldehydes, syn-4a and syn-4b, both react poorly, affording all four possible diastereoisomeric oxasilacycle products. In contrast, the anti aldehydes anti-4a and anti-4b react analogously to substrates that lack substitution at the α-site, affording only two of the four possible allylation products. Conclusion The outcome of the reaction with anti-aldehydes is in accord with reaction proceeding through a chair-like transition state (T.S.. In these systems, the sense of 1,3-stereoinduction can be rationalised by the aldehyde electrophile adopting a pseudoaxial orientation, which will minimise dipole-dipole interactions in the T.S. The 1,4-stereoinduction in these substrates is modest and seems to be modulated by the R substituent in the starting material. In the case of the syn-substrates, cyclisation through a chair T.S. is unlikely as this would require the methyl substituent α to the reacting carbonyl group to adopt an unfavourable pseudoaxial position. It is therefore proposed that these substrates react through poorly-defined T.S.s and consequently exhibit essentially no stereoselectivity.

Chalcogen-containing oxazolines in the palladium-catalyzed asymmetric allylic alkylation

Directory of Open Access Journals (Sweden)

Braga Antonio L.

2006-01-01

Full Text Available A comparative study about the ability of chiral chalcogen-containing oxazolines to act as chiral ligands in the palladium-catalyzed allylic alkylation of rac-1,3-diphenyl-2-propenyl acetate with dimethyl malonate is reported. Differences in the catalytic performance are observed with sulfur, selenium and tellurium analogues.

Synthesis of a Novel Allyl-Functionalized Deep Eutectic Solvent to Promote Dissolution of Cellulose

Directory of Open Access Journals (Sweden)

Hongwei Ren

2016-08-01

Full Text Available Deep eutectic solvents (DESs offer attractive options for the “green” dissolution of cellulose. However, the protic hydroxyl group causes weak dissolving ability of DESs, requiring the substitution of hydroxyl groups in the cation. In this study, a novel allyl-functionalized DES was synthesized and characterized, and its possible effect on improved dissolution of cellulose was investigated. The DES was synthesized by a eutectic mixture of allyl triethyl ammonium chloride ([ATEAm]Cl and oxalic acid (Oxa at a molar ratio of 1:1 and a freezing point of 49 °C. The [ATEAm]Cl-Oxa exhibited high polarity (56.40 kcal/mol, dipolarity/polarizability effects (1.10, hydrogen-bond donating acidity (0.41, hydrogen-bond basicity (0.89, and low viscosity (76 cP at 120 °C owing to the π-π conjugative effect induced by the allyl group. The correlation between temperature and viscosity on the [ATEAm]Cl-Oxa fit the Arrhenius equation well. The [ATEAm]Cl-Oxa showed low pseudo activation energy for viscous flow (44.56 kJ/mol. The improved properties of the [ATEAm]Cl-Oxa noticeably promoted the solubility (6.48 wt.% of cellulose.

1-Allyl-3-amino-1H-pyrazole-4-carboxylic acid

Directory of Open Access Journals (Sweden)

Feng-Ling Yang

2008-12-01

Full Text Available The title compound, C7H9N3O2, was prepared by alkaline hydrolysis of ethyl 1-allyl-3-amino-1H-pyrazole-4-carboxylate. The crystal structure is stabilized by three types of intermolecular hydrogen bond (N—H...O, N—H...N and O—H...N.

Enantioselective Allylation of Thiophene-2-carbaldehyde: Formal Total Synthesis of Duloxetine

Czech Academy of Sciences Publication Activity Database

Motloch, P.; Valterová, Irena; Kotora, M.

2014-01-01

Roč. 356, č. 1 (2014), s. 199-204 ISSN 1615-4150 Grant - others:GA ČR(CZ) GAP207/11/0587 Institutional support: RVO:61388963 Keywords : aldehydes * allylation * Lewis bases * organocatalysis * synthetic methods Subject RIV: CC - Organic Chemistry Impact factor: 5.663, year: 2014

Anion-π Catalysis of Enolate Chemistry: Rigidified Leonard Turns as a General Motif to Run Reactions on Aromatic Surfaces.

Science.gov (United States)

Cotelle, Yoann; Benz, Sebastian; Avestro, Alyssa-Jennifer; Ward, Thomas R; Sakai, Naomi; Matile, Stefan

2016-03-18

To integrate anion-π, cation-π, and ion pair-π interactions in catalysis, the fundamental challenge is to run reactions reliably on aromatic surfaces. Addressing a specific question concerning enolate addition to nitroolefins, this study elaborates on Leonard turns to tackle this problem in a general manner. Increasingly refined turns are constructed to position malonate half thioesters as close as possible on π-acidic surfaces. The resulting preorganization of reactive intermediates is shown to support the disfavored addition to enolate acceptors to an absolutely unexpected extent. This decisive impact on anion-π catalysis increases with the rigidity of the turns. The new, rigidified Leonard turns are most effective with weak anion-π interactions, whereas stronger interactions do not require such ideal substrate positioning to operate well. The stunning simplicity of the motif and its surprisingly strong relevance for function should render the introduced approach generally useful. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Genome Wide Association Mapping in Arabidopsis thaliana Identifies Novel Genes Involved in Linking Allyl Glucosinolate to Altered Biomass and Defense.

Science.gov (United States)

Francisco, Marta; Joseph, Bindu; Caligagan, Hart; Li, Baohua; Corwin, Jason A; Lin, Catherine; Kerwin, Rachel E; Burow, Meike; Kliebenstein, Daniel J

2016-01-01

A key limitation in modern biology is the ability to rapidly identify genes underlying newly identified complex phenotypes. Genome wide association studies (GWAS) have become an increasingly important approach for dissecting natural variation by associating phenotypes with genotypes at a genome wide level. Recent work is showing that the Arabidopsis thaliana defense metabolite, allyl glucosinolate (GSL), may provide direct feedback regulation, linking defense metabolism outputs to the growth, and defense responses of the plant. However, there is still a need to identify genes that underlie this process. To start developing a deeper understanding of the mechanism(s) that modulate the ability of exogenous allyl GSL to alter growth and defense, we measured changes in plant biomass and defense metabolites in a collection of natural 96 A. thaliana accessions fed with 50 μM of allyl GSL. Exogenous allyl GSL was introduced exclusively to the roots and the compound transported to the leaf leading to a wide range of heritable effects upon plant biomass and endogenous GSL accumulation. Using natural variation we conducted GWAS to identify a number of new genes which potentially control allyl responses in various plant processes. This is one of the first instances in which this approach has been successfully utilized to begin dissecting a novel phenotype to the underlying molecular/polygenic basis.

Genome wide association mapping in Arabidopsis thaliana identifies novel genes involved in linking allyl glucosinolate to altered biomass and defense

Directory of Open Access Journals (Sweden)

Marta Francisco

2016-07-01

Full Text Available A key limitation in modern biology is the ability to rapidly identify genes underlying newly identified complex phenotypes. Genome wide association studies (GWAS have become an increasingly important approach for dissecting natural variation by associating phenotypes with genotypes at a genome wide level. Recent work is showing that the Arabidopsis thaliana defense metabolite, allyl glucosinolate (GSL, may provide direct feedback regulation, linking defense metabolism outputs to the growth and defense responses of the plant. However, there is still a need to identify genes that underlie this process. To start developing a deeper understanding of the mechanism(s that modulate the ability of exogenous allyl GSL to alter growth and defense, we measured changes in plant biomass and defense metabolites in a collection of natural 96 A. thaliana accessions fed with 50 µM of allyl GSL. Exogenous allyl GSL was introduced exclusively to the roots and the compound transported to the leaf leading to a wide range of heritable effects upon plant biomass and endogenous GSL accumulation. Using natural variation we conducted GWAS to identify a number of new genes which potentially control allyl responses in various plant processes. This is one of the first instances in which this approach has been successfully utilized to begin dissecting a novel phenotype to the underlying molecular/polygenic basis.

Direct preparation of 14C-labelled 5-allyl- and 5-propyl-2'-deoxyuridine from [2-14C]2'-deoxyuridine

International Nuclear Information System (INIS)

Ruth, J.L.; White, S.K.; Bergstrom, D.E.

1982-01-01

[2- 14 C]5-Allyl-2'-deoxyuridine was synthesized directly from [2- 14 C]2'-deoxyuridine using mercury, palladium, and 3-chloropropene. [2- 14 C]5-Propyl-2'-deoxyuridine was obtained by hydrogenation of the [ 14 C]5-allyl-2'-deoxyuridine. Advantages of the synthetic method and its application to the preparation of other radiolabeled 5-alkyl/alkenyl-2'-deoxyuridines are discussed. (author)

A stable enol from a 6-substituted benzanthrone and its unexpected behaviour under acidic conditions

Directory of Open Access Journals (Sweden)

Marc Debeaux

2009-06-01

Full Text Available Treatment of benzanthrone (1 with biphenyl-2-yl lithium leads to the surprisingly stable enol 4, which is converted by dehydrogenation into the benzanthrone derivative 7. Under acidic conditions 4 isomerises to the spiro compound 11 and the bicyclo[4.3.1]decane derivative 12. Furthermore, the formation of 7 and the hydrogenated compound 13 is observed. A mechanism for the formation of the reaction products is proposed and supported by DFT calculations.

In(OTf)3 catalyzed allylation reaction of imines with tetraallyltin

Institute of Scientific and Technical Information of China (English)

Xiao Ning Wei; Ling Yan Liu; Bing Wang; Wei Xing Chang; Jing Li

2009-01-01

In the presence of catalytic amount of In(OTf)3 (10 mol%), a series of aldimines reacted with tetraallyltin in a 2:1 molar ratio to afford the corresponding homoallylic amines in good yields. The good atom efficiency was achieved under mild reaction conditions and a new protocol (allyl)4Sn/In(OTf)3 for simple imines was developed.

Total synthesis of broussonetine F: the orthoamide Overman rearrangement of an allylic diol.

Science.gov (United States)

Hama, Naoto; Aoki, Toshihiro; Miwa, Shohei; Yamazaki, Miki; Sato, Takaaki; Chida, Noritaka

2011-02-18

A first total synthesis of broussonetine F from diethyl L-tartrate was achieved. The cornerstone of our synthesis was an orthoamide Overman rearrangement, which provided an allylic amino alcohol with complete diastereoselectivity.

Chirality Transfer in Gold(I)-Catalysed Direct Allylic Etherifications of Unactivated Alcohols: Experimental and Computational Study.

Science.gov (United States)

Barker, Graeme; Johnson, David G; Young, Paul C; Macgregor, Stuart A; Lee, Ai-Lan

2015-09-21

Gold(I)-catalysed direct allylic etherifications have been successfully carried out with chirality transfer to yield enantioenriched, γ-substituted secondary allylic ethers. Our investigations include a full substrate-scope screen to ascertain substituent effects on the regioselectivity, stereoselectivity and efficiency of chirality transfer, as well as control experiments to elucidate the mechanistic subtleties of the chirality-transfer process. Crucially, addition of molecular sieves was found to be necessary to ensure efficient and general chirality transfer. Computational studies suggest that the efficiency of chirality transfer is linked to the aggregation of the alcohol nucleophile around the reactive π-bound Au-allylic ether complex. With a single alcohol nucleophile, a high degree of chirality transfer is predicted. However, if three alcohols are present, alternative proton transfer chain mechanisms that erode the efficiency of chirality transfer become competitive. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Interaction between the thyroid hormone receptor and co-factors on the promoter of the gene encoding phospho enol pyruvate carboxykinase

NARCIS (Netherlands)

Schmidt, E. D.; van Beeren, M.; Glass, C. K.; Wiersinga, W. M.; Lamers, W. H.

1993-01-01

Using transient transfection studies we localized a thyroid hormone-responsive element on the promoter of the rat phospho-enol pyruvate carboxykinase gene between 355 and 174 bp upstream of the transcription start site. DNAse 1 footprinting analysis within this region showed that a 28 bp fragment at

The introduction of a double bond on the steroid skeleton - the preparation of enol silyl ether derivatives from vicinal diols

Czech Academy of Sciences Publication Activity Database

Marek, Aleš; Klepetářová, Blanka; Elbert, Tomáš

2011-01-01

Roč. 76, č. 5 (2011), s. 443-456 ISSN 0010-0765 R&D Projects: GA AV ČR IAA400550801 Institutional research plan: CEZ:AV0Z40550506 Keywords : enol silyl ether * vicinal diol * steroids Subject RIV: CC - Organic Chemistry Impact factor: 1.283, year: 2011

Polyfunctional beta-Dicarbonyl Compounds by Michael Addition Reactions of Ester Enolates to alpha-Benzylidene and alpha-Alkylidene-beta-dicarbonyl Compounds

Czech Academy of Sciences Publication Activity Database

Holan, Martin; Pohl, Radek; Císařová, I.; Jahn, Ullrich

-, č. 18 (2012), s. 3459-3475 ISSN 1434-193X R&D Projects: GA ČR GA203/09/1936 Institutional research plan: CEZ:AV0Z40550506 Keywords : Michael addition * diastereoselectivity * regioselectivity * enols * dicarbonyl compounds Subject RIV: CC - Organic Chemistry Impact factor: 3.344, year: 2012

No metabolic effects of mustard allyl-isothiocyanate compared with placebo in men

NARCIS (Netherlands)

Langeveld, Mirjam; Tan, Chong Yew; Soeters, Maarten R.; Virtue, Samuel; Watson, Laura Pe; Murgatroyd, Peter R.; Ambler, Graeme K.; Vidal-Puig, Santiago; Chatterjee, Krishna V.; Vidal-Puig, Antonio

2017-01-01

Background: Induction of nonshivering thermogenesis can be used to influence energy balance to prevent or even treat obesity. The pungent component of mustard, allyl-isothiocyanate (AITC), activates the extreme cold receptor transient receptor potential channel, subfamily A, member 1 and may thus

Scope and mechanism in palladium-catalyzed isomerizations of highly substituted allylic, homoallylic, and alkenyl alcohols.

Science.gov (United States)

Larionov, Evgeny; Lin, Luqing; Guénée, Laure; Mazet, Clément

2014-12-03

Herein we report the palladium-catalyzed isomerization of highly substituted allylic alcohols and alkenyl alcohols by means of a single catalytic system. The operationally simple reaction protocol is applicable to a broad range of substrates and displays a wide functional group tolerance, and the products are usually isolated in high chemical yield. Experimental and computational mechanistic investigations provide complementary and converging evidence for a chain-walking process consisting of repeated migratory insertion/β-H elimination sequences. Interestingly, the catalyst does not dissociate from the substrate in the isomerization of allylic alcohols, whereas it disengages during the isomerization of alkenyl alcohols when additional substituents are present on the alkyl chain.

Synthesis of Novel β-Keto-Enol Derivatives Tethered Pyrazole, Pyridine and Furan as New Potential Antifungal and Anti-Breast Cancer Agents

Directory of Open Access Journals (Sweden)

Smaail Radi

2015-11-01

Full Text Available Recently, a new generation of highly promising inhibitors bearing β-keto-enol functionality has emerged. Reported herein is the first synthesis and use of novel designed drugs based on the β-keto-enol group embedded with heterocyclic moieties such as pyrazole, pyridine, and furan, prepared in a one-step procedure by mixed Claisen condensation. All the newly synthesized compounds were characterized by FT-IR, 1H-NMR, 13C-NMR, ESI/LC-MS, elemental analysis, and evaluated for their in vitro antiproliferative activity against breast cancer (MDA-MB241 human cell lines and fungal strains (Fusarium oxysporum f.sp albedinis FAO. Three of the synthesized compounds showed potent activity against fungal strains with IC50 values in the range of 0.055–0.092 µM. The results revealed that these compounds showed better IC50 values while compared with positive controls.

α,β-Unsaturated imines via Ru-catalyzed coupling of allylic alcohols and amines.

Science.gov (United States)

Rigoli, Jared W; Moyer, Sara A; Pearce, Simon D; Schomaker, Jennifer M

2012-03-07

A convenient synthesis of α,β-unsaturated imines requiring only an allylic alcohol, an amine and a Ru catalyst has been developed. The use of large excesses of oxidant and the purification of sensitive intermediates can be avoided.

BIOACTIVITIES AND MECHANISM OF SPIRO ENOL ETHER ANALOGUES AGAINST PIERIS RAPAE

Institute of Scientific and Technical Information of China (English)

Zhi-xiangZhang; Dong-meiCheng; Han-hongXu; Yu-linWu; andJun-faFan

2004-01-01

Nineteen kinds of spiro enol ether analogues were screened with larvae of Pieris rapae for antifeedant activity. The results showed that the antifeedant activity of compounds No.20 and No.12 was higher than others. In non-choice test, AFC50 values within 24 h of compounds No.20 and No.12 against 3rd instar larvae of P. rapae were 226.93ug/mL and 370.00ug/mL, and that in choice test against 4th larvae were 280.54 ug/mL and 398.88 ug/mL, respectively. Compd. No.20 could prolong the eggs hatch time and reduce the haemolymph content and the protein content in haemolymph of 4th instar larvae obviously. Compd. No.20 could protect tested leaves and control larvae of P. rapae effectively.

Reactivity of olefin and allyl ligands in π-complexes of metals

International Nuclear Information System (INIS)

Kukushkin, Yu.N.

1987-01-01

The data on reactivity of olefin and allyl ligands in transition metal (Ru, W) π-complexes, published up to 1984 are presented. Metal ion coordination of olefins causes their appreciable reactivity change. Transformations of π-olefin ligands into σ-alkyl ones, interaction of π-complexes with oxygen nucleophilic reagents, amines, halogenides and pseudohalogenides are considered

Modeling of chemical reactions in micelle: water-mediated keto-enol interconversion as a case study.

Science.gov (United States)

Marracino, Paolo; Amadei, Andrea; Apollonio, Francesca; d'Inzeo, Guglielmo; Liberti, Micaela; di Crescenzo, Antonello; Fontana, Antonella; Zappacosta, Romina; Aschi, Massimiliano

2011-06-30

The effect of a zwitterionic micelle environment on the efficiency of the keto-enol interconversion of 2-phenylacetylthiophene has been investigated by means of a joint application of experimental and theoretical/computational approaches. Results have revealed a reduction of the reaction rate constant if compared with bulk water essentially because of the different solvation conditions experienced by the reactant species, including water molecules, in the micelle environment. The slight inhibiting effect due to the application of a static electric field has also been theoretically investigated and presented.

Cu-Catalyzed Asymmetric Allylic Alkylation of Phosphonates and Phosphine Oxides with Grignard Reagents

NARCIS (Netherlands)

Hornillos, Valentin; Perez, Manuel; Fananas-Mastral, Martin; Feringa, Ben L.

An efficient and highly enantioselective copper-catalyzed allylic alkylation of phosphonates and phosphine oxides with Grignard reagents and Taniaphos or phosphoramidites as chiral ligands is reported. Transformation of these products leads to a variety of new phosphorus-containing chiral

Biomarkers derived from heterolytic and homolytic cleavage of allylic hydroperoxides resulting from alkenone autoxidation

Digital Repository Service at National Institute of Oceanography (India)

Rontania, J.F.; Harji, R.; Volkmanc, J.K.

Laboratory incubation of alkenone mixtures with tert-butyl hydroperoxide and di-tert-butyl nitroxide (radical initiator) in hexane, as a means to simulate alkenone autoxidation processes, rapidly led to the formation of allylic hydroperoxides, whose...

Unexpected catalytic reactions of silyl-protected enol diazoacetates with nitrile oxides that form 5-arylaminofuran-2(3H)-one-4-carboxylates.

Science.gov (United States)

Xu, Xinfang; Shabashov, Dmitry; Zavalij, Peter Y; Doyle, Michael P

2012-02-03

Silyl-protected enol diazoacetates undergo dirhodium(II)-catalyzed reactions with nitrile oxides to form acid-labile ketenimines via dipolar cycloaddition of nitrile oxides to a donor/acceptor cyclopropene and Lossen rearrangement of the dipolar adduct; acid catalysis converts the ketenimine to the furan product. © 2012 American Chemical Society

Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso–ene mechanism

Directory of Open Access Journals (Sweden)

David Porter

2015-12-01

Full Text Available Iron(II complexes of the tetradentate amines tris(2-pyridylmethylamine (TPA and N,N′-bis(2-pyridylmethyl-N,N′-dimethylethane-1,2-diamine (BPMEN are established catalysts of C–O bond formation, oxidising hydrocarbon substrates via hydroxylation, epoxidation and dihydroxylation pathways. Herein we report the capacity of these catalysts to promote C–N bond formation, via allylic amination of alkenes. The combination of N-Boc-hydroxylamine with either FeTPA (1 mol % or FeBPMEN (10 mol % converts cyclohexene to the allylic hydroxylamine (tert-butyl cyclohex-2-en-1-yl(hydroxycarbamate in moderate yields. Spectroscopic studies and trapping experiments suggest the reaction proceeds via a nitroso–ene mechanism, with involvement of a free N-Boc-nitroso intermediate. Asymmetric induction is not observed using the chiral tetramine ligand (+-(2R,2′R-1,1′-bis(2-pyridylmethyl-2,2′-bipyrrolidine ((R,R′-PDP.

Development of chiral terminal-alkene-phosphine hybrid ligands for palladium-catalyzed asymmetric allylic substitutions.

Science.gov (United States)

Liu, Zhaoqun; Du, Haifeng

2010-07-02

A variety of novel chiral terminal-alkene-phosphine hybrid ligands were successfully developed from diethyl L-tartrate for palladium-catalyzed asymmetric allylic alkylations, etherifications, and amination to give the desired products in excellent yields and ee's.

Synthesis of 11C labelled methyl esters: transesterification of enol esters versus BF3 catalysed esterification-a comparative study

International Nuclear Information System (INIS)

Ackermann, Uwe; Blanc, Paul; Falzon, Cheryl L.; Issa, William; White, Jonathan; Tochon-Danguy, Henri J.; Sachinidis, John I.; Scott, Andrew M.

2006-01-01

C-11 labelled methyl esters have been synthesized via the transesterification of enol esters in the presence of C-11 methanol and 1,3 dichlorodibutylstannoxane as catalyst. This method leaves functional groups intact and allows access to a wider variety of C-11 labelled methyl esters compared to the BF 3 catalysed ester formation, which uses carboxylic acids and C-11 methanol as starting materials

Mechanism of the Suzuki–Miyaura Cross-Coupling Reaction Mediated by [Pd(NHC)(allyl)Cl] Precatalysts

KAUST Repository

Meconi, Giulia Magi

2017-05-24

Density functional theory calculations have been used to investigate the activation mechanism for the precatalyst series [Pd]-X-1–4 derived from [Pd(IPr)(R-allyl)X] species by substitutions at the terminal position of the allyl moiety ([Pd] = Pd(IPr); R = H (1), Me (2), gem-Me2 (3), Ph (4), X = Cl, Br). Next, we have investigated the Suzuki–Miyaura cross-coupling reaction for the active catalyst species IPr-Pd(0) using 4-chlorotoluene and phenylboronic acid as substrates and isopropyl alcohol as a solvent. Our theoretical findings predict an upper barrier trend, corresponding to the activation mechanism for the [Pd]-Cl-1–4 series, in good agreement with the experiments. They indeed provide a quantitative explanation of the low yield (12%) displayed by [Pd]-Cl-1 species (ΔG⧧ ≈ 30.0 kcal/mol) and of the high yields (≈90%) observed in the case of [Pd]-Cl-2–4 complexes (ΔG⧧ ≈ 20.0 kcal/mol). Additionally, the studied Suzuki–Miyaura reaction involving the IPr-Pd(0) species is calculated to be thermodynamically favorable and kinetically facile. Similar investigations for the [Pd]-Br-1–4 series, derived from [Pd(IPr)(R-allyl)Br], indicate that the oxidative addition step for IPr-Pd(0)-mediated catalysis with 4-bromotoluene is kinetically more favored than that with 4-chlorotoluene. Finally, we have explored the potential of Ni-based complexes [Ni((IPr)(R-allyl)X] (X = Cl, Br) as Suzuki–Miyaura reaction catalysts. Apart from a less endergonic reaction energy profile for both precatalyst activation and catalytic cycle, a steep increase in the predicted upper energy barriers (by 2.0–15.0 kcal/mol) is calculated in the activation mechanism for the [Ni]-X-1–4 series compared to the [Pd]-X-1–4 series. Overall, these results suggest that Ni-based precatalysts are expected to be less active than the Pd-based precatalysts for the studied Suzuki–Miyaura reaction.

Antiviral activity of an N-allyl acridone against dengue virus

OpenAIRE

Mazzucco, María Belén; Talarico, Laura Beatriz; Vatansever, Sezen; Carro, Ana Clara; Fascio, Mirta Liliana; D'Accorso, Norma Beatriz; Garcia, Cybele; Damonte, Elsa Beatriz

2016-01-01

Dengue virus (DENV), a member of the family Flaviviridae, is at present the most widespread causative agent of a human viral disease transmitted by mosquitoes. Despite the increasing incidence of this pathogen, there are no antiviral drugs or vaccines currently available for treatment or prevention. In a previous screening assay, we identified a group of N-allyl acridones as effective virus inhibitors. Here, the antiviral activity and mode of action targeted to viral RNA replication of one of...

Elucidation of the regio- and chemoselectivity of enzymatic allylic oxidations with Pleurotus sapidus – conversion of selected spirocyclic terpenoids and computational analysis

Directory of Open Access Journals (Sweden)

Verena Weidmann

2013-10-01

Full Text Available Allylic oxidations of olefins to enones allow the efficient synthesis of value-added products from simple olefinic precursors like terpenes or terpenoids. Biocatalytic variants have a large potential for industrial applications, particularly in the pharmaceutical and food industry. Herein we report efficient biocatalytic allylic oxidations of spirocyclic terpenoids by a lyophilisate of the edible fungus Pleurotus sapidus. This ‘’mushroom catalysis’’ is operationally simple and allows the conversion of various unsaturated spirocyclic terpenoids. A number of new spirocyclic enones have thus been obtained with good regio- and chemoselectivity and chiral separation protocols for enantiomeric mixtures have been developed. The oxidations follow a radical mechanism and the regioselectivity of the reaction is mainly determined by bond-dissociation energies of the available allylic CH-bonds and steric accessibility of the oxidation site.

Combined experimental and theoretical mechanistic investigation of the Barbier allylation in aqueous media

DEFF Research Database (Denmark)

Dam, Johan Hygum; Fristrup, Peter; Madsen, Robert

2008-01-01

-determining step. For Zn, In, Sn, Sb, and Bi, an inverse secondary kinetic isotope effect was found (k(H)/k(D) = 0.75-0.95), which was compatible with the formation of a discrete organometallic species prior to allylation via a closed six-membered transition state. With Mg, a significantly larger build...

Oxidation reaction of 4-allyl-4-hydroperoxy-2-methoxycyclohexa-2,5-dienone in the presence of potassium permanganate without a co-oxidant

Directory of Open Access Journals (Sweden)

Mehmet Serdar Gültekin

2016-12-01

Full Text Available 4-Allyl-4-hydroperoxy-2-methoxycyclohexa-2,5-dienone (5 was synthesized by photooxygenation of commercially available Eugenol in the presence of tetraphenylporphyrin (TPP as a singlet oxygen sensitizer. The brief and one-pot syntheses of some natural product skeletons were conducted using the corresponding allylic hydroperoxide at different temperatures (0 oC and room temperature with potassium permanganate (KMnO 4 in mild condition at N 2(g atm.

Enantioselective γ-Alkylation of α,β-Unsaturated Malonates and Ketoesters by a Sequential Ir-Catalyzed Asymmetric Allylic Alkylation/Cope Rearrangement

OpenAIRE

Liu, Wen-Bo; Okamoto, Noriko; Alexy, Eric J.; Hong, Allen Y.; Tran, Kristy; Stoltz, Brian M.

2016-01-01

A catalytic, enantioselective ? -alkylation of ?,?-unsaturated malonates and ketoesters is reported. This strategy entails a highly regio- and enantioselective iridium-catalyzed ?-alkylation of an extended enolate, and a subsequent translocation of chirality to the ?-position via a Cope rearrangement.

Stereochemical features of unsaturated aminodiesters - intermediates in the synthesis of Richlocaine

Directory of Open Access Journals (Sweden)

Meyrambek Ospanov

2014-10-01

Full Text Available The article provides information on the methods for synthesis of unsaturated aminodiesters, which are the key intermediates in the synthesis of N-substituted 2,5-dimethyl-piperidin-4-ones, including 1,2,5-trimetilpieridin-3-one. The developed method includes reaction of methyl ester of methacrylic acid with alkyl (alkenyl amines. The obtained N-alkyl(alkenyl-(2-methyl-2- carbmetoxyethyl methylamine are attached to acetoacetic ester being in the enol form. The optimal conditions for synthesis of N-alkyl(alkenyl-(2-methyl-2-carbethoxyethenemethylamines have been established. Results of gas chromatographic analysis has showed that, at room temperature, the reaction in polar solvents is delayed for two days. In non-polar solvents, the reaction runs with simultaneous distillation of water as an azeotrope with the solvent. Increase of the radical size at N atom has little effect on the reaction rate. Introduction of allyl radical at the nitrogen atom, apparently due to steric hindrance, resulted in lower reactivity of the monoester with allyl radical by condensation with acetoacetic ester. The structure of (1-methyl-2-carbethoxyethene-(2-methyl-2-carbmethoxyethyl methylamine has been studied by PMR spectroscopy. Study of the effect of chirality on the NMR spectra showed that, if the molecule of the organic compound has an asymmetric carbon atom, it may lead to the disappearance of the magnetic equivalence of neighboring protons or group of protons. Presence of an asymmetric carbon atom in b-position to the amino group of enamine leads to the disappearance of the magnetic equivalence of the neighboring protons is observed in the form of two quartets. For enaminodiesters, equilibrium is shifted toward the trans-S-cis conformer where less steric hindrance is pronounced.

An iron/amine-catalyzed cascade process for the enantioselective functionalization of allylic alcohols.

Science.gov (United States)

Quintard, Adrien; Constantieux, Thierry; Rodriguez, Jean

2013-12-02

Three is a lucky number: An enantioselective transformation of allylic alcohols into β-chiral saturated alcohols has been developed by combining two distinct metal- and organocatalyzed catalytic cycles. This waste-free triple cascade process merges an iron-catalyzed borrowing-hydrogen step with an aminocatalyzed nucleophilic addition reaction. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of carbonate esters by carboxymethylation using NaAlO2 as a highly active heterogeneous catalyst

OpenAIRE

Ramesh, Sreerangappa; Indukuri, Kiran; Riant, Olivier; Debecker, Damien

2018-01-01

Sodium aluminate is presented as a highly active heterogeneous catalyst able to convert a range of alcohols into the corresponding mixed carbonate esters, in high yield and under green conditions. The reaction is carried out using dimethyl carbonate both as a reactant and solvent, at 90°C. Allylic, aliphatic and aromatic alcohols are converted in good yields. The solid catalyst is shown to be truly heterogeneous, resistant to leaching, and recyclable.

Modification of Bisphenol-A Based Bismaleimide Resin (BPA-BMI) with an Allyl-Terminated Hyperbranched Polyimide (AT-PAEKI)

National Research Council Canada - National Science Library

Qin, Haihu; Mather, Patrick T; Baek, Jong-Beom; Tan, Loon-Seng

2006-01-01

As a continuation of previous work involving synthesis of an allyl-functionalized hyperbranched polyimide, AT-PAEKI, we have studied the use of this reactive polymer as a modifier of bisphenol-A based...

Catalytic Enantioselective Synthesis of Naturally Occurring Butenolides via Hetero-Allylic Alkylation and Ring Closing Metathesis

NARCIS (Netherlands)

Mao, Bin; Geurts, Koen; Fañanás-Mastral, Martín; Zijl, Anthoni W. van; Fletcher, Stephen P.; Minnaard, Adriaan J.; Feringa, Bernard

2011-01-01

An efficient catalytic asymmetric synthesis of chiral γ-butenolides was developed based on the hetero-allylic asymmetric alkylation (h-AAA) in combination with ring closing metathesis (RCM). The synthetic potential of the h-AAA-RCM protocol was illustrated with the facile synthesis of (-)-whiskey

One-pot synthesis of enantiomerically pure N-protected allylic amines from N-protected α-amino esters

Directory of Open Access Journals (Sweden)

Gastón Silveira-Dorta

2016-05-01

Full Text Available An improved protocol for the synthesis of enantiomerically pure allylic amines is reported. N-Protected α-amino esters derived from natural amino acids were submitted to a one-pot tandem reduction–olefination process. The sequential reduction with DIBAL-H at −78 °C and subsequent in situ addition of organophosphorus reagents yielded the corresponding allylic amines without the need to isolate the intermediate aldehyde. This circumvents the problem of instability of the aldehydes. The method tolerates well both Wittig and Horner–Wadsworth–Emmons organophosphorus reagents. A better Z-(diastereoselectivity was observed when compared to the previous one-pot method. The (diastereoselectivity of the process was affected neither by the reaction solvent nor by the amount of DIBAL-H employed. The method is compatible with the presence of free hydroxy groups as shown with serine and threonine derivatives.

Palladium Catalyzed Allylic C-H Alkylation

DEFF Research Database (Denmark)

Engelin, Casper Junker; Fristrup, Peter

2011-01-01

are highlighted with emphasis on those leading to C-C bond formation, but where it was deemed necessary for the general understanding of the process closely related C-H oxidations and aminations are also included. It is found that C-H cleavage is most likely achieved by ligand participation which could involve......-H alkylation reaction which is the topic of the current review. Particular emphasis is put on current mechanistic proposals for the three reaction types comprising the overall transformation: C-H activation, nucleophillic addition, and re-oxidation of the active catalyst. Recent advances in C-H bond activation...... an acetate ion coordinated to Pd. Several of the reported systems rely on benzoquinone for re-oxidation of the active catalyst. The scope for nucleophilic addition in allylic C-H alkylation is currently limited, due to demands on pKa of the nucleophile. This limitation could be due to the pH dependence...

Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

Science.gov (United States)

Sych, N. V.; Trofymenko, S. I.; Poddubnaya, O. I.; Tsyba, M. M.; Sapsay, V. I.; Klymchuk, D. O.; Puziy, A. M.

2012-11-01

Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 °C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (SBET = 2081 m2/g, Vtot = 1.1 cm3/g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0-2.6), weakly acidic carboxylic (pK = 4.7-5.0), enol/lactone (pK = 6.7-7.4; 8.8-9.4) and phenol (pK = 10.1-10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

An Investigation of the Enolization and Isomeric Products Distribution in the Water Promoted Aldol Reaction of Tropinone and Granatanone

Directory of Open Access Journals (Sweden)

Ryszard Lazny

2016-01-01

Full Text Available The exo,anti/exo,syn-diastereoselectivity of water promoted direct aldol reactions of tropinone and granatanone (pseudopelletierine is strongly dependent on the amount of water added and aromatic aldehyde used. DFT methods were applied to calculate the free energies of tropinone and granatanone enols, transition states, and isomeric aldol products. A theoretical model was verified by comparison of results from several DFT methods and functionals with experiments. The 6-31g(d/CPCM method proved most suited to the problem, although all methods tested predicted similar trends. Explicit inclusion of a water molecule bonded to the amino ketones resulted in increased stability of the enol forms. The dependence of the anti/syn-diastereoselectivity on the amount of water used may be rationalized on the basis of change in the polarity of the reaction medium. The predicted stabilities of competing products agreed with experimental results supporting the notion of thermodynamic control. The isomeric products distributions for the aldol reaction of several aromatic aldehydes in solventless (neat conditions were accurately calculated from free energies of the aldol addition step in the gas phase using B3LYP/6-31g(d method and in aqueous conditions using the CPCM-B3LYP/6-31g(d model. Our methodology can be useful for predicting the outcome of this type of aldol reactions.

Surface compounds and the routes of formation of the reaction products in the interaction of propylene with zinc oxide

Energy Technology Data Exchange (ETDEWEB)

Davydov, A.A.; Yefremov, A.A.; Mikhalchenko, V.G.; Sokolovskii, V.D.

1979-06-15

Temperature programed desorption of propylene and allyl bromide from zinc oxide in the absence and presence of oxygen and an IR spectroscopic study of the adsorbed allyl bromide showed that propylene chemisorbed reversibly as a m-allyl species which may undergo dimerization at higher pressures or temperatures but does not form acrolein because the necessary electron transfer does not proceed on the n-type zinc oxide; that propylene also forms carbon dioxide and water via carbonate/carboxylate intermediates; and that the allyl bromide, which forms cations on the zinc oxide surface, is oxidized to acrolein.

The reactivity of allyl and propargyl alcohols with solvated electrons: temperature and solvent effects

International Nuclear Information System (INIS)

Afanassiev, A.M.; Okazaki, K.; Freeman, G.R.

1979-01-01

The rate constants K 1 for the reaction of solvated electrons with allyl alcohol in a number of hydroxylic solvents differ by up to two orders of magnitude and decrease in the order tert-butyl alcohol > 2-propanol > l-propanol approximately ethanol > methanol approximately ethylene glycol > water. In methanol and ethylene glycol the rate constants (7 x 10 7 M -1 s -1 at 298 K) and activation energies (16 kJ/mol) are equal, in spite of a 32-fold difference in solvent viscosity (0.54 and 17.3 cP, respectively) and 3-fold difference in its activation energy (11 and 32 kJ/mol, respectively). The reaction in tert-butyl alcohol is nearly diffusion controlled and has a high activation energy that is characteristic of transport in that liquid (E 1 = 31 kJ/mol, E sub(eta) = 39 kJ/mol). The activation energies in the other alcohols are all 16 kJ/mol, and it is 14 kJ/mol in water. They do not correlate with transport properties. The solvent effect is connected primarily with the entropy of activation. The rate constants correlate with the solvated electron trap depth. When the electron affinity of the scavenger is small, a favorable configuration of solvent molecules about the electron/scavenger encounter pair is required for the electron jump to take place. The behavior of the rate parameters for propargyl alcohol is similar to that for allyl alcohol, but k 1 , A 1 , and E 1 are larger for the former. The ratio k(propargyl)/k(allyl) at 298 K equals 10.5 in water and decreases through the series, reaching 1.3 in tert-butyl alcohol. Rate parameters for several other scavengers are also reported. (author)

Iron(III) chloride catalyzed glycosylation of peracylated sugars with allyl/alkynyl alcohols

Energy Technology Data Exchange (ETDEWEB)

Narayanaperumal, Senthil; Silva, Rodrigo Cesar da; Monteiro, Julia L.; Correa, Arlene G.; Paixao, Marcio W., E-mail: mwpaixao@ufscar.br [Universidade Federal de Sao Carlos (UFSCAR), SP (Brazil). Dept. de Quimica

2012-11-15

In this work, the use of ferric chloride as an efficient catalyst in glycosylation reactions of sugars in the presence of allyl and alkynyl alcohols is described. The corresponding glycosides were obtained with moderate to good yields. This new procedure presented greater selectivity when compared to classic methods found in the literature. Principal features of this simple method include non-hazardous reaction conditions, low-catalyst loading, good yields and high anomeric selectivity (author)

Limonene dehydrogenase hydroxylates the allylic methyl group of cyclic monoterpenes in the anaerobic terpene degradation by Castellaniella defragrans.

Science.gov (United States)

Puentes-Cala, Edinson; Liebeke, Manuel; Markert, Stephanie; Harder, Jens

2018-05-01

The enzymatic functionalization of hydrocarbons is a central step in the global carbon cycle initiating the mineralization of methane, isoprene and monoterpenes, the most abundant biologically produced hydrocarbons. Also, terpene-modifying enzymes have found many applications in the energy-economic biotechnological production of fine chemicals. Here we describe a limonene dehydrogenase that was purified from the facultatively anaerobic betaproteobacterium Castellaniella defragrans 65Phen grown on monoterpenes under denitrifying conditions in the absence of molecular oxygen. The purified limonene:ferrocenium oxidoreductase activity hydroxylated the methyl group of limonene (1-methyl-4-(1-methylethenyl)-cyclohex-1-ene) yielding perillyl alcohol ([4-(prop-1-en-2-yl)cyclohex-1-en-1-yl]methanol). The enzyme had a dithiothreitol:perillyl alcohol oxidoreductase activity yielding limonene. Mass spectrometry and molecular size determinations revealed a heterodimeric enzyme comprising CtmA and CtmB. Recently the two proteins had been identified by transposon mutagenesis and proteomics as part of the cyclic terpene metabolism ( ctm ) in Castellaniella defragrans and were annotated as FAD-dependent oxidoreductases of the protein domain family phytoene dehydrogenases and related proteins (COG1233). CtmAB is the first heterodimeric enzyme in this protein superfamily. Flavins in the purified CtmAB are oxidized by ferrocenium and are reduced by limonene. Heterologous expression of CtmA, CtmB and CtmAB in E. coli demonstrated that limonene dehydrogenase activity required both subunits carrying each a flavin cofactor. Native CtmAB oxidized a wide range of monocyclic monoterpenes containing the allylic methyl group motif (1-methyl-cyclohex-1-ene). In conclusion, we have identified CtmAB as a hydroxylating limonene dehydrogenase and the first heteromer in a family of FAD-dependent dehydrogenases acting on allylic methylene or methyl CH-bonds. We suggest a placement in EC 1

Hydrogen-Bond Directed Regioselective Pd-Catalyzed Asymmetric Allylic Alkylation: The Construction of Chiral α-Amino Acids with Vicinal Tertiary and Quaternary Stereocenters.

Science.gov (United States)

Wei, Xuan; Liu, Delong; An, Qianjin; Zhang, Wanbin

2015-12-04

A Pd-catalyzed asymmetric allylic alkylation of azlactones with 4-arylvinyl-1,3-dioxolan-2-ones was developed, providing "branched" chiral α-amino acids with vicinal tertiary and quaternary stereocenters, in high yields and with excellent selectivities. Mechanistic studies revealed that the formation of a hydrogen bond between the Pd-allylic complex and azlactone isomer is responsible for the excellent regioselectivities. This asymmetric alkylation can be carried out on a gram scale without a loss of catalytic efficiency, and the resulting product can be further transformed to a chiral azetidine in two simple steps.

Effect of three 2-allyl-p-mentha-6,8-dien-2-ols on inhibition of mild steel corrosion in 1 M HCl

Directory of Open Access Journals (Sweden)

S. Kharchouf

2014-11-01

Full Text Available 2-Allyl-p-mentha-6,8-dien-2-ols P1−P3 synthesized from carvone P are tested as corrosion inhibitors of steel in 1 M HCl using weight loss measurements, potentiodynamic polarisation and impedance spectroscopy (EIS methods. The addition of 2-allyl-p-mentha-6,8-dien-2-ols reduced the corrosion rate. Potentiodynamic polarisation studies clearly reveal that the presence of inhibitors does not change the mechanism of hydrogen evolution and that they act essentially as cathodic inhibitors. 2-Allyl-p-mentha-6,8-dien-2-ols tested adsorb on the steel surface according to Langmuir isotherm. From the adsorption isotherm some thermodynamic data for the adsorption process are calculated and discussed. EIS measurements show the increase of the charge-transfer resistance with the inhibitor concentration. The highest inhibition efficiency (92% is obtained for P1 at 3 g/L. The corrosion rate decreases with the rise of temperature. The corresponding activation energies are determined.

Inactivation of Salmonella in tomato stem scars by organic acid wash and chitosan-allyl isothiocyanate coating

Science.gov (United States)

The objective of this study was to evaluate inactivation of inoculated Salmonella enterica on tomato stem scars exploiting integrated treatment of organic acid wash (AW) followed by chitosan-allyl isothiocyanate (CT-AIT) coating. The treatment effect on microbial loads and fruit quality during 21 d...

Pendant allyl crosslinking as a tunable shape memory actuator for vascular applications.

Science.gov (United States)

Boire, Timothy C; Gupta, Mukesh K; Zachman, Angela L; Lee, Sue Hyun; Balikov, Daniel A; Kim, Kwangho; Bellan, Leon M; Sung, Hak-Joon

2015-09-01

Thermo-responsive shape memory polymers (SMPs) can be programmed to fit into small-bore incisions and recover their functional shape upon deployment in the body. This property is of significant interest for developing the next generation of minimally-invasive medical devices. To be used in such applications, SMPs should exhibit adequate mechanical strengths that minimize adverse compliance mismatch-induced host responses (e.g. thrombosis, hyperplasia), be biodegradable, and demonstrate switch-like shape recovery near body temperature with favorable biocompatibility. Combinatorial approaches are essential in optimizing SMP material properties for a particular application. In this study, a new class of thermo-responsive SMPs with pendant, photocrosslinkable allyl groups, x%poly(ε-caprolactone)-co-y%(α-allyl carboxylate ε-caprolactone) (x%PCL-y%ACPCL), are created in a robust, facile manner with readily tunable material properties. Thermomechanical and shape memory properties can be drastically altered through subtle changes in allyl composition. Molecular weight and gel content can also be altered in this combinatorial format to fine-tune material properties. Materials exhibit highly elastic, switch-like shape recovery near 37°C. Endothelial compatibility is comparable to tissue culture polystyrene (TCPS) and 100%PCL in vitro and vascular compatibility is demonstrated in vivo in a murine model of hindlimb ischemia, indicating promising suitability for vascular applications. With the ongoing thrust to make surgeries minimally-invasive, it is prudent to develop new biomaterials that are highly compatible and effective in this workflow. Thermo-responsive shape memory polymers (SMPs) have great potential for minimally-invasive applications because SMP medical devices (e.g. stents, grafts) can fit into small-bore minimally-invasive surgical devices and recover their functional shape when deployed in the body. To realize their potential, it is imperative to devise

FeCl3-catalysed Zn-mediated allylation of cyclic enol ethers in water

Indian Academy of Sciences (India)

Organic reactions in aqueous medium has attracted global attention from the chemists due to its safe environmentally benign character. Surprisingly, nature also permits aqueous medium for all the enzymatic processes. Since Breslow1 introduced the Diels–Alder reaction in aqueous medium, there has been an increas-.

Mechanistic Dichotomy in the Asymmetric Allylation of Aldehydes with Allyltrichlorosilanes Catalyzed by Chiral Pyridine N-Oxides

Czech Academy of Sciences Publication Activity Database

Malkov, A. V.; Stončius, S.; Bell, M.; Castelluzzo, F.; Ramírez-López, P.; Biedermannová, Lada; Langer, V.; Rulíšek, Lubomír; Kočovský, P.

2013-01-01

Roč. 19, č. 28 (2013), s. 9167-9185 ISSN 0947-6539 R&D Projects: GA MŠk LC512 Institutional support: RVO:61388963 ; RVO:86652036 Keywords : allylation * allylsilanes * calculations * organocatalysis * pyridine N-oxides Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.696, year: 2013

Enzymatic synthesis of γ-L-glutamyl-S-allyl-L-cysteine, a naturally occurring organosulfur compound from garlic, by Bacillus licheniformis γ-glutamyltranspeptidase.

Science.gov (United States)

Chen, Yi-Yu; Lo, Huei-Fen; Wang, Tzu-Fan; Lin, Min-Guan; Lin, Long-Liu; Chi, Meng-Chun

2015-01-01

In the practical application of Bacillus licheniformis γ-glutamyltranspeptidase (BlGGT), we describe a straightforward enzymatic synthesis of γ-L-glutamyl-S-allyl-L-cysteine (GSAC), a naturally occurring organosulfur compound found in garlic, based on a transpeptidation reaction involving glutamine as the γ-glutamyl donor and S-allyl-L-cysteine as the acceptor. With the help of thin layer chromatography technique and computer-assisted image analysis, we performed the quantitative determination of GSAC. The optimum conditions for a biocatalyzed synthesis of GSAC were 200 mM glutamine, 200 mM S-allyl-L-cysteine, 50 mM Tris-HCl buffer (pH 9.0), and BlGGT at a final concentration of 1.0 U/mL. After a 15-h incubation of the reaction mixture at 60 °C, the GSAC yield for the free and immobilized enzymes was 19.3% and 18.3%, respectively. The enzymatic synthesis of GSAC was repeated under optimal conditions at 1-mmol preparative level. The reaction products together with the commercially available GSAC were further subjected to an ESI-MS/MS analysis. A significant signal with m/z of 291.1 and the protonated fragments at m/z of 73.0, 130.1, 145.0, and 162.1 were observed in the positive ESI-MS/MS spectrum, which is consistent with those of the standard compound. These results confirm the successful synthesis of GSAC from glutamine and S-allyl-L-cysteine by BlGGT. Copyright © 2015 Elsevier Inc. All rights reserved.

Preparation of pyrrolizinone derivatives via sequential transformations of cyclic allyl imides: synthesis of quinolactacide and marinamide.

Science.gov (United States)

Simic, Milena; Tasic, Gordana; Jovanovic, Predrag; Petkovic, Milos; Savic, Vladimir

2018-03-28

A facile synthetic route has been developed for the preparation of pyrrolizinone derivatives employing N-allyl imides as starting materials. The nucleophilic addition of a vinyl Grignard reagent/RCM/elimination sequence afforded pyrrolizinones in good yields and has been applied for the preparation of naturally occurring quinolactacide and marinamide.

Nickel-Catalyzed Alkoxy-Alkyl Interconversion with Alkylborane Reagents through C−O Bond Activation of Aryl and Enol Ethers

KAUST Repository

Guo, Lin

2016-11-07

A nickel-catalyzed alkylation of polycyclic aromatic methyl ethers as well as methyl enol ethers with B-alkyl 9-BBN and trialkylborane reagents that involves the cleavage of stable C(sp2)−OMe bonds is described. The transformation has a wide substrate scope and good chemoselectivity profile while proceeding under mild reaction conditions; it provides a versatile way to form C(sp2)−C(sp3) bonds that does not suffer from β-hydride elimination. Furthermore, a selective and sequential alkylation process by cleavage of inert C−O bonds is presented to demonstrate the advantage of this method.

Aqueous protocol for allylic arylation of cinnamyl acetates with sodium tetraphenylborate using Bedford-type palladacycle catalyst

KAUST Repository

Ghorpade, Seema Arun; Sawant, Dinesh N; Renn, Dominik; Zernickel, Anna; Du, Weiyuan; Sekar, Nethi; Eppinger, Jö rg

2018-01-01

Allylic arylation of cinnamyl acetates with sodium tetraphenylborate using 0.002 mol % of Bedford-type palladacycle catalyst is described. The developed methodology is applicable for wide range of cinnamyl acetates furnishing excellent yields up to 93%. Notably all reactions proceed smoothly under mild reaction conditions in water under air atmosphere.

Aqueous protocol for allylic arylation of cinnamyl acetates with sodium tetraphenylborate using Bedford-type palladacycle catalyst

KAUST Repository

Ghorpade, Seema Arun

2018-03-19

Allylic arylation of cinnamyl acetates with sodium tetraphenylborate using 0.002 mol % of Bedford-type palladacycle catalyst is described. The developed methodology is applicable for wide range of cinnamyl acetates furnishing excellent yields up to 93%. Notably all reactions proceed smoothly under mild reaction conditions in water under air atmosphere.

Modulation of the multidrug efflux pump EmrD-3 from Vibrio cholerae by Allium sativum extract and the bioactive agent allyl sulfide plus synergistic enhancement of antimicrobial susceptibility by A. sativum extract.

Science.gov (United States)

Bruns, Merissa M; Kakarla, Prathusha; Floyd, Jared T; Mukherjee, Mun Mun; Ponce, Robert C; Garcia, John A; Ranaweera, Indrika; Sanford, Leslie M; Hernandez, Alberto J; Willmon, T Mark; Tolson, Grace L; Varela, Manuel F

2017-10-01

The causative agent of cholera, Vibrio cholerae, is a public health concern. Multidrug-resistant V. cholerae variants may reduce chemotherapeutic efficacies of severe cholera. We previously reported that the multidrug efflux pump EmrD-3 from V. cholerae confers resistance to multiple structurally distinct antimicrobials. Medicinal plant compounds are potential candidates for EmrD-3 efflux pump modulation. The antibacterial activities of garlic Allium sativum, although poorly understood, predicts that a main bioactive component, allyl sulfide, modulates EmrD-3 efflux. Thus, we tested whether A. sativum extract acts in synergy with antimicrobials and that a main bioactive component allyl sulfide inhibits EmrD-3 efflux. We found that A. sativum extract and allyl sulfide inhibited ethidium bromide efflux in cells harboring EmrD-3 and that A. sativum lowered the MICs of multiple antibacterials. We conclude that A. sativum and allyl sulfide inhibit EmrD-3 and that A. sativum extract synergistically enhances antibacterial agents.

Chemoenzymatic synthesis of chiral 2,2'-bipyridine ligands and their N-oxide derivatives: applications in the asymmetric aminolysis of epoxides and asymmetric allylation of aldehydes.

Science.gov (United States)

Boyd, D R; Sharma, N D; Sbircea, L; Murphy, D; Malone, J F; James, S L; Allen, C C R; Hamilton, J T G

2010-03-07

A series of enantiopure 2,2'-bipyridines have been synthesised from the corresponding cis-dihydrodiol metabolites of 2-chloroquinolines. Several of the resulting hydroxylated 2,2'-bipyridines were found to be useful chiral ligands for the asymmetric aminolysis of meso-epoxides leading to the formation of enantioenriched amino alcohols (-->84% ee). N-oxide and N,N'-dioxide derivatives of these 2,2'-bipyridines, including separable atropisomers, have been synthesised and used as enantioselective organocatalysts in the asymmetric allylation of aldehydes to give allylic alcohols (-->86% ee).

Synthesis and reactivity of compounds containing ruthenium-carbon, -nitrogen, and -oxygen bonds

International Nuclear Information System (INIS)

Hartwig, J.F.

1990-12-01

The products and mechanisms of the thermal reactions of several complexes of the general structure (PMe 3 ) 4 Ru(X)(Y) and (DMPM) 2 Ru(X)(Y) where X and Y are hydride, aryl, and benzyl groups, have been investigated. The mechanism of decomposition depends critically on the structure of the complex and the medium in which the thermolysis is carried out. The alkyl hydride complexes are do not react with alkane solvent, but undergo C-H activation processes with aromatic solvents by several different mechanisms. Thermolysis of (PMe 3 ) 4 Ru(Ph)(Me) or (PMe 3 ) 4 Ru(Ph) 2 leads to the ruthenium benzyne complex (PMe 3 ) 4 Ru(η 2 -C 6 H 4 ) (1) by a mechanism which involves reversible dissociation of phosphine. In many ways its chemistry is analogous to that of early rather than late organo transition metal complexes. The synthesis, structure, variable temperature NMR spectroscopy and reactivity of ruthenium complexes containing aryloxide or arylamide ligands are reported. These complexes undergo cleavage of a P-C bond in coordinated trimethylphosphine, insertion of CO and CO 2 and hydrogenolysis. Mechanistic studies on these reactions are described. The generation of a series of reactive ruthenium complexes of the general formula (PMe 3 ) 4 Ru(R)(enolate) is reported. Most of these enolates have been shown to bind to the ruthenium center through the oxygen atom. Two of the enolate complexes 8 and 9 exist in equilibrium between the O- and C-bound forms. The reactions of these compounds are reported, including reactions to form oxygen-containing metallacycles. The structure and reactivity of these ruthenium metallacycles is reported, including their thermal chemistry and reactivity toward protic acids, electrophiles, carbon monoxide, hydrogen and trimethylsilane. 243 refs., 10 tabs

Synthesis and reactivity of compounds containing ruthenium-carbon, -nitrogen, and -oxygen bonds

Energy Technology Data Exchange (ETDEWEB)

Hartwig, J.F.

1990-12-01

The products and mechanisms of the thermal reactions of several complexes of the general structure (PMe{sub 3}){sub 4}Ru(X)(Y) and (DMPM){sub 2}Ru(X)(Y) where X and Y are hydride, aryl, and benzyl groups, have been investigated. The mechanism of decomposition depends critically on the structure of the complex and the medium in which the thermolysis is carried out. The alkyl hydride complexes are do not react with alkane solvent, but undergo C-H activation processes with aromatic solvents by several different mechanisms. Thermolysis of (PMe{sub 3}){sub 4}Ru(Ph)(Me) or (PMe{sub 3}){sub 4}Ru(Ph){sub 2} leads to the ruthenium benzyne complex (PMe{sub 3}){sub 4}Ru({eta}{sup 2}-C{sub 6}H{sub 4}) (1) by a mechanism which involves reversible dissociation of phosphine. In many ways its chemistry is analogous to that of early rather than late organo transition metal complexes. The synthesis, structure, variable temperature NMR spectroscopy and reactivity of ruthenium complexes containing aryloxide or arylamide ligands are reported. These complexes undergo cleavage of a P-C bond in coordinated trimethylphosphine, insertion of CO and CO{sub 2} and hydrogenolysis. Mechanistic studies on these reactions are described. The generation of a series of reactive ruthenium complexes of the general formula (PMe{sub 3}){sub 4}Ru(R)(enolate) is reported. Most of these enolates have been shown to bind to the ruthenium center through the oxygen atom. Two of the enolate complexes 8 and 9 exist in equilibrium between the O- and C-bound forms. The reactions of these compounds are reported, including reactions to form oxygen-containing metallacycles. The structure and reactivity of these ruthenium metallacycles is reported, including their thermal chemistry and reactivity toward protic acids, electrophiles, carbon monoxide, hydrogen and trimethylsilane. 243 refs., 10 tabs.

Stereoselective syntheses of (+- isoretronecanol and (+-5-epi-tashiromine via addition of chiral titanium (iv enolates to cyclic n-acyliminium ions

Directory of Open Access Journals (Sweden)

Elaine Pereira

2008-01-01

Full Text Available The stereoselective addition of the titanium (IV enolates derived from (S-4-isopropyl-N-4-chlorobutyryl-1,3-thiazolidine-2-thione (8 and from (S-4-isopropyl-N-4-chloropentanoyl-1,3-thiazolidine-2-thione (9 to N-Boc-2-methoxypyrrolidine (5b afforded the addition products (+-10 and (+-11 in 84% yield in both cases, as 8.6:1 and 10:1 diastereoisomeric mixtures, respectively. A three-step sequence allowed to convert these adducts to (+-isoretronecanol (1 and (+-5-epi-tashiromine (2 in 43% and 49% overall yield, respectively.

Stereoselective syntheses of (+)- isoretronecanol and (+)-5-epi-tashiromine via addition of chiral titanium (IV) enolates to cyclic n-acyliminium ions

Energy Technology Data Exchange (ETDEWEB)

Pereira, Elaine; Alves, Conceicao de Fatima; Boeckelmann, Maria Alice; Pilli, Ronaldo A [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Inst. de Quimica

2008-07-01

The stereoselective addition of the titanium (IV) enolates derived from (S)-4-isopropyl-N-4-chlorobutyryl-1,3-thiazolidine-2-thione (8) and from (S)-4-isopropyl-N-4-chloropentanoyl-1,3-thiazolidine-2-thione (9) to N-Boc-2-methoxypyrrolidine (5b) afforded the addition products (+)-10 and (+)-11 in 84% yield in both cases, as 8.6:1 and 10:1 diastereoisomeric mixtures, respectively. A three-step sequence allowed to convert these adducts to (+)-isoretronecanol (1) and (+)-5-epi-tashiromine (2) in 43% and 49% overall yield, respectively. (author)

S-Allyl cysteine improves nonalcoholic fatty liver disease in type 2 diabetes Otsuka Long-Evans Tokushima Fatty rats via regulation of hepatic lipogenesis and glucose metabolism

OpenAIRE

Takemura, Shigekazu; Minamiyama, Yukiko; Kodai, Shintaro; Shinkawa, Hiroji; Tsukioka, Takuma; Okada, Shigeru; Azuma, Hideki; Kubo, Shoji

2013-01-01

It is important to prevent and improve diabetes mellitus and its complications in a safe and low-cost manner. S-Allyl cysteine, an aged garlic extract with antioxidant activity, was investigated to determine whether S-allyl cysteine can improve type 2 diabetes in Otsuka Long-Evans Tokushima Fatty rats with nonalcoholic fatty liver disease. Male Otsuka Long-Evans Tokushima Fatty rats and age-matched Long-Evans Tokushima Otsuka rats were used and were divided into two groups at 29 weeks of age....

Therapeutic Efficacy of Allyl Isothiocyanate Evaluated on N-Nitrosodiethylamine/Phenobarbitol induced Hepatocarcinogenesis in Wistar Rats

Directory of Open Access Journals (Sweden)

G. Thiyagarajan

2010-07-01

Full Text Available N-nitrosodiethylamine (NDEA is a potential carcinogenic agent that induces liver cancer. To evaluate the chemotherapeutic effect of Allyl isothiocyanate in the experimental model, Wistar male rats were administered single dose of intraperitoneal (IP injection of NDEA. Two weeks after administration of NDEA, Phenobarbital at the concentration of 0.05% was incorporated in rat chow for up to 14 successive weeks to promote liver cancer. Allyl isothiocyanate (AITC (2mg/kg body weight in addition with 0.5ml of corn oil was given orally on a daily basis. At the end of this experimental period, the rats were sacrificed and the blood samples were taken for biochemical studies. The levels of the marker enzymes for liver function were measured in serum. The results of the biochemical studies showed that NDEA administration followed by phenobarbital induces macro and microscopic liver tumors that increase the levels of marker enzymes and decreases the level of antioxidant in the serum in addition to loss of body weight. Conclusively, the administration of AITC as therapeutic treatment for hepatocarcinoma has significantly reduced the tumor development and counteracted all the biochemical effects induced by NDEA.

Method of preparing water purification membranes. [polymerization of allyl amine as thin films in plasma discharge

Science.gov (United States)

Hollahan, J. R.; Wydeven, T. J., Jr. (Inventor)

1974-01-01

Allyl amine and chemically related compounds are polymerized as thin films in the presence of a plasma discharge. The monomer compound can be polymerized by itself or in the presence of an additive gas to promote polymerization and act as a carrier. The polymerized films thus produced show outstanding advantages when used as reverse osmosis membranes.

Synthesis of New Chiral 2,2'-bipyridine ligands and their application in copper-catalyzed asymmetric allylic oxidation and cyclopropanation

Czech Academy of Sciences Publication Activity Database

Malkov, A. V.; Pernazza, D.; Bell, M.; Bella, M.; Massa, A.; Teplý, Filip; Meghani, P.; Kočovský, P.

2003-01-01

Roč. 68, č. 12 (2003), s. 4727-4742 ISSN 0022-3263 Institutional research plan: CEZ:AV0Z4055905 Keywords : optically-active bipyridine * enantioselective cyclopropanation * allylic oxidation Subject RIV: CC - Organic Chemistry Impact factor: 3.297, year: 2003

Highly Diastereoselective Indium-Mediated Allylation of Proline-Derived Hydrazones

International Nuclear Information System (INIS)

Satyender, Apuri; Jang, Doo Ok

2013-01-01

A highly diastereoselective indium-mediated addition reaction to L-proline-derived hydrazones has been developed. The method affords an efficient and general synthesis of homoallylic amines of high optically purity in high yields and diastereomeric ratios up to 98:2. It is well known that (S)-1-amino-2-methoxymethylpyrro-lidine and (S)-4-isopropyl- or (S)-4-phenylmethyl-oxa-zolidin-2-one-derived hydrazones have been used for metal-mediated diastereoselective allylation additions to produce chiral homoallylic amines. However, the optically pure hydrazine precursors are either commercially expensive and/or involve laborious synthetic procedures employing toxic reagents for their preparation. Thus, the design of novel classes of chiral hydrazines that would further broaden the scope of asymmetric synthesis to access optically pure homoallylic amines is highly desirable

Formation of Ketenimines via the Palladium-Catalyzed Decarboxylative π-Allylic Rearrangement of N-Alloc Ynamides.

Science.gov (United States)

Alexander, Juliana R; Cook, Matthew J

2017-11-03

A new approach for the formation of ketenimines via a decarboxylative allylic rearrangement pathway that does not require strong stabilizing or protecting groups has been developed. The products can be readily hydrolyzed into their corresponding secondary amides or reacted with sulfur ylides to perform an additional [2,3]-Wittig process. Mechanistic studies suggest an outer-sphere process in which reductive alkylation is rate-limiting.

Eosin Y-catalyzed, visible-light-promoted carbophosphinylation of allylic alcohols via a radical neophyl rearrangement.

Science.gov (United States)

Yin, Yao; Weng, Wei-Zhi; Sun, Jian-Guo; Zhang, Bo

2018-03-28

A visible-light-promoted phosphinylation of allylic alcohols with concomitant 1,2-aryl migration is described. This transformation proceeds smoothly under metal-free and mild conditions by using an inexpensive organic dye, eosin Y, as the photocatalyst, affording various β-aryl-γ-ketophosphine oxides in moderate to good yields. Mechanistic studies suggested that the 1,2-aryl migration proceeded through a radical (neophyl) rearrangement.

Oxidant-free Rh(III)-catalyzed direct C-H olefination of arenes with allyl acetates.

Science.gov (United States)

Feng, Chao; Feng, Daming; Loh, Teck-Peng

2013-07-19

Rh(III)-catalyzed direct olefination of arenes with allyl acetate via C-H bond activation is described using N,N-disubstituted aminocarbonyl as the directing group. The catalyst undergoes a redox neutral process, and high to excellent yields of trans-products are obtained. This protocol exhibits a wide spectrum of functionality compatibility because of the simple reaction conditions employed and provides a highly effective synthetic method in the realm of C-H olefination.

γ‐ and δ-Lactams through Palladium-Catalyzed Intramolecular Allylic Alkylation: Enantioselective Synthesis, NMR Investigation, and DFT Rationalization

DEFF Research Database (Denmark)

Bantreil, Xavier; Prestat, Guillaume; Moreno, Aitor

2011-01-01

the cyclization reactions to take place in up to 94:6 enantiomeric ratio. A model Pd-allyl complex has been prepared and studied through NMR spectroscopic analysis, which provided insight into the processes responsible for the observed enantiomeric ratios. DFT studies were used to characterize the diastereomeric...

Highly efficient and generalized asymmetric synthesis of quaternary stereogenic carbon-containing β-amino indanones/indanoles via Mannich-type additions between 1-indanones and N-tert-butanesulfinylketimines.

Science.gov (United States)

Wu, Lingmin; Xie, Chen; Mei, Haibo; Soloshonok, Vadim A; Han, Jianlin; Pan, Yi

2014-07-14

Here we report that, unlike other ketones, 1-indanone and acetophenone derived enolates undergo Mannich-type addition reactions with N-tert-butanesulfinyl ketimines with excellent yields (up to 98%) and diastereoselectivity (>99/1). The resulting compounds represent a new type of biologically relevant β-aminoketone derivative bearing quaternary stereogenic carbon, which could be further converted into the corresponding β-amino ketones and β-amino alcohols, possessing three consecutive stereogenic centres.

Redox and Lewis acid relay catalysis: a titanocene/zinc catalytic platform in the development of multicomponent coupling reactions.

Science.gov (United States)

Gianino, Joseph B; Campos, Catherine A; Lepore, Antonio J; Pinkerton, David M; Ashfeld, Brandon L

2014-12-19

A titanocene-catalyzed multicomponent coupling is described herein. Using catalytic titanocene, phosphine, and zinc dust, zinc acetylides can be generated from the corresponding iodoalkynes to affect sequential nucleophilic additions to aromatic aldehydes. The intermediate propargylic alkoxides are trapped in situ with acetic anhydride, which are susceptible to a second nucleophilic displacement upon treatment with a variety of electron-rich species, including acetylides, allyl silanes, electron-rich aromatics, silyl enol ethers, and silyl ketene acetals. Additionally, employing cyclopropane carboxaldehydes led to ring-opened products resulting from iodine incorporation. Taken together, these results form the basis for a new mode of three-component coupling reactions, which allows for rapid access to value added products in a single synthetic operation.

Inicios de la microbiología enológica gallega

Directory of Open Access Journals (Sweden)

Carrascosa, Alfonso V.

2010-12-01

parte de este esfuerzo fue finalmente aplicado a la enología, cristalizando en la Teoría Ecológica del Vino. Los primeros estudios científicos de microbiología enológica gallega fueron realizados en el Departamento de Microbiología del Instituto de Fermentaciones Industriales del CSIC (IFI-CSIC en la década de los 70, y formaron parte de las evidencias que sirvieron para establecer dicha teoría. Instalaciones inadecuadas, unidas al empleo masivo de fungicidas y sulfuroso como antisépticos, fueron identificados como posibles causas de los problemas detectados durante el estudio de la vinificación. Finalmente se recomendaría como idóneo para salvaguardar el tipismo de los vinos gallegos, y reducir al mínimo el empleo de dióxido de azufre, la inoculación secuencial de los mostos con las levaduras que fueron aisladas en el estudio y que todavía se conservan en el IFI-CSIC. En este artículo se presentan los resultados de esos estudios, sus consecuencias, y la situación en la que se encontraba la microbiología enológica española en esos momentos.

Fluorinated benzamide neuroleptics--III. Development of (S)-N-[(1-allyl-2-pyrrolidinyl)methyl]-5-(3-[{sup 18}F]fluoropropyl)-2,3- dimethoxybenzamide as an improved dopamine D-2 receptor tracer

Energy Technology Data Exchange (ETDEWEB)

Mukherjee, Jogeshwar; Zhiying, Yang; Das, Malay K; Brown, Terry

1995-04-01

We have prepared five new analogs (n-propyl, iso-propyl, allyl, n-butyl, and iso-butyl) of the dopamine D-2 receptor antagonist, FPMB which result from modifications of the ethyl group at the pyrrolidine nitrogen in FPMB. As expected, all new derivatives showed higher apparent lipophilicity (log k{sub w}), with iso-butyl being the most lipophilic (log k{sub w} = 2.52), followed by the allyl derivative (log k{sub w} = 2.43). The allyl group showed the largest increase in affinity (from 0.26 nM for the ethyl substituent to 0.03 nM for the allyl substituent, almost 10-fold), followed by the n-propyl substituent which showed approximately five-fold better affinity than did the ethyl substituent. Radiosynthesis of S-N-[(1-allyl-2-pyrrolidinyl)methyl]-5-(3-[{sup 18}F]fluoropropyl)-2,3-dimethoxybenzamide ([{sup 18}F]fallypride) was carried out by nucleophilic substitution reaction of (S)-N-[(1-allyl-2-pyrrolidinyl)methyl]-5-(3-tosyloxypropyl)-2,3- dimethoxybenzamide with no carrier added {sup 18}F{sup -}. [{sup 18}F]Fallypride was obtained in approximately 20-40% yields (EOS/EOB, decay corrected) in specific activities of 900-1700 Ci/mmol after reverse phase HPLC purification in 60 min from EOB. High striatal uptake (upto 2.5% injected dose/g) of [{sup 18}F]fallypride in rats was observed with striatal/cerebellar ratios of 17, 42, 63 and 122 at 30, 60, 90 and 120 min post-injection, respectively. PET experiments with [{sup 18}F]fallypride in a cebus monkey showed a brain uptake of 0.10% injected dose/cc. In rhesus monkeys [{sup 18}F]fallypride showed rapid specific uptake in the striata (0.04-0.06% injected dose/cc) with striata/cerebellum ratios of approx. 3.0 at 14 min, 5.0 at 35 min and 8 at 70 min post-injection. Specifically bound [{sup 18}F]fallypride was displaced with haloperidol (1 mg/kg) with a half-life of 18 min in the rhesus monkey.

Structural dependence of the multi-functionalized carbon nanotubes to the substituents on the grafted diazo compounds

Science.gov (United States)

Amiri, Rahebeh; Rasouli, Sousan; Ghasemi, Alireza; Eghbali, Babak; Mohammadi, Soutodeh

2014-05-01

Systematic studies on the covalent functionalization of multi-walled carbon nanotubes were performed by a series of azo molecules with different substituents. For this investigation, 4-substituted diazonium reagents have been used in the reaction with the functionalized multi-walled carbon nanotubes. We analyzed the effect of the substituted groups on the diazo component affinity in the grafting. Also, the structural differences of the final products were evaluated by visual dispersion test, UV-Vis absorption. Fourier transforms infrared, Raman, and several complementary techniques (scanning electron microscopy, thermal gravimetric analysis, and colorimetry test). Nuclear magnetic resonance spectroscopy has been used to confirm the allylic protons attached to the surface of carbon nanotubes after functionalization.

Reprint of: Pendant allyl crosslinking as a tunable shape memory actuator for vascular applications.

Science.gov (United States)

Boire, Timothy C; Gupta, Mukesh K; Zachman, Angela L; Lee, Sue Hyun; Balikov, Daniel A; Kim, Kwangho; Bellan, Leon M; Sung, Hak-Joon

2016-04-01

Thermo-responsive shape memory polymers (SMPs) can be programmed to fit into small-bore incisions and recover their functional shape upon deployment in the body. This property is of significant interest for developing the next generation of minimally-invasive medical devices. To be used in such applications, SMPs should exhibit adequate mechanical strengths that minimize adverse compliance mismatch-induced host responses (e.g. thrombosis, hyperplasia), be biodegradable, and demonstrate switch-like shape recovery near body temperature with favorable biocompatibility. Combinatorial approaches are essential in optimizing SMP material properties for a particular application. In this study, a new class of thermo-responsive SMPs with pendant, photocrosslinkable allyl groups, x%poly(ε-caprolactone)-co-y%(α-allyl carboxylate ε-caprolactone) (x%PCL-y%ACPCL), are created in a robust, facile manner with readily tunable material properties. Thermomechanical and shape memory properties can be drastically altered through subtle changes in allyl composition. Molecular weight and gel content can also be altered in this combinatorial format to fine-tune material properties. Materials exhibit highly elastic, switch-like shape recovery near 37 °C. Endothelial compatibility is comparable to tissue culture polystyrene (TCPS) and 100%PCL in vitro and vascular compatibility is demonstrated in vivo in a murine model of hindlimb ischemia, indicating promising suitability for vascular applications. With the ongoing thrust to make surgeries minimally-invasive, it is prudent to develop new biomaterials that are highly compatible and effective in this workflow. Thermo-responsive shape memory polymers (SMPs) have great potential for minimally-invasive applications because SMP medical devices (e.g. stents, grafts) can fit into small-bore minimally-invasive surgical devices and recover their functional shape when deployed in the body. To realize their potential, it is imperative to devise

Turismo enológico en Uruguay: ¿qué quiere el visitante local?

Directory of Open Access Journals (Sweden)

Gianfranca María Camussi Calvi

2016-01-01

Full Text Available El turismo enológico en Uruguay comienza a desarrollarse, con una demanda compuesta mayoritariamente por turistas extranjeros y visitantes locales en segundo plano. Con el objetivo de aportar conocimiento sobre el visitante doméstico y sus expectativas y aspiraciones, para el logro de un plan de marketing ajustado, se realizó una encuesta, a residentes de Montevideo de alto nivel socioeconómico. El 86% desea realizar enoturismo; los intereses específicos permiten separar grupos por afinidad. Respecto a las actividades propias del enoturismo, se diferencia un grupo que desea focalizarse en degustar y comprar vino, y otro que prefiere conocer el proceso productivo completo. Todos desean actividades complementarias, y se dicotomizan en - un grupo que prefiere gastronomía, cultura y arte, - mientras el otro, deportes o actividades al aire libre. Se ha identificado la amplitud de servicios para un turismo del vino exitoso que busque la satisfacción del cliente y la fidelización de los visitantes locales.

Isovanillin derived N-(un)substituted hydroxylamines possessing an ortho-allylic group: valuable precursors to bioactive N-heterocycles.

Science.gov (United States)

Dulla, Balakrishna; Tangellamudi, Neelima D; Balasubramanian, Sridhar; Yellanki, Swapna; Medishetti, Raghavender; Kumar Banote, Rakesh; Hari Chaudhari, Girish; Kulkarni, Pushkar; Iqbal, Javed; Reiser, Oliver; Pal, Manojit

2014-04-28

The intramolecular 1,3-dipolar cycloaddition of isovanillin derived N-aryl hydroxylamines possessing ortho-allylic dipolarophiles affords novel benzo analogues of tricyclic isoxazolidines that can be readily transformed into functionalized lactams, γ-aminoalcohols and oxazepines. The corresponding N-unsubstituted hydroxylamines give rise to tetrahydroisoquinolines. Anxiogenic properties of these compounds are tested in zebra fish.

Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate.

Science.gov (United States)

Ding, Liyuan; Yu, Chunbing; Zhao, Zhenqiang; Li, Feifei; Zhang, Jian; Zhong, Guofu

2017-06-21

Direct cross-coupling between two alkenes via vinylic C-H bond activation represents an efficient strategy for the synthesis of butadienes with high atomic and step economy. However, this functionality-directed cross-coupling reaction has not been developed, as there are still limited directing groups in practical use. In particular, a stoichiometric amount of oxidant is usually required, producing a large amount of waste. Due to our interest in novel 1,3-butadiene synthesis, we describe the ruthenium-catalyzed olefination of electron-deficient alkenes using allyl acetate and without external oxidant. The reaction of 2-phenyl acrylamide and allyl acetate was chosen as a model reaction, and the desired diene product was obtained in 80% isolated yield with good stereoselectivity (Z,E/Z,Z = 88:12) under optimal conditions: [Ru(p-cymene) Cl2]2 (3 mol %) and AgSbF6 (20 mol %) in DCE at 110 ºC for 16 h. With the optimized catalytic conditions in hand, representative α- and/or β-substituted acrylamides were investigated, and all reacted smoothly, regardless of aliphatic or aromatic groups. Also, differently N-substituted acrylamides have proven to be good substrates. Moreover, we examined the reactivity of different allyl derivatives, suggesting that the chelation of acetate oxygen to the metal is crucial for the catalytic process. Deuterium-labeled experiments were also conducted to investigate the reaction mechanism. Only Z-selective H/D exchanges on acrylamide were observed, indicating a reversible cyclometalation event. In addition, a kinetic isotope effect (KIE) of 3.2 was observed in the intermolecular isotopic study, suggesting that the olefinic C-H metalation step is probably involved in the rate-determining step.

Structure and stability of acrolein and allyl alcohol networks on Ag(111) from density functional theory based calculations with dispersion corrections

Science.gov (United States)

Ferullo, Ricardo M.; Branda, Maria Marta; Illas, Francesc

2013-11-01

The interaction of acrolein and allyl alcohol with the Ag(111) surface has been studied by means of periodic density functional theory based calculations including explicitly dispersion terms. Different coverage values have been explored going from isolated adsorbed molecules to isolated dimers, interacting dimers or ordered overlayers. The inclusion of the dispersion terms largely affects the calculated values of the adsorption energy and also the distance between adsorbed molecule and the metallic surface but much less the adsorbate-adsorbate interactions. Owing to the large dipole moment of acrolein, the present calculations predict that at high coverage this molecule forms a stable extensive two-dimensional network on the surface, caused by the alignment of the adsorbate dipoles. For the case of allyl alcohol, dimers and complex networks exhibit similar stability.

Unusual selectivity-determining factors in the phosphine-free Heck arylation of allyl ethers

DEFF Research Database (Denmark)

Ambrogio, I.; Fabrizi, G.; Cacchi, S.

2008-01-01

The Heck reaction of aryl iodides and bromides with allyl ethers has been investigated. Using phosphinefree Pd(OAc)(2) in DNIF at 90 degrees C in the presence of Bu4NOAc, the reaction gave cinnamyl derivatives, usually in good to high yields, with a wide range of aryl halides. The reaction...... tolerates a variety of functional groups, including ether, amide, alcohol, aldehyde, ketone, ester, cyano, carboxylic acid, and nitro groups. Ortho-substituted arylating agents afforded moderate yields in some cases, though good to high yields were obtained with o-iodotoluene, iodovanillin, and 1...

Methods for Shortening and Extending the Carbon Chain in Carbohydrates

DEFF Research Database (Denmark)

Monrad, Rune Nygaard

2008-01-01

in this thesis focuses on the development and application of transition metal mediated methods for shortening and extending the carbon chain in carbohydrates thereby providing access to lower and higher sugars.A new catalytic procedure for shortening unprotected sugars by one carbon atom has been developed....... The procedure has been employed as the key step in a short five-step synthesis of the unnatural sugar L-threose in 74% overall yield from D-glucose. A zinc-mediated one-pot fragmentation-allylation reaction has been used to elongate D-glucose and D-ribose by three carbon atoms thereby producing carbohydrate......-derived α,ω-dienes, which have been converted into the natural products calystegine A3 and gabosine A. The glycosidase inhibitor calystegine A3 was produced by two similar routes from commercially available methyl α-D-glucopyranoside in 13 and 14 steps with 8.3 and 5.3% overall yield, respectively...

Ion beam-induced topographical and chemical modification on the poly(styrene-co-allyl alcohol) and its effect on the molecular interaction between the modified surface and liquid crystals

International Nuclear Information System (INIS)

Jeong, Hae-Chang; Park, Hong-Gyu; Lee, Ju Hwan; Jang, Sang Bok; Oh, Byeong-Yun; Seo, Dae-Shik

2016-01-01

We demonstrated uniform liquid crystal (LC) alignment on ion beam (IB)-irradiated poly(styrene-co-allyl alcohol) by modifying the chemical bonding on the surface. An IB-irradiated copolymer was used for the alignment layer. We used physico-chemical analysis to determine the IB-irradiated surface modification and LC alignment mechanism on the surface. During IB treatment on poly(styrene-co-allyl alcohol), IB irradiation induces breaking of chemical bonds on the surface to give rise to new bonds with oxygen atoms. This causes a strong Van der Waals interaction between LCs and the modified surface, thereby resulting in uniform LC alignment. The results of contact angle (CA) studies of the copolymer support the chemical bonding changes that were investigated by XPS. We achieved uniform homogeneous LC alignment and obtained stable electro-optical performance by controlling the IB energy. Therefore, the LC cells with IB-irradiated poly(styrene-co-allyl alcohol) exhibited a good potential for alternative alignment of layers in LC applications.

Ion beam-induced topographical and chemical modification on the poly(styrene-co-allyl alcohol) and its effect on the molecular interaction between the modified surface and liquid crystals

Energy Technology Data Exchange (ETDEWEB)

Jeong, Hae-Chang [Information Display Device Laboratory, Department of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-749 (Korea, Republic of); Park, Hong-Gyu [School of Electrical, Electronic & Control Engineering, Changwon National University, 20 Changwondaehak-ro, Uichang-gu, Changwon-si, Gyeongsangnam-do, 51140 (Korea, Republic of); Lee, Ju Hwan; Jang, Sang Bok [Information Display Device Laboratory, Department of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-749 (Korea, Republic of); Oh, Byeong-Yun [ZeSHTech Co., Ltd., Business Incubator, Gwangju Institute of Science and Technology, 123, Cheomdangwagi-ro, Buk-gu, Gwangju, 500-712 (Korea, Republic of); Seo, Dae-Shik, E-mail: dsseo@yonsei.ac.kr [Information Display Device Laboratory, Department of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-749 (Korea, Republic of)

2016-10-01

We demonstrated uniform liquid crystal (LC) alignment on ion beam (IB)-irradiated poly(styrene-co-allyl alcohol) by modifying the chemical bonding on the surface. An IB-irradiated copolymer was used for the alignment layer. We used physico-chemical analysis to determine the IB-irradiated surface modification and LC alignment mechanism on the surface. During IB treatment on poly(styrene-co-allyl alcohol), IB irradiation induces breaking of chemical bonds on the surface to give rise to new bonds with oxygen atoms. This causes a strong Van der Waals interaction between LCs and the modified surface, thereby resulting in uniform LC alignment. The results of contact angle (CA) studies of the copolymer support the chemical bonding changes that were investigated by XPS. We achieved uniform homogeneous LC alignment and obtained stable electro-optical performance by controlling the IB energy. Therefore, the LC cells with IB-irradiated poly(styrene-co-allyl alcohol) exhibited a good potential for alternative alignment of layers in LC applications.

Living catalyzed-chain-growth polymerization and block copolymerization of isoprene by rare-earth metal allyl precursors bearing a constrained-geometry-conformation ligand.

Science.gov (United States)

Jian, Zhongbao; Cui, Dongmei; Hou, Zhaomin; Li, Xiaofang

2010-05-07

Aminophenyl functionalized cyclopentadienyl ligated rare-earth metal allyl mediated cationic systems display high cis-1,4 selectivity for the polymerization of isoprene, and living reversible and rapid chain transfer to aluminium additives.

A zinc enolate of amide: Preparation and application in reformasky-like reaction leading to β-hydroxy amides

Energy Technology Data Exchange (ETDEWEB)

Cho, Hyun Hee; Kim, Seung Hoi [Dept. of Chemistry, Dankook University, Cheonan (Korea, Republic of)

2015-04-15

One of the best known functionalized organic complexes is the β-hydroxy carbonyl compound. This unique functionality has been frequently found in naturally occurring bioactive derivatives. The cross-coupling reaction of A with aldehydes were carried out in the absence of any catalyst and completed in most cases within 1.0 h at room temperature. We have developed an efficient synthetic route for the preparation of β-hydroxy amides. The method involved the preparation of room-temperature-stable organo zinc reagents (A, B, and C) in THF and their subsequent coupling reactions with various carbonyl derivatives under mild conditions. Significantly, this approach using zinc enolate of amides could expand the scope of Reformatsky-like reactions. Further studies to elucidate this synthetic protocol are currently under way in our laboratory.

Mechanism of copper(I)-catalyzed allylic alkylation of phosphorothioate esters: influence of the leaving group on α regioselectivity.

Science.gov (United States)

Sheng, Wenhao; Wang, Mian; Lein, Matthias; Jiang, Linbin; Wei, Wanxing; Wang, Jianyi

2013-10-11

The mechanism of Cu(I) -catalyzed allylic alkylation and the influence of the leaving groups (OPiv, SPiv, Cl, SPO(OiPr)2 ; Piv: pivavloyl) on the regioselectivity of the reaction have been explored by using density functional theory (DFT). A comprehensive comparison of many possible reaction pathways shows that [(iPr)2 Cu](-) prefers to bind first oxidatively to the double bond of the allylic substrate at the anti position with respect to the leaving group, and this is followed by dissociation of the leaving group. If the leaving group is not taken into account, the reaction then undergoes an isomerization and a reductive elimination process to give the α- or γ-selective product. If OPiv, SPiv, Cl, or SPO(OiPr)2 groups are present, the optimal route for the formation of both α- and γ-substituted products changes from the stepwise elimination to the direct process, in which the leaving group plays a stabilizing role for the reactant and destabilizes the transition state. The differences to the energy barrier for the α- and γ-substituted products are 2.75 kcal mol(-1) with SPO(OiPr)2 , 2.44 kcal mol(-1) with SPiv, 2.33 kcal mol(-1) with OPiv, and 1.98 kcal mol(-1) with Cl, respectively; these values show that α regioselectivity in the allylic alkylation follows a SPO(OiPr)2 >SPiv>OPiv>Cl trend, which is in satisfactory agreement with the experimental findings. This trend mainly originates in the differences between the attractive electrostatic forces and the repelling steric interactions of the SPO(OiPr)2 , SPiv, OPiv, and Cl groups on the Cu group. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A simple approach to unsymmetric atropoisomeric bipyridine N,N'-dioxides and their application in enantioselective allylation of aldehydes

Czech Academy of Sciences Publication Activity Database

Hrdina, R.; Valterová, Irena; Hodačová, Jana; Císařová, I.; Kotora, Martin

2007-01-01

Roč. 349, č. 6 (2007), s. 822-826 ISSN 1615-4150 R&D Projects: GA ČR(CZ) GA203/05/0102; GA MŠk(CZ) LC06070 Institutional research plan: CEZ:AV0Z40550506 Keywords : allylation * asymmetric catalysis * Lewis bases Subject RIV: CC - Organic Chemistry Impact factor: 4.977, year: 2007

Aldehyde Selective Wacker Oxidations of Phthalimide Protected Allylic Amines : A New Catalytic Route to beta(3)-Amino Acids

NARCIS (Netherlands)

Weiner, Barbara; Baeza Garcia, Alejandro; Jerphagnon, Thomas; Feringa, Ben L.

2009-01-01

A new method for the synthesis of B-3-amino acids is presented. Phthalimide protected allylic amines are oxidized under Wacker conditions selectively to aldehydes using PdCl2 and CuCl or Pd(MeCN)(2)Cl(NO2) and CuCl2 as complementary catalyst systems. The aldehydes are produced in excellent yields

Olefination of Electron-Deficient Alkenes with Allyl Acetate: Stereo- and Regioselective Access to (2Z,4E)-Dienamides.

Science.gov (United States)

Li, Feifei; Yu, Chunbing; Zhang, Jian; Zhong, Guofu

2016-09-16

A Ru-catalyzed direct olefination of electron-deficient alkenes with allyl acetate via C-H bond activation is disclosed. By using N,N-disubstituted aminocarbonyl as the directing group, this external oxidant-free protocol resulted in high reaction efficiency and good stereo- and regioselectivities, which opens a novel synthetic passway for access to (Z,E)-butadiene skeletons.

An Expeditious Synthesis of [1,2]Isoxazolidin-5-ones and [1,2]Oxazin-6-ones from Functional Allyl Bromide Derivatives

Directory of Open Access Journals (Sweden)

Imen Beltaïef

2010-06-01

Full Text Available Reaction of allyl bromide (Z-1 and (Z-2 with N-substituted hydroxylamine hydrochlorides in presence of tert-butoxide in tert-butanol at reflux provides a short and effective route to [1,2]isoxazolidin-5-ones 3 and [1,2]oxazin-6-ones 4.

Využití B-H karbonátů v organokatalytických transformacích

OpenAIRE

Tichá, Iveta

2014-01-01

This diploma thesis is focused on the preparation of enantiomerically pure compounds based on organocatalytic allylic substitution using Baylis-Hillman carbonates. As selected substrates for the allylic substitution were chosen α-azidoketones such as azidoacetophenone, 2-azido-1-indanone and then heterocyclic compounds (N-phenylrhodanine and its derivate) belonging to the pharmaceutical privileged compounds. Other substrate for allylic substitution was allylmalononitrile. In addition, this th...

Biological distribution of iodo-allyl Gabapentin and iodo-Gabapentin

International Nuclear Information System (INIS)

Akat, H.; Yildirim, Y.; Balcan, M.; Yurt Lambrecht, F.; Yilmaz, O.; Duman, Y.

2008-01-01

Gabapentin (GBP) is an anticonvulsant and is widely used in the treatment of epilepsy. In this study, GBP and an allyl derivative of GBP were radioiodinated with 131 I using the iodogen method; then their radiopharmaceutical potential in rats and rabbits was investigated. The radiochemical purity of 131 I-GBP and its derivatives was determined by RTLC. The labeling yield was 95±2%. Biological evaluation was performed in normal rats and rabbits. Labeled compounds were intravenously injected into two rabbits via the ear vein after anesthetizing. The dynamic and static scintigrams were obtained using a gamma camera at different time. Then the labeled compounds were administered intravenously into the rats. The distribution was studied by counting the radioactivity in the removed organs. The results of biodistribution in the rats showed the clearance of 131 IALGBP was faster than 131 I-GBP. On the other hand, the uptake of 131 I-ALGBP in the brain was higher than 131 I-GBP at 60 minutes. (author)

Polymerization of allyl alcohol by radiation to obtain microencapsulated structure

International Nuclear Information System (INIS)

Usanmaz, A.; Saricilar, S.

1989-01-01

Allyl alcohol was polymerized by radiation under various conditions. The limiting conversions were about 30 % in bulk, 35 % when containing 0.03 mole fraction AlCl 3 and 50 % when water was contained at 27 % (v/v). Irradiation was done with Co-60 gamma rays at room temperature and under vacuum. The presence of oxygen did not cause any change in the reaction rate. Molecular weights were determined by viscosity and cryoscopic methods. K and α values were found to be 3.57 x 10 -4 and 0.62 for solutions in methanol at 25degC. The polymers up to about 10 % conversion were viscous liquids having microcapsular structures: at high conversions, they became hard and glassy. The microencapsulated structures were also retained in solutions in methanol, acetone, and isopropyl alcohol. The samples were insoluble in water, benzene, and toluence. (author)

Synthesis of [11C]-labelled methyl esters: transesterification of enol esters versus BF3 etherate catalysed esterification - a comparative study

International Nuclear Information System (INIS)

Ackermann, U.; Falzon, C.; Issa, W.; Tochon-Danguy, H.J.; Sachinidis, J.I.; Blanc, P.; White, J.; Scott, A.M.

2005-01-01

An important issue in Positron Emission Tomography (PET) is the development of labelling techniques to incorporate positron emitting radionuclides into biologically active compounds. When labelling with 11C, the short 20 minutes half-life of the radionuclide significantly limits the number of synthetic protocols available to the radiochemist. C-l synthons such as [HCJ-methyl iodide (1) or methyl triflate (2) are readily available and are frequently used as alkylating agents for the preparation of radiopharmaceuticals. However, the use of these alkylating agents often makes it necessary to introduce protecting groups in order to prevent labelling at unwanted sites on the molecule. Since the removal of protecting groups is a time-consuming process, a more direct synthesis strategy is desirable. This has prompted us to investigate the esterification of carboxylic acids using [1 lC]-mcthanol and BF3 etherate as Lewis acid catalyst. Our results have demonstrated that the reaction conditions necessary to promote the esterification can cleave functional groups such as ethers. We have therefore shifted our attention towards the irreversible transesterification of enol esters using [HCl-methanol and a tin catalyst as an alternative strategy to [HC]-methyl ester formation. We have prepared a series of 5 aromatic ethoxy vinyl esters bearing various functional groups. The transesterification (radiolabelling) was carried out in DMSO at 150 Degrees C for 7 minutes in the presence of [HQMeOH and 1.3-dichlo-rotetrabutyldistannoxane as catalyst. We have found that the transesterification of enol esters is a mild and efficient labelling method for the formation of [HCl-methyl esters. The reaction proceeds smoothly and leaves functional groups intact. It requires only one synthesis step compared to two steps for the conventional method, and gives a radiochemical yields of 25%

{sup 1} H and {sup 13} C NMR studies on the enoling of 5-benzyl barbituric acids; Estudos por H-1 e C-13 RMN da enolizacao de acidos 5-benzil barbituricos

Energy Technology Data Exchange (ETDEWEB)

Villar, Jose Daniel Figueroa; Santos, Nedina Lucia dos; Cruz, Elizabete Rangel [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Quimica

1992-12-31

This work shows that the derivatives of the 5-benzyl barbituric acids hydroxylated at the ortho position of the aromatic ring only exist in the enol form. and that the alkylation of this hydroxyl gives products which exist mainly in the ketone form of the DMSO 5 refs., 2 figs., 2 tabs.

Trifluoroethylation of Alkynes: Synthesis of Allylic-CF3 Compounds by Visible-Light Photocatalysis

Institute of Scientific and Technical Information of China (English)

Geum-bee Roh; Naeem Iqbal; Eun Jin Cho

2016-01-01

Two types of allylic trifluoromethylated compounds were synthesized by reacting alkynes with CF3CH2I using visible-light photocatalysis.Subtle differences in the catalytic system controlled the selectivity of iodotrifluoroethylation and hydrotrifluoroethylation.The iodotrifluoroethylated products were obtained in the presence of [Ru(bpy)3]C12 and TMEDA in CH3CN under visible-light irradiation,whereas hydrotrifluoroethylated products were synthesized usingfac-[Ir(ppy)3] and a mixture of DBU and K2CO3 in DMF.The iodotrifluoroethylation reaction worked particularly well,even at gram-scale,and the synthetic utility of iodotrifluoroethylated products was proved by their coupling reactions,providing complex CF3-containing products.

Asymmetric Benzylic Allylic Alkylation Reaction of 3-Furfural Derivatives by Dearomatizative Dienamine Activation.

Science.gov (United States)

He, Xiao-Long; Zhao, Hui-Ru; Duan, Chuan-Qi; Han, Xu; Du, Wei; Chen, Ying-Chun

2018-04-20

The dearomatizative dienamine-type ortho-quinodimethane species are smoothly generated between 2-alkyl-3-furfurals and chiral secondary amine catalysts, which undergo asymmetric benzylic allylic alkylation reactions with 2-nitroallylic acetates efficiently. A spectrum of densely functionalized 3-furfural derivatives are delivered in moderate to high yields with good to excellent diastereo- and enantioselectivity (up to 98 % yield, >19:1 d.r., >99 % ee). The latent transformations allow the facile production of some enantioenriched architectures, such as 1,1,2,2-tetraarylethanes and triarylmethanes, which are not easily available from other protocols. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Non-thermal plasma destruction of allyl alcohol in waste gas: kinetics and modelling

Science.gov (United States)

DeVisscher, A.; Dewulf, J.; Van Durme, J.; Leys, C.; Morent, R.; Van Langenhove, H.

2008-02-01

Non-thermal plasma treatment is a promising technique for the destruction of volatile organic compounds in waste gas. A relatively unexplored technique is the atmospheric negative dc multi-pin-to-plate glow discharge. This paper reports experimental results of allyl alcohol degradation and ozone production in this type of plasma. A new model was developed to describe these processes quantitatively. The model contains a detailed chemical degradation scheme, and describes the physics of the plasma by assuming that the fraction of electrons that takes part in chemical reactions is an exponential function of the reduced field. The model captured the experimental kinetic data to less than 2 ppm standard deviation.

Non-thermal plasma destruction of allyl alcohol in waste gas: kinetics and modelling

International Nuclear Information System (INIS)

Visscher, A de; Dewulf, J; Durme, J van; Leys, C; Morent, R; Langenhove, H Van

2008-01-01

Non-thermal plasma treatment is a promising technique for the destruction of volatile organic compounds in waste gas. A relatively unexplored technique is the atmospheric negative dc multi-pin-to-plate glow discharge. This paper reports experimental results of allyl alcohol degradation and ozone production in this type of plasma. A new model was developed to describe these processes quantitatively. The model contains a detailed chemical degradation scheme, and describes the physics of the plasma by assuming that the fraction of electrons that takes part in chemical reactions is an exponential function of the reduced field. The model captured the experimental kinetic data to less than 2 ppm standard deviation

Molecular detection and in vitro antioxidant activity of S-allyl-L-cysteine (SAC) extracted from Allium sativum.

Science.gov (United States)

Sun, Y-E; Wang, W-D

2016-06-30

It is well known that Allium sativum has potential applications to clinical treatment of various cancers due to its remarkable ability in eliminating free radicals and increasing metabolism. An allyl-substituted cysteine derivative - S-allyl-L-cysteine (SAC) was separated and identified from Allium sativum. The extracted SAC was reacted with 1-pyrenemethanol to obtain pyrene-labelled SAC (Py-SAC) to give SAC fluorescence properties. Molecular detection of Py-SAC was conducted by steady-state fluorescence spectroscopy and time-resolved fluorescence method to quantitatively measure concentrations of Py-SAC solutions. The ability of removing 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical using Py-SAC was determined through oxygen radical absorbance capacity (ORAC). Results showed the activity of Py-SAC and Vitamin C (VC) with ORAC as index, the concentrations of Py-SAC and VC were 58.43 mg/L and 5.72 mg/L respectively to scavenge DPPH, and 8.16 mg/L and 1.67 mg/L to scavenge •OH respectively. Compared with VC, the clearance rates of Py-SAC to scavenge DPPH were much higher, Py-SAC could inhibit hydroxyl radical. The ability of removing radical showed a dose-dependent relationship within the scope of the drug concentration.

Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

International Nuclear Information System (INIS)

Sych, N.V.; Trofymenko, S.I.; Poddubnaya, O.I.; Tsyba, M.M.; Sapsay, V.I.; Klymchuk, D.O.; Puziy, A.M.

2012-01-01

Highlights: ► Phosphoric acid activation results in formation of carbons with acidic surface groups. ► Maximum amount of surface groups is introduced at impregnation ratio 1.25. ► Phosphoric acid activated carbons show high capacity to copper. ► Phosphoric acid activated carbons are predominantly microporous. ► Maximum surface area and pore volume achieved at impregnation ratio 1.0. - Abstract: Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 °C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (S BET = 2081 m 2 /g, V tot = 1.1 cm 3 /g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0–2.6), weakly acidic carboxylic (pK = 4.7–5.0), enol/lactone (pK = 6.7–7.4; 8.8–9.4) and phenol (pK = 10.1–10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

Energy Technology Data Exchange (ETDEWEB)

Sych, N.V.; Trofymenko, S.I.; Poddubnaya, O.I.; Tsyba, M.M. [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine); Sapsay, V.I.; Klymchuk, D.O. [M.G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine, 2 Tereshchenkivska St., 01601 Kyiv (Ukraine); Puziy, A.M., E-mail: alexander.puziy@ispe.kiev.ua [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine)

2012-11-15

Highlights: Black-Right-Pointing-Pointer Phosphoric acid activation results in formation of carbons with acidic surface groups. Black-Right-Pointing-Pointer Maximum amount of surface groups is introduced at impregnation ratio 1.25. Black-Right-Pointing-Pointer Phosphoric acid activated carbons show high capacity to copper. Black-Right-Pointing-Pointer Phosphoric acid activated carbons are predominantly microporous. Black-Right-Pointing-Pointer Maximum surface area and pore volume achieved at impregnation ratio 1.0. - Abstract: Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 Degree-Sign C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (S{sub BET} = 2081 m{sup 2}/g, V{sub tot} = 1.1 cm{sup 3}/g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0-2.6), weakly acidic carboxylic (pK = 4.7-5.0), enol/lactone (pK = 6.7-7.4; 8.8-9.4) and phenol (pK = 10.1-10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

Exciton Coupling in Circular Dichroic Spectroscopy as a Tool for Establishing the Absolute Configuration of alpha,beta-Unsaturated Esters of Allylic Alcohols

DEFF Research Database (Denmark)

Lauridsen, A.; Cornett, Claus; Christensen, S. B.

1991-01-01

alpha-beta-Unsaturated esters of allylic alcohols have been shown to exhibit exciton coupling by circular dichroic spectroscopy. This coupling permits the establishment of the absolute configuration. The method was used to prove the absolute configuration at C-2 of archangelolide. Detailed NMR sp...

Enantioselective allylations of selected alpha, beta, gamma, delta-unsaturated aldehydes by axially chiral N,N'-dioxides. Synthesis of the left-hand part of papulacandin D

Czech Academy of Sciences Publication Activity Database

Vlašaná, K.; Betík, R.; Valterová, Irena; Nečas, D.; Kotora, M.

2016-01-01

Roč. 3, č. 3 (2016), s. 301-305 ISSN 2213-3372 Institutional support: RVO:61388963 Keywords : allylation * aldehyde * Lewis base * asymmetric synthesis * organocatalysis * homoallylic alcohol s Subject RIV: CC - Organic Chemistry

Low-temperature synthesis of allyl dimethylamine by selective heating under microwave irradiation used for water treatment

International Nuclear Information System (INIS)

Tian Binghui; Luan Zhaokun; Li Mingming

2005-01-01

Low-temperature synthesis of allyl dimethylamine (ADA) by selective heating under microwave irradiation (MI) used for water treatment is investigated. The effect of MI, ultrasound irradiation (UI) and conventional heating on yield of ADA, reaction time and the flocculation efficiency of polydiallyl dimethylammunion chloride (PDADMAC) prepared form ADA were studied. The results show that by selective heating at low temperature, MI not only increases yield of ADA and reduces reaction time, but also greatly enhances the flocculation efficiency of PDADMAC

Pyridine synthesis by reactions of allyl amines and alkynes proceeding through a Cu(OAc)2 oxidation and Rh(III)-catalyzed N-annulation sequence.

Science.gov (United States)

Kim, Dong-Su; Park, Jung-Woo; Jun, Chul-Ho

2012-11-28

A new methodology has been developed for the synthesis of pyridines from allyl amines and alkynes, which involves sequential Cu(II)-promoted dehydrogenation of the allylamine and Rh(III)-catalyzed N-annulation of the resulting α,β-unsaturated imine and alkyne.

Involvement of H(+)-ATPase and carbonic anhydrase in inorganic carbon uptake for endosymbiont photosynthesis.

Science.gov (United States)

Furla, P; Allemand, D; Orsenigo, M N

2000-04-01

Symbiotic cnidarians absorb inorganic carbon from seawater to supply intracellular dinoflagellates with CO(2) for their photosynthesis. To determine the mechanism of inorganic carbon transport by animal cells, we used plasma membrane vesicles prepared from ectodermal cells isolated from tentacles of the sea anemone, Anemonia viridis. H(14)CO(-)(3) uptake in the presence of an outward NaCl gradient or inward H(+) gradient, showed no evidence for a Cl(-)- or H(+)- driven HCO(-)(3) transport. H(14)CO(-)(3) and (36)Cl(-) uptakes were stimulated by a positive inside-membrane diffusion potential, suggesting the presence of HCO(-)(3) and Cl(-) conductances. A carbonic anhydrase (CA) activity was measured on plasma membrane (4%) and in the cytoplasm of the ectodermal cells (96%) and was sensitive to acetazolamide (IC(50) = 20 nM) and ethoxyzolamide (IC(50) = 2.5 nM). A strong DIDS-sensitive H(+)-ATPase activity was observed (IC(50) = 14 microM). This activity was also highly sensitive to vanadate and allyl isothiocyanate, two inhibitors of P-type H(+)-ATPases. Present data suggest that HCO(-)(3) absorption by ectodermal cells is carried out by H(+) secretion by H(+)-ATPase, resulting in the formation of carbonic acid in the surrounding seawater, which is quickly dehydrated into CO(2) by a membrane-bound CA. CO(2) then diffuses passively into the cell where it is hydrated in HCO(-)(3) by a cytosolic CA.

Allyl isothiocyanate enhances shelf life of minimally processed shredded cabbage.

Science.gov (United States)

Banerjee, Aparajita; Penna, Suprasanna; Variyar, Prasad S

2015-09-15

The effect of allyl isothiocyanate (AITC), in combination with low temperature (10°C) storage on post harvest quality of minimally processed shredded cabbage was investigated. An optimum concentration of 0.05μL/mL AITC was found to be effective in maintaining the microbial and sensory quality of the product for a period of 12days. Inhibition of browning was shown to result from a down-regulation (1.4-fold) of phenylalanine ammonia lyase (PAL) gene expression and a consequent decrease in PAL enzyme activity and o-quinone content. In the untreated control samples, PAL activity increased following up-regulation in PAL gene expression that could be linearly correlated with enhanced o-quinone formation and browning. The efficacy of AITC in extending the shelf life of minimally processed shredded cabbage and its role in down-regulation of PAL gene expression resulting in browning inhibition in the product is reported here for the first time. Copyright © 2015 Elsevier Ltd. All rights reserved.

Palladium-catalyzed regio- and stereoselective cross-addition of terminal alkynes to ynol ethers and synthesis of 1,4-enyn-3-ones.

Science.gov (United States)

Babu, Madala Hari; Dwivedi, Vikas; Kant, Ruchir; Reddy, Maddi Sridhar

2015-03-16

Conjugated enynes, enol ethers, and enynones are versatile building blocks that can be elaborated by a wide variety of synthetic transformations. The selective synthesis of such units is a prerequisite for their effective utilization. The synthesis of conjugated 2-phenoxyenynes through a palladium-catalyzed cross-addition of terminal alkynes to phenylethynyl ethers (hydroalkynylation) is now presented. The reaction is highly regio-, stereo-, and chemoselective, and shows excellent tolerance toward functional groups. The addition further features very mild reaction conditions (room temperature) and an inexpensive catalytic system (without a ligand and with a cheaply available Pd catalyst). The thus synthesized enynyl ethers with allylic hydroxy tethers, which survived the reaction, were shown to be ready precursors for valuable 1-en-4-yn-3-ones. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

ANÁLISIS COMPARATIVO DE LA SITUACIÓN LABORAL DE LAS MUJERES RURALES: Vitivinicultura, Industria Vitivinícola y Turismo Enológico. El Caso del Valle de Colchagua, Chile

Directory of Open Access Journals (Sweden)

Ana María Dávila

2011-11-01

Full Text Available Resumen: La inserción de la mujer rural en espacios laborales fuera de su hogar, forma parte de un escenario de cambios, que se conoce como “nueva ruralidad”. Asimismo la llegada del turismo rural a diferentes zonas y la inclusión de las mujeres rurales en esta nueva actividad productiva, son aspectos que se hacen relevantes en zonas vitivinícolas como el valle de Colchagua, Chile. Esta investigación tiene como objetivo determinar los cambios socioeconómicos en la situación de las mujeres rurales producto de su participación en empresas y actividades de turismo enológico y establecer si estos cambios observados modifican la situación de las mujeres que trabajan en la agricultura y en la agroindustria.  A través de entrevistas realizadas a tres grupos de mujeres, pertenecientes al ámbito de la agricultura, la agroindustria y el turismo de las viñas, se realiza un análisis comparativo de los cambios generados, tanto en el contexto familiar, como en las condiciones de trabajo y en aspectos de formación y capacitación de la mujer rural. Palabras claves: Turismo Enológico. Mujeres Rurales. Empleo Rural. Vale Colchagua. Chile

Protection of Grain Products from Sitophilus oryzae (L.) Contamination by Anti-Insect Pest Repellent Sachet Containing Allyl Mercaptan Microcapsule.

Science.gov (United States)

Chang, Yoonjee; Lee, Soo-Hyun; Na, Ja Hyun; Chang, Pahn-Shick; Han, Jaejoon

2017-11-01

The purpose of this study was to develop an anti-insect pest repellent sachet to prevent Sitophilus oryzae (L.) (Coleoptera: Curculionidae) contamination in grain packaging. The anti-insect pest activities of essential oils (EOs) from garlic (Allium Sativum), ginger (Zingiber Officinalis), black pepper (Piper nigrum), onion (Allium cepa), and fennel (Foeniculum vulgare) as well as major compounds (allyl disulfide, AD; allyl mercaptan, AM) isolated from of garlic and onion (AD and AM) were measured against S. oryzae. The results revealed that garlic EO, onion EO, AD, and AM showed strong fumigant insecticidal activities. Among these, AM showed the highest acetylcholinesterase (AChE) inhibition rate, indicating that the fumigation insecticidal efficacy of AM is related with its AChE inhibition ability. Subsequently, the microcapsules were produced with a high efficiency (80.02%) by using AM as a core material and rice flour as a wall material. Finally, sachet composed of rice flour microcapsule containing 2% AM (RAM) was produced. Repellent assay was performed to measure anti-insect pest ability of the RAM sachet, showed remarkable repelling effect within 48 h both in the presence or absence of attractant. In a release profile of RAM sachet, it was expected to last over 20 mo during the distribution period of brown rice. Moreover, RAM sachet showed no undesirable changes to the sensory properties of the rice both before and after cooking. Taken together, these results suggest that the newly developed RAM sachet could be used as a packaging material to protect grain products from S. oryzae contamination. The rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), causes damages to stored products and its contamination in grain products has become a major problem in cereal market. To preserve brown rice, an anti-insect pest repellent sachet containing 2% allyl mercaptan was newly developed and it showed remarkable repellent abilities against S. oryzae. It

Gold(I)-assisted catalysis - a comprehensive view on the [3,3]-sigmatropic rearrangement of allyl acetate

Science.gov (United States)

Freindorf, Marek; Cremer, Dieter; Kraka, Elfi

2018-03-01

The unified reaction valley approach (URVA) combined with the local mode, ring puckering and electron density analysis is applied to elucidate the mechanistic differences of the non-catalysed and the Au[I]-N-heterocyclic carbene (NHC)-catalysed [3,3]-sigmatropic rearrangement of allyl acetate. Using a dual-level approach (DFT and DLPNO-CCSD(T)), the influence of solvation, counter-ions, bulky and electron withdrawing/donating substituents as well as the exchange of the Au[I]-NHC with a Au[I]-phosphine catalyst is investigated. The catalyst breaks up the rearrangement into two steps by switching between Au[I]-π and Au[I]-σ complexation, thus avoiding the energy-consuming CO cleavage in the first step. Based on local stretching force constants ka(C=C), we derive for the first time a quantitative measure of the π-acidity of the Au[I] catalyst; in all catalysed reactions, the bond order n(C=C) drops from 2 to 1.65. The ring puckering analysis clarifies that all reactions start and end via a six-membered ring with a boat form. All Au[I]-σ-complex intermediates show a considerable admixture of the chair form. The non-catalysed [3,3]-sigmatropic rearrangement goes through a maximum of charge separation between the allyl and acetate units at the transition state, while all catalysed reactions proceed via a minimum of charge separation reached in the region of the Au[I]-σ-complex.

A Divergent Mechanistic Course of Pd(0)-Catalyzed Aza-Claisen Rearrangement and Aza-Rautenstrauch-Type Cyclization of N-Allyl-Ynamides

Science.gov (United States)

DeKorver, Kyle A.; Hsung, Richard P.; Lohse, Andrew G.; Zhang, Yu

2010-01-01

A fascinating mechanistic study of ynamido-palladium-π-allyl complexes is described that features isolation of a unique silyl-ketenimine via aza-Claisen rearrangement, which can be accompanied by an unusual thermal N-to-C 1,3-Ts shift in the formation of tertiary nitriles, and a novel cyclopentenimine formation via a palladium catalyzed aza-Rautenstrauch-type cyclization pathway. PMID:20337418

An Efficient Amide-Aldehyde-Alkene Condensation: Synthesis for the N-Allyl Amides.

Science.gov (United States)

Quan, Zheng-Jun; Wang, Xi-Cun

2016-02-01

The allylamine skeleton represents a significant class of biologically active nitrogen compounds that are found in various natural products and drugs with well-recognized pharmacological properties. In this personal account, we will briefly discuss the synthesis of allylamine skeletons. We will focus on showing a general protocol for Lewis acid-catalyzed N-allylation of electron-poor N-heterocyclic amides and sulfonamide via an amide-aldehyde-alkene condensation reaction. The substrate scope with respect to N-heterocyclic amides, aldehydes, and alkenes will be discussed. This method is also capable of preparing the Naftifine motif from N-methyl-1-naphthamide or methyl (naphthalene-1-ylmethyl)carbamate, with paraformaldehyde and styrene in a one-pot manner. © 2016 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis, Molecular Structure and Characterization of Allylic Derivatives of 6-Amino-3-methyl-1,2,4-triazolo[3,4-f][1,2,4]-triazin-8(7H-one

Directory of Open Access Journals (Sweden)

Gene-Hsiang Lee

2006-06-01

Full Text Available 1-Allyl- (2 and 7-allyl-6-amino-3-methyl-1,2,4-triazolo[3,4-f][1,2,4]triazin-8(7H-one (3 were obtained via the 18-crown-6-ether catalyzed room temperature reactionof 6-amino-3-methyl-1,2,4-triazolo[3,4-f][1,2,4]triazin-8(7H-one (1 with potassiumcarbonate and allyl bromide in dry acetone. The structures of these two derivatives wereverified by 2D-NMR measurements, including gHSQC and gHMBC measurements. Theminor compound 2 may possess aromatic character. A single crystal X-ray diffractionexperiment indicated that the major compound 3 crystallizes from dimethyl sulfoxide in themonoclinic space group P21/n and its molecular structure includes an attached dimethylsulfoxide molecule, resulting in the molecular formula C10H16N6O2S. Molecular structuresof 3 are linked by extensive intermolecular N-H···N hydrogen bonding [graph set C 1 (7]. 1Each molecule is attached to the dimethyl sulfoxide oxygen via N-H···O intermolecularhydrogen bonding. The structure is further stabilized by π-π stacking interactions.

SYNTHESIS OF 7-DEHYDROCHOLESTEROL THROUGH ...

African Journals Online (AJOL)

Preferred Customer

allylic moiety like acetate, halide, hydroxide, etc. are alkylated by molybdenum catalyst in the presence of a nucleophile [16]. Allyl-molybdenum complex formation of alkene and subsequent .... temperature molybdenum has the ability to eliminate any acetoxyl group attached to carbon [19] in the form of acetic acid molecule.

Poly(allyl methacrylate) functionalized hydroxyapatite nanocrystals via the combination of surface-initiated RAFT polymerization and thiol-ene protocol: a potential anticancer drug nanocarrier.

Science.gov (United States)

Bach, Long Giang; Islam, Md Rafiqul; Vo, Thanh-Sang; Kim, Se-Kwon; Lim, Kwon Taek

2013-03-15

Hydroxyapatite nanocrystals (HAP NCs) were encapsulated by poly(allyl methacrylate) (PolyAMA) employing controlled surface-initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization of allyl methacrylate to afford HAP-PolyAMA nanohybrids. The subsequent thiol-ene coupling of nanohybrids with 2-mercaptosuccinic acid resulted HAP-Poly(AMA-COOH) possessing multicarboxyl group. The formation of the nanohybrids was confirmed by FT-IR and EDS analyses. The TGA and FE-SEM investigation were further suggested the grafting of PolyAMA onto HAP NCs. The utility of the HAP-PolyAMA nanohybrid as drug carrier was also explored. The pendant carboxyl groups on the external layers of nanohybrids were conjugated with anticancer drug cisplatin to afford HAP-Poly(AMA-COOH)/Pt complex. The formation of the complex was confirmed by FT-IR, XPS, and FE-SEM. In vitro evaluation of the synthesized complex as nanomedicine revealed its potential chemotherapeutic efficacy against cancer cell lines. Copyright © 2012 Elsevier Inc. All rights reserved.

Extraction of allyl isothiocyanate from horseradish (Armoracia rusticana) and its fumigant insecticidal activity on four stored-product pests of paddy.

Science.gov (United States)

Wu, Hua; Zhang, Guo-An; Zeng, Shuiyun; Lin, Kai-chun

2009-09-01

Isothiocyanates (ITCs) extracted from Armoracia rusticana Gaertn., May & Scherb. have been shown previously to have insecticidal activity. Allyl isothiocyanate (AITC), a major component of ITCs with high volatility, was therefore extracted using different methods and tested as a fumigant against four major pest species of stored products, maize weevil Sitophilus zeamais (Motsch.), lesser grain borer Rhizopertha dominica (F.), Tribolium ferrugineum (F.) and book louse Liposcelis entomophila (Enderlein). Whereas there was no significant difference between hydrodistillation and supercritical carbon dioxide fluid extraction in extraction rate for AITC from A. rusticana, both methods resulted in higher extraction efficiency than water extraction. AITC fumigation showed strong toxicity to the four species of stored-product pests. Adult mortality of 100% of all four pest species, recorded after 72 h exposure to AITC fumes at an atmospheric concentration of 3 microg mL(-1), showed no significant difference from that of insects exposed to phosphine at 5 microg mL(-1), the recommended dose for phosphine. The results suggest good insecticidal efficacy of AITC against the four stored-product pests, with non-gaseous residuals on stored products. AITC obtained from A. rusticana may be an alternative to phosphine and methyl bromide against the four pest species. Copyright 2009 Society of Chemical Industry.

Structural analysis by reductive cleavage with LiAlH4 of an allyl ether choline-phospholipid, archaetidylcholine, from the hyperthermophilic methanoarchaeon Methanopyrus kandleri

Directory of Open Access Journals (Sweden)

Masateru Nishihara

2002-01-01

Full Text Available A choline-containing phospholipid (PL-4 in Methanopyrus kandleri cells was identified as archaetidylcholine, which has been described by Sprott et al. (1997. The PL-4 consisted of a variety of molecular species differing in hydrocarbon composition. Most of the PL-4 was acid-labile because of its allyl ether bond. The identity of PL-4 was confirmed by thin-layer chromatography (TLC followed by positive staining with Dragendorff-reagent and fast-atom bombardment–mass spectrometry. A new method of LiAlH4 hydrogenolysis was developed to cleave allyl ether bonds and recover the corresponding hydrocarbons. We confirmed the validity of the LiAlH4 method in a study of the model compound synthetic unsaturated archaetidic acid (2,3-di-O-geranylgeranyl-sn-glycerol-1-phosphate. Saturated ether bonds were not cleaved by the LiAlH4 method. The hydrocarbons formed following LiAlH4 hydrogenolysis of PL-4 were identified by gas–liquid chromatography and mass spectrometry. Four kinds of hydrocarbons with one to four double bonds were detected: 47% of the hydrocarbons had four double bonds; 11% had three double bonds; 14% had two double bonds; 7% had one double bond; and 6% were saturated species. The molecular species composition of PL-4 was also estimated based on acid lability: 77% of the molecular species had two acid-labile hydrocarbons; 11% had one acid-labile and one acid-stable hydrocarbon; and 11% had two acid-stable hydrocarbons. To our knowledge, this is the first report of a specific chemical degradation method for the structural analysis of allyl ether phospholipid in archaea.

Titanocene Dichloride Complexes Bonded to Carbosilane Dendrimers Via a Spacer of Variable Length – Molecular Dynamics Calculations and Catalysis of Allylic Coupling Reactions

Czech Academy of Sciences Publication Activity Database

Strašák, Tomáš; Jaroschik, F.; Malý, M.; Čermák, Jan; Sýkora, Jan; Fajgar, Radek; Karban, Jindřich; Harakat, D.

2014-01-01

Roč. 409, SI (2014), s. 137-146 ISSN 0020-1693 R&D Projects: GA MŠk(CZ) LC06070 Grant - others:UJEP(CZ) GA13-06989S Institutional support: RVO:67985858 Keywords : metallodendrimers * titanocene dichloride * allylic homocoupling * molecular dynamics Subject RIV: CC - Organic Chemistry Impact factor: 2.046, year: 2014

Theoretical study on keto-enol tautomerisation of glutarimide for exploration of the isomerisation reaction pathway of glutamic acid in proteins using density functional theory

Science.gov (United States)

Fukuyoshi, Shuichi; Nakayoshi, Tomoki; Takahashi, Ohgi; Oda, Akifumi

2017-03-01

In order to elucidate the reason why glutamic acid residues have lesser racemisation reactivity than asparaginic acid, we investigated the racemisation energy barrier of piperidinedione, which is the presumed intermediate of the isomerisation reaction of L-Glu to D-Glu, by density functional theory calculations. In two-water-molecule-assisted racemisation, the activation barrier for keto-enol isomerisation was 28.1 kcal/mol. The result showed that the activation barrier for the racemisation of glutamic acid residues was not different from that for the racemisation of aspartic acid residues. Thus, glutamic acid residues can possibly cause the racemisation reaction if the cyclic intermediate stably exists.

Contact and fumigant toxicity of Armoracia rusticana essential oil, allyl isothiocyanate and related compounds to Dermatophagoides farinae.

Science.gov (United States)

Yun, Yeon-Kyeong; Kim, Hyun-Kyung; Kim, Jun-Ran; Hwang, Kumnara; Ahn, Young-Joon

2012-05-01

The toxicity to adult Dermatophagoides farinae of allyl isothiocyanate identified in horseradish, Armoracia rusticana, oil and another 27 organic isothiocyanates was evaluated using contact + fumigant and vapour-phase mortality bioassays. Results were compared with those of two conventional acaricides, benzyl benzoate and dibutyl phthalate. Horseradish oil (24 h LC(50), 1.54 µg cm(-2)) and allyl isothiocyanate (2.52 µg cm(-2)) were highly toxic. Benzyl isothiocyanate (LC(50) , 0.62 µg cm(-2)) was the most toxic compound, followed by 4-chlorophenyl, 3-bromophenyl, 3,5-bis(trifluoromethyl)phenyl, cyclohexyl, 2-chlorophenyl, 4-bromophenyl and 2-bromophenyl isothiocyanates (0.93-1.41 µg cm(-2)). All were more effective than either benzyl benzoate (LC(50) , 4.58 µg cm(-2)) or dibutyl phthalate (24.49 µg cm(-2)). The structure-activity relationship indicates that types of functional group and chemical structure appear to play a role in determining the isothiocyanate toxicities to adult D. farinae. In the vapour-phase mortality bioassay, these isothiocyanates were consistently more toxic in closed versus open containers, indicating that their mode of delivery was, in part, a result of vapour action. In the light of global efforts to reduce the level of highly toxic synthetic acaricides in indoor environments, the horseradish oil-derived compounds and the isothiocyanates described herein merit further study as potential acaricides for the control of house dust mite populations as fumigants with contact action. Copyright © 2011 Society of Chemical Industry.

Effect of allyl isothiocyanate on ultra-structure and the activities of four enzymes in adult Sitophilus zeamais.

Science.gov (United States)

Wu, Hua; Liu, Xue-ru; Yu, Dong-dong; Zhang, Xing; Feng, Jun-tao

2014-02-01

Rarefaction and vacuolization of the mitochondrial matrix of AITC-treated (allyl isothiocyanate-treated) adult Sitophilus zeamais were evident according to the ultra-structural by TEM. Four important enzymes in adult S. zeamais were further studied after fumigation treatment with allyl isothiocyanate (AITC) extracted from Armoracia rusticana roots and shoots. The enzymes were glutathione S-transferase (GST), catalase (CAT), cytochrome c oxidase, and acetylcholinesterase (AChE). The results indicated that the activities of the four enzymes were strongly time and dose depended. With prolonged exposure time, treatment with 0.74μg/mL AITC inhibited the activities of cytochrome c oxidase, AChE, and CAT, but induced the activity of GST. The activities of cytochrome c oxidase, AChE, and CAT were remarkably induced at a low AITC dosage (0.25μg/mL), but were restrained with increased AITC dosage. The activity of GST was inhibited at a low AITC dosage (0.5μg/mL), but was induced at a high AITC dosage (1.5μg/mL). According to the results of TEM, toxic symptoms and enzymes activities, it suggested that mitochondrial maybe the one site of action of AITC against the adult S. zeamais and it also suggested that cytochrome c oxidase maybe one target protein of AITC against the adult S. zeamais, which need to further confirmed by protein function tested. Copyright © 2014 Elsevier Inc. All rights reserved.

Syntheses of the hexahydroindene cores of indanomycin and stawamycin by combinations of iridium-catalyzed asymmetric allylic alkylations and intramolecular Diels-Alder reactions.

Science.gov (United States)

Gärtner, Martin; Satyanarayana, Gedu; Förster, Sebastian; Helmchen, Günter

2013-01-02

Short and concise syntheses of the hexahydroindene cores of the antibiotics indanomycin (X-14547 A) and stawamycin are presented. Key methods used are an asymmetric iridium-catalyzed allylic alkylation, a modified Julia olefination, a Suzuki-Miyaura coupling, and an intramolecular Diels-Alder reaction. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Immobilization/hybridization of amino-modified DNA on plasma-polymerized allyl chloride

International Nuclear Information System (INIS)

Zhang Zhihong; Feng Chuanliang

2007-01-01

The present work describes the fabrication and characterization of chloride-derivatized polymer coatings prepared by continuous wave (cw) plasma polymerization as adhesion layers in DNA immobilization/hybridization. The stability of plasma-polymerized allyl chloride (ppAC) in H 2 O was characterized by variation of the thickness of polymer films and its wettability was examined by water contact angle technique. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to study polymer matrix properties and oligonucleotide/DNA binding interaction. With the same carrier gas rate and process pressure, plasma polymers deposited at different input powers show various comparable immobilization properties; nevertheless, low input power plasma-polymerized films gives a lower sensitivity toward DNA binding than that from high input power plasma-deposited films. The following DNA immobilization on chloride-functionalized surfaces was found dependence on the macromolecular architecture of the plasma films. The hybridization between probe DNA and total mismatch target DNA shows no non-specific adsorption between target and ppAC

Preservation of beech and spruce wood by allyl alcohol-based copolymers

International Nuclear Information System (INIS)

Solpan, Dilek; Gueven, Olgun

1999-01-01

Allyl alcohol (AA), acrylonitrile (AN), methyl methacrylate (MMA), monomers and monomer mixtures AA+AN, AA+MMA were used to conserve and consolidate Beech and Spruce. After impregnation, copolymerisation and polymerisation were accomplished by gamma irradiation. The fine structure of wood+polymer(copolymer) composites was investigated by Scanning Electron Microscopy (SEM). It was observed that copolymer obtained from AA+MMA monomer mixture showed the optimum compatibility. The compressional strength and Brinell Hardness Numbers determined for untreated and treated wood samples indicated that the mechanical strength of wood+copolymer composites was increased. It was found that the mechanical strength of the wood samples containing the AA+MMA copolymer was higher than the others. In the presence of P(AA/MMA), at highest conversion, the compressive strength perpendicular to the fibres in Beech and Spruce increased approximately 100 times. The water uptake capacity of wood+copolymer composites was observed to decrease by more than 50% relative to the original samples, and biodegradation did not take place

Lanthanum triflate triggered synthesis of tetrahydroquinazolinone derivatives of N-allyl quinolone and their biological assessment

Directory of Open Access Journals (Sweden)

Jardosh Hardik H.

2012-01-01

Full Text Available A series of 24 derivatives of tetrahydroquinazolinone has been synthesized by one-pot cyclocondensation reaction of N-allyl quinolones, cyclic β-diketones and (thiourea/N-phenylthiourea in presence of lanthanum triflate catalyst. This methodology allowed us to achieve the products in excellent yield by stirring at room temperature. All the synthesized compounds were investigated against a representative panel of pathogenic strains using broth microdilution MIC (minimum inhibitory concentration method for their in vitro antimicrobial activity. Amongst these sets of heterocyclic compounds 5h, 6b, 6h, 5f, 5l, 5n and 6g found to have admirable activity.

Inhibition of E. coli P-enolpyruvate carboxylase by P-enol-3-bromopyruvate

International Nuclear Information System (INIS)

Asem, K.; Smith, T.E.

1986-01-01

The generality of the mechanism based inhibition of P-enolpyruvate carboxylases (PEPCase) by P-enol-3-bromopyruvate (BrPEP) was tested by measuring its effects on the allosterically regulated enzyme from E. coli. In the presence of 1mM Mn 2+ , BrPEP appears to be a competitive inhibitor (K/sub i/ = 0.0087mM) of PEPCase. Incubation of 0.005mM PEPCase with 0.5mM (or 1.0mM)BrPEP along with H 14 CO 3 - and Mn 2+ , yielded, upon reduction with NaBH 4 , a protein containing radioactivity in an amount approximately proportional to that expected from the loss of catalytic activity. At both a 25- and a 50-fold excess (0.5mM and 1.0mM, respectively) of BrPEP to PEPCase subunits, first order loss of activity occurred with k values of 5.24 x 10 -3 min -1 and 1.03 x 10 -2 min -1 , respectively. At the lower concentration of BrPEP the inactivation process appeared to be reversible after 40 min with no further inhibition occurring even up to two hours of incubation. At the higher concentration of BrPEP, the rate of inhibition slowed dramatically after 50 min and appeared insignificant over the next hour. These data suggest that BrPEP irreversibly inactivates the E. coli PEP carboxylase, but that there may be considerable dissociation of the product, Br-oxaloacetate, before irreversible binding occurs, and that the reduced rate of inactivation may be due to depletion of BrPEP

Subtle trade-off existing between (anti)aromaticity, push-pull interaction, keto-enol tautomerism, and steric hindrance when defining the electronic properties of conjugated structures.

Science.gov (United States)

Kleinpeter, Erich; Bölke, Ute; Koch, Andreas

2010-07-22

The spatial magnetic properties (through space NMR shieldings, TSNMRS) of conjugated structures (benzenoid/quinonoid keto/enol tautomers, 1,3-dihydroxyaryl-2-aldehydes, Don-pi-Acc chromophores with trade-off existing push-pull vs aromatic behavior) have been calculated by the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept, and visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. The TSNMRS values, thus obtained, can be successfully employed to quantify and visualize (anti)aromaticity and to identify readily hereby zwitterionic structures due to push-pull behavior of the compounds studied. In addition, the push-pull behavior was quantified by the quotient (pi*/pi) approach of the central partial C=C double bond.

Allyl isothiocyanate affects the cell cycle of Arabidopsis thaliana

Directory of Open Access Journals (Sweden)

Signe Elisabeth Åsberg

2015-05-01

Full Text Available Isothiocyanates (ITCs are degradation products of glucosinolates present in members of the Brassicaceae family acting as herbivore repellents and antimicrobial compounds. Recent results indicate that allyl ITC (AITC has a role in defense responses such as glutathione depletion, ROS generation and stomatal closure. In this study we show that exposure to non-lethal concentrations of AITC causes a shift in the cell cycle distribution of Arabidopsis thaliana leading to accumulation of cells in S-phases and a reduced number of cells in non-replicating phases. Furthermore, transcriptional analysis revealed an AITC-induced up-regulation of the gene encoding cyclin-dependent kinase A while several genes encoding mitotic proteins were down-regulated, suggesting an inhibition of mitotic processes. Interestingly, visualization of DNA synthesis indicated that exposure to AITC reduced the rate of DNA replication. Taken together, these results indicate that non-lethal concentrations of AITC induce cells of A. thaliana to enter the cell cycle and accumulate in S-phases, presumably as a part of a defensive response. Thus, this study suggests that AITC has several roles in plant defense and add evidence to the growing data supporting a multifunctional role of glucosinolates and their degradation products in plants.

Conformational analysis of a Chlamydia-specific disaccharide α-Kdo-(2→8)-α-Kdo-(2→O)-allyl in aqueous solution and bound to a monoclonal antibody: Observation of intermolecular transfer NOEs

International Nuclear Information System (INIS)

Sokolowski, Tobias; Haselhorst, Thomas; Scheffler, Karoline; Weisemann, Ruediger; Kosma, Paul; Brade, Helmut; Brade, Lore; Peters, Thomas

1998-01-01

The disaccharide α-Kdo-(2 → 8)-α-Kdo (Kdo: 3-deoxy-d-manno-oct-2-ulosonic acid) represents a genus-specific epitope of the lipopolysaccharide of the obligate intracellular human pathogen Chlamydia. The conformation of the synthetically derived disaccharide α-Kdo-(2 → 8)-α-Kdo-(2 → O)-allyl was studied in aqueous solution, and complexed to a monoclonal antibody S25-2. Various NMR experiments based on the detection of NOEs (or transfer NOEs) and ROEs (or transfer ROEs) were performed. A major problem was the extensive overlap of almost all 1 H NMR signals of α-Kdo-(2 → 8)-α-Kdo-(2 → O)-allyl. To overcome this difficulty, HMQC-NOESY and HMQC-trNOESY experiments were employed. Spin diffusion effects were identified using trROESY experiments, QUIET-trNOESY experiments and MINSY experiments. It was found that protein protons contribute to the observed spin diffusion effects. At 800 MHz, intermolecular trNOEs were observed between ligand protons and aromatic protons in the antibody binding site. From NMR experiments and Metropolis Monte Carlo simulations, it was concluded that α-Kdo-(2 → 8)-α-Kdo-(2 → O)-allyl in aqueous solution exists as a complex conformational mixture. Upon binding to the monoclonal antibody S25-2, only a limited range of conformations is available to α-Kdo-(2 → 8)-α-Kdo-(2 → O)-allyl. These possible bound conformations were derived from a distance geometry analysis using transfer NOEs as experimental constraints. It is clear that a conformation is selected which lies within a part of the conformational space that is highly populated in solution. This conformational space also includes the conformation found in the crystal structure. Our results provide a basis for modeling studies of the antibody-disaccharide complex

Allyl isothiocyanate induced stress response in Caenorhabditis elegans

Directory of Open Access Journals (Sweden)

Saini AkalRachna K

2011-11-01

Full Text Available Abstract Background Allyl isothiocyanate (AITC from mustard is cytotoxic; however the mechanism of its toxicity is unknown. We examined the effects of AITC on heat shock protein (HSP 70 expression in Caenorhabditis elegans. We also examined factors affecting the production of AITC from its precursor, sinigrin, a glucosinolate, in ground Brassica juncea cv. Vulcan seed as mustard has some potential as a biopesticide. Findings An assay to determine the concentration of AITC in ground mustard seed was improved to allow the measurement of AITC release in the first minutes after exposure of ground mustard seed to water. Using this assay, we determined that temperatures above 67°C decreased sinigrin conversion to AITC in hydrated ground B. juncea seed. A pH near 6.0 was found to be necessary for AITC release. RT-qPCR revealed no significant change in HSP70A mRNA expression at low concentrations of AITC ( 1.0 μM resulted in a four- to five-fold increase in expression. A HSP70 ELISA showed that AITC toxicity in C. elegans was ameliorated by the presence of ground seed from low sinigrin B. juncea cv. Arrid. Conclusions • AITC induced toxicity in C. elegans, as measured by HSP70 expression. • Conditions required for the conversion of sinigrin to AITC in ground B. juncea seed were determined. • The use of C. elegans as a bioassay to test AITC or mustard biopesticide efficacy is discussed.

Mechanistic Insights into Solvent and Ligand Dependency in Cu(I)-Catalyzed Allylic Alkylation with gem-Diborylalkanes.

Science.gov (United States)

Zhang, Qi; Wang, Bing; Liu, Jia-Qin; Fu, Yao; Wu, Yu-Cheng

2018-01-19

The recent Cu-catalyzed allylic substitution reaction between gem-diboryalkane and allyl electrophiles shows intriguing solvent and ligand-controlled regioselectivity. The α-alkylation product was obtained in DMF solvent, while γ-alkylation product was obtained in dioxane solvent and the dioxane and NHC ligand situation. In the present study, density functional theory calculations have been used to investigate the reaction mechanism and origin of the regioselectivity. For both dioxane and DMF, γ-alkylation undergoes successive oxidative addition (CH 2 Bpin trans to leaving group) and direct Cγ-C reductive elimination. The α-alkylation is found to undergo oxidative addition (CH 2 Bpin trans to leaving group), isomerization, and Cα-C reductive elimination rather than the previously proposed oxidative addition (-CH 2 Bpin cis to the leaving group) and Cα-C reductive elimination. The γ-alkylation and α-alkylation is, respectively, favorable for dioxane and DMF solvent, which is consistent with the γ- and α-selectivity in experiment. The solvent interferes the isomerization step, thereby affects the relative facility of the α- and γ-alkylation. Further investigation shows that η 1 -intermediate formation promoted by solvent is the rate-determining step of the isomerization. The stronger electron-donating ability of DMF than dioxane facilitates the η 1 -intermediate formation and finally results in the easier isomerization in DMF. For dioxane and NHC situation, in the presence of neutral NHC ligand, the -PO 4 Et 2 group tightly coordinates with the Cu center after the oxidative addition, preventing the isomerization process. The regioselectivity is determined by the relative facility of the oxidative addition step. Therefore, the favorable oxidative addition (in which -CH 2 Bpin trans to the leaving group) results in the facility of γ-alkylation.

Zinc Enolate/Sulfinate Prepared from a Single-Run Reaction Using Zinc Dust with O-Tosylated 4-Hydroxy Coumarin and Pyrone

Energy Technology Data Exchange (ETDEWEB)

Shin, Ueon Sang; Joo, Seong-Ryu; Kim, Seung-Hoi [Dankook University, Cheonan (Korea, Republic of)

2016-07-15

We demonstrated the preparation of new zinc complexes, 2-oxo-2H-chromen-4-yloxy tosylzinc (I), and 6-methyl-2-oxo-2H-pyran-4-yloxy tosylzinc (II), by the oxidative addition of readily available zinc dust into the corresponding 4-tosylated coumarin (A) and pyrone (B), respectively. Of special interest, the thus-obtained zinc complexes showed an electrophile-dependent reactivity. The subsequent coupling reactions of I and II with a variety of acid chlorides provided the O-acylation product in moderate yields. More interestingly, it should be emphasized that the thus-prepared zinc complexes (I and II) functioned both as zinc enolate and zinc sulfinate, providing C(3)-disubstituted product (b) and sulfone (c), respectively, from a single-run reaction when I or II was treated with benzyl halides. Even though somewhat low yields were achieved under the nonoptimized conditions, the novel zinc complexes present another potential application for zinc reagents. Versatile applications of this discovery are currently underway.

Zinc Enolate/Sulfinate Prepared from a Single-Run Reaction Using Zinc Dust with O-Tosylated 4-Hydroxy Coumarin and Pyrone

International Nuclear Information System (INIS)

Shin, Ueon Sang; Joo, Seong-Ryu; Kim, Seung-Hoi

2016-01-01

We demonstrated the preparation of new zinc complexes, 2-oxo-2H-chromen-4-yloxy tosylzinc (I), and 6-methyl-2-oxo-2H-pyran-4-yloxy tosylzinc (II), by the oxidative addition of readily available zinc dust into the corresponding 4-tosylated coumarin (A) and pyrone (B), respectively. Of special interest, the thus-obtained zinc complexes showed an electrophile-dependent reactivity. The subsequent coupling reactions of I and II with a variety of acid chlorides provided the O-acylation product in moderate yields. More interestingly, it should be emphasized that the thus-prepared zinc complexes (I and II) functioned both as zinc enolate and zinc sulfinate, providing C(3)-disubstituted product (b) and sulfone (c), respectively, from a single-run reaction when I or II was treated with benzyl halides. Even though somewhat low yields were achieved under the nonoptimized conditions, the novel zinc complexes present another potential application for zinc reagents. Versatile applications of this discovery are currently underway

Statistical analysis of fragmentation patterns of electron ionization mass spectra of enolized-trimethylsilylated anabolic androgenic steroids

Science.gov (United States)

Fragkaki, A. G.; Angelis, Y. S.; Tsantili-Kakoulidou, A.; Koupparis, M.; Georgakopoulos, C.

2009-08-01

Anabolic androgenic steroids (AAS) are included in the List of prohibited substances of the World Anti-Doping Agency (WADA) as substances abused to enhance athletic performance. Gas chromatography coupled to mass spectrometry (GC-MS) plays an important role in doping control analyses identifying AAS as their enolized-trimethylsilyl (TMS)-derivatives using the electron ionization (EI) mode. This paper explores the suitability of complementary GC-MS mass spectra and statistical analysis (principal component analysis, PCA and partial least squares-discriminant analysis, PLS-DA) to differentiate AAS as a function of their structural and conformational features expressed by their fragment ions. The results obtained showed that the application of PCA yielded a classification among the AAS molecules which became more apparent after applying PLS-DA to the dataset. The application of PLS-DA yielded a clear separation among the AAS molecules which were, thus, classified as: 1-ene-3-keto, 3-hydroxyl with saturated A-ring, 1-ene-3-hydroxyl, 4-ene-3-keto, 1,4-diene-3-keto and 3-keto with saturated A-ring anabolic steroids. The study of this paper also presents structurally diagnostic fragment ions and dissociation routes providing evidence for the presence of unknown AAS or chemically modified molecules known as designer steroids.

Conformational analysis of a Chlamydia-specific disaccharide {alpha}-Kdo-(2{sup {yields}}8)-{alpha}-Kdo-(2{sup {yields}}O)-allyl in aqueous solution and bound to a monoclonal antibody: Observation of intermolecular transfer NOEs

Energy Technology Data Exchange (ETDEWEB)

Sokolowski, Tobias; Haselhorst, Thomas; Scheffler, Karoline [Medizinische Universitaet, Institut fuer Chemie (Germany); Weisemann, Ruediger [Bruker Analytik GmbH, Silberstreifen (Germany); Kosma, Paul [Institut fuer Chemie der Universitaet fuer Bodenkultur Wien (Austria); Brade, Helmut; Brade, Lore [Forschungszentrum Borstel, Zentrum fuer Medizin und Biowissenschaften Parkallee 22 (Germany); Peters, Thomas [Medizinische Universitaet, Institut fuer Chemie (Germany)

1998-07-15

The disaccharide {alpha}-Kdo-(2{sup {yields}}8)-{alpha}-Kdo (Kdo: 3-deoxy-d-manno-oct-2-ulosonic acid) represents a genus-specific epitope of the lipopolysaccharide of the obligate intracellular human pathogen Chlamydia. The conformation of the synthetically derived disaccharide {alpha}-Kdo-(2{sup {yields}}8)-{alpha}-Kdo-(2{sup {yields}}O)-allyl was studied in aqueous solution, and complexed to a monoclonal antibody S25-2. Various NMR experiments based on the detection of NOEs (or transfer NOEs) and ROEs (or transfer ROEs) were performed. A major problem was the extensive overlap of almost all {sup 1}H NMR signals of {alpha}-Kdo-(2{sup {yields}}8)-{alpha}-Kdo-(2{sup {yields}}O)-allyl. To overcome this difficulty, HMQC-NOESY and HMQC-trNOESY experiments were employed. Spin diffusion effects were identified using trROESY experiments, QUIET-trNOESY experiments and MINSY experiments. It was found that protein protons contribute to the observed spin diffusion effects. At 800 MHz, intermolecular trNOEs were observed between ligand protons and aromatic protons in the antibody binding site. From NMR experiments and Metropolis Monte Carlo simulations, it was concluded that {alpha}-Kdo-(2{sup {yields}}8)-{alpha}-Kdo-(2{sup {yields}}O)-allyl in aqueous solution exists as a complex conformational mixture. Upon binding to the monoclonal antibody S25-2, only a limited range of conformations is available to {alpha}-Kdo-(2{sup {yields}}8)-{alpha}-Kdo-(2{sup {yields}}O)-allyl. These possible bound conformations were derived from a distance geometry analysis using transfer NOEs as experimental constraints. It is clear that a conformation is selected which lies within a part of the conformational space that is highly populated in solution. This conformational space also includes the conformation found in the crystal structure. Our results provide a basis for modeling studies of the antibody-disaccharide complex.

Determination of thermodynamic parameters of tautomerization in gas phase by mass spectrometry and DFT calculations: Keto-enol versus nitrile-ketenimine equilibria.

Science.gov (United States)

Giussi, Juan M; Gastaca, Belen; Albesa, Alberto; Cortizo, M Susana; Allegretti, Patricia E

2011-02-01

The study of tautomerics equilibria is really important because the reactivity of each compound with tautomeric capacity can be determined from the proportion of each tautomer. In the present work the tautomeric equilibria in some γ,δ-unsaturated β-hydroxynitriles and γ,δ-unsaturated β-ketonitriles were studied. The first family of compounds presents two possible theoretical tautomers, nitrile and ketenimine, while the second one presents four possible theoretical tautomers, keto-nitrile, enol (E and Z)-nitrile and keto-ketenimine. The equilibrium in gas phase was studied by gas chromatography-mass spectrometry (GC-MS). Tautomerization enthalpies were calculated by this methodology, and results were compared with those obtained by density functional theory (DFT) calculations, observing a good agreement between them. Nitrile tautomers were favored within the first family of compounds, while keto-nitrile tautomers were favored in the second family. Copyright © 2010 Elsevier B.V. All rights reserved.

Organometallic Methods for Forming and Cleaving Carbon-Carbon Bonds

DEFF Research Database (Denmark)

Christensen, Stig Holden

with concomitant C-C bond formation was studied with a number of Grignard reagents. The transformation was performed in a sealed vial by heating to about 160 °C in an aluminum block or at 180 °C in a microwave oven. Good yields of the product alcohols were obtained with allyl- and benzylmagnesium halides when...

Practical synthesis, anticonvulsant, and antimicrobial activity of N-allyl and N-propargyl di(indolyl)indolin-2-ones.

Science.gov (United States)

Praveen, Chandrasekaran; Ayyanar, Asairajan; Perumal, Paramasivan Thirumalai

2011-07-01

An operation friendly protocol for the synthesis of novel di(indolyl)indolin-2-ones via Cu(OTf)(2) catalyzed bis-addition of N-allyl and N-propargyl indole with isatin was developed. This methodology allowed us to achieve the products in excellent yields without requiring purification technique like column chromatography. All the synthesized compounds were evaluated for their in vivo anticonvulsant activity against maximal electroshock test. Six compounds showed maximum activity compared to the standard drug phenytoin. The scope of the new molecules as antimicrobial agents were tested against two bacterial strains (Staphylococcus aureus and Escherichia coli) and one fungal strain (Candida albicans). Copyright © 2011 Elsevier Ltd. All rights reserved.

Circumvention of orbital symmetry restraints by 1,3-H-shifts of enolic radical cations.

Science.gov (United States)

Hudson, Charles E; McAdoo, David J

2004-07-01

The reaction coordinates of 1,3-H-shifts across double bonds are traced by theory for three reactions, CH(3)C(OH)CH(2)(+*) (1) --> CH(3)C(O(+*))CH(3) (2), CH(2)C(OH)(2)(+*) (3) --> CH(3)CO(2)H(+*) (4) and CH(3)C(OH)CH(2)(+*) (1) --> CH(2)C(OH)CH(3)(+*) (1'), to explore how the need to conserve orbital symmetry influences the pathways for these reactions. In the first and second reactions, prior to the start of the H-transfer the methylene rotates from being in the skeletal plane to being bisected by it. Thus these reactions are neither antarafacial nor suprafacial, but precisely between those possibilities. This stems from a counterbalancing between the need to conserve orbital symmetry and the large distorting forces required to attain an allowed antarafacial transition state. In contrast to the first two reactions, 1 --> 1' follows a suprafacial pathway. However, this pathway does not violate conservation of orbital symmetry, as it utilizes lower lying orbitals of appropriate symmetry rather than the antisymmetric uppermost occupied allyl-type orbital. Changes in geometry which presumably produce asymmetric vibrational excitation and the unequal losses of methyl that follow 1 --> 2, i.e., nonergodic behavior, are also characterized.

SYNTHESIS AND ANTITUMOR ACTIVITY OF COPPER, NICKEL AND COBALT COORDINATION COMPOUNDS WITH 1-(2-HYDROXYPHENYL)ETHANONE N(4)-ALLYL-3-THIOSEMICARBAZONE

OpenAIRE

Vasilii GRAUR; Serghei SAVCIN; Victor TSAPKOV; Aurelian GULEA

2015-01-01

The paper presents the synthesis of the ligand 1-(2-hydroxyphenyl)ethanone N(4)-allyl-3-thiosemicarbazone (H2L) and six coordination compounds of copper, nickel and cobalt with this ligand. The structure of thiosemicarbazone H2L was studied using 1H and 13С NMR spectroscopy. The synthesized coordination compounds were studied using elemental analysis, gravimetric analysis of water content, molar conductivity, and magnetochemistry. For H2L the antitumor activity towards human leukemia HL-60 ce...

Synthesis of 2,6-trans- and 3,3,6-trisubstituted tetrahydropyran-4-ones from Maitland-Japp derived 2H-dihydropyran-4-ones: a total synthesis of diospongin B.

Science.gov (United States)

Clarke, Paul A; Nasir, Nadiah Mad; Sellars, Philip B; Peter, Alejandra M; Lawson, Connor A; Burroughs, James L

2016-07-12

6-Substituted-2H-dihydropyran-4-one products of the Maitland-Japp reaction have been converted into tetrahydropyrans containing uncommon substitution patterns. Treatment of 6-substituted-2H-dihydropyran-4-ones with carbon nucleophiles led to the formation of tetrahydropyran rings with the 2,6-trans-stereochemical arrangement. Reaction of the same 6-substituted-2H-dihydropyran-4-ones with l-Selectride led to the formation of 3,6-disubstituted tetrahydropyran rings, while trapping of the intermediate enolate with carbon electrophiles in turn led to the formation 3,3,6-trisubstituted tetrahydropyran rings. The relative stereochemical configuration of the new substituents was controlled by the stereoelectronic preference for pseudo-axial addition of the nucleophile and trapping of the enolate from the opposite face. Application of these methods led to a synthesis of the potent anti-osteoporotic diarylheptanoid natural product diospongin B.

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

Directory of Open Access Journals (Sweden)

David W. Manley

2015-09-01

Full Text Available Heterogeneous semiconductor photoredox catalysis (SCPC, particularly with TiO2, is evolving to provide radically new synthetic applications. In this review we describe how photoactivated SCPCs can either (i interact with a precursor that donates an electron to the semiconductor thus generating a radical cation; or (ii interact with an acceptor precursor that picks up an electron with production of a radical anion. The radical cations of appropriate donors convert to neutral radicals usually by loss of a proton. The most efficient donors for synthetic purposes contain adjacent functional groups such that the neutral radicals are resonance stabilized. Thus, ET from allylic alkenes and enol ethers generated allyl type radicals that reacted with 1,2-diazine or imine co-reactants to yield functionalized hydrazones or benzylanilines. SCPC with tertiary amines enabled electron-deficient alkenes to be alkylated and furoquinolinones to be accessed. Primary amines on their own led to self-reactions involving C–N coupling and, with terminal diamines, cyclic amines were produced. Carboxylic acids were particularly fruitful affording C-centered radicals that alkylated alkenes and took part in tandem addition cyclizations producing chromenopyrroles; decarboxylative homo-dimerizations were also observed. Acceptors initially yielding radical anions included nitroaromatics and aromatic iodides. The latter led to hydrodehalogenations and cyclizations with suitable precursors. Reductive SCPC also enabled electron-deficient alkenes and aromatic aldehydes to be hydrogenated without the need for hydrogen gas.

Diallyl 5-[(4-hexyl-oxyphen-yl)imino-meth-yl]-m-phenyl-ene dicarbonate.

Science.gov (United States)

Herrera-González, Ana María; López-Velázquez, Delia; Bernès, Sylvain

2009-10-23

The title mol-ecule, C(27)H(31)NO(7), an imine derivative bearing both carbonate and allyl functionalities, was synthesized in the hope of obtaining a mesogenic polymerizable material. The allyl-carbonate arms are fully disordered over two sets of sites, reflecting a large degree of rotational freedom about σ bonds [occupancies: 0.665 (9)/0.335 (9) for one substituent, 0.564 (9)/0.436 (9) for the other]. In contrast, the hexyl chain is ordered, and presents the common all-trans extended conformation. The benzene rings connected via the imine group make a dihedral angle of 9.64 (11)°. In the crystal, the Y-shaped mol-ecules are weakly associated into centrosymmetric dimers through pairs of C-H⋯O(hex-yl) contacts. The resulting layers of dimers, approximately parallel to (25), are closely packed in the crystal, allowing π⋯π inter-actions between benzene rings of neighboring layers: the separation between the centroid of the benzene ring substituted by allyl-carbonate and the centroid of the benzene ring bearing the hex-yloxy group in the adjacent layer is 3.895 (1) Å.

Densities and derived thermodynamic properties of the binary systems of 1,1-dimethylethyl methyl ether with allyl methacrylate, butyl methacrylate, methacrylic acid, and vinyl acetate at T = (298.15 and 308.15) K

International Nuclear Information System (INIS)

Wisniak, Jaime; Peralta, Rene D.; Infante, Ramiro; Cortez, Gladis

2005-01-01

Densities of the binary systems of 1,1-dimethylethyl methyl ether (MTBE) with allyl methacrylate, butyl methacrylate, methacrylic acid, and vinyl acetate have been measured as a function of the composition, at 298.15 and 308.15 K and atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess molar volumes were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. The excess molar volumes are negative for the binaries of MTBE + methacrylates; the system MTBE with vinyl acetate presents near ideal behavior. The excess coefficient of thermal expansion is positive for all the systems studied here; the value of the coefficient for the system MTBE + allyl methacrylate is at least three times larger than that for the other systems

Enantioselective construction of quaternary N-heterocycles by palladium-catalysed decarboxylative allylic alkylation of lactams

KAUST Repository

Behenna, Douglas C.

2011-12-18

The enantioselective synthesis of nitrogen-containing heterocycles (N-heterocycles) represents a substantial chemical research effort and resonates across numerous disciplines, including the total synthesis of natural products and medicinal chemistry. In this Article, we describe the highly enantioselective palladium-catalysed decarboxylative allylic alkylation of readily available lactams to form 3,3-disubstituted pyrrolidinones, piperidinones, caprolactams and structurally related lactams. Given the prevalence of quaternary N-heterocycles in biologically active alkaloids and pharmaceutical agents, we envisage that our method will provide a synthetic entry into the de novo asymmetric synthesis of such structures. As an entry for these investigations we demonstrate how the described catalysis affords enantiopure quaternary lactams that intercept synthetic intermediates previously used in the synthesis of the Aspidosperma alkaloids quebrachamine and rhazinilam, but that were previously only available by chiral auxiliary approaches or as racemic mixtures. © 2012 Macmillan Publishers Limited. All rights reserved.

Synthesis of 2-(2-R1-Hydrazino-5-(R2-benzyl-2-thiazolines on the Basis of Meerweins Arylation Products of Allyl Isothiocyanate

Directory of Open Access Journals (Sweden)

Mykola I. Ganushchak

2003-02-01

Full Text Available 3-Aryl-2-chloropropylisothiocyanates (1 are formed by interaction of arenediazonium chlorides with allyl isothiocyanate. Adducts 1 react with monoacylhydrazines to form 1-acyl-4-(3-aryl-2-chloropropylthiosemicarbazides (2a–d. Thiosemicarbazides 2a–d in the presence of bases selectively transform into 2-(2-R1-hydrazino-5-(R2-benzyl-2-thiazolines (3a–d.

Hydrolysis of cellulose catalyzed by quaternary ammonium perrhenates in 1-allyl-3-methylimidazolium chloride.

Science.gov (United States)

Wang, Jingyun; Zhou, Mingdong; Yuan, Yuguo; Zhang, Quan; Fang, Xiangchen; Zang, Shuliang

2015-12-01

Quaternary ammonium perrhenates were applied as catalyst to promote the hydrolysis of cellulose in 1-allyl-3-methylimidazolium chloride ([Amim]Cl). The quaternary ammonium perrhenates displayed good catalytic performance for cellulose hydrolysis. Water was also proven to be effective to promote cellulose hydrolysis. Accordingly, 97% of total reduced sugar (TRS) and 42% of glucose yields could be obtained under the condition of using 5mol% of tetramethyl ammonium perrhenate as catalyst, 70μL of water, ca. 0.6mmol of microcrystalline cellulose (MCC) and 2.0g of [Amim]Cl as solvent under microwave irradiation for 30min at 150°C (optimal conditions). The influence of quaternary ammonium cation on the efficiency of cellulose hydrolysis was examined based on different cation structures of perrhenates. The mechanism on perrhenate catalyzed cellulose hydrolysis is also discussed, whereas hydrogen bonding between ReO4 anion and hydroxyl groups of cellulose is assumed to be the key step for depolymerization of cellulose. Copyright © 2015. Published by Elsevier Ltd.

Density Functional Calculation of the 0.5ML-Terminated Allyl Mercaptan/Si(100)-(2 × 1) Surface

International Nuclear Information System (INIS)

Chun-Mei, Tang; Kai-Ming, Deng; Xuan, Chen; Chuan-Yun, Xiao; Yu-Zhen, Liu; Qun-Xiang, Li

2009-01-01

The structural and electronic properties of the 0.5 ML-terminated allyl mercaptan (ALM)/Si(100)-(2 × 1) surface are studied using the density functional method. The calculated absorption energy of the ALM molecule on the 0.5 ML-terminated ALM/Si(100)-(2 × 1) surface is 3.36 eV, implying that adsorption is strongly favorable. The electronic structure calculations show that the ALM/Si(100)-(2 × 1), the clean Si(100)-(2 × 1), and the fully-terminated H/Si(100)-(2 × 1) surfaces have the nature of an indirect band gap semiconductor. The highest occupied molecular orbital is dominated by the ALM, confirming the mechanism proposed by Hossain for its chain reaction. (condensed matter: structure, mechanical and thermal properties)

Scientific development and modern wine industry: the origins and consolidation of Enology Station of Mendoza (Argentina, 1904-1920 Desarrollo científico e industria vitivinícola moderna: orígenes y consolidación de la Estación Enológica de Mendoza (Argentina, 1904- 1920

Directory of Open Access Journals (Sweden)

Florencia Rodríguez Vázquez

2009-01-01

Full Text Available In this article we propose to undertake a reconstruction of the development of the 'Estación Enológica', next to 'Escuela Nacional de Vitivinicultura', between 1904 to 1920 in Mendoza province. This study is of vital importance as we consider this place was a pioneer center in the achievement of scientific and technical studies. These were the basis for the consolidation of quality wine industry , which had many shortcomings by then, and they triggered changes in Mendoza's agroindustry. Besides, Estación Enológica became a meeting place for people who graduated from that school to share experiences and concerns. Apart from carrying out the reconstruction of the development, we will also investigate possibilities of applying these studies to vineyardsEn el presente artículo nos proponemos realizar una reconstrucción de la trayectoria de la Estación Enológica de Mendoza, anexa a la Escuela Nacional de Vitivinicultura, desde 1904 a 1920. El mismo cobra vital importancia en tanto la consideramos un centro pionero en la realización de estudios científicos y técnicos que sirvieron de base a la consolidación de una vitivinicultura de calidad -y que por entonces contaba con múltiples deficiencias- y un impulsor de cambios técnicos en la agroindustria local. A su vez, su importancia radicaría en que fue un espacio aglutinador de las experiencias e inquietudes de los enólogos graduados de la mencionada Escuela. Por último, nos referiremos a las posibilidades de recepción y divulgación de los estudios entre los vitivinicultores

Inhibition of high affinity choline uptake by N-allyl-3-quinuclidinol

International Nuclear Information System (INIS)

Asermely, K.E.; O'Neill, J.J.

1986-01-01

The peripheral actions of N-allyl-3-quinuclidinol (N-Al-3-OHQ) on high affinity choline uptake (HAChU) on rat phrenic nerve diaphragm are described. Endplate regions (EPA) identified by the Koelle histochemical techniques for acetylcholinesterase, were dissected from adult rat hemidiaphragms and placed in cold Krebs solution (pH-7.35). All measurements of HAChU were at 37 0 C in buffers containing tritium choline (5 μM 0.124 μC/mmole) at intervals of 1, 2, 4, 8, 15 and 30 min. Tissues were washed 3x, digested in 1N NaOH and counted for tritium in Chaikoff's solution. All data are expressed as pmole Ch/g wet weight. Comparison between EPA and non-EPA tissue demonstrate HAChU and slow choline diffusion, respectively. Steady state is observed in 15 min. N-Al-3-OHQ produces 15% inhibition at 5 x 10 -5 M compared with 50% inhibition on brain synaptosomes. At 5 x 10 -4 M N-Al-3-OHQ, 30% inhibition is observed. Attempts to deplete ACh by pre-stimulation with high K + -ion (25 mM) were unsuccessful; tissue 3 H-choline uptake appeared to oscillate over a 30 min period

Inhibition of high affinity choline uptake by N-allyl-3-quinuclidinol

Energy Technology Data Exchange (ETDEWEB)

Asermely, K.E.; O' Neill, J.J.

1986-03-01

The peripheral actions of N-allyl-3-quinuclidinol (N-Al-3-OHQ) on high affinity choline uptake (HAChU) on rat phrenic nerve diaphragm are described. Endplate regions (EPA) identified by the Koelle histochemical techniques for acetylcholinesterase, were dissected from adult rat hemidiaphragms and placed in cold Krebs solution (pH-7.35). All measurements of HAChU were at 37/sup 0/C in buffers containing tritium choline (5 ..mu..M 0.124 ..mu..C/mmole) at intervals of 1, 2, 4, 8, 15 and 30 min. Tissues were washed 3x, digested in 1N NaOH and counted for tritium in Chaikoff's solution. All data are expressed as pmole Ch/g wet weight. Comparison between EPA and non-EPA tissue demonstrate HAChU and slow choline diffusion, respectively. Steady state is observed in 15 min. N-Al-3-OHQ produces 15% inhibition at 5 x 10/sup -5/ M compared with 50% inhibition on brain synaptosomes. At 5 x 10/sup -4/ M N-Al-3-OHQ, 30% inhibition is observed. Attempts to deplete ACh by pre-stimulation with high K/sup +/-ion (25 mM) were unsuccessful; tissue /sup 3/H-choline uptake appeared to oscillate over a 30 min period.

Neuroprotective effect of S-allyl-l-cysteine derivatives against endoplasmic reticulum stress-induced cytotoxicity is independent of calpain inhibition.

Science.gov (United States)

Imai, Toru; Kosuge, Yasuhiro; Saito, Hiroaki; Uchiyama, Taketo; Wada, Taira; Shimba, Shigeki; Ishige, Kumiko; Miyairi, Shinichi; Makishima, Makoto; Ito, Yoshihisa

2016-03-01

S-allyl-l-cysteine (SAC) is known to have neuroprotective properties. We synthesized various SAC derivatives and tested their effects on endoplasmic reticulum stress-induced neurotoxicity in cultured hippocampal neurons (HPNs). Among the compounds tested, S-propyl-l-cysteine (SPC) exhibited the strongest neuroprotective activity in HPNs, followed by S-ethyl-l-cysteine (SEC) and S-methyl-l-cysteine (SMC). Unlike SAC and SMC, SPC and SEC did not have inhibitory activity on μ-calpain, suggesting that the mechanism underlying the protective activity of SPC and SEC differs from that of SAC. Copyright © 2016 Japanese Pharmacological Society. Production and hosting by Elsevier B.V. All rights reserved.

Allyl m-Trifluoromethyldiazirine Mephobarbital: An Unusually Potent Enantioselective and Photoreactive Barbiturate General Anesthetic

Energy Technology Data Exchange (ETDEWEB)

Savechenkov, Pavel Y.; Zhang, Xi; Chiara, David C.; Stewart, Deirdre S.; Ge, Rile; Zhou, Xiaojuan; Raines, Douglas E.; Cohen, Jonathan B.; Forman, Stuart A.; Miller, Keith W.; Bruzik, Karol S. (Harvard-Med); (Mass. Gen. Hosp.); (UIC)

2012-12-10

We synthesized 5-allyl-1-methyl-5-(m-trifluoromethyl-diazirynylphenyl)barbituric acid (14), a trifluoromethyldiazirine-containing derivative of general anesthetic mephobarbital, separated the racemic mixture into enantiomers by chiral chromatography, and determined the configuration of the (+)-enantiomer as S by X-ray crystallography. Additionally, we obtained the {sup 3}H-labeled ligand with high specific radioactivity. R-(-)-14 is an order of magnitude more potent than the most potent clinically used barbiturate, thiopental, and its general anesthetic EC{sub 50} approaches those for propofol and etomidate, whereas S-(+)-14 is 10-fold less potent. Furthermore, at concentrations close to its anesthetic potency, R-(-)-14 both potentiated GABA-induced currents and increased the affinity for the agonist muscimol in human {alpha}1{beta}2/3{gamma}2L GABA{sub A} receptors. Finally, R-(-)-14 was found to be an exceptionally efficient photolabeling reagent, incorporating into both {alpha}1 and {beta}3 subunits of human {alpha}1{beta}3 GABAA receptors. These results indicate R-(-)-14 is a functional general anesthetic that is well-suited for identifying barbiturate binding sites on Cys-loop receptors.

Quantification of allyl hexanoate in pineapple beverages and yogurts as a case study to characterise a source of uncertainty in dietary exposure assessment to flavouring substances.

Science.gov (United States)

Raffo, A; D'Aloise, A; Magrì, A D; Leclercq, C

2012-01-01

One source of uncertainty in the estimation of dietary exposure to flavouring substances is the uncertainty in the occurrence and concentration levels of these substances naturally present or added to foodstuffs. The aim of this study was to assess the variability of concentration levels of allyl hexanoate, considered as a case study, in two main food categories to which it is often added: pineapple juice-based beverages and yogurts containing pineapple. Thirty-four beverages and 29 yogurts, with pineapple fruit or juice and added flavourings declared as ingredients on the package, were purchased from the local market (in Rome) and analysed. Analytical methods based on the stir bar sorptive extraction (SBSE) technique for the isolation of the target analyte, and on GC-MS analysis for final determination, were developed for the two food categories. In beverages, allyl hexanoate concentrations ranged from less than 0.01 to 16.71 mg l(-1), whereas in yogurts they ranged from 0.02 to 89.41 mg kg(-1). Average concentrations in beverages and yogurts with pineapple as the main fruit ingredient (1.91 mg l(-1) for beverages, 9.61 mg kg(-1) for yogurts) were in fair agreement with average use level data reported from industry surveys for the relevant food categories (4.5 and 6.0 mg kg(-1), respectively). Within the group of yogurts a single product was found to contain a level of allyl hexanoate more than 10-fold higher than the average reported use level. The screening techniques developed by the European Food Safety Authority (EFSA) using use level data provided by industry gave estimates of exposure that were of the same order of magnitude as the estimates obtained for regular consumers who would be loyal to the pineapple yogurt and beverage products containing the highest observed concentration of the substance of interest. In this specific case the uncertainty in the results obtained with the use of standard screening techniques for exposure assessment based on industry

N,3,4-Trisubstituted pyrrolidines by electron transfer-induced oxidative cyclizations of N-allylic beta-amino ester enolates

Czech Academy of Sciences Publication Activity Database

Jahn, Ullrich; Kafka, František; Pohl, Radek; Jones, P.G.

2009-01-01

Roč. 65, č. 52 (2009), s. 10917-10929 ISSN 0040-4020 Institutional research plan: CEZ:AV0Z40550506 Keywords : electron transfer * pyrrolidines * oxidation Subject RIV: CC - Organic Chemistry Impact factor: 3.219, year: 2009

A Modular Approach to Aryl-C-ribonucleosides via the Allylic Substitution and Ring-Closing Metathesis Sequence. A Stereocontrolled Synthesis of All Four alpha-/beta- and D-/L-C-Nucleoside Stereoisomers

Czech Academy of Sciences Publication Activity Database

Štambaský, J.; Kapras, V.; Štefko, Martin; Kysilka, O.; Hocek, Michal; Malkov, A. V.; Kočovský, P.

2011-01-01

Roč. 76, č. 19 (2011), s. 7781-7803 ISSN 0022-3263 R&D Projects: GA MŠk LC512; GA AV ČR IAA400550902 Institutional research plan: CEZ:AV0Z40550506 Keywords : C-nucleosides * allylic substitution * metathesis * dihydroxylation Subject RIV: CC - Organic Chemistry Impact factor: 4.450, year: 2011

A theoretical study of the reaction of O(3P) with an allyl radical C3H5

Science.gov (United States)

Park, Jong-Ho; Lee, Hohjai; Choi, Jong-Ho

2003-11-01

Ab initio calculations of the reaction of ground-state atomic oxygen [O(3P)] with an allyl radical (C3H5) have been carried out using the density functional method and the complete basis set model. On the calculated lowest doublet potential energy surface, the barrierless association of O(3P) to C3H5 forms three energy-rich addition intermediates, which are predicted to undergo subsequent isomerization and decomposition steps leading to various products: C3H4O+H, CH2O+C2H3, C2H4+CHO, C2H2O+CH3, C2H5+CO, C3H4+OH, and C2H4O+CH. The respective reaction mechanisms through the three addition intermediates are presented, and it has been found that the barrier height, reaction enthalpy, and the number of intermediates involved along the reaction coordinate are of extreme importance in understanding such reactive scattering processes. With the aid of Rice-Ramsperger-Kassel-Marcus calculations, the major reaction pathway is predicted to be the formation of acrolein (C3H4O)+H, which is consistent with the previous gas-phase bulk kinetic experiment performed by Gutman et al. [J. Phys. Chem. 94, 3652 (1990)]. For the minor C3H4+OH channel, which has been newly found in the recent crossed beam investigations, a second barrierless, direct H-atom abstraction from the central carbon of C3H5 is calculated to compete with the addition process due to the little C-H bond dissociation energy and the formation of a stable allene product. The dynamic and kinetic characteristics of the reaction mechanism are discussed on the basis of the comparison of prior statistical calculations to the nascent internal distributions of the observed OH product.

Allyl Isothiocyanate Inhibits Actin-Dependent Intracellular Transport in Arabidopsis thaliana

Directory of Open Access Journals (Sweden)

Bjørnar Sporsheim

2015-12-01

Full Text Available Volatile allyl isothiocyanate (AITC derives from the biodegradation of the glucosinolate sinigrin and has been associated with growth inhibition in several plants, including the model plant Arabidopsis thaliana. However, the underlying cellular mechanisms of this feature remain scarcely investigated in plants. In this study, we present evidence of an AITC-induced inhibition of actin-dependent intracellular transport in A. thaliana. A transgenic line of A. thaliana expressing yellow fluorescent protein (YFP-tagged actin filaments was used to show attenuation of actin filament movement by AITC. This appeared gradually in a time- and dose-dependent manner and resulted in actin filaments appearing close to static. Further, we employed four transgenic lines with YFP-fusion proteins labeling the Golgi apparatus, endoplasmic reticulum (ER, vacuoles and peroxisomes to demonstrate an AITC-induced inhibition of actin-dependent intracellular transport of or, in these structures, consistent with the decline in actin filament movement. Furthermore, the morphologies of actin filaments, ER and vacuoles appeared aberrant following AITC-exposure. However, AITC-treated seedlings of all transgenic lines tested displayed morphologies and intracellular movements similar to that of the corresponding untreated and control-treated plants, following overnight incubation in an AITC-absent environment, indicating that AITC-induced decline in actin-related movements is a reversible process. These findings provide novel insights into the cellular events in plant cells following exposure to AITC, which may further expose clues to the physiological significance of the glucosinolate-myrosinase system.

Comparative studies on mitochondrial electron transport chain complexes of Sitophilus zeamais treated with allyl isothiocyanate and calcium phosphide.

Science.gov (United States)

Zhang, Chao; Wu, Hua; Zhao, Yuan; Ma, Zhiqing; Zhang, Xing

2016-01-01

With Sitophilus zeamais as the target organism, the present study for the first time attempted to elucidate the comparative effects between allyl isothiocyanate (AITC) and calcium phosphide (Ca3P2), exposure on mitochondrial electron transport chain (ETC.) complex I & IV and their downstream effects on enzymes relevant to reactive oxygen species (ROS). In vivo, both AITC and Ca3P2 inhibited complex I and IV with similar downstream effects. In contrast with Ca3P2, the inhibition of complex I caused by AITC was dependent on time and dose. In vitro, AITC inhibited complex IV more significantly than complex I. These results indicate that mitochondrial complex IV is the primary target of AITC, and that complex I is another potential target. Copyright © 2015 Elsevier B.V. All rights reserved.

Double-Mutated 5-Enol Pyruvylshikimate-3-phosphate Synthase Protein Expressed in MZHG0JG Corn (Zea mays L.) Has No Impact on Toxicological Safety and Nutritional Composition.

Science.gov (United States)

Matthews, Bethany A; Launis, Karen L; Bauman, Patricia A; Juba, Nicole C

2017-09-27

MZHG0JG corn will offer growers the flexibility to alternate between herbicides with two different modes of action in their weed-management programs, helping to mitigate and manage the evolution of herbicide resistance in weed populations. The proteins conferring herbicide tolerence in MZHG0JG corn, double-mutated 5-enol pyruvylshikimate-3-phosphate synthase protein (mEPSPS) and phosphinothricin acetyltransferase (PAT), as well as the MZHG0JG corn event, have been assessed by regulatory authorities globally and have been determined to be safe for humans, animals, and the environment. In addition to the safety data available for these proteins, further studies were conducted on MZHG0JG corn to assess levels of mEPSPS as compared to previously registered genetically modified (GM) corn. The results support the conclusion of no impact on toxicological safety or nutritional composition.

Carbonic anhydrase inhibitors. Comparison of chlorthalidone, indapamide, trichloromethiazide, and furosemide X-ray crystal structures in adducts with isozyme II, when several water molecules make the difference.

Science.gov (United States)

Temperini, Claudia; Cecchi, Alessandro; Scozzafava, Andrea; Supuran, Claudiu T

2009-02-01

Thiazide and high ceiling diuretics were recently shown to inhibit all mammalian isoforms of carbonic anhydrase (CA, EC 4.2.1.1) with a very different profile as compared to classical inhibitors, such as acetazolamide, methazolamide, and ethoxzolamide. Some of these structurally related compounds have a very different behavior against the widespread isozyme CA II, with chlorthalidone, trichloromethiazide, and furosemide being efficient inhibitors against CA II (K(I)s of 65-138 nM), whereas indapamide is a much weaker one (K(I) of 2520 nM). Furthermore, some of these diuretics are quite efficient (low nanomolar) inhibitors of other isoforms, for example, chlorthalidone against hCA VB, VII, IX, and XIII; indapamide against CA VII, IX, XII, and XIII, trichloromethiazide against CA VII and IX, and furosemide against CA I and XIV. Examining the four X-ray crystal structures of their CA II adducts, we observed several (2-3) active site water molecules interacting with the chlorthalidone, trichloromethiazide, and furosemide scaffolds which may be responsible for this important difference of activity. Indeed, indapamide bound to CA II has no interactions with active site water molecules. Chlorthalidone bound within the CA II active site is in an enolic (lactimic) tautomeric form, with the enolic OH also participating in two strong hydrogen bonds with Asn67 and a water molecule. The newly evidenced binding modes of these diuretics may be exploited for designing better CA II inhibitors as well as compounds with selectivity/affinity for various isoforms with medicinal chemistry applications.

Synthesis and Cyclopolymerzation of N-Aryl Di ‎AllylAmins As Antioxidants for Lubricant's Oil

Directory of Open Access Journals (Sweden)

Firyal M. Ali ‎

2017-12-01

Full Text Available In this research many new N-aryl substituted di allylAmins were  synthesized [ A1-A2 ] which were Polymerized by free radically mechanism by using Ammonium per sulfate  as an initiator at 700C .The new hindered   amines   as  cyclo  polymers  were  characterized  by FTIR  and  H-NMR Spectroscopies ,Physical   and   chemical properties were measured  using TGA and DSC to   study   the thermal stability  of   prepared  cyclopolymers  . These   prepared  N-aromatic  substituted di allylamins cyclopolymers [ A3 - A4 ]  were  used  as  antioxidants  for  lubricant  oil  .   which   give    high stability   when  comparing  with standard  antioxidant . The oxidation stability of base  oil with (1% additive  were  examined according to Institute of Petroleum testing method IP280 

Synthesis and Cyclopolymerzation of N-Aryl Di ‎AllylAmins As Antioxidants for Lubricant's Oil

Directory of Open Access Journals (Sweden)

Firyal M. Ali ‎

2017-12-01

Full Text Available In this research many new N-aryl substituted di allylAmins were  synthesized [ A1-A2 ] which were Polymerized by free radically mechanism by using Ammonium per sulfate  as an initiator at 700C .The new hindered   amines   as  cyclo  polymers  were  characterized  by FTIR  and  H-NMR Spectroscopies ,Physical   and   chemical properties were measured  using TGA and DSC to   study   the thermal stability  of   prepared  cyclopolymers  . These   prepared  N-aromatic  substituted di allylamins cyclopolymers [ A3 - A4 ]  were  used  as  antioxidants  for  lubricant  oil  .   which   give    high stability   when  comparing  with standard  antioxidant . The oxidation stability of base  oil with (1% additive  were  examined according to Institute of Petroleum testing method IP280

Sustainable and Low Viscous 1-Allyl-3-methylimidazolium Acetate + PEG Solvent for Cellulose Processing

Directory of Open Access Journals (Sweden)

Airong Xu

2017-02-01

Full Text Available Developing sustainable, low viscous and efficient solvents are always advantageous to the processing/fabricating of cellulose materials in practical applications. To this end, in this work novel solvents were developed; ([Amim][CH3COO]/PEG by dissolving polyethylene glycol 200 (PEG-200 in 1-allyl-3-methylimidazolium acetate ([Amim][CH3COO]. The solubilities of cellulose in [Amim][CH3COO]/PEG solvents were determined as a function of temperature, and the possible dissolution mechanism of cellulose in [Amim][CH3COO]/PEG solvent was investigated. The novel solvent exhibits outstanding advantages for good dissolution capacity of cellulose, such as low viscosity, negligible vapor pressure, and recycling capability. The [CH3COO]− anion and the [Amim]+ cation of [Amim][CH3COO] in [Amim][CH3COO]/PEG-10 are the driving force for cellulose dissolution verified by the 13C NMR spectra. In addition, the regenerated cellulose films from [Amim][CH3COO]/PEG solvent were characterized by scanning electron microscopy (SEM, X-ray diffraction (XRD, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR, and thermogravimetric analysis (TGA to estimate their morphologies and structures.

Increased presevation of sliced mozzarella cheese by antimibrobial sachet incorporated with allyl isothiocyanate

Directory of Open Access Journals (Sweden)

Ana Clarissa dos Santos Pires

2009-12-01

Full Text Available There is an increasing tendency to add natural antimicrobials of plant origin into food. The objective of this work was to develop a microbial sachet incorporated with allyl isothiocyanate (AIT, a volatile compound of plant origin, and to test its efficiency against growth of yeasts and molds, Staphylococcus sp. and psychrotrophic bacteria on sliced mozzarella cheese. Another objective was to quantify the concentration of AIT in the headspace of cheese packaging. A reduction of 3.6 log cycles was observed in yeasts and molds counts in the mozzarella packed with the antimicrobial sachet over 15-day storage time. The sachet also showed an antibacterial effect on Staphylococcus sp., reducing 2.4 log cycles after 12-day storage. Psychrotrophic bacteria species were the most resistant to the antimicrobial action. The highest concentration of AIT (0.08µg.mL-1 inside the active packaging system was observed at the 6-day of storage at 12 ºC ± 2 ºC. At the end of the storage time, AIT concentration decreased to only 10% of the initial concentration. Active packaging containing antimicrobial sachet has a potential use for sliced mozzarella, with molds and yeasts being the most sensitive to the antimicrobial effects.

Radical-scavenging Activity of Natural Methoxyphenols vs. Synthetic Ones using the Induction Period Method

Directory of Open Access Journals (Sweden)

Seiichiro Fujisawa

2007-02-01

Full Text Available The radical-scavenging activities of the synthetic antioxidants 2-allyl-4-X-phenol (X=NO2, Cl, Br, OCH3, COCH3, CH3, t-(CH33, C6H5 and 2,4-dimethoxyphenol, and the natural antioxidants eugenol and isoeugenol, were investigated using differential scanning calorimetry (DSC by measuring their anti-1,1-diphenyl-2-picrylhydrazyl (DPPH radical activity and the induction period for polymerization of methyl methacrylate (MMA initiated by thermal decomposition of 2,2'-azobisisobutyronitrile (AIBN and benzoyl peroxide (BPO. 2-Allyl-4-methoxyphenol and 2,4-dimethoxy-phenol scavenged not only oxygen-centered radicals (PhCOO. derived from BPO, but also carbon-centered radicals (R. derived from the AIBN and DPPH radical much more efficiently, in comparison with eugenol and isoeugenol. 2-Allyl-4-methoxyphenol may be useful for its lower prooxidative activity.

DFT Mechanistic Study of the Selective Terminal C-H Activation of n-Pentane with a Tungsten Allyl Nitrosyl Complex

KAUST Repository

Lee, Richmond

2017-01-17

Mechanistic insights into the selective C-H terminal activation of n-pentane with tungsten allyl nitrosyl complex reported by Legzdins were gained by employing density functional theory with B3LYP hybrid functional. Using Bader’s atom in molecules (AIM) analysis on the elementary steps of the hydrogen transfer process, TS1 and TS2, it was observed that the calculated H-transfer models were closely similar to Hall’s metal-assisted σ-bond metathesis through bond critical point (BCP) comparisons. One distinguishable feature was the fact that the formal oxidation state of the W changed in the concerted H-transfer process. To better differentiate, we term these processes as ‘Formal Reductive Hydrogen Transfer’ (FRHT) for TS1 and ‘Formal Oxidative Hydrogen Transfer’ (FOHT) for TS2.

DFT Mechanistic Study of the Selective Terminal C-H Activation of n-Pentane with a Tungsten Allyl Nitrosyl Complex

KAUST Repository

Lee, Richmond; Tan, Davin; Liu, Chaoli; Li, Huaifeng; Guo, Hao; Shyue, Jing-Jong; Huang, Kuo-Wei

2017-01-01

Mechanistic insights into the selective C-H terminal activation of n-pentane with tungsten allyl nitrosyl complex reported by Legzdins were gained by employing density functional theory with B3LYP hybrid functional. Using Bader’s atom in molecules (AIM) analysis on the elementary steps of the hydrogen transfer process, TS1 and TS2, it was observed that the calculated H-transfer models were closely similar to Hall’s metal-assisted σ-bond metathesis through bond critical point (BCP) comparisons. One distinguishable feature was the fact that the formal oxidation state of the W changed in the concerted H-transfer process. To better differentiate, we term these processes as ‘Formal Reductive Hydrogen Transfer’ (FRHT) for TS1 and ‘Formal Oxidative Hydrogen Transfer’ (FOHT) for TS2.

Conformational and structural analysis of 2-allyl-1,2-benzisothiazol-3(2 H)-one 1,1-dioxide as probed by matrix-isolation spectroscopy and quantum chemical calculations

Science.gov (United States)

Gómez-Zavaglia, Andrea; Kaczor, Agnieszka; Coelho, Daniela; Cristiano, M. Lurdes S.; Fausto, Rui

2009-02-01

2-Allyl-1,2-benzisothiazol-3(2 H)-one 1,1-dioxide (ABIOD) has been studied by matrix-isolation infrared spectroscopy and quantum chemical calculations. A conformational search on the B3LYP/6 -311++G(3df,3pd) potential energy surface of the molecule demonstrated the existence of three conformers, Sk, Sk' and C, with similar energies, differing in the orientation of the allyl group. The calculations predicted the Sk form as the most stable in the gaseous phase, whereas the Sk' and C conformers have calculated relative energies of ca. 0.6 and 0.8-3.0 kJ mol -1, respectively (depending on the level of theory). In agreement with the relatively large (>6 kJ mol -1) calculated barriers for conformational interconversion, the three conformers could be efficiently trapped in an argon matrix at 10 K, the experimental infrared spectrum of the as-deposited matrix fitting well the simulated spectrum built from the calculated spectra for individual conformers scaled by their predicted populations at the temperature of the vapour of the compound prior to matrix deposition. Upon annealing the matrix at 24 K, however, both Sk and Sk' conformers were found to convert to the more polar C conformer, indicating that this latter form becomes the most stable ABIOD conformer in the argon matrix.

Correlation of quinone reductase activity and allyl isothiocyanate formation among different genotypes and grades of horseradish roots.

Science.gov (United States)

Ku, Kang-Mo; Jeffery, Elizabeth H; Juvik, John A; Kushad, Mosbah M

2015-03-25

Horseradish (Armoracia rusticana) is a perennial crop and its ground root tissue is used in condiments because of the pungency of the glucosinolate (GS)-hydrolysis products allyl isothiocyanate (AITC) and phenethyl isothiocyanate (PEITC) derived from sinigrin and gluconasturtiin, respectively. Horseradish roots are sold in three grades: U.S. Fancy, U.S. No. 1, and U.S. No. 2 according to the USDA standards. These grading standards are primarily based on root diameter and length. There is little information on whether root grades vary in their phytochemical content or potential health promoting properties. This study measured GS, GS-hydrolysis products, potential anticancer activity (as quinone reductase inducing activity), total phenolic content, and antioxidant activities from different grades of horseradish accessions. U.S. Fancy showed significantly higher sinigrin and AITC concentrations than U.S. No. 1 ,whereas U.S. No. 1 showed significantly higher concentrations of 1-cyano 2,3-epithiopropane, the epithionitrile hydrolysis product of sinigrin, and significantly higher total phenolic concentrations than U.S. Fancy.

Alleviative effects of s-allyl cysteine and s-ethyl cysteine on MCD diet-induced hepatotoxicity in mice.

Science.gov (United States)

Lin, Chun-che; Yin, Mei-chin; Liu, Wen-hu

2008-11-01

Alleviative effects of s-allyl cysteine (SAC) and s-ethyl cysteine (SEC) upon methionine and choline deficient (MCD) diet-induced hepatotoxicity in mice were examined. SAC or SEC at 1g/L was added into drinking water for 7 weeks with MCD diet. MCD feeding significantly increased hepatic triglyceride and cholesterol levels, and elevated the activity of glucose-6-phosphate dehydrogenase (G6PDH), malic enzyme, fatty acid synthase (FAS) and 3-hydroxy-3-methylglutaryl coenzyme A reductase (P MCD feeding significantly lowered serum and hepatic glutathione (GSH) levels, increased malondialdehyde (MDA) and oxidized glutathione (GSSG) formation, and suppressed the activity and mRNA expression of glutathione peroxidase (GPX), superoxide dismutase (SOD) and catalase (P MCD feeding significantly enhanced the mRNA expression of interleukin (IL)-1beta, IL-6, tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta1, matrix metalloproteinases-9 (MMP-9) and collagen-alpha1 (P MCD-induced hepatotoxicity.

A versatile synthesis of cyclic dipeptides using the stepwise construction of the piperazine-2,5-dione ring from simple precursors: synthetic sequence and the structure of a representative product, (3RS)-4-(2-allyl-3,5-dimethylphenyl)-1-benzyl-3-phenylpiperazine-2,5-dione.

Science.gov (United States)

Acosta Quintero, Lina M; Palma, Alirio; Cobo, Justo; Glidewell, Christopher

2018-02-01

A versatile synthesis of multiply substituted cyclic dipeptides has been designed, based on the stepwise construction of the piperazine-2,5-dione ring using molecular fragments from four different precursor molecules. Starting from substituted 2-allylanilines, reaction with methyl 2-bromo-2-phenylacetate yields the corresponding methyl 2-(2-allylanilino)-2-phenylacetates, which react with haloacetyl chlorides to give methyl 2-[N-(2-allylphenyl)-2-haloacetamido]-2-phenylacetates, which then undergo ring closure with benzylamine to yield the corresponding cyclic dipeptides of type 4-(2-allylphenyl)-1-benzyl-3-phenylpiperazine-2,5-dione. (3RS)-4-(2-Allyl-3,5-dimethylphenyl)-1-benzyl-3-phenylpiperazine-2,5-dione, C 28 H 28 N 2 O 2 , (IIId), crystallizes with Z' = 2 in the space group P2 1 /c; the allyl groups in the two independent molecules adopt different conformations and, in one of them, the allyl group is disordered over two sets of atomic sites having occupancies of 0.534 (4) and 0.466 (4). In both molecules, the piperazine-2,5-dione ring adopts a boat conformation, with the 3-phenyl ring in a quasi-axial site. The molecules of (IIId) are linked into a three-dimensional framework structure by a combination of three C-H...O hydrogen bonds and three C-H...π(arene) hydrogen bonds. Comparisons are made with some related structures.

Ruthenium(II) bipyridine complexes bearing new keto-enol azoimine ligands: synthesis, structure, electrochemistry and DFT calculations.

Science.gov (United States)

Al-Noaimi, Mousa; Awwadi, Firas F; Mansi, Ahmad; Abdel-Rahman, Obadah S; Hammoudeh, Ayman; Warad, Ismail

2015-01-25

The novel azoimine ligand, Ph-NH-N=C(COCH3)-NHPh(C≡CH) (H2L), was synthesized and its molecular structure was determined by X-ray crystallography. Catalytic hydration of the terminal acetylene of H2L in the presence of RuCl3·3H2O in ethanol at reflux temperature yielded a ketone (L1=Ph-N=N-C(COCH3)=N-Ph(COCH3) and an enol (L2=Ph-N=N-C(COCH3)=N-PhC(OH)=CH2) by Markovnikov addition of water. Two mixed-ligand ruthenium complexes having general formula, trans-[Ru(bpy)(Y)Cl2] (1-2) (where Y=L1 (1) and Y=L2 (2), bpy is 2.2'-bipyrdine) were achieved by the stepwise addition of equimolar amounts of (H2L) and bpy ligands to RuCl3·3H2O in absolute ethanol. Theses complexes were characterized by elemental analyses and spectroscopic (IR, UV-Vis, and NMR (1D (1)H NMR, (13)C NMR, (DEPT-135), (DEPT-90), 2D (1)H-(1)H and (13)C-(1)H correlation (HMQC) spectroscopy)). The two complexes exhibit a quasi-reversible one electron Ru(II)/Ru(III) oxidation couple at 604 mV vs. ferrocene/ferrocenium (Cp2Fe(0/+)) couple along with one electron ligand reduction at -1010 mV. The crystal structure of complex 1 showed that the bidentate ligand L1 coordinates to Ru(II) by the azo- and imine-nitrogen donor atoms. The complex adopts a distorted trans octahedral coordination geometry of chloride ligands. The electronic spectra of 1 and 1+ in dichloromethane have been modeled by time-dependent density functional theory (TD-DFT). Copyright © 2014 Elsevier B.V. All rights reserved.

Composition of amino acid using carbon monoxide. Amide carbonylation reaction

Energy Technology Data Exchange (ETDEWEB)

Izawa, Kunisuke (Ajinomoto Co., Inc., Tokyo (Japan))

1989-02-01

Amide carbonylation reaction is a method to compose N-acyl-{alpha}-amino acid from aldehyde, carboxylic acid amide, and carbon monoxide in a phase and with high yield. Unlike the conventional Strecker reaction, this method does not use HCN which is in question on public pollution and does not require hydrolysis. This amide carbonylation reaction was discovered by Wakamatsu and others of Ajinomoto Co.,Ltd. Present application examples of this method are the composition of N-acetyl amino acid from the aldehyde class, the composition of N-Acyl amino acid from olefin, the composition of N-acyl or acetyl amino acid from the raw material of alcohol and the halide class, the composition of N-acyl or acetyl amino acid via the isomerization of epoxide and allyl alcohol, the composition of amino dicarboxylic acid, applying deoxidation of ring acid anhydride, the composition of N-acyl amino acid from the raw material of the amine class, the stereoselective composition of -substitution ring-{alpha}-amino acid, and the composition of amino aldehyde. 24 refs., 2 figs., 2 tabs.

Substituent Effects on Regioselectivity of the Diels-Alder Reactions: Reactions of 10-Allyl-1,8-dichloroanthracene with 2-Chloroacrylonitrile, 1-Cyanovinyl Acetate and Phenyl Vinyl Sulfone

Directory of Open Access Journals (Sweden)

Mujeeb A. Sultan

2016-01-01

Full Text Available Diels-Alder reaction of 10-allyl-1,8-dichloroanthracene (3 with 2-chloroacrylonitrile (4 and 1-cyanovinyl acetate (5 gives exclusively the ortho isomer while its reaction with phenyl vinyl sulfone (10 yields a mixture of two isomeric adducts with priority to ortho isomer. The reactions proceeded under microwave condition in xylene. Configurations of these isomers have been assigned with the help of NMR spectra. The results indicated that the steric effect is dominating toward the isomer regioselectivity in the Diels-Alder reaction of the present compounds.

Combining the catalytic enantioselective reaction of visible-light-generated radicals with a by-product utilization system.

Science.gov (United States)

Huang, Xiaoqiang; Luo, Shipeng; Burghaus, Olaf; Webster, Richard D; Harms, Klaus; Meggers, Eric

2017-10-01

We report an unusual reaction design in which a chiral bis-cyclometalated rhodium(iii) complex enables the stereocontrolled chemistry of photo-generated carbon-centered radicals and at the same time catalyzes an enantioselective sulfonyl radical addition to an alkene. Specifically, employing inexpensive and readily available Hantzsch esters as the photoredox mediator, Rh-coordinated prochiral radicals generated by a selective photoinduced single electron reduction are trapped by allyl sulfones in a highly stereocontrolled fashion, providing radical allylation products with up to 97% ee. The hereby formed fragmented sulfonyl radicals are utilized via an enantioselective radical addition to form chiral sulfones, which minimizes waste generation.

Vinylogous Nicholas reactions in the synthesis of bi- and tricyclic cycloheptynedicobalt complexes.

Science.gov (United States)

Kolodziej, Izabela; Green, James R

2015-11-28

The Lewis acid mediated intramolecular Nicholas reactions of allylic acetate enyne-Co2(CO)6 complexes afford cycloheptenyne-Co2(CO)6 complexes in three manifestations. Electron rich aryl substituted alkyne complexes give tricyclic 6,7,x-benzocycloheptenyne complexes, with x = 5, 6, or 7. Allylsilane substituted complexes afford exo methylene bicyclic x,7-cycloheptenyne complexes (x = 6,7). The allyl acetate function may also be replaced by a benzylic acetate, to afford dibenzocycloheptyne-Co2(CO)6 complexes. Following reductive complexation, the methodology may be applied to the synthesis of the icetexane diterpene carbon framework.

Concise stereocontrolled formal synthesis of (+/-)-quinine and total synthesis of (+/-)-7- hydroxyquinine via merged Morita-Baylis-Hillman-Tsuji-Trost cyclization.

Science.gov (United States)

Webber, Peter; Krische, Michael J

2008-12-05

Concise stereoselective syntheses of (+/-)-quinine and (+/-)-7-hydroxyquinine are achieved using a catalytic enone cycloallylation that combines the nucleophilic features of the Morita-Baylis-Hillman reaction and the electrophilic features of the Tsuji-Trost reaction. Cyclization of enone-allyl carbonate 11 delivers the product of cycloallylation 13 in 68% yield. Diastereoselective conjugate reduction of the enone 13 (>20:1 dr) followed by exchange of the N-protecting group provides the saturated N-Boc-protected methyl ketone 19, which upon aldol dehydration provides quinoline containing enone 15, possessing all carbon atoms of quinine. Exposure of ketone 15 to L-selectride enables diastereoselective carbonyl reduction (>20:1 dr) to furnish the allylic alcohol 16. Stereoselective hydroxyl-directed epoxidation using an oxovanadium catalyst modified by N-hydroxy-N-Me-pivalamide delivers epoxide 17 (17:1 dr). Cyclization of the resulting amine-epoxide 17 provides (+/-)-7-hydroxyquinine in 13 steps and 11% overall yield from aminoacetaldehyde diethyl acetal. Notably, highly stereoselective formation of five contiguous stereocenters is achieved through a series of 1,2-asymmetric induction events. Deoxygenation of the N-Cbz-protected allylic acetate 22 provides olefin 23, which previously has been converted to quinine. Thus, (+/-)-quinine is accessible in 16 steps and 4% overall yield from commercial aminoacetaldehyde diethyl acetal.

Brown seaweed (Saccharina japonica) as an edible natural delivery matrix for allyl isothiocyanate inhibiting food-borne bacteria.

Science.gov (United States)

Siahaan, Evi Amelia; Pendleton, Phillip; Woo, Hee-Chul; Chun, Byung-Soo

2014-01-01

The edible, brown seaweed Saccharina japonica was prepared as powder in the size range 500-900 μm for the desorption release of allyl isothiocyanate (AITC). Powders were used as raw (containing lipids) and as de-oiled, where the lipid was removed. In general, de-oiled powders adsorbed larger masses of AITC after vapour or solution contact. Mass adsorbed due to solution contact exceeded vapour contact. Larger particles adsorbed more than smaller particles. No chemical bonding between AITC and the powder surface occurred. Release from vapour deposited particles reached 70-85% available within 72 h; solution deposited reached 70-90% available at 192 h. The larger amounts of AITC adsorbed via solution deposition resulted in greater vapour-phase concentrations at 72 h for antimicrobial activity studies. No loss of activity was detected against Escherichia coli, Salmonella Typhimurium or Bacillus cereus. Only a nominal activity against Staphylococcus aureus was demonstrated. S. japonica powder could be used as an edible, natural vehicle for AITC delivery. Copyright © 2013 Elsevier Ltd. All rights reserved.

A dioxygenase of Pleurotus sapidus transforms (+)-valencene regio-specifically to (+)-nootkatone via a stereo-specific allylic hydroperoxidation.

Science.gov (United States)

Krügener, Sven; Krings, Ulrich; Zorn, Holger; Berger, Ralf G

2010-01-01

A selective and highly efficient allylic oxidation of the sesquiterpene (+)-valencene to the grapefruit flavour compound (+)-nootkatone was achieved with lyophilisate of the edible mushroom Pleurotus sapidus. The catalytic reaction sequence was elucidated through the identification of intermediate, (+)-valencene derived hydroperoxides. A specific staining of hydroperoxides allowed the semi-preparative isolation of two secondary (+)-valencene hydroperoxides, 6(R)-Isopropenyl-4(R),4a(S)-dimethyl-2,3,4,4a,5,6,7,8-octahydro-naphthalen-4(S)-yl-hydroperoxide and 6(R)-Isopropenyl-4(R),4a(S)-dimethyl-2,3,4,4a,5,6,7,8-octahydro-naphthalen-2(R)-yl-hydroperoxide. Chemical reduction of the biotransformation products yielded a tertiary alcohol identified as 2(R)-Isopropenyl-8(R),8a(S)-dimethyl-1,3,4,7,8,8a-hexahydro-2H-naphthalen-4a(R)-ol. This suggested a lipoxygenase-type oxidation of (+)-valencene via secondary and tertiary hydroperoxides and confirmed homology data of the key enzyme obtained previously from amino acid sequencing.

A general enantioselective route to the chamigrene natural product family

KAUST Repository

White, David E.; Stewart, Ian C.; Seashore-Ludlow, Brinton A.; Grubbs, Robert H.; Stoltz, Brian M.

2010-01-01

Described in this report is an enantioselective route toward the chamigrene natural product family. The key disconnections in our synthetic approach include sequential enantioselective decarboxylative allylation and ring-closing olefin metathesis to form the all-carbon quaternary stereocenter and spirocyclic core present in all members of this class of compounds. The generality of this strategy is demonstrated by the first total syntheses of elatol and the proposed structure of laurencenone B, as well as the first enantioselective total syntheses of laurencenone C and α-chamigrene. A brief exploration of the substrate scope of the enantioselective decarboxylative allylation/ring-closing metathesis sequence with fully substituted vinyl chlorides is also presented.

A general enantioselective route to the chamigrene natural product family

KAUST Repository

White, David E.

2010-06-01

Described in this report is an enantioselective route toward the chamigrene natural product family. The key disconnections in our synthetic approach include sequential enantioselective decarboxylative allylation and ring-closing olefin metathesis to form the all-carbon quaternary stereocenter and spirocyclic core present in all members of this class of compounds. The generality of this strategy is demonstrated by the first total syntheses of elatol and the proposed structure of laurencenone B, as well as the first enantioselective total syntheses of laurencenone C and α-chamigrene. A brief exploration of the substrate scope of the enantioselective decarboxylative allylation/ring-closing metathesis sequence with fully substituted vinyl chlorides is also presented.

Allylic ionic liquid electrolyte-assisted electrochemical surface passivation of LiCoO2 for advanced, safe lithium-ion batteries

Science.gov (United States)

Mun, Junyoung; Yim, Taeeun; Park, Jang Hoon; Ryu, Ji Heon; Lee, Sang Young; Kim, Young Gyu; Oh, Seung M.

2014-01-01

Room-temperature ionic liquid (RTIL) electrolytes have attracted much attention for use in advanced, safe lithium-ion batteries (LIB) owing to their nonvolatility, high conductivity, and great thermal stability. However, LIBs containing RTIL-electrolytes exhibit poor cyclability because electrochemical side reactions cause problematic surface failures of the cathode. Here, we demonstrate that a thin, homogeneous surface film, which is electrochemically generated on LiCoO2 from an RTIL-electrolyte containing an unsaturated substituent on the cation (1-allyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide, AMPip-TFSI), can avert undesired side reactions. The derived surface film comprised of a high amount of organic species from the RTIL cations homogenously covered LiCoO2 with a <25 nm layer and helped suppress unfavorable thermal reactions as well as electrochemical side reactions. The superior performance of the cell containing the AMPip-TFSI electrolyte was further elucidated by surface, electrochemical, and thermal analyses. PMID:25168309

Time-resolved fluorescence sensing of pesticides chlorpyrifos, crotoxyphos and endosulfan by the luminescent Eu(III)-8-allyl-3-carboxycoumarin probe

Science.gov (United States)

Azab, Hassan A.; Khairy, Gasser M.; Kamel, Rasha M.

2015-09-01

This work describes the application of time resolved fluorescence in microtiter plates for investigating the interactions of europium-allyl-3-carboxycoumarin with pesticides chlorpyrifos, endosulfan and crotoxyphos. Stern-Volmer studies at different temperatures for chlorpyrifos and crotoxyphos shows dynamic and static quenching mechanisms respectively. Direct methods for the determination of the pesticides under investigation have been developed using the luminescence variations of the probe in solution. The detection limits are 6.53, 0.004, 3.72 μmol/L for chlorpyrifos, endosulfan, and crotoxyphos, respectively. The binding constants and thermodynamic parameters of the pesticides with probe were evaluated. A thermodynamic analysis showed that the reaction is spontaneous with negative ΔG. Effect of some relevant interferents on the detection of pesticides has been investigated. The new method was applied to the determination of the pesticides in different types of water samples (tap, mineral, and waste water).

Synthesis of prostanoids; enantiomeric purity of alcohols by a 31P NMR technique

International Nuclear Information System (INIS)

Penning, T.D.

1985-01-01

The enone, 2,2-diemthyl-3aβ, 6aβ-dihydro-4H-cyclopenta-1,3-dioxol-4-one, has been synthesized in six steps from cyclopentadiene, resolved using sulfoximine chemistry, and converted into (-)-prostaglandin E 2 methyl ester in three steps. Introduction of the optically pure omega side-chain using a conjugate addition of a stabilized organocopper reagent, followed by direct alkylation of the enolate with the α side-chain allylic iodide in the presence of hexamethylphosphoramide, afforded a trans, vicinally disubstituted cyclopentanone. Deprotection of the C-15 alcohol, followed by aluminum amalgam reduction of the C-10/oxygen bond, provided (-)-PGE 2 methyl ester in 47% overall yield from the enone. In an extension of previously described work, 2-chloro-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholidine 2-sulfide, prepared from l-ephedrine and thiophosphoryl chloride, was used to determine the enantiomeric excess of chiral alcohols in conjunction with 31 P NMR. Chiral primary and secondary alcohols added quantitatively to the phospholidine to give diastereomers which could be analyzed by 31 P NMR and HPLC. A number of other phosphorus heterocycles were also explored as potential chiral derivatizing reagents

Optical, structural, and chemical properties of CR-39 implanted with 5.2 MeV doubly charged carbon ions

Science.gov (United States)

Ali, Dilawar; Butt, M. Z.; Ishtiaq, Mohsin; Waqas Khaliq, M.; Bashir, Farooq

2016-11-01

Poly-allyl-diglycol-carbonate (CR-39) specimens were irradiated with 5.2 MeV doubly charged carbon ions using Pelletron accelerator. Ion dose was varied from 5 × 1013 to 5 × 1015 ions cm-2. Optical, structural, and chemical properties were investigated by UV-vis spectroscopy, x-ray diffractometer, and FTIR/Raman spectroscopy, respectively. It was found that optical absorption increases with increasing ion dose. Absorption edge shifts from UV region to visible region. The measured opacity values of pristine and ion implanted CR-39 range from 0.0519 to 4.7959 mm-1 following an exponential growth (9141%) with the increase in ion dose. The values of direct and indirect band gap energy decrease exponentially with an increase in ion dose by 59% and 71%, respectively. However, average refractive index in the visible region increases from 1.443 to 2.864 with an increase in ion dose, by 98%. A linear relation between band gap energy and crystallite size was observed. Both the number of carbon atoms in conjugation length and the number of carbon atoms per cluster increase linearly with the increase in ion dose. FTIR spectra showed that on C+2 ions irradiation, the intensity of all bands decreases gradually without appearance of any new band, indicating degradation of polymer after irradiation. Raman spectra revealed that the density of -CH2- group decreases on C+2 ions irradiation. However, the structure of CR-39 is completely destroyed on irradiation with ion dose 1 × 1015 and 5 × 1015 ions cm-2.

Configurations and conformations in acyclic, unsaturated hydrocarbons. A 13C NMR study

NARCIS (Netherlands)

Haan, de J.W.; Ven, van de L.J.M.

1973-01-01

13C NMR (CMR) spectra of a number of di- and trisubstituted ethylenes have been measured. Very consistent values are found for the differential shieldings of allylic carbons in a number of linear, (Z)- and (E)-disubstituted ethylenes. The discrepancies between the several structural elements are

(Liquid + liquid) equilibrium for the ternary systems {heptane + toluene + 1-allyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide} and {heptane + toluene + 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide} ionic liquids

International Nuclear Information System (INIS)

Garcia, Silvia; Larriba, Marcos; Garcia, Julian; Torrecilla, Jose S.; Rodriguez, Francisco

2011-01-01

Highlights: → Values of D 1 and D 2 for [mpim][Tf 2 N] are higher than those for [amim][Tf 2 N]. → Values of α 2,1 for [mpim][Tf 2 N] are lower than those for [amim][Tf 2 N]. → Values of D 2 for both ionic liquids are higher than those for sulfolane. → Values of α 2,1 for [mpim][Tf 2 N] are lower than those for sulfolane at x 2 I 2 N] could be considered as an alternative solvent to sulfolane. - Abstract: The (liquid + liquid) equilibrium (LLE) data for two systems containing heptane, toluene, and 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide ([mpim][Tf 2 N]) or 1-allyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([amim][Tf 2 N]) ionic liquids (ILs) were determined at T = 313.2 K and atmospheric pressure. The effect of a double bond in an alkyl side chain in the imidazolium cation was evaluated in terms of selectivity and extractive capacity. The results show a decrease of the amount of toluene and heptane dissolved in the IL with the allyl group. Thus, the distribution ratios of toluene and heptane of [mpim][Tf 2 N] IL are higher than those of [amim][Tf 2 N] IL. On the other hand, the separation factor of the [amim][Tf 2 N] IL increases comparing to [mpim][Tf 2 N] IL. The NRTL model was used to correlate satisfactorily the experimental LLE data for the two studied ternary systems.

Proton conductive membranes based on poly (styrene-co-allyl alcohol semi-IPN

Directory of Open Access Journals (Sweden)

Felipe Augusto Moro Loureiro

2014-01-01

Full Text Available The optimization of fuel cell materials, particularly polymer membranes, for PEMFC has driven the development of methods and alternatives to achieve systems with more adequate properties to this application. The sulfonation of poly (styrene-co-allyl alcohol (PSAA, using sulfonating agent:styrene ratios of 2:1, 1:1, 1:2, 1:4, 1:6, 1:8 and 1:10, was previously performed to obtain proton conductive polymer membranes. Most of those membranes exhibited solubility in water with increasing temperature and showed conductivity of approximately 10-5 S cm-1. In order to optimize the PSAA properties, especially decreasing its solubility, semi-IPN (SIPN membranes are proposed in the present study. These membranes were obtained from the diglycidyl ether of bisphenol A (DGEBA, curing reactions in presence of DDS (4,4-diaminodiphenyl sulfone and PSAA. Different DGEBA/PSAA weight ratios were employed, varying the PSAA concentration between 9 and 50% and keeping the mass ratio of DGEBA:DDS as 1:1. The samples were characterized by FTIR and by electrochemical impedance spectroscopy. Unperturbed bands of PSAA were observed in the FTIR spectra of membranes, suggesting that chemical integrity of the polymer is maintained during the synthesis. In particular, bands involving C-C stretching (1450 cm-1, C=C (aromatic, ~ 3030 cm-1 and C-H (2818 and 2928 cm-1 were observed, unchanged after the synthesis. The disappearance or reduction of the intensity of the band at 916 cm-1, attributed to the DGEBA epoxy ring, is evidenced for all samples, indicating the epoxy ring opening and the DGEBA crosslinking. Conductivity of H3PO4 doped membranes increases with temperature, reaching 10-4 S cm-1.

Third-order nonlinear optical properties of open-shell supermolecular systems composed of acetylene linked phenalenyl radicals.

Science.gov (United States)

Nakano, Masayoshi; Kishi, Ryohei; Yoneda, Kyohei; Inoue, Yudai; Inui, Tomoya; Shigeta, Yasuteru; Kubo, Takashi; Champagne, Benoît

2011-08-11

The third-order nonlinear optical (NLO) properties, at the molecular level, the static second hyperpolarizabilities, γ, of supermolecular systems composed of phenalenyl and pyrene rings linked by acetylene units are investigated by employing the long-range corrected spin-unrestricted density functional theory, LC-UBLYP, method. The phenalenyl based superethylene, superallyl, and superbutadiene in their lowest spin states have intermediate diradical characters and exhibit larger γ values than the closed-shell pyrene based superpolyene systems. The introduction of a positive charge into the phenalenyl based superallyl radical changes the sign of γ and enhances its amplitude by a factor of 35. Although such sign inversion is also observed in the allyl radical and cation systems in their ground state equilibrium geometries, the relative amplitude of γ is much different, that is, |γ(regular allyl cation)/γ(regular allyl radical)| = 0.61 versus |γ(phenalenyl based superallyl cation)/γ(phenalenyl based superallyl radical)| = 35. In contrast, the model ethylene, allyl radical/cation, and butadiene systems with stretched carbon-carbon bond lengths (2.0 Å), having intermediate diradical characters, exhibit similar γ features to those of the phenalenyl based superpolyene systems. This exemplifies that the size dependence of γ as well as its sign change by introducing a positive charge on the phenalenyl based superpolyene systems originate from their intermediate diradical characters. In addition, the change from the lowest to the highest π-electron spin states significantly reduces the γ amplitudes of the neutral phenalenyl based superpolyene systems. For phenalenyl based superallyl cation, the sign inversion of γ (from negative to positive) is observed upon switching between the singlet and triplet states, which is predicted to be associated with a modification of the balance between the positive and negative contributions to γ. The present study paves the way

Organotrichlorogermane synthesis by the reaction of elemental germanium, tetrachlorogermane and organic chloride via dichlorogermylene intermediate.

Science.gov (United States)

Okamoto, Masaki; Asano, Takuya; Suzuki, Eiichi

2004-08-07

Organotrichlorogermanes were synthesized by the reaction of elemental germanium, tetrachlorogermane and organic chlorides, methyl, propyl, isopropyl and allyl chlorides. Dichlorogermylene formed by the reaction of elemental germanium with tetrachlorogermane was the reaction intermediate, which was inserted into the carbon-chlorine bond of the organic chloride to give organotrichlorogermane. When isopropyl or allyl chloride was used as an organic chloride, organotrichlorogermane was formed also in the absence of tetrachlorogermane. These chlorides were converted to hydrogen chloride, which subsequently reacted with elemental germanium to give the dichlorogermylene intermediate. The reaction of elemental germanium, tetrachlorogermane and organic chlorides provides a simple and easy method for synthesizing organotrichlorogermanes, and all the raw materials are easily available.

RIR MAPLE procedure for deposition of carbon rich Si/C/H films

International Nuclear Information System (INIS)

Dřínek, Vladislav; Strašák, Tomáš; Novotný, Filip; Fajgar, Radek; Bastl, Zdeněk

2014-01-01

We applied the resonant infrared matrix assisted pulsed laser evaporation (RIR MAPLE) technique to demonstrate a new approach to a controlled deposition of carbon rich amorphous Si/C/H film. In absence of radicals and accelerated species commonly generated in PECVD and sputtering setups, the RIR MAPLE method does not decompose precursor molecules. Moreover, unlike the standard MAPLE procedure, in which solvent molecules absorb laser energy from excimer or near infrared lasers, we applied the pulsed TEA CO 2 laser to excite the dendrimer precursor molecules in a frozen target. In this manner we achieved just cross-linking of the starting precursor on substrates and the deposition of carbon rich Si/C/H film. The film was analyzed by Fourier Transformed Infrared (FTIR), UV/VIS, Raman and X-ray Photoelectron (XPS) spectroscopy and Atomic Force Microscopy (AFM) technique. According to analyses the film retained the precursor elemental composition free of graphitic (sp 2 ) clusters. In course of reaction only the peripheral allyl groups containing C=C bonds were opened to achieve cross-linking. Whereas annealing to 300 °C was necessary for the elimination of =C–H 1 , 2 bonds in the films prepared at 200 °C, those bonds vanished completely for the films prepared at substrate temperature 255 °C. The film posseses a smooth surface with root mean square (RMS) parameter up to 10 nm within scanned distance 2.5 μm.

RIR MAPLE procedure for deposition of carbon rich Si/C/H films

Energy Technology Data Exchange (ETDEWEB)

Dřínek, Vladislav, E-mail: drinek@icpf.cas.cz [Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Rozvojova 135, 165 02 Prague 6 (Czech Republic); Strašák, Tomáš [Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Rozvojova 135, 165 02 Prague 6 (Czech Republic); Novotný, Filip [Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University, 115 19 Prague (Czech Republic); Fajgar, Radek [Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Rozvojova 135, 165 02 Prague 6 (Czech Republic); Bastl, Zdeněk [J. Heyrovsky Institute of Physical Chemistry of the ASCR, v. v. i., Dolejškova 2155/3, 182 23 Prague 8 (Czech Republic)

2014-02-15

We applied the resonant infrared matrix assisted pulsed laser evaporation (RIR MAPLE) technique to demonstrate a new approach to a controlled deposition of carbon rich amorphous Si/C/H film. In absence of radicals and accelerated species commonly generated in PECVD and sputtering setups, the RIR MAPLE method does not decompose precursor molecules. Moreover, unlike the standard MAPLE procedure, in which solvent molecules absorb laser energy from excimer or near infrared lasers, we applied the pulsed TEA CO{sub 2} laser to excite the dendrimer precursor molecules in a frozen target. In this manner we achieved just cross-linking of the starting precursor on substrates and the deposition of carbon rich Si/C/H film. The film was analyzed by Fourier Transformed Infrared (FTIR), UV/VIS, Raman and X-ray Photoelectron (XPS) spectroscopy and Atomic Force Microscopy (AFM) technique. According to analyses the film retained the precursor elemental composition free of graphitic (sp{sup 2}) clusters. In course of reaction only the peripheral allyl groups containing C=C bonds were opened to achieve cross-linking. Whereas annealing to 300 °C was necessary for the elimination of =C–H{sub 1}, {sub 2} bonds in the films prepared at 200 °C, those bonds vanished completely for the films prepared at substrate temperature 255 °C. The film posseses a smooth surface with root mean square (RMS) parameter up to 10 nm within scanned distance 2.5 μm.

Rhodium(II-Catalysed Intramolecular O-H Insertion of a-Diazo-g-Azido-d-Hydroxy-b-Ketoesters: Evidence for a Novel Sigmatropic Rearrangement of an Allylic Azide Intermediate

Directory of Open Access Journals (Sweden)

Padwa Albert

1999-01-01

Full Text Available The Rh2(OAc4 catalyzed intramolecular O-H insertion reaction of delta-hydroxy-alpha-diazoesters affords 3(2H-furanone-2-carboxylates in good yield but with moderate selectivity (d.e. ca 60%. The initially formed 2,5-substituted cis-furanones were found to epimerize to the corresponding 2,5-trans isomers when subjected to silica gel chromatography. The Rh2(OAc4 catalyzed decomposition of gamma-azido-delta-hydroxy-alpha-diazoesters also furnished 3(2H-furanone-2-carboxylates. These compounds are derived by a sequential O-H insertion reaction followed by a concerted [3,3]-sigmatropic shift of the allylic azide intermediate.

Large-scale single-chirality separation of single-wall carbon nanotubes by simple gel chromatography

Science.gov (United States)

Liu, Huaping; Nishide, Daisuke; Tanaka, Takeshi; Kataura, Hiromichi

2011-01-01

Monostructured single-wall carbon nanotubes (SWCNTs) are important in both scientific research and electronic and biomedical applications; however, the bulk separation of SWCNTs into populations of single-chirality nanotubes remains challenging. Here we report a simple and effective method for the large-scale chirality separation of SWCNTs using a single-surfactant multicolumn gel chromatography method utilizing one surfactant and a series of vertically connected gel columns. This method is based on the structure-dependent interaction strength of SWCNTs with an allyl dextran-based gel. Overloading an SWCNT dispersion on the top column results in the adsorption sites of the column becoming fully occupied by the nanotubes that exhibit the strongest interaction with the gel. The unbound nanotubes flow through to the next column, and the nanotubes with the second strongest interaction with the gel are adsorbed in this stage. In this manner, 13 different (n, m) species were separated. Metallic SWCNTs were finally collected as unbound nanotubes because they exhibited the lowest interaction with the gel. PMID:21556063

Concise Stereocontrolled Formal Synthesis of (±)-Quinine and Total Synthesis of (±)-7-Hydroxyquinine via Merged Morita-Baylis-Hillman-Tsuji-Trost Cyclization

Science.gov (United States)

Webber, Peter; Krische, Michael J.

2010-01-01

Concise stereoselective syntheses of (±)-quinine and (±)-7-hydroxyquinine are achieved using a catalytic enone cycloallylation that combines the nucleophilic features of the Morita-Baylis-Hillman reaction and the electrophilic features of the Tsuji-Trost reaction. Cyclization of enone-allyl carbonate 11 delivers the product of cycloallylation 13 in 68% yield. Diastereoselective conjugate reduction of the enone 13 (>20:1 dr) followed by exchange of N-protecting groups provides the saturated N-Boc-protected methyl ketone 19, which upon aldol dehydration provides quinoline containing enone 15, possessing all carbon atoms of quinine. Exposure of ketone 15 to L-selectride enables diastereoselective carbonyl reduction (>20:1 dr) to furnish the allylic alcohol 16. Stereoselective hydroxyl-directed epoxidation using an oxovanadium catalyst modified by N-hydroxy-N-Me-pivalamide delivers epoxide 17 (17:1 dr). Cyclization of the resulting amine-epoxide 17 provides (±)-7-hydroxyquinine in 13 steps and 11% overall yield from aminoacetaldehyde diethyl acetal. Notably, highly stereoselective formation of five contiguous stereocenters is achieved through a series of 1,2-asymmetric induction events. A formal synthesis of (±)-quinine is achieved upon deoxygenation of the N-Cbz-protected allylic acetate 22 to provide olefin 23, which previously has been converted to quinine. Thus, (±)-quinine is accessible in 16 steps and 4% overall yield from commercial aminoacetaldehyde diethyl acetal, making this route the most concise approach to quinine, to date. PMID:18989927

Symmetric Assembly of a Sterically Encumbered Allyl Complex: Mechanochemical and Solution Synthesis of the Tris(allylberyllate, K[BeA′3] (A′ = 1,3-(SiMe32C3H3

Directory of Open Access Journals (Sweden)

Nicholas C. Boyde

2017-05-01

Full Text Available The ball milling of beryllium chloride with two equivalents of the potassium salt of bis(1,3-trimethylsilylallyl anion, K[A′] (A′ = [1,3-(SiMe32C3H3], produces the tris(allylberyllate K[BeA’3] (1 rather than the expected neutral BeA’2. The same product is obtained from reaction in hexanes; in contrast, although a similar reaction conducted in Et2O was previously shown to produce the solvated species BeA’2(OEt2, it can produce 1 if the reaction time is extended (16 h. The tris(allylberyllate is fluxional in solution, and displays the strongly downfield 9Be NMR shift expected for a three-coordinate Be center (δ22.8 ppm. A single crystal X-ray structure reveals that the three allyl ligands are bound to beryllium in an arrangement with approximate C3 symmetry (Be–C (avg = 1.805(10 Å, with the potassium cation engaging in cation–π interactions with the double bonds of the allyl ligands. Similar structures have previously been found in complexes of zinc and tin, i.e., M[M′A′3L] (M′ = Zn, M = Li, Na, K; M′ = Sn, M = K; L = thf. Density functional theory (DFT calculations indicate that the observed C3-symmetric framework of the isolated anion ([BeA′3]− is 20 kJ·mol−1 higher in energy than a C1 arrangement; the K+ counterion evidently plays a critical role in templating the final conformation.

Novel N-allyl/propargyl tetrahydroquinolines: Synthesis via Three-component Cationic Imino Diels-Alder Reaction, Binding Prediction, and Evaluation as Cholinesterase Inhibitors.

Science.gov (United States)

Rodríguez, Yeray A; Gutiérrez, Margarita; Ramírez, David; Alzate-Morales, Jans; Bernal, Cristian C; Güiza, Fausto M; Romero Bohórquez, Arnold R

2016-10-01

New N-allyl/propargyl 4-substituted 1,2,3,4-tetrahydroquinolines derivatives were efficiently synthesized using acid-catalyzed three components cationic imino Diels-Alder reaction (70-95%). All compounds were tested in vitro as dual acetylcholinesterase and butyryl-cholinesterase inhibitors and their potential binding modes, and affinity, were predicted by molecular docking and binding free energy calculations (∆G) respectively. The compound 4af (IC50 = 72 μm) presented the most effective inhibition against acetylcholinesterase despite its poor selectivity (SI = 2), while the best inhibitory activity on butyryl-cholinesterase was exhibited by compound 4ae (IC50 = 25.58 μm) with considerable selectivity (SI = 0.15). Molecular docking studies indicated that the most active compounds fit in the reported acetylcholinesterase and butyryl-cholinesterase active sites. Moreover, our computational data indicated a high correlation between the calculated ∆G and the experimental activity values in both targets. © 2016 The Authors Chemical Biology & Drug Design Published by John Wiley & Sons Ltd.

Efficient and highly enantioselective formation of the all-carbon quaternary stereocentre of lyngbyatoxin A

DEFF Research Database (Denmark)

Vital, Paulo J.V.; Tanner, David

2006-01-01

Indole 25, an advanced intermediate in a projected enantioselective total synthesis of lyngbyatoxin A 1, was prepared from allylic alcohol 11 in 9 steps and >95% ee, key transformations being the enantiospecific rearrangement of vinyl epoxide 14 and the Hemetsberger-Knittel reaction of azide 24....

Latent tracks in polymeric etched track detectors

International Nuclear Information System (INIS)

Yamauchi, Tomoya

2013-01-01

Track registration properties in polymeric track detectors, including Poly(allyl diglycol carbonate), Bispenol A polycarbonate, Poly(ethylen terephtarate), and Polyimide, have been investigated by means of Fourie transform Infararede FT-IR spectrometry. Chemical criterion on the track formation threshold has been proposes, in stead of the conventional physical track registration models. (author)

Studies toward the synthesis of palhinine lycopodium alkaloids: a Morita-Baylis-Hillman/intramolecular Diels-Alder approach.

Science.gov (United States)

Sizemore, Nicholas; Rychnovsky, Scott D

2014-02-07

A synthetic route to the isotwistane core of palhinine lycopodium alkaloids is described. A Morita-Baylis-Hillman/intramolecular Diels-Alder (IMDA) strategy sets the vicinal all-carbon quaternary centers present in this family of natural products. The regioselectivity of the IMDA reaction is dictated by the conditions employed for silyl enol ether formation, with one set of conditions providing the core of cardionine and alternate conditions generating the desired isotwistane core of isopalhinine.

Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(-)-myrtenol nitrate.

Science.gov (United States)

Bew, Sean P; Hiatt-Gipson, Glyn D; Mills, Graham P; Reeves, Claire E

2016-01-01

Here we report the chemoselective synthesis of several important, climate relevant isoprene nitrates using silver nitrate to mediate a 'halide for nitrate' substitution. Employing readily available starting materials, reagents and Horner-Wadsworth-Emmons chemistry the synthesis of easily separable, synthetically versatile 'key building blocks' (E)- and (Z)-3-methyl-4-chlorobut-2-en-1-ol as well as (E)- and (Z)-1-((2-methyl-4-bromobut-2-enyloxy)methyl)-4-methoxybenzene has been achieved using cheap, 'off the shelf' materials. Exploiting their reactivity we have studied their ability to undergo an 'allylic halide for allylic nitrate' substitution reaction which we demonstrate generates (E)- and (Z)-3-methyl-4-hydroxybut-2-enyl nitrate, and (E)- and (Z)-2-methyl-4-hydroxybut-2-enyl nitrates ('isoprene nitrates') in 66-80% overall yields. Using NOESY experiments the elucidation of the carbon-carbon double bond configuration within the purified isoprene nitrates has been established. Further exemplifying our 'halide for nitrate' substitution chemistry we outline the straightforward transformation of (1R,2S)-(-)-myrtenol bromide into the previously unknown monoterpene nitrate (1R,2S)-(-)-myrtenol nitrate.

Carbon-14 methylation of the 2-methylbutyryl side chain of mevinolin and its analogs

International Nuclear Information System (INIS)

Prakash, S.R.; Ellsworth, R.L.

1988-01-01

A one step procedure for the preparation of three labeled mevinolin analogs possessing the 2,2-dimethylbutyryloxy side chain is described. Three lactones were converted into potassium salts of their corresponding di or trihydroxy carboxylic acids from which anionic ester enolates were generated and alkylated with [ 14 ]methyl iodide. Workup and purification by reverse phase HPLC provided the three radiochemically pure mevinolin analogs. The labeled lactones were converted into ammonium salts of their corresponding di or trihydroxy acids. (author)

The synthesis of thebaine-1-3H

International Nuclear Information System (INIS)

Choudhry, S.C.; Serico, L.; Cupano, J.; Malarek, D.H.; Liebman, A.A.

1989-01-01

A synthesis of thebaine is described where the C-1 position is labelled with tritium to specific activity of 16 Ci/mmole. From codeine, 1-iodocodeine was prepared and converted to 1-iodothebaine in 3 steps. The subsequent key reaction was the selective hydrogenolysis of the carbon-iodine bond in 1-iodothebaine in the presence of the dienic-enol ether system. Using 10% Pd/C as catalyst, the desired reaction occurs in about 80% yield. (author)

The synthesis of thebaine-1- sup 3 H

Energy Technology Data Exchange (ETDEWEB)

Choudhry, S.C.; Serico, L.; Cupano, J.; Malarek, D.H.; Liebman, A.A. (Hoffmann-La Roche, Inc., Nutley, NJ (USA). Chemical Research Dept.)

1989-12-01

A synthesis of thebaine is described where the C-1 position is labelled with tritium to specific activity of 16 Ci/mmole. From codeine, 1-iodocodeine was prepared and converted to 1-iodothebaine in 3 steps. The subsequent key reaction was the selective hydrogenolysis of the carbon-iodine bond in 1-iodothebaine in the presence of the dienic-enol ether system. Using 10% Pd/C as catalyst, the desired reaction occurs in about 80% yield. (author).

Robust Crosslinked Stereocomplexes and C60 Inclusion Complexes of Vinyl-Functionalized Stereoregular Polymers Derived from Chemo/Stereoselective Coordination Polymerization

KAUST Repository

Vidal, Fernando

2016-07-07

The successful synthesis of highly syndiotactic polar vinyl polymers bearing the reactive pendant vinyl group on each repeat unit, which is enabled by perfectly chemoselective and highly syndiospecific coordination polymerization of divinyl polar monomers developed through this work, has allowed the construction of robust crosslinked supramolecular stereocomplexes and C60 inclusion complexes. The metal-mediated coordination polymerization of three representative polar divinyl monomers, including vinyl methacrylate (VMA), allyl methacrylate (AMA), and N,N-diallyl acrylamide (DAA) by Cs-ligated zirconocenium ester enolate catalysts under ambient conditions exhibits complete chemoselectivity and high stereoselectivity, thus producing the corresponding vinyl-functionalized polymers with high (92% rr) to quantitative (>99% rr) syndiotacticity. A combined experimental (synthetic, kinetic, and mechanistic) and theoretical (DFT) investigation has yielded a unimetallic, enantiomorphic-site controlled propagation mechanism. Post-functionalization of the obtained syndiotactic vinyl-functionalized polymers via the thiol-ene click and photocuring reactions readily produced the corresponding thiolated polymers and flexible crosslinked thin film materials, respectively. Complexation of such syndiotactic vinyl-functionalized polymers with isotactic poly(methyl methacrylate) and fullerene C60 generates supramolecular crystalline helical stereocomplexes and inclusion complexes, respectively. Crosslinking of such complexes afforded robust crosslinked stereocomplexes that are solvent resistant and also exhibit considerably enhanced thermal and mechanical properties as compared to the uncrosslinked stereocompexes.

Robust Crosslinked Stereocomplexes and C60 Inclusion Complexes of Vinyl-Functionalized Stereoregular Polymers Derived from Chemo/Stereoselective Coordination Polymerization

KAUST Repository

Vidal, Fernando; Falivene, Laura; Caporaso, Lucia; Cavallo, Luigi; Chen, Eugene Y.-X.

2016-01-01

The successful synthesis of highly syndiotactic polar vinyl polymers bearing the reactive pendant vinyl group on each repeat unit, which is enabled by perfectly chemoselective and highly syndiospecific coordination polymerization of divinyl polar monomers developed through this work, has allowed the construction of robust crosslinked supramolecular stereocomplexes and C60 inclusion complexes. The metal-mediated coordination polymerization of three representative polar divinyl monomers, including vinyl methacrylate (VMA), allyl methacrylate (AMA), and N,N-diallyl acrylamide (DAA) by Cs-ligated zirconocenium ester enolate catalysts under ambient conditions exhibits complete chemoselectivity and high stereoselectivity, thus producing the corresponding vinyl-functionalized polymers with high (92% rr) to quantitative (>99% rr) syndiotacticity. A combined experimental (synthetic, kinetic, and mechanistic) and theoretical (DFT) investigation has yielded a unimetallic, enantiomorphic-site controlled propagation mechanism. Post-functionalization of the obtained syndiotactic vinyl-functionalized polymers via the thiol-ene click and photocuring reactions readily produced the corresponding thiolated polymers and flexible crosslinked thin film materials, respectively. Complexation of such syndiotactic vinyl-functionalized polymers with isotactic poly(methyl methacrylate) and fullerene C60 generates supramolecular crystalline helical stereocomplexes and inclusion complexes, respectively. Crosslinking of such complexes afforded robust crosslinked stereocomplexes that are solvent resistant and also exhibit considerably enhanced thermal and mechanical properties as compared to the uncrosslinked stereocompexes.

Preparation methods and properties of allylboranes

International Nuclear Information System (INIS)

Mikhajlov, B.M.

1976-01-01

The methods of synthesis and chemical properties of allylboron compounds of different types are considered as well as the application in organic chemistry, for example, for synthesis of 1-boroadamantane and adamantane compounds. PMR study of triallylborane reveals permanent allyl rearrangement. The paper describes the ability to complex formation, reactions with organometal compounds and some other agents, reactions with diborane and tetraalkyldiboranes, reactions with carbonyl compounds and nitriles, reactions with compounds containing activated double carbon-carbon bond, reactions with acetylene compounds, and reaction with allene compounds

Finding of 13(2) , 17(3) -cyclopheophorbide a enol as a degradation product of chlorophyll in shrunk zooxanthellae of the coral Montipora digitata.

Science.gov (United States)

Suzuki, Toshiyuki; Casareto, Beatriz Estela; Shioi, Yuzo; Ishikawa, Yoshio; Suzuki, Yoshimi

2015-02-01

We examined the morphology and pigment composition of zooxanthellae in corals subjected to normal temperature (27°C) and thermal stress (32°C). We observed several normal and abnormal morphological types of zooxanthellar cells. Normal cells were intact and their chloroplasts were unbroken (healthy); abnormal cells were shrunken and had partially degraded or broken chloroplasts, or they were bleached and without chloroplasts. At 27°C, most healthy zooxanthellar cells were retained in the coral tissue, whereas shrunken zooxanthellae were expelled. Under thermal stress, the abundance of healthy zooxanthellae declined and the proportion of shrunken/abnormal cells increased in coral tissues. The rate of algal cell expulsion was reduced under thermal stress. Within the shrunken cells, we detected the presence of a chl-like pigment that is not ordinarily found in healthy zooxanthellae. Analysis of the absorption spectrum, absorption maxima, and retention time (by HPLC) indicated that this pigment was 13(2) , 17(3) -cyclopheophorbide a enol (cPPB-aE), which is frequently found in marine and lacustrine sediments, and in protozoans that graze on phytoplankton. The production of cPPB-aE in shrunken zooxanthellae suggests that the chls have been degraded to cPPB-aE, a compound that is not fluorescent. The lack of a fluorescence function precludes the formation of reactive oxygen species. We therefore consider the formation of cPPB-aE in shrunken zooxanthellae to be a mechanism for avoiding oxidative stress. © 2014 The Authors. Journal of Phycology published by Wiley Periodicals, Inc. on behalf of Phycological Society of America.

Synthesis of dexamethasone-4-14C

International Nuclear Information System (INIS)

Rao, P.N.; Cessac, J.W.; Hill, K.A.

1982-01-01

The bismethylenedioxy (BMD) derivative of dexamethasone 2 was silylated with trimethylchlorosilane and imidazole in dimethylformamide to give the 11β-trimethylsilyloxy BMD derivative 3. The Δ 1 -double bond in 3 was hydrogenated over 5% palladium on carbon to give the Δ 4 -3-oxo steroid 4. Oxidation of 4 with potassium permanganate-sodium metaperiodate gave the seco-acid 5 which on subsequent treatment with acetic anhydride; sodium acetate and triethylamine gave the enol-lactone 6. The enol-lactone 6 was reacted with 14 C-methylmagnesium iodide to give an adduct 7a which on heating at reflux with lithium 2,6-di-t-butylphenoxide in dioxane gave the Δ 4 -3-oxo derivative 8. Compound 8 was heated at reflux with m-iodylbenzoic acid and diphenyl diselenide in toluene to give the Δsup(1,4)-3-oxo steroid 9. The protecting BMD and silyl groups were removed in a single step by reaction with aqueous trifluoroacetic acid containing 2N hydrochloric acid at room temperature to give dexamethasone-4- 14 C 10. (author)

Radiation-induced changes affecting polyester based polyurethane binder

Science.gov (United States)

Pierpoint, Sujita Basi

The application of thermoplastic polyurethane elastomers as binders in the high energy explosives particularly when used in weapons presents a significantly complex and challenging problem due to the impact of the aging of this polymer on the useful service life of the explosive. In this work, the effects of radiation on the aging of the polyester based polyurethane were investigated using both electron beam and gamma irradiation at various dose rates in the presence and absence of oxygen. It was found by means of GPC that, in the presence and absence of oxygen, the poly (ester urethane) primarily undergoes cross-linking, by means of a carbon-centered secondary alkyl radical. It was also concluded that the polymer partially undergoes scission of the backbone of the main chain at C-O, N-C, and C-C bonds. Substantial changes in the conditions of irradiation and in dose levels did not affect the cross-linking and scission yields. Experiments were also performed with EPR spectroscopy for the purpose of identifying the initial carbon-centered free radicals and for studying the decay mechanisms of these radicals. It was found that the carbon-centered radical which is produced via C-C scission (primary alkyl radical) is rapidly converted to a long-lived allylic species at higher temperatures; more than 80% radicals are converted to allyl species in 2.5 hours. In the presence of oxygen, the allyl radical undergoes a fast reaction to produce a peroxyl radical; this radical decays with a 1.7 hour half-life by pseudo first-order kinetics to negligible levels in 13 hours. FTIR measurements were conducted to identify the radiation-induced changes to the functional groups in the polyester polyurethane. These measurements show an increase in carbonyl, amine and carboxylic groups as a result of reaction of H atoms with R-C-O·, ·NH-R and R-COO·. The FTIR results also demonstrate the production of the unsaturation resulting from hydrogen atom transfer during intrachain conversion

A Catalytic, Asymmetric Formal Synthesis of (+)-Hamigeran B

KAUST Repository

Mukherjee, Herschel

2011-03-04

A concise asymmetric, formal synthesis of (+)-hamigeran B is reported. A Pd-catalyzed, decarboxylative allylic alkylation, employing a trifluoromethylated derivative of t-BuPHOX, is utilized as the enantioselective step to form the critical quaternary carbon center in excellent yield and enantioselectivity. The product is converted in three steps to a late-stage intermediate previously used in the synthesis of hamigeran B.

A Catalytic, Asymmetric Formal Synthesis of (+)-Hamigeran B

KAUST Repository

Mukherjee, Herschel; McDougal, Nolan T.; Virgil, Scott C.; Stoltz, Brian M.

2011-01-01

A concise asymmetric, formal synthesis of (+)-hamigeran B is reported. A Pd-catalyzed, decarboxylative allylic alkylation, employing a trifluoromethylated derivative of t-BuPHOX, is utilized as the enantioselective step to form the critical quaternary carbon center in excellent yield and enantioselectivity. The product is converted in three steps to a late-stage intermediate previously used in the synthesis of hamigeran B.

Well-defined mono(η3-allyl)nickel complex MONi(η3-C3H5) (M = Si or Al) grafted onto silica or alumina: A molecularly dispersed nickel precursor for syntheses of supported small size nickel nanoparticles

KAUST Repository

Li, Lidong; Abou-Hamad, Edy; Anjum, Dalaver H.; Zhou, Lu; Laveille, Paco; Emsley, Lyndon; Basset, Jean-Marie

2014-01-01

Preparing evenly-dispersed small size nickel nanoparticles over inert oxides remains a challenge today. In this context, a versatile method to prepare supported small size nickel nanoparticles (ca. 1-3 nm) with narrow size distribution via a surface organometallic chemistry (SOMC) route is described. The grafted mono(η3-allyl)nickel complexes MONi(η 3-C3H5) (M = Si or Al) as precursors are synthesized and fully characterized by elemental analysis, FTIR spectroscopy and paramagnetic solid-state NMR. © 2014 the Partner Organisations.

Origin of Stereodivergence in Cooperative Asymmetric Catalysis with Simultaneous Involvement of Two Chiral Catalysts.

Science.gov (United States)

Bhaskararao, Bangaru; Sunoj, Raghavan B

2015-12-23

Accomplishing high diastereo- and enantioselectivities simultaneously is a persistent challenge in asymmetric catalysis. The use of two chiral catalysts in one-pot conditions might offer new avenues to this end. Chirality transfer from a catalyst to product gets increasingly complex due to potential chiral match-mismatch issues. The origin of high enantio- and diastereoselectivities in the reaction between a racemic aldehyde and an allyl alcohol, catalyzed by using axially chiral iridium phosphoramidites PR/S-Ir and cinchona amine is established through transition-state modeling. The multipoint contact analysis of the stereocontrolling transition state revealed how the stereodivergence could be achieved by inverting the configuration of the chiral catalysts that are involved in the activation of the reacting partners. While the enantiocontrol is identified as being decided in the generation of PR/S-Ir-π-allyl intermediate from the allyl alcohol, the diastereocontrol arises due to the differential stabilizations in the C-C bond formation transition states. The analysis of the weak interactions in the transition states responsible for chiral induction revealed that the geometric disposition of the quinoline ring at the C8 chiral carbon of cinchona-enamine plays an anchoring role. The quinolone ring is noted as participating in a π-stacking interaction with the phenyl ring of the Ir-π-allyl moiety in the case of PR with the (8R,9R)-cinchona catalyst combination, whereas a series of C-H···π interactions is identified as vital to the relative stabilization of the stereocontrolling transition states when PR is used with (8S,9S)-cinchona.

Aplicação de taninos enológicos na elaboração de vinho Cabernet Sauvignon e seus efeitos sobre a qualidade sensorial Application of enological tannins in the development of Cabert Sauvignon and their effects on the sensory quality

Directory of Open Access Journals (Sweden)

Vitor Manfroi

2010-02-01

Full Text Available Objetivou-se estudar o efeito do uso de taninos enológicos na composição sensorial do vinho Cabernet Sauvignon. O trabalho foi conduzido em Bento Gonçalves, Rio Grande do Sul (RS, com uvas Cabernet Sauvignon, safra 2004. Trata-se de uma cultivar que se destaca no Brasil pela importância na produção de vinhos tintos de guarda. Porém, em algumas safras, possui dificuldades para uma adequada maturação, o que dificulta a elaboração de vinhos com o perfil sensorial desejado pelos consumidores. Dentre as estratégias para minimizar esse problema, está o manejo do vinhedo, aliado a ajustes tecnológicos nas etapas de elaboração do vinho. Para tal, foram usados taninos de quebracho e castanheira, aplicados em três dosagens (5,0g hl-1, 10,0g hl-1, 20,0g hl-1 e em três momentos de aplicação (maceração, descuba, e após a fermentação malolática. Nos vinhos estabilizados, realizaram-se análises sensoriais, em relação aos atributos ligados aos perfis olfativos e gustativos, com análise de oito descritores olfativos e nove descritores gustativos, além de um conceito geral. Assim, verificou-se que os taninos enológicos imprimiram algumas diferenças, principalmente no perfil aromático dos vinhos, que apresentaram acréscimo de qualidade quando tratados com os taninos enológicos. Da mesma maneira, houve superioridade olfativa e gustativa nos vinhos que receberam tratamentos com taninos na etapa de maceração.The objective of this research was to study the effect of enological tannins in the sensory composition of the Cabernet Sauvignon wine. The study was conducted in Bento Gonçalves, RS, with Cabernet Sauvignon grapes, harvest 2004. This is a cultivar that stands out in importance in Brazil for the production of red wines. However, in some crops there are difficulties for a proper maturation, which hampers the development of wines with the sensory profile desired by consumers. Among the strategies to minimize this problem

Tandem Carbocupration/Oxygenation of Terminal Alkynes

Science.gov (United States)

Zhang, Donghui; Ready, Joseph M.

2008-01-01

A direct and general synthesis of α-branched aldehydes and their enol derivatives is described. Carbocupration of terminal alkynes and subsequent oxygenation with lithium tert-butyl peroxide generates a metallo-enolate. Trapping with various electrophiles provides α-branched aldehydes or stereo-defined trisubstituted enol esters or silyl ethers. The tandem carbocupration/oxygenation tolerates alkyl and silyl ethers, esters and tertiary amines. The reaction is effective with organocopper complexes derived from primary, secondary and tertiary Grignard reagents and from n-butyllithium. PMID:16321021

Inhibition of bladder cancer cell proliferation by allyl isothiocyanate (mustard essential oil)

Energy Technology Data Exchange (ETDEWEB)

Sávio, André Luiz Ventura, E-mail: savio.alv@gmail.com [UNESP – Universidade Estadual Paulista, Faculdade de Medicina de Botucatu, Departamento de Patologia, Botucatu, SP (Brazil); Nicioli da Silva, Glenda [UFOP – Universidade Federal de Ouro Preto, Escola de Farmácia, Departamento de Análises Clínicas, Ouro Preto, MG (Brazil); Salvadori, Daisy Maria Fávero [UNESP – Universidade Estadual Paulista, Faculdade de Medicina de Botucatu, Departamento de Patologia, Botucatu, SP (Brazil)

2015-01-15

Highlights: • AITC inhibits mutant and wild-type TP53 cell proliferation. • Morphological changes and cells debris were observed after AITC treatment in both cells. • BAX and BCL2 expression modulation was observed in wild-type TP53 cells. • BCL2, BAX and ANLN increased and S100P decreased expression was detected in mutated TP53 cells. • AITC effects in gene modulation are dependent TP53 gene status. - Abstract: Natural compounds hold great promise for combating antibiotic resistance, the failure to control some diseases, the emergence of new diseases and the toxicity of some contemporary medical products. Allyl isothiocyanate (AITC), which is abundant in cruciferous vegetables and mustard seeds and is commonly referred to as mustard essential oil, exhibits promising antineoplastic activity against bladder cancer, although its mechanism of action is not fully understood. Therefore, the aim of this study was to investigate the effects of AITC activity on bladder cancer cell lines carrying a wild type (wt; RT4) or mutated (T24) TP53 gene. Morphological changes, cell cycle kinetics and CDK1, SMAD4, BAX, BCL2, ANLN and S100P gene expression were evaluated. In both cell lines, treatment with AITC inhibited cell proliferation (at 62.5, 72.5, 82.5 and 92.5 μM AITC) and induced morphological changes, including scattered and elongated cells and cellular debris. Gene expression profiles revealed increased S100P and BAX and decreased BCL2 expression in RT4 cells following AITC treatment. T24 cells displayed increased BCL2, BAX and ANLN and decreased S100P expression. No changes in SMAD4 and CDK1 expression were observed in either cell line. In conclusion, AITC inhibits cell proliferation independent of TP53 status. However, the mechanism of action of AITC differed in the two cell lines; in RT4 cells, it mainly acted via the classical BAX/BCL2 pathway, while in T24 cells, AITC modulated the activities of ANLN (related to cytokinesis) and S100P. These data confirm

Inhibition of bladder cancer cell proliferation by allyl isothiocyanate (mustard essential oil)

International Nuclear Information System (INIS)

Sávio, André Luiz Ventura; Nicioli da Silva, Glenda; Salvadori, Daisy Maria Fávero

2015-01-01

Highlights: • AITC inhibits mutant and wild-type TP53 cell proliferation. • Morphological changes and cells debris were observed after AITC treatment in both cells. • BAX and BCL2 expression modulation was observed in wild-type TP53 cells. • BCL2, BAX and ANLN increased and S100P decreased expression was detected in mutated TP53 cells. • AITC effects in gene modulation are dependent TP53 gene status. - Abstract: Natural compounds hold great promise for combating antibiotic resistance, the failure to control some diseases, the emergence of new diseases and the toxicity of some contemporary medical products. Allyl isothiocyanate (AITC), which is abundant in cruciferous vegetables and mustard seeds and is commonly referred to as mustard essential oil, exhibits promising antineoplastic activity against bladder cancer, although its mechanism of action is not fully understood. Therefore, the aim of this study was to investigate the effects of AITC activity on bladder cancer cell lines carrying a wild type (wt; RT4) or mutated (T24) TP53 gene. Morphological changes, cell cycle kinetics and CDK1, SMAD4, BAX, BCL2, ANLN and S100P gene expression were evaluated. In both cell lines, treatment with AITC inhibited cell proliferation (at 62.5, 72.5, 82.5 and 92.5 μM AITC) and induced morphological changes, including scattered and elongated cells and cellular debris. Gene expression profiles revealed increased S100P and BAX and decreased BCL2 expression in RT4 cells following AITC treatment. T24 cells displayed increased BCL2, BAX and ANLN and decreased S100P expression. No changes in SMAD4 and CDK1 expression were observed in either cell line. In conclusion, AITC inhibits cell proliferation independent of TP53 status. However, the mechanism of action of AITC differed in the two cell lines; in RT4 cells, it mainly acted via the classical BAX/BCL2 pathway, while in T24 cells, AITC modulated the activities of ANLN (related to cytokinesis) and S100P. These data confirm

Growth of nano hexagon-like flake arrays cerium carbonate created with PAH as the substrate

Energy Technology Data Exchange (ETDEWEB)

Li, M., E-mail: limei@imust.cn [School of Materials Science and Engineering, Beijing University of Chemical Engineering, Department of Materials, Beijing 100029 (China); School of Materials and Metallurgy, Inner Mongolia University of Science and Technology, Department of Inorganic and Metalloid Materials, Key Laboratory of New Technologies of Modern Metallurgy and Application of Rare Materials, Baotou 014010 (China); Hu, Y.H., E-mail: bthyh@163.com [School of Materials Science and Engineering, Beijing University of Chemical Engineering, Department of Materials, Beijing 100029 (China); School of Materials and Metallurgy, Inner Mongolia University of Science and Technology, Department of Inorganic and Metalloid Materials, Key Laboratory of New Technologies of Modern Metallurgy and Application of Rare Materials, Baotou 014010 (China); Liu, Z.G.; Wang, X.F.; Wang, M.T. [School of Materials and Metallurgy, Inner Mongolia University of Science and Technology, Department of Inorganic and Metalloid Materials, Key Laboratory of New Technologies of Modern Metallurgy and Application of Rare Materials, Baotou 014010 (China)

2015-01-15

Petals-like Ce{sub 2}(CO{sub 3}){sub 3} on Ce{sub 2}(CO{sub 3}){sub 3} nano hexagon-like flake arrays have been precipitatingly fabricated using PAH substrates. By changing the way of feeding, PAH concentration and aging time, petals-like Ce{sub 2}(CO{sub 3}){sub 3} was created best when adding PAH into the Ce(NO{sub 3}){sub 3} solution, joined (NH{sub 4}){sub 2}CO{sub 3} solution along with mixing, PAH concentration is 0.9 g/L, aging time is 4 h. A growth mechanism was proposed to account for the growth of the petals-like Ce{sub 2}(CO{sub 3}){sub 3} with PAH as the substrate. Poly allylamine hydrochloride (PAH) is as template agent which forms π-allyl complex with Ce{sup 3+} and controls the morphology of Ce{sub 2}(CO{sub 3}){sub 3} particle. PAH and Ce{sup 3+} form π-allyl complex, and then induce the formation of Ce{sub 2}(CO{sub 3}){sub 3} crystal nucleus. And infrared spectrum analysis verified. XRD show that after adding PAH which is adsorbed on the crystal plane, the growth of Ce{sub 2}(CO{sub 3}){sub 3} crystal is inhibited on (2 4 2), the growth is promoted on (2 0 2) which is differentiated into the new (1 5 1), (2 2 2) is unchanged, Ce{sub 2}(CO{sub 3}){sub 3} crystal is accumulated petals shape by hexagon-like flake. UV absorption spectra show that CeO{sub 2} as prepared precursor Ce{sub 2}(CO{sub 3}){sub 3} after calcinations in air at high temperatures, the petal-like CeO{sub 2} has strong UV absorption and reflection effects, and absorption interval changed significantly by the move to UVA from UVB. - Graphical abstract: Each Ce-atom connects three Cl-atoms and three allyls in three dimensional spaces. To take the plane as a reference plane which is arrayed with three Ce-atom as equilateral triangle. The triangular each vertex is Ce-atom, the triangular center place is Cl-atom, the equilateral triangle which is mutually perpendicular with Ce-triangle surface and the inclined angle is 60° is made up with three Cl-atoms. - Highlights: • Petals

Acrolein toxicity involves oxidative stress caused by glutathione depletion in the yeast Saccharomyces cerevisiae.

Science.gov (United States)

Kwolek-Mirek, M; Bednarska, S; Bartosz, G; Biliński, T

2009-08-01

Exposure of yeast cells to allyl alcohol results in intracellular production of acrolein. The toxicity of so formed acrolein involves oxidative stress, as (1) strains deficient in antioxidant defense are hypersensitive to allyl alcohol, (2) exposure to allyl alcohol increases the level of thiobarbituric-acid-reactive substances and decreases glutathione level in the cells, (3) hypoxic and anoxic atmosphere and antioxidants protect against allyl alcohol toxicity, and (4) allyl alcohol causes activation of Yap1p. No increased formation of reactive oxygen species was detected in cells exposed to allyl alcohol, so oxidative stress is due to depletion of cellular thiols and thus alteration in the redox state of yeast cells.

Densities, isobaric thermal compressibilities and derived thermodynamic properties of the binary systems of cyclohexane with allyl methacrylate, butyl methacrylate, methacrylic acid, and vinyl acetate at t = (298.15 and 308.15) K

Energy Technology Data Exchange (ETDEWEB)

Wisniak, Jaime [Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)]. E-mail: wisniak@bgumail.bgu.ac.il; Peralta, Rene D. [Centro de Investigacion en Quimica Aplicada, Saltillo 25100, Coahuila (Mexico); Infante, Ramiro [Centro de Investigacion en Quimica Aplicada, Saltillo 25100, Coahuila (Mexico); Cortez, Gladis [Centro de Investigacion en Quimica Aplicada, Saltillo 25100, Coahuila (Mexico); Lopez, R.G. [Centro de Investigacion en Quimica Aplicada, Saltillo 25100, Coahuila (Mexico)

2005-10-15

Densities of the binary systems of cyclohexane with allyl methacrylate, butyl methacrylate, methacrylic acid, and vinyl acetate have been measured as a function of the composition, at 298.15 and 308.15 K and atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess molar volumes were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. The excess molar volumes are positive for the four binaries studied. Within the short temperature range considered here the coefficient of thermal expansion is positive for all the systems studied; it varies only slightly with the nature of the acrylate except for the system cyclohexane + vinyl acetate.

Allyl isothiocyanate that induces GST and UGT expression confers oxidative stress resistance on C. elegans, as demonstrated by nematode biosensor.

Directory of Open Access Journals (Sweden)

Koichi Hasegawa

Full Text Available BACKGROUND: Electrophilic xenobiotics and endogenous products from oxidative stresses induce the glutathione S-transferases (GSTs, which form a large family within the phase II enzymes over both animal and plant kingdoms. The GSTs thus induced in turn detoxify these external as well as internal stresses. Because these stresses are often linked to ageing and damage to health, the induction of phase II enzymes without causing adverse effects would be beneficial in slowing down ageing and keeping healthy conditions. METHODOLOGY/PRINCIPAL FINDINGS: We have tested this hypothesis by choosing allyl isothiocyanate (AITC, a functional ingredient in wasabi, as a candidate food ingredient that induces GSTs without causing adverse effects on animals' lives. To monitor the GST induction, we constructed a gst::gfp fusion gene and used it to transform Caenorhabditis elegans for use as a nematode biosensor. With the nematode biosensor, we found that AITC induced GST expression and conferred tolerance on the nematode against various oxidative stresses. We also present evidence that the transcription factor SKN-1 is involved in regulating the GST expression induced by AITC. CONCLUSIONS/SIGNIFICANCE: We show the applicability of the nematode biosensor for discovering and evaluating functional food substances and chemicals that would provide anti-ageing or healthful benefits.

Endophytic fungi from the roots of horseradish (Armoracia rusticana) and their interactions with the defensive metabolites of the glucosinolate - myrosinase - isothiocyanate system.

Science.gov (United States)

Szűcs, Zsolt; Plaszkó, Tamás; Cziáky, Zoltán; Kiss-Szikszai, Attila; Emri, Tamás; Bertóti, Regina; Sinka, László Tamás; Vasas, Gábor; Gonda, Sándor

2018-05-09

The health of plants is heavily influenced by the intensively researched plant microbiome. The microbiome has to cope with the plant's defensive secondary metabolites to survive and develop, but studies that describe this interaction are rare. In the current study, we describe interactions of endophytic fungi with a widely researched chemical defense system, the glucosinolate - myrosinase - isothiocyanate system. The antifungal isothiocyanates are also of special interest because of their beneficial effects on human consumers. Seven endophytic fungi were isolated from horseradish roots (Armoracia rusticana), from the genera Fusarium, Macrophomina, Setophoma, Paraphoma and Oidiodendron. LC-ESI-MS analysis of the horseradish extract incubated with these fungi showed that six of seven strains could decompose different classes of glucosinolates. Aliphatic, aromatic, thiomethylalkyl and indolic glucosinolates were decomposed by different strains at different rates. SPME-GC-MS measurements showed that two strains released significant amounts of allyl isothiocyanate into the surrounding air, but allyl nitrile was not detected. The LC-ESI-MS analysis of many strains' media showed the presence of allyl isothiocyanate - glutathione conjugate during the decomposition of sinigrin. Four endophytic strains also accepted sinigrin as the sole carbon source. Isothiocyanates inhibited the growth of fungi at various concentrations, phenylethyl isothiocyanate was more potent than allyl isothiocyanate (mean IC 50 was 2.30-fold lower). As a control group, ten soil fungi from the same soil were used. They decomposed glucosinolates with lower overall efficiency: six of ten strains had insignificant or weak activities and only three could use sinigrin as a carbon source. The soil fungi also showed lower AITC tolerance in the growth inhibition assay: the median IC 50 values were 0.1925 mM for endophytes and 0.0899 mM for soil fungi. The host's glucosinolates can be used by the tested

The reaction of organocerium reagents with easily enolizable ketones

International Nuclear Information System (INIS)

Imamoto, Tsuneo; Kusumoto, Tetsuo; Sugiura, Yasushi; Suzuki, Nobuyo; Takiyama, Nobuyuki

1985-01-01

Organocerium (III) reagents were conveniently generated by the reaction of organolithium compounds with anhydrous cerium (III) chloride. The reagents are less basic than organolithiums and Grignard reagents, and they react readily at -78 deg C with easily enolizable ketones such as 2-tetralone to afford addition products in high yields. Cerium (III) enolates were also generated from lithium enolates and cerium (III) chloride. The cerium (III) enolates undergo aldol addition with ketones or sterically crowded aldehyde to give the corresponding β-hydroxy ketones in good to high yields. (author)

Structural Changes of Bagasse dusring the Homogeneous Esterification with Maleic Anhydride in Ionic Liquid 1-Allyl-3-methylimidazolium Chloride

Directory of Open Access Journals (Sweden)

Huihui Wang

2018-04-01

Full Text Available The maleation of bagasse could greatly increase the compatibility between bagasse and composite matrixes, and the percentage of substitution (PS of bagasse maleates could be regulated in the homogeneous system. However, due to the complicated components and the linkages of bagasse, it was difficult to control the reaction behaviors of each component. In this paper, the detailed structural changes of bagasse during the homogeneous maleation in ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl were comparatively investigated with the three main components (cellulose, hemicelluloses, and lignin from bagasse. The PS of the maleated bagasse was 12.52%, and the PS of the maleated cellulose, hemicelluloses, and lignin were 13.50%, 10.89%, and 14.03%, respectively. Fourier translation infrared (FT-IR and NMR analyses confirmed that the three main components were all involved in the homogeneous maleation. 1H-13C HSQC analysis indicated that the predominant monoesterification of cellulose, diesterification of hemicelluloses and lignin, and the degradation of the three main components simultaneously occurred. Besides, the quantitative analysis from 1H-13C HSQC revealed the relative PS of reactive sites in each component. 31P NMR results showed that the reactivity of lignin aliphatic hydroxyls was higher than that of phenolic ones, and the reactivity of phenolic hydroxyls followed the order of p-hydroxyphenyl hydroxyls > guaiacyl hydroxyls > syringyl hydroxyls.

Synthesis and optimization of novel allylated mono-carbonyl analogs of curcumin (MACs) act as potent anti-inflammatory agents against LPS-induced acute lung injury (ALI) in rats.

Science.gov (United States)

Zhu, Heping; Xu, Tingting; Qiu, Chenyu; Wu, Beibei; Zhang, Yali; Chen, Lingfeng; Xia, Qinqin; Li, Chenglong; Zhou, Bin; Liu, Zhiguo; Liang, Guang

2016-10-04

A series of novel symmetric and asymmetric allylated mono-carbonyl analogs of curcumin (MACs) were synthesized using an appropriate synthetic route and evaluated experimentally thru the LPS-induced expression of TNF-α and IL-6. Most of the obtained compounds exhibited improved water solubility as a hydrochloride salt compared to lead molecule 8f. The most active compound 7a was effective in reducing the Wet/Dry ratio in the lungs and protein concentration in bronchoalveolar lavage fluid. Meanwhile, 7a also inhibited mRNA expression of several inflammatory cytokines, including TNF-α, IL-6, IL-1β, and VCAM-1, in Beas-2B cells after Lipopolysaccharide (LPS) challenge. These results suggest that 7a could be therapeutically beneficial for use as an anti-inflammatory agent in the clinical treatment of acute lung injury (ALI). Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Highly enantio- and diastereoselective synthesis of β-methyl-γ- monofluoromethyl-substituted alcohols

KAUST Repository

Yang, Wenguo

2011-06-07

Enanatiopure β-methyl-γ-monofluoromethyl alcohols were prepared from the allylic alkylation between fluorobis(phenylsulfonyl)methane with Morita-Baylis-Hillman carbonates. The reaction was catalyzed by using the Cinchona alkaloid derivative, (DHQD)2AQN. The origin of the stereoselectivity was verified by DFT methods. Calculated geometries and relative energies of various transition states strongly support the observed stereoselectivity. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cobalt-catalyzed C-H olefination of aromatics with unactivated alkenes.

Science.gov (United States)

Manoharan, Ramasamy; Sivakumar, Ganesan; Jeganmohan, Masilamani

2016-08-18

A cobalt-catalyzed C-H olefination of aromatic and heteroaromatic amides with unactivated alkenes, allyl acetates and allyl alcohols is described. This method offers an efficient route for the synthesis of vinyl and allyl benzamides in a highly stereoselective manner. It is observed that the ortho substituent on the benzamide moiety is crucial for the observation of allylated products in unactivated alkenes.

Theoretical Kinetic Study of the Unimolecular Keto–Enol Tautomerism Propen-2-ol ↔ Acetone. Pressure Effects and Implications in the Pyrolysis of tert- and 2-Butanol

KAUST Repository

Grajales Gonzalez, Edwing

2018-03-21

The need for renewable and cleaner sources of energy has made biofuels an interesting alternative to fossil fuels, especially in the case of butanol isomers, with its favorable blend properties and low hygroscopicity. Although C4 alcohols are prospective fuels, some key reactions governing their pyrolysis and combustion have not been adequately studied, leading to incomplete kinetic models. Enols are important intermediates in the combustion of C4 alcohols, as well as in atmospheric processes. Butanol reactions kinetics is poorly understood. Specifically, the unimolecular tautomerism of propen-2-ol ↔ acetone, which is included in butanol combustion kinetic models, is assigned rate parameters based on the tautomerism vinyl alcohol ↔ acetaldehyde as an analogy. In an attempt to update current kinetic models for tert- and 2-butanol, a theoretical kinetic study of the titled reaction was carried out by means of CCSD(T,FULL)/aug-cc-pVTZ//CCSD(T)/6-31+G(d,p) ab initio calculations, with multistructural torsional anharmonicity and variational transition state theory considerations in a wide temperature and pressure range (200-3000 K; 0.1-108 kPa). Results differ from vinyl alcohol ↔ acetaldehyde analogue reaction, which shows lower rate constant values. It was observed that decreasing pressure leads to a decrease in rate constants, describing the expected falloff behavior. Tunneling turned out to be important, especially at low temperatures. Accordingly, pyrolysis simulations in a batch reactor for tert- and 2-butanol with computed rate constants showed important differences in comparison with previous results, such as larger acetone yield and quicker propen-2-ol consumption.

Theoretical Kinetic Study of the Unimolecular Keto–Enol Tautomerism Propen-2-ol ↔ Acetone. Pressure Effects and Implications in the Pyrolysis of tert- and 2-Butanol

KAUST Repository

Grajales Gonzalez, Edwing Javier; Monge Palacios, Manuel; Sarathy, Mani

2018-01-01

The need for renewable and cleaner sources of energy has made biofuels an interesting alternative to fossil fuels, especially in the case of butanol isomers, with its favorable blend properties and low hygroscopicity. Although C4 alcohols are prospective fuels, some key reactions governing their pyrolysis and combustion have not been adequately studied, leading to incomplete kinetic models. Enols are important intermediates in the combustion of C4 alcohols, as well as in atmospheric processes. Butanol reactions kinetics is poorly understood. Specifically, the unimolecular tautomerism of propen-2-ol ↔ acetone, which is included in butanol combustion kinetic models, is assigned rate parameters based on the tautomerism vinyl alcohol ↔ acetaldehyde as an analogy. In an attempt to update current kinetic models for tert- and 2-butanol, a theoretical kinetic study of the titled reaction was carried out by means of CCSD(T,FULL)/aug-cc-pVTZ//CCSD(T)/6-31+G(d,p) ab initio calculations, with multistructural torsional anharmonicity and variational transition state theory considerations in a wide temperature and pressure range (200-3000 K; 0.1-108 kPa). Results differ from vinyl alcohol ↔ acetaldehyde analogue reaction, which shows lower rate constant values. It was observed that decreasing pressure leads to a decrease in rate constants, describing the expected falloff behavior. Tunneling turned out to be important, especially at low temperatures. Accordingly, pyrolysis simulations in a batch reactor for tert- and 2-butanol with computed rate constants showed important differences in comparison with previous results, such as larger acetone yield and quicker propen-2-ol consumption.

Rhodium(I) catalysis in olefin photoreactions

International Nuclear Information System (INIS)

Salomon, R.G.; El Sanadi, N.

1975-01-01

The photorearrangement (254 nm) of 1,5-cyclooctadiene (1) in the presence of rhodium(I) chloride to give 1,4-cyclooctadiene (4) was found by deuterium labeling to involve an intramolecular [1,3] shift of hydrogen. A rate-determining cleavage of an allylic C--H bond is indicated by a deuterium isotope effect, k/sub H//k/sub D/ = 1.55 +- 0.03 for the 1 → 4 rearrangement. The acyclic 1,5-diene, 3,3-dimethyl-1,5-hexadiene (8), rearranges in the presence of rhodium(I) chloride upon uv irradiation (254 nm) to give cis-3,3-dimethyl-1,4-hexadiene (10) and the trans isomer 11 in a 1:4 ratio, respectively. This observation supports a mechanism for the photorearrangement of olefins catalyzed by rhodium(I) involving an initial photodissociation of one of two rhodium(I) coordinated carbon-carbon double bonds. This results in an increase in the coordinative unsaturation of rhodium(I) and enhances the proclivity of this d/sub s/ metal atom toward oxidative addition of an allylic C--H bond. A eta 3 -allylrhodium hydride intermediate then gives rearranged olefin by reductive elimination. Lastly, a novel photochemical, rhodium(I) catalyzed hydrogen transfer is reported which gives cyclooctene (7) from cyclooctadienes under unprecedentedly mild conditions. (auth)

Secondary deuterium isotope effects and transition state structure in the aromatic claisen rearrangement

International Nuclear Information System (INIS)

McMichael, K.D.; Korver, G.L.

1979-01-01

Kinetic experiments were carried out simultaneously on separate methyl salicylate solutions of allyl phenyl ether and its deuterated phenyl analogues at 170 to 195 0 C. Gas chromatographic analysis for allyl phenyl ether using an internal standard (anisole) and mechanical integration produced concentration/time data which were fitted to the exponential form of the first-order rate equation by a standard and nonlinear least-square program. At least 15 points were obtained for each run, covering 10 to 85% reaction. The derived isotope effects show no temperature dependence. Averages for 6 runs with each compound are k/sub H//k/sub α-D 2 / = 1.18 and K/sub H//k/sub γ-D 2 / = 0.95. An equilibrium α effect of 1.30 and a γ effect of 0.87 may be calculated for both deuterium atoms at 185 0 C. These results show that the C--H vibration frequencies are approximately (1.18 - 1)/(1.27 - 1) or 57 to 77% of the way from those of allyl phenyl ether to those of the cyclohexadiene intermediate. The C--H frequencies of the γ carbon in the transition state are about (0.95 - 1)/(0.88 - 1) or 22 to 62% of the way to those of the intermediate. The structure of the transition state, as far as these bonding frequencies are concerned, is consistent with the Claisen rearrangement

Removal of residual functionalized ionic liquids from water by ultrasound-assisted zero-valent iron/activated carbon.

Science.gov (United States)

Zhou, Haimei; Lv, Ping; Qi, Hang; Ma, Jinqi; Wang, Jianji

2018-03-02

Numerous applications of ionic liquids (ILs) are often accompanied by the generation of aqueous wastes. Due to the high toxicity and poor biodegradability of ILs, effective chemical treatment is of great importance for their removal from aqueous solution. In this work, an ultrasound-assisted zero-valent iron/activated carbon (US-ZVI/AC) micro-electrolysis technique was used to degrade residual functionalized ILs, 1-butyl-3-methyl benzimidazolium bromide ([BMBIM]Br) and 1-allyl-3-methylimidazolium chloride ([AMIM]Cl) in aqueous solution, and the degradation degree, degradation kinetics and possible degradation pathways were investigated. It was shown that the degradation of these functionalized ILs was highly efficient in the US-ZVI/AC system, and the degradation degree was as high as 96.1% and 92.9% in 110 min for [BMBIM]Br and [AMIM]Cl, respectively. The degradation of [BMBIM]Br could be described by the second-order kinetics model, and [BMBIM] + was decomposed in two ways: (i) sequential cleavage of N-alkyl side chain of the cation produced three intermediates; (ii) the 2-positioned H atoms of the benzimidazolium ring were first oxidized, and then the imidazolium ring was opened. The degradation of [AMIM]Cl followed the first-order kinetics rule, and the 2,4,5-positioned H atoms of the imidazolium ring were oxidized to induce ring opening. In addition, the removal of total organic carbon was found to be >87%, which indicates that most of the ILs was mineralized in the degradation process. These results suggest that ultrasound-assisted ZVI/AC micro-electrolysis is highly effective for the removal of residual functionalized ILs from aqueous environment.

Z-2-(β-D-glucopyranosyloxy)-3-phenylpropenoic acid, an α-hydroxy acid from rooibos (Aspalathus linearis) with hypoglycemic activity

DEFF Research Database (Denmark)

Muller, C.J.F.; Joubert, Elizabeth; Pheiffer, Carmen

2013-01-01

Scope: The rare enolic phenylpyruvic acid glucoside, Z-2-(β-D-glucopyranosyloxy)-3-phenylpropenoic acid (PPAG) is one of the major constituents of fermented rooibos infusions. 3-Phenylpyruvic acid (2-oxo-3-phenylpropanoic acid) (PPA), without the sugar moiety and with a keto instead of enolic arr...

Genes encoding chavicol/eugenol synthase from the creosote bush Larrea tridentata

Science.gov (United States)

Lewis, Norman G.; Davin, Laurence B.; Kim, Sung -Jin; Vassao, Daniel Giddings; Patten, Ann M.; Eichinger, Dietmar

2015-09-15

Particular aspects provide novel methods for redirecting carbon allocation in plants or cell culture from lignification to inherently more useful and tractable materials, and to facilitate the generation of, e.g., biofuels from the remaining plant ro culture biomass. Particular aspects provided novel methods for converting monolignols into allyl/propenyl phenols, and for chavicol/eugenol formation or production. Additional aspects relate to the discovery of novel chavicol/eugenol synthases that convert p-coumaryl/coniferyl alcohol esters into chavicol/eugenol, and to novel compositions (e.g., novel proteins and nucleic acids encoding same), and novel methods using same for producing or forming chavicol/eugenol and other derivatives in cell culture and/or genetically modified plants, and for re-engineering the composition of plant biomass. Particular aspects provide novel methods for generation in culture or in planta of liquid/combustible allyl/propenyl phenols, and these phenolic products are utilized for (non-ethanol) biofuel/bioenergy purposes, while the remaining plant biomass facilitates the generation of other biofuels.

Influence of the antimicrobial compound allyl isothiocyanate against the Aspergillus parasiticus growth and its aflatoxins production in pizza crust.

Science.gov (United States)

Quiles, Juan M; Manyes, Lara; Luciano, Fernando; Mañes, Jordi; Meca, Giuseppe

2015-09-01

Aflatoxins (AFs) are secondary metabolites produced by different species of Aspergillus, such as Aspergillus flavus and Aspergillus parasiticus, which possess mutagenic, teratogenic and carcinogenic activities in humans. In this study, active packaging devices containing allyl isothiocyanate (AITC) or oriental mustard flour (OMF) + water were tested to inhibit the growth of A. parasiticus and AFs production in fresh pizza crust after 30 d. The antimicrobial and anti-aflatoxin activities were compared to a control group (no antimicrobial treatment) and to a group added with commercial preservatives (sorbic acid + sodium propionate). A. parasiticus growth was only inhibited after 30 d by AITC in filter paper at 5 μL/L and 10 μL/L, AITC sachet at 5 μL/L and 10 μL/L and OMF sachet at 850 mg + 850 μL of water. However, AFs production was inhibited by all antimicrobial treatments in a dose-dependent manner. More importantly, AITC in a filter paper at 10 μL/L, AITC sachet at 10 μL/L, OMF sachet at 850 mg + 850 μL of water and sorbic acid + sodium propionate at 0.5-2.0 g/Kg completely inhibited AFs formation. The use of AITC in active packaging devices could be a natural alternative to avoid the growth of mycotoxinogenic fungi in refrigerated bakery products in substitution of common commercial preservatives. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Porphobilinogen Conundrum in Prebiotic Routes to Tetrapyrrole Macrocycles

Science.gov (United States)

Taniguchi, Masahiko; Ptaszek, Marcin; Chandrashaker, Vanampally; Lindsey, Jonathan S.

2017-03-01

Attempts to develop a credible prebiotic route to tetrapyrroles have relied on enzyme-free recapitulation of the extant biosynthesis, but this process has foundered from the inability to form the pyrrole porphobilinogen ( PBG) in good yield by self-condensation of the precursor δ-aminolevulinic acid ( ALA). PBG undergoes robust oligomerization in aqueous solution to give uroporphyrinogen (4 isomers) in good yield. ALA, PBG, and uroporphyrinogen III are universal precursors to all known tetrapyrrole macrocycles. The enzymic formation of PBG entails carbon-carbon bond formation between the less stable enolate/enamine of one ALA molecule (3-position) and the carbonyl/imine (4-position) of the second ALA molecule; without enzymes, the first ALA reacts at the more stable enolate/enamine (5-position) and gives the pyrrole pseudo-PBG. pseudo-PBG cannot self-condense, yet has one open α-pyrrole position and is proposed to be a terminator of oligopyrromethane chain-growth from PBG. Here, 23 analogues of ALA have been subjected to density functional theoretical (DFT) calculations, but no motif has been identified that directs reaction at the 3-position. Deuteriation experiments suggested 5-(phosphonooxy)levulinic acid would react preferentially at the 3- versus 5-position, but a hybrid condensation with ALA gave no observable uroporphyrin. The results suggest efforts toward a biomimetic, enzyme-free route to tetrapyrroles from ALA should turn away from structure-directed reactions and focus on catalysts that orient the two aminoketones to form PBG in a kinetically controlled process, thereby avoiding formation of pseudo-PBG.

Interaction of water, alkyl hydroperoxide, and allylic alcohol with a single-site homogeneous Ti-Si epoxidation catalyst: A spectroscopic and computational study.

Science.gov (United States)

Urakawa, Atsushi; Bürgi, Thomas; Skrabal, Peter; Bangerter, Felix; Baiker, Alfons

2005-02-17

Tetrakis(trimethylsiloxy)titanium (TTMST, Ti(OSiMe3)4) possesses an isolated Ti center and is a highly active homogeneous catalyst in epoxidation of various olefins. The structure of TTMST resembles that of the active sites in some heterogeneous Ti-Si epoxidation catalysts, especially silylated titania-silica mixed oxides. Water cleaves the Ti-O-Si bond and deactivates the catalyst. An alkyl hydroperoxide, TBHP (tert-butyl hydroperoxide), does not cleave the Ti-O-Si bond, but interacts via weak hydrogen-bonding as supported by NMR, DOSY, IR, and computational studies. ATR-IR spectroscopy combined with computational investigations shows that more than one, that is, up to four, TBHP can undergo hydrogen-bonding with TTMST, leading to the activation of the O-O bond of TBHP. The greater the number of TBHP molecules that form hydrogen bonds to TTMST, the more electrophilic the O-O bond becomes, and the more active the complex is for epoxidation. An allylic alcohol, 2-cyclohexen-1-ol, does not interact strongly with TTMST, but the interaction is prominent when it interacts with the TTMST-TBHP complex. On the basis of the experimental and theoretical findings, a hydrogen-bond-assisted epoxidation mechanism of TTMST is suggested.

NMR and IR investigations of strong intramolecular hydrogen bonds

DEFF Research Database (Denmark)

Hansen, Poul Erik; Spanget-Larsen, Jens

2017-01-01

been used as a parameter for hydrogen bond strength in O–H···O systems. On a broad scale, a correlation between OH stretching wavenumbers and O···O distances is observed, as demonstrated experimentally as well as theoretically, but for substituted beta-diketone enols this correlation is relatively weak.......–1, and 19 >  dOH > 15 ppm. Recent results as well as an account of theoretical advances are presented for a series of important classes of compounds such as beta-diketone enols, beta-thioxoketone enols, Mannich bases, proton sponges, quinoline N-oxides and diacid anions. The O···O distance has long...

Solvent control of intramolecular proton transfer

DEFF Research Database (Denmark)

Manolova, Y.; Marciniak, Heinz; Tschierlei, S.

2017-01-01

of molecules in the enol and zwitterionic proton transfer (PT) form exists in the ground state. However, the zwitterion is the energetically favored one in the electronically excited state. Optical excitation of the enol form results in intramolecular proton transfer and formation of the PT form within 1.4 ps...

A theoretical and spectroscopic study of conformational structures of piroxicam

Science.gov (United States)

Souza, Kely Ferreira de; Martins, José A.; Pessine, Francisco B. T.; Custodio, Rogério

2010-02-01

Piroxicam (PRX) has been widely studied in an attempt to elucidate the causes and mechanisms of its side effects, mainly the photo-toxicity. In this paper fluorescence spectra in non-protic solvents and different polarities were carried out along with theoretical calculations. Preliminary potential surfaces of the keto and enol forms were obtained at AM1 level of theory providing the most stable conformers, which had their structure re-optimized through the B3LYP/CEP-31G(d,p) method. From the optimized structures, the electronic spectra were calculated using the TD-DFT method in vacuum and including the solvent effect through the PCM method and a single water molecule near PRX. A new potential surface was constructed to the enol tautomer at DFT level and the most stable conformers were submitted to the QST2 calculations. The experimental data showed that in apolar media, the solution fluorescence is raised. Based on conformational analysis for the two tautomers, keto and enol, the results indicated that the PRX-enol is the main tautomer related to the drug fluorescence, which is reinforced by the spectra results, as well as the interconvertion barrier obtained from the QST2 calculations. The results suggest that the PRX one of the enol conformers presents great possibility of involvement in the photo-toxicity mechanisms.

Micro-structure, Mechanical Properties and Dielectric Properties of Bisphenol A Allyl Compound-Bismaleimide Modified by Super-Critical Silica and Polyethersulfone Composite

Science.gov (United States)

Chen, Yufei; Wang, Botao; Li, Fangliang; Teng, Chengjun

2017-07-01

Bisphenol A allyl compound-bismaleimide (MBAE) composite modified by SCE-SiO2 and polyethersulfone (PES) resin has been prepared and researched. SCE-SiO2 was modified by super-critical ethanol and PES thermoplastic resin used as modifiers. The composite was prepared via the hot melting method. The FT-IR measurements indicated that ethanol molecular had adsorbed on the nano-SiO2 surface. SEM images showed that the composite had a multiphase structure, PES and SCE-SiO2 existed as a dispersed phase, and the interaction of the three phases affected each other, such that the bending fracture behavior transformed from brittle fracture to ductile fracture, and the modifiers of SCE-SiO2 and PES resin could improve the mechanical properties. The impact and the bending strength of the composite was 16.5 kJ/mm2 and 150.4 MPa, improved by 68.3% and 56.7% compared with those of the MBAE matrix, respectively, when the content of SCE-SiO2 was 2 wt.% and PES 5 wt.%. The dielectric constant ( ɛ) of the composites was less than 3.9 and decreased with increasing frequency, and the dielectric loss was less than 9 × 10-3 for frequencies between 102 Hz and 105 Hz. These properties could meet the requirement of insulating material.

A Novel Synthetic Approach to C-Glycosyl-D- and L-Alanines

Directory of Open Access Journals (Sweden)

Miroslava Martinková

2008-12-01

Full Text Available C-Glycosyl-(S- and (R-alanines 12a and 12b were synthesized from the known β-C-glycoside 1. The nitrogen function was introduced by aza-Claisen rearrangement of the allylic thiocyanate 7, derived from the corresponding alcohol 6. The absolute configuration of the newly created chiral carbon center (C-3 was assigned by X-ray diffraction analysis of the intermediate 3(S-isothiocyanato-D-glycero-D-galacto-decose 8a.

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Allyl and benzyl ethers of alcohols can be prepared conveniently and in high yield with allyl and benzyl bromide in the presence of solid potassium hydroxide without use of any solvent. Phenols can be converted to allyl ethers but are inert to benzylation under above conditions.

Excited-state intramolecular proton transfer of 2-acetylindan-1,3-dione studied by ultrafast absorption and fluorescence spectroscopy

Directory of Open Access Journals (Sweden)

Pramod Kumar Verma

2016-03-01

Full Text Available We employ transient absorption from the deep-UV to the visible region and fluorescence upconversion to investigate the photoinduced excited-state intramolecular proton-transfer dynamics in a biologically relevant drug molecule, 2-acetylindan-1,3-dione. The molecule is a ß-diketone which in the electronic ground state exists as exocyclic enol with an intramolecular H-bond. Upon electronic excitation at 300 nm, the first excited state of the exocyclic enol is initially populated, followed by ultrafast proton transfer (≈160 fs to form the vibrationally hot endocyclic enol. Subsequently, solvent-induced vibrational relaxation takes place (≈10 ps followed by decay (≈390 ps to the corresponding ground state.

1,5-Asymmetric induction in the boron-mediated aldol reaction of β-oxygenated methyl ketones

International Nuclear Information System (INIS)

Dias, Luiz C.

2007-01-01

High levels of substrate-based 1,5-stereo induction are obtained in the boron-mediated aldol reactions of β-oxygenated methyl ketones with achiral and chiral aldehydes. Remote induction from the boron enolates gives the 1,5-anti adducts, with the enolate pi-facial selectivity critically dependent upon the nature of the beta-alkoxy protecting group. This 1,5-anti aldol methodology has been strategically employed in the total synthesis of several natural products. At present, the origin of the high level of 1,5-anti induction obtained with the boron enolates is unclear, although a model based on a hydrogen bonding between the alkoxy oxygen and the formyl hydrogen has been recently proposed. (author)

Modified Julia Olefination on Anhydrides: Extension and Limitations. Application to the Synthesis of Maculalactone B.

Science.gov (United States)

Dussart, Nicolas; Trinh, Huu Vinh; Gueyrard, David

2016-10-07

The preparation of exo-enol esters from cyclic anhydrides is reported using a modified Julia olefination. The reaction is highly stereoselective. The Smiles rearrangement can be performed in a one-pot process, giving a straightforward access to exo-enol lactones. Furthermore, the reaction was extended to semistabilized sulfones, and this methodology was applied to the synthesis of maculalactone B.

Evaluation of the Effects of S-Allyl-L-cysteine, S-Methyl-L-cysteine, trans-S-1-Propenyl-L-cysteine, and Their N-Acetylated and S-Oxidized Metabolites on Human CYP Activities.

Science.gov (United States)

Amano, Hirotaka; Kazamori, Daichi; Itoh, Kenji

2016-01-01

Three major organosulfur compounds of aged garlic extract, S-allyl-L-cysteine (SAC), S-methyl-L-cysteine (SMC), and trans-S-1-propenyl-L-cysteine (S1PC), were examined for their effects on the activities of five major isoforms of human CYP enzymes: CYP1A2, 2C9, 2C19, 2D6, and 3A4. The metabolite formation from probe substrates for the CYP isoforms was examined in human liver microsomes in the presence of organosulfur compounds at 0.01-1 mM by using liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Allicin, a major component of garlic, inhibited CYP1A2 and CYP3A4 activity by 21-45% at 0.03 mM. In contrast, a CYP2C9-catalyzed reaction was enhanced by up to 1.9 times in the presence of allicin at 0.003-0.3 mM. SAC, SMC, and S1PC had no effect on the activities of the five isoforms, except that S1PC inhibited CYP3A4-catalyzed midazolam 1'-hydroxylation by 31% at 1 mM. The N-acetylated metabolites of the three compounds inhibited the activities of several isoforms to a varying degree at 1 mM. N-Acetyl-S-allyl-L-cysteine and N-acetyl-S-methyl-L-cysteine inhibited the reactions catalyzed by CYP2D6 and CYP1A2, by 19 and 26%, respectively, whereas trans-N-acetyl-S-1-propenyl-L-cysteine showed weak to moderate inhibition (19-49%) of CYP1A2, 2C19, 2D6, and 3A4 activities. On the other hand, both the N-acetylated and S-oxidized metabolites of SAC, SMC, and S1PC had little effect on the reactions catalyzed by the five isoforms. These results indicated that SAC, SMC, and S1PC have little potential to cause drug-drug interaction due to CYP inhibition or activation in vivo, as judged by their minimal effects (IC 50 >1 mM) on the activities of five major isoforms of human CYP in vitro.

Photoluminescence of PMMA doped with fluorescein and carbosilane dendrimer and lasing in PBG resonance cavity

International Nuclear Information System (INIS)

Li Chunfang; Jin Feng; Dong Xianzi; Chen Weiqiang; Duan Xuanming

2007-01-01

Carbosilane dendrimers with terminal allyl groups were synthesized and used to encapsulate the allyl derivative of fluorescein (allyl-FL) doped in PMMA. The optical property of this system was investigated and the results showed that the concentration of allyl-FL in PMMA could be increased to 4.5 wt% without decrease of the luminescence efficiency by adding the dendrimer into the system. The allyl-FL/dendrimer/PMMA film was embedded into a resonance cavity composed of two pieces of photonic band gap (PBG) materials to form a new-type solid-state laser. A laser emission at 589 nm was obtained when excited with a third harmonic generation (THG) of a pulsed Nd:YAG laser (355 nm) and its full-width at half-maximum of the spectrum was 1.7 nm

Evaluation of allyl isothiocyanate as a soil fumigant against soil-borne diseases in commercial tomato (Lycopersicon esculentum Mill.) production in China.

Science.gov (United States)

Ren, Zongjie; Li, Yuan; Fang, Wensheng; Yan, Dongdong; Huang, Bin; Zhu, Jiahong; Wang, Xiaoning; Wang, Xianli; Wang, Qiuxia; Guo, Meixia; Cao, Aocheng

2018-03-12

Root-knot nematodes (Meloidogyne spp.), soil-borne diseases and weeds seriously reduce the commercial yield of tomatoes grown under protected cultivation in China. Allyl isothiocyanate (AITC), a natural product obtained from damaged Brassica tissues, was evaluated as a potential replacement for the fumigant methyl bromide (MB) for use in the greenhouse production of tomatoes in China. The dose-response assay indicates that AITC has high biological activity against major bacterial and fungal pathogens (EC 50 of 0.225-4.199 mg L -1 ). The bioassay results indicate that AITC has good efficacy against root-knot nematodes (LC 50 of 18.046 mg kg -1 ), and moderate efficacy against fungal pathogens (LC 50 of 27.999-29.497 mg kg -1 ) and weeds (LC 50 of 17.300-47.660 mg kg -1 ). The potting test indicates that AITC significantly improved plant vigor. Field trials indicate that AITC showed good efficacy against Meloidogyne spp. and Fusarium spp. (both ∼ 80%) as well as Phytophthora spp. and Pythium spp. (both ∼ 70%), and improved plant vigor and marketable yield. AITC used as a soil fumigant (30-50 g m -2 ) effectively controlled major bacterial and fungal pathogens, root-knot nematode, weeds and increased plant vigor, yield and farmers' income in tomato cultivated under protected agriculture in China. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Pilot-Scale Silicone Process for Low-Cost Carbon Dioxide Capture

Energy Technology Data Exchange (ETDEWEB)

Farnum, Rachel; Perry, Robert; Wood, Benjamin

2014-12-31

GE Global Research is developing technology to remove carbon dioxide (CO 2) from the flue gas of coal-fired powerplants. A mixture of 3-aminopropyl end-capped polydimethylsiloxane (GAP-1m) and triethylene glycol (TEG) is the preferred CO2-capture solvent. GE Global Research was contracted by the Department of Energy to test a pilot-scale continuous CO2 absorption/desorption system using a GAP-1m/TEG mixture as the solvent. As part of that effort, an Environmental, Health, and Safety (EH&S) assessment for a CO2-capture system for a 550 MW coal-fired powerplant was conducted. Five components of the solvent, CAS#2469-55-8 (GAP-0), CAS#106214-84-0 (GAP-1-4), TEG, and methanol and xylene (minor contaminants from the aminosilicone) are included in this assessment. One by-product, GAP- 1m/SOX salt, and dodecylbenzenesulfonicacid (DDBSA) were also identified foranalysis. An EH&S assessment was also completed for the manufacturing process for the GAP-1m solvent. The chemicals associated with the manufacturing process include methanol, xylene, allyl chloride, potassium cyanate, sodium hydroxide (NaOH), tetramethyldisiloxane (TMDSO), tetramethyl ammonium hydroxide, Karstedt catalyst, octamethylcyclotetrasiloxane (D4), Aliquat 336, methyl carbamate, potassium chloride, trimethylamine, and (3-aminopropyl) dimethyl silanol. The toxicological effects of each component of both the CO2 capture system and the manufacturing process were defined, and control mechanisms necessary to comply with U.S. EH&S regulations are summarized. Engineering and control systems, including environmental abatement, are described for minimizing exposure and release of the chemical components. Proper handling and storage recommendations are made for each chemical to minimize risk to workers and the surrounding community.

Effect of allyl alcohol on hepatic transporter expression: Zonal patterns of expression and role of Kupffer cell function

International Nuclear Information System (INIS)

Campion, Sarah N.; Tatis-Rios, Cristina; Augustine, Lisa M.; Goedken, Michael J.; Rooijen, Nico van; Cherrington, Nathan J.; Manautou, Jose E.

2009-01-01

During APAP toxicity, activation of Kupffer cells is critical for protection from hepatotoxicity and up-regulation of multidrug resistance-associated protein 4 (Mrp4) in centrilobular hepatocytes. The present study was performed to determine the expression profile of uptake and efflux transporters in mouse liver following treatment with allyl alcohol (AlOH), a periportal hepatotoxicant. This study also investigated the role of Kupffer cells in AlOH hepatotoxicity, and whether changes in transport protein expression by AlOH are dependent on the presence of Kupffer cells. C57BL/6J mice received 0.1 ml clodronate liposomes to deplete Kupffer cells or empty liposomes 48 h prior to dosing with 60 mg/kg AlOH, i.p. Hepatotoxicity was assessed by plasma ALT and histopathology. Hepatic transporter mRNA and protein expression were determined by branched DNA signal amplification assay and Western blotting, respectively. Depletion of Kupffer cells by liposomal clodronate treatment resulted in heightened susceptibility to AlOH toxicity. Exposure to AlOH increased mRNA levels of several Mrp genes, while decreasing organic anion transporting polypeptides (Oatps) mRNA expression. Protein analysis mirrored many of these mRNA changes. The presence of Kupffer cells was not required for the observed changes in uptake and efflux transporters induced by AlOH. Immunofluorescent analysis revealed enhanced Mrp4 staining exclusively in centrilobular hepatocytes of AlOH treated mice. These findings demonstrate that Kupffer cells are protective from AlOH toxicity and that induction of Mrp4 occurs in liver regions away from areas of AlOH damage independent of Kupffer cell function. These results suggest that Kupffer cell mediators do not play a role in mediating centrilobular Mrp4 induction in response to periportal damage by AlOH

Tandem rhodium catalysis: exploiting sulfoxides for asymmetric transition-metal catalysis.

Science.gov (United States)

Kou, K G M; Dong, V M

2015-06-07

Sulfoxides are uncommon substrates for transition-metal catalysis due to their propensity to inhibit catalyst turnover. In a collaborative effort with Ken Houk, we developed the first dynamic kinetic resolution (DKR) of allylic sulfoxides using asymmetric rhodium-catalyzed hydrogenation. A detailed mechanistic analysis of this transformation using both experimental and theoretical methods revealed rhodium to be a tandem catalyst that promoted both hydrogenation of the alkene and racemization of the allylic sulfoxide. Using a combination of deuterium labelling and DFT studies, a novel mode of allylic sulfoxide racemization via a Rh(III)-π-allyl intermediate was identified.

Discovery of an 'internal heating effect' during electrochemical etching of polymeric dosimeters: a study of polymer characteristics

International Nuclear Information System (INIS)

Sohrabi, M.

1986-01-01

This paper investigates the importance of the internal heating effect by studying the role of different polymer physical and chemical characteristics (composition, effective foil size, thickness and electrical properties), on the rate of heating or temperature rise responses for cellulose tri-acetate (CTA), cellulose acetate (CA), allyl diglycol carbonate (CR-39), cellulose nitrate (CN), cellulose acetate butyrate (CAB), polyester (PES), polycarbonate (PC) and polyethylene (PE). Efforts have been made to justify the observed effects by different mechanisms such as dielectric loss, electro-osmosis, dielectrophoresis, and electrostriction. (author)

Direct asymmetric allylic alkenylation of N-itaconimides with Morita-Baylis-Hillman carbonates

KAUST Repository

Yang, Wenguo; Tan, Davin; Li, Lixin; Han, Zhiqiang; Yan, Lin; Huang, Kuo-Wei; Tan, Choonhong; Jiang, Zhiyong

2012-01-01

-methylene-β-maleimide esters were attained in moderate to excellent yields (up to 99%) and good to excellent enantioselectivities (up to 91% ee). The origin of the regio- and stereoselectivity was verified by DFT methods. Calculated geometries and relative energies of various

Biosynthesis of sterols from mevalonate in a starfish, Coscinasterias acutispina

International Nuclear Information System (INIS)

Teshima, Shin-ichi; Kanazawa, Akio

1976-01-01

This study deals with the biosynthesis of sterols from mevalonate in a starfish, Coscinasterias acutispina. After injection of mevalonate-2- 14 C, the metabolites were investigated by using thin-layer, column, and gas-liquid chromatographic techniques. The detailed investigation of radioactive desmethylsterols showed that radioactivity was mainly associated with cholest-7-enol. However, there was no evidence for the incorporation of mevalonate-2- 14 C into C 26 -, C 28 -, and C 29 -sterols besides cholestanol and cholesterol. The results indicated that the starfish, C. acutispina, is capable of synthesizing at least cholest-7-enol from mevalonate via probably squalene and lanosterol etc. But not sterols other than C 27 -sterols. Also, it was suggested that the conversion of cholest-7-enol to cholesterol may not proceed in this starfish. (auth.)

Carbon foam/hydroxyapatite coating for carbon/carbon composites: Microstructure and biocompatibility

Energy Technology Data Exchange (ETDEWEB)

Zhang, Leilei, E-mail: zhangleilei1121@aliyun.com; Li, Hejun; Li, Kezhi; Zhang, Shouyang; Lu, Jinhua; Li, Wei; Cao, Sheng; Wang, Bin

2013-12-01

To improve the surface biocompatibility of carbon/carbon composites, a carbon foam/hydroxyapatite coating was applied using a combination method of slurry procedure and ultrasound-assisted electrochemical deposition procedure. The morphology, microstructure and chemical composition of the coating were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray diffraction. The biocompatibility of the carbon foam/hydroxyapatite coating was investigated by osteoblast-like MG63 cell culture tests. The results showed that the carbon foam could provide a large number of pores on the surface of carbon/carbon composites. The hydroxyapatite crystals could infiltrate into the pores and form the carbon foam/hydroxyapatite coating. The coating covered the carbon/carbon composites fully and uniformly with slice morphology. The cell response tests showed that the MG63 cells on carbon foam/hydroxyapatite coating had a better cell adhesion and cell proliferation than those on uncoated carbon/carbon composites. The carbon foam/hydroxyapatite coatings were cytocompatible and were beneficial to improve the biocompatibility. The approach presented here may be exploited for fabrication of carbon/carbon composite implant surfaces.

Carbon foam/hydroxyapatite coating for carbon/carbon composites: Microstructure and biocompatibility

International Nuclear Information System (INIS)

Zhang, Leilei; Li, Hejun; Li, Kezhi; Zhang, Shouyang; Lu, Jinhua; Li, Wei; Cao, Sheng; Wang, Bin

2013-01-01

To improve the surface biocompatibility of carbon/carbon composites, a carbon foam/hydroxyapatite coating was applied using a combination method of slurry procedure and ultrasound-assisted electrochemical deposition procedure. The morphology, microstructure and chemical composition of the coating were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray diffraction. The biocompatibility of the carbon foam/hydroxyapatite coating was investigated by osteoblast-like MG63 cell culture tests. The results showed that the carbon foam could provide a large number of pores on the surface of carbon/carbon composites. The hydroxyapatite crystals could infiltrate into the pores and form the carbon foam/hydroxyapatite coating. The coating covered the carbon/carbon composites fully and uniformly with slice morphology. The cell response tests showed that the MG63 cells on carbon foam/hydroxyapatite coating had a better cell adhesion and cell proliferation than those on uncoated carbon/carbon composites. The carbon foam/hydroxyapatite coatings were cytocompatible and were beneficial to improve the biocompatibility. The approach presented here may be exploited for fabrication of carbon/carbon composite implant surfaces.

Protonation of 1-alkyl-2-allyllithium-0-carboranes and 1-methyl-2-allylmaonesium chloride-0-carborane

International Nuclear Information System (INIS)

Ivanova, N.N.; Kazantsev, A.V.; Zakharkin, L.I.

1975-01-01

The ratio of 1-alkyl-2-allyl and 1-alkyl-2-propenyl-0-carboranes generated in protonation of 1-alkyl-2-lithium allyl-0-carboranes with various protolytic agents in ether, THF and liquid ammonia depends on the nature of protolytic agent and solvent. The rat:o of these allyl and propenyl isomers is also affected by steric effects of the protolytic agent and 0-carborane nucleus

Oxidation of tertiary homoallylic alcohols by thallium trinitrate: fragmentation versus ring contraction

International Nuclear Information System (INIS)

Silva Junior, Luiz F.; Quintiliano, Samir A.P.; Ferraz, Helena M.C.; Santos, Leonardo S.; Eberlin, Marcos N.

2006-01-01

The oxidation of tertiary homoallylic alcohols with thallium trinitrate (TTN) was investigated. The alcohols bearing an allylic methyl group lose a molecule of acetone via a fragmentation reaction that leads to isomeric secondary allylic alcohols as major products, together with their corresponding acetylated derivatives. On the other hand, treating analogous tertiary alcohols without the allylic methyl group with TTN gives indans, through a ring contraction reaction. (author)

Latest Permian carbonate carbon isotope variability traces heterogeneous organic carbon accumulation and authigenic carbonate formation

Science.gov (United States)

Schobben, Martin; van de Velde, Sebastiaan; Gliwa, Jana; Leda, Lucyna; Korn, Dieter; Struck, Ulrich; Vinzenz Ullmann, Clemens; Hairapetian, Vachik; Ghaderi, Abbas; Korte, Christoph; Newton, Robert J.; Poulton, Simon W.; Wignall, Paul B.

2017-11-01

Bulk-carbonate carbon isotope ratios are a widely applied proxy for investigating the ancient biogeochemical carbon cycle. Temporal carbon isotope trends serve as a prime stratigraphic tool, with the inherent assumption that bulk micritic carbonate rock is a faithful geochemical recorder of the isotopic composition of seawater dissolved inorganic carbon. However, bulk-carbonate rock is also prone to incorporate diagenetic signals. The aim of the present study is to disentangle primary trends from diagenetic signals in carbon isotope records which traverse the Permian-Triassic boundary in the marine carbonate-bearing sequences of Iran and South China. By pooling newly produced and published carbon isotope data, we confirm that a global first-order trend towards depleted values exists. However, a large amount of scatter is superimposed on this geochemical record. In addition, we observe a temporal trend in the amplitude of this residual δ13C variability, which is reproducible for the two studied regions. We suggest that (sub-)sea-floor microbial communities and their control on calcite nucleation and ambient porewater dissolved inorganic carbon δ13C pose a viable mechanism to induce bulk-rock δ13C variability. Numerical model calculations highlight that early diagenetic carbonate rock stabilization and linked carbon isotope alteration can be controlled by organic matter supply and subsequent microbial remineralization. A major biotic decline among Late Permian bottom-dwelling organisms facilitated a spatial increase in heterogeneous organic carbon accumulation. Combined with low marine sulfate, this resulted in varying degrees of carbon isotope overprinting. A simulated time series suggests that a 50 % increase in the spatial scatter of organic carbon relative to the average, in addition to an imposed increase in the likelihood of sampling cements formed by microbial calcite nucleation to 1 out of 10 samples, is sufficient to induce the observed signal of carbon

Latest Permian carbonate carbon isotope variability traces heterogeneous organic carbon accumulation and authigenic carbonate formation

Directory of Open Access Journals (Sweden)

M. Schobben

2017-11-01

Full Text Available Bulk-carbonate carbon isotope ratios are a widely applied proxy for investigating the ancient biogeochemical carbon cycle. Temporal carbon isotope trends serve as a prime stratigraphic tool, with the inherent assumption that bulk micritic carbonate rock is a faithful geochemical recorder of the isotopic composition of seawater dissolved inorganic carbon. However, bulk-carbonate rock is also prone to incorporate diagenetic signals. The aim of the present study is to disentangle primary trends from diagenetic signals in carbon isotope records which traverse the Permian–Triassic boundary in the marine carbonate-bearing sequences of Iran and South China. By pooling newly produced and published carbon isotope data, we confirm that a global first-order trend towards depleted values exists. However, a large amount of scatter is superimposed on this geochemical record. In addition, we observe a temporal trend in the amplitude of this residual δ13C variability, which is reproducible for the two studied regions. We suggest that (sub-sea-floor microbial communities and their control on calcite nucleation and ambient porewater dissolved inorganic carbon δ13C pose a viable mechanism to induce bulk-rock δ13C variability. Numerical model calculations highlight that early diagenetic carbonate rock stabilization and linked carbon isotope alteration can be controlled by organic matter supply and subsequent microbial remineralization. A major biotic decline among Late Permian bottom-dwelling organisms facilitated a spatial increase in heterogeneous organic carbon accumulation. Combined with low marine sulfate, this resulted in varying degrees of carbon isotope overprinting. A simulated time series suggests that a 50 % increase in the spatial scatter of organic carbon relative to the average, in addition to an imposed increase in the likelihood of sampling cements formed by microbial calcite nucleation to 1 out of 10 samples, is sufficient to induce the

SYNTHESIS AND ANTITUMOR ACTIVITY OF COPPER, NICKEL AND COBALT COORDINATION COMPOUNDS WITH 1-(2-HYDROXYPHENYLETHANONE N(4-ALLYL-3-THIOSEMICARBAZONE

Directory of Open Access Journals (Sweden)

Vasilii GRAUR

2015-12-01

Full Text Available The paper presents the synthesis of the ligand 1-(2-hydroxyphenylethanone N(4-allyl-3-thiosemicarbazone (H2L and six coordination compounds of copper, nickel and cobalt with this ligand. The structure of thiosemicarbazone H2L was studied using 1H and 13С NMR spectroscopy. The synthesized coordination compounds were studied using elemental analysis, gravimetric analysis of water content, molar conductivity, and magnetochemistry. For H2L the antitumor activity towards human leukemia HL-60 cells and cervical cancer HeLa cells was determined. It was established that the substitution of hydrogen atom with methyl group in the azomethinic fragment leads to the growth of antitumor activity.SINTEZA ŞI ACTIVITATEA ANTITUMORALĂ A COMPUŞILOR COMPLECŞI AI CUPRULUI, NICHELULUI ŞI COBALTULUI CU N(4-ALIL-3-TIOSEMICARBAZONA 1-(2-HIDROXIFENILETANONEILucrarea conţine descrierea sintezei N(4-alil-3-tiosemicarbazonei 1-(2-hidroxifeniletanonei (H2L şi a şase compuşi coordinativi ai cuprului, nichelului şi cobaltului cu acest ligand. Structura tiosemicarbazonei H2L a fost stabilită în baza datelor spectroscopiei RMN 1H şi 13C. Compuşi coordinativi au fost studiaţi cu ajutorul analizei elementale, analizei gravimetrice a conţinutului de apă, conductivitaţii molare şi magnetochimiei. Pentru H2L a fost determinată activitatea antitumorală faţă de celulele leucemiei umane HL-60 şi ale cancerului cervical HeLa. S-a stabilit că înlocuirea atomului de hidrogen cu o grupare metil în fragmentul azomethinic conduce la creşterea activitaţii antitumorale.

Rhodium-catalyzed chemo-, regio-, and enantioselective addition of 2-pyridones to terminal allenes.

Science.gov (United States)

Li, Changkun; Kähny, Matthias; Breit, Bernhard

2014-12-08

A rhodium-catalyzed chemo-, regio-, and enantioselective addition of 2-pyridones to terminal allenes to give branched N-allyl 2-pyridones is reported. Preliminary mechanistic studies support the hypothesis that the reaction was initiated from the more acidic 2-hydroxypyridine form, and the initial kinetic O-allylation product was finally converted into the thermodynamically more stable N-allyl 2-pyridones. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Primary photodissociation pathways of epichlorohydrin and analysis of the C-C bond fission channels from an O(3P)+allyl radical intermediate

International Nuclear Information System (INIS)

FitzPatrick, Benjamin L.; Alligood, Bridget W.; Butler, Laurie J.; Lee, Shih-Huang; Lin, Jim Jr-Min

2010-01-01

This study initially characterizes the primary photodissociation processes of epichlorohydrin, c-(H 2 COCH)CH 2 Cl. The three dominant photoproduct channels analyzed are c-(H 2 COCH)CH 2 +Cl, c-(H 2 COCH)+CH 2 Cl, and C 3 H 4 O+HCl. In the second channel, the c-(H 2 COCH) photofission product is a higher energy intermediate on C 2 H 3 O global potential energy surface and has a small isomerization barrier to vinoxy. The resulting highly vibrationally excited vinoxy radicals likely dissociate to give the observed signal at the mass corresponding to ketene, H 2 CCO. The final primary photodissociation pathway HCl+C 3 H 4 O evidences a recoil kinetic energy distribution similar to that of four-center HCl elimination in chlorinated alkenes, so is assigned to production of c-(H 2 COC)=CH 2 ; the epoxide product is formed with enough vibrational energy to isomerize to acrolein and dissociate. The paper then analyzes the dynamics of the C 3 H 5 O radical produced from C-Cl bond photofission. When the epoxide radical photoproduct undergoes facile ring opening, it is the radical intermediate formed in the O( 3 P)+allyl bimolecular reaction when the O atom adds to an end C atom. We focus on the HCO+C 2 H 4 and H 2 CO+C 2 H 3 product channels from this radical intermediate in this report. Analysis of the velocity distribution of the momentum-matched signals from the HCO+C 2 H 4 products at m/e=29 and 28 shows that the dissociation of the radical intermediate imparts a high relative kinetic energy, peaking near 20 kcal/mol, between the products. Similarly, the energy imparted to relative kinetic energy in the H 2 CO+C 2 H 3 product channel of the O( 3 P)+allyl radical intermediate also peaks at high-recoil kinetic energies, near 18 kcal/mol. The strongly forward-backward peaked angular distributions and the high kinetic energy release result from tangential recoil during the dissociation of highly rotationally excited nascent radicals formed photolytically in this experiment

Primary photodissociation pathways of epichlorohydrin and analysis of the C-C bond fission channels from an O(3P)+allyl radical intermediate

Science.gov (United States)

FitzPatrick, Benjamin L.; Alligood, Bridget W.; Butler, Laurie J.; Lee, Shih-Huang; Lin, Jim-Min, Jr.

2010-09-01

This study initially characterizes the primary photodissociation processes of epichlorohydrin, c-(H2COCH)CH2Cl. The three dominant photoproduct channels analyzed are c-(H2COCH)CH2+Cl, c-(H2COCH)+CH2Cl, and C3H4O+HCl. In the second channel, the c-(H2COCH) photofission product is a higher energy intermediate on C2H3O global potential energy surface and has a small isomerization barrier to vinoxy. The resulting highly vibrationally excited vinoxy radicals likely dissociate to give the observed signal at the mass corresponding to ketene, H2CCO. The final primary photodissociation pathway HCl+C3H4O evidences a recoil kinetic energy distribution similar to that of four-center HCl elimination in chlorinated alkenes, so is assigned to production of c-(H2COC)=CH2; the epoxide product is formed with enough vibrational energy to isomerize to acrolein and dissociate. The paper then analyzes the dynamics of the C3H5O radical produced from C-Cl bond photofission. When the epoxide radical photoproduct undergoes facile ring opening, it is the radical intermediate formed in the O(P3)+allyl bimolecular reaction when the O atom adds to an end C atom. We focus on the HCO+C2H4 and H2CO+C2H3 product channels from this radical intermediate in this report. Analysis of the velocity distribution of the momentum-matched signals from the HCO+C2H4 products at m/e=29 and 28 shows that the dissociation of the radical intermediate imparts a high relative kinetic energy, peaking near 20 kcal/mol, between the products. Similarly, the energy imparted to relative kinetic energy in the H2CO+C2H3 product channel of the O(P3)+allyl radical intermediate also peaks at high-recoil kinetic energies, near 18 kcal/mol. The strongly forward-backward peaked angular distributions and the high kinetic energy release result from tangential recoil during the dissociation of highly rotationally excited nascent radicals formed photolytically in this experiment. The data also reveal substantial branching to an HCCH+H3

A General Catalyst for Site-Selective C(sp(3))-H Bond Amination of Activated Secondary over Tertiary Alkyl C(sp(3))-H Bonds.

Science.gov (United States)

Scamp, Ryan J; Jirak, James G; Dolan, Nicholas S; Guzei, Ilia A; Schomaker, Jennifer M

2016-06-17

The discovery of transition metal complexes capable of promoting general, catalyst-controlled and selective carbon-hydrogen (C-H) bond amination of activated secondary C-H bonds over tertiary alkyl C(sp(3))-H bonds is challenging, as substrate control often dominates when reactive nitrene intermediates are involved. In this letter, we report the design of a new silver complex, [(Py5Me2)AgOTf]2, that displays general and good-to-excellent selectivity for nitrene insertion into propargylic, benzylic, and allylic C-H bonds over tertiary alkyl C(sp(3))-H bonds.

Dosimetry and microdosimetry using LET spectrometer based on the track-etch detector: radiotherapy Bremsstrahlung beam, onboard aircraft radiation field

International Nuclear Information System (INIS)

Jadrnickova, I.; Spurny, F.

2006-01-01

The spectrometer of linear energy transfer (Let) based on the chemically etched poly-allyl-diglycol-carbonate (P.A.D.C.) track-etch detector was developed several years ago in our institute. This Let spectrometer enables determining Let of particles approximately from 10 to 700 keV/μm. From the Let spectra, dose characteristics can be calculated. The contribution presents the Let spectra and other dosimetric characteristics obtained onboard a commercial aircraft during more than 6 months long exposure and in the 18 MV radiotherapy Bremsstrahlung beam. (authors)

Palladium-Catalyzed Reductive Insertion of Alcohols into Aryl Ether Bonds

Energy Technology Data Exchange (ETDEWEB)

Wang, Meng [Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Gutiérrez, Oliver Y. [Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Camaioni, Donald M. [Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Lercher, Johannes A. [Institute for Integrated Catalysis, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Department of Chemistry and Catalysis Research Institute, TU München, Lichtenbergstrasse 4 85748 Garching Germany

2018-03-06

Pd/C catalyzes C-O bond cleavage of aryl ethers (diphenyl ether and cyclohexyl phenyl ether) by methanol in H2. The aromatic C-O bond is cleaved by reductive methanolysis, which is initiated by Pd-catalyzed partial hydrogenation of one phenyl ring to form an enol ether. The enol ether reacts rapidly with methanol to form a ketal, which generates methoxycyclohexene by eliminating phenol or an alkanol. Subsequent hydrogenation leads to methoxycyclohexane.

Carbon-On-Carbon Manufacturing

Science.gov (United States)

Mungas, Gregory S. (Inventor); Buchanan, Larry (Inventor); Banzon, Jr., Jose T. (Inventor)

2017-01-01

The presently disclosed technology relates to carbon-on-carbon (C/C) manufacturing techniques and the resulting C/C products. One aspect of the manufacturing techniques disclosed herein utilizes two distinct curing operations that occur at different times and/or using different temperatures. The resulting C/C products are substantially non-porous, even though the curing operation(s) substantially gasify a liquid carbon-entrained filler material that saturates a carbon fabric that makes up the C/C products.

Stereospecific 7α-alkylation of 20-hydroxyecdysone in a lithium-ammonia solution.

Science.gov (United States)

Galyautdinov, Ilgiz V; Khairullina, Zarema R; Zaripova, Elvira R; Sametov, Valery P; Mescheryakova, Ekaterina S; Muslimov, Zabir S; Mozgovoi, Oleg S; Khalilov, Leonard M; Odinokov, Victor N

2015-06-01

The reaction of 20-hydroxyecdysone with methyl or ethyl iodide or allyl bromide in a lithium-ammonia solution results in stereospecific 7α-alkylation to give 7α-methyl-, 7α-ethyl-, and 7α-allyl-14-deoxy-Δ(8(14))-20-hydroxyecdysones, respectively. By catalytic hydrogenation (Pd-C/MeOH), the 7α-allyl derivative was converted to 7α-n-propyl-14-deoxy-Δ(8(14))-20-hydroxyecdysone. Copyright © 2015 Elsevier Inc. All rights reserved.

Noxious heat threshold temperature and pronociceptive effects of allyl isothiocyanate (mustard oil) in TRPV1 or TRPA1 gene-deleted mice.

Science.gov (United States)

Tékus, Valéria; Horváth, Ádám; Hajna, Zsófia; Borbély, Éva; Bölcskei, Kata; Boros, Melinda; Pintér, Erika; Helyes, Zsuzsanna; Pethő, Gábor; Szolcsányi, János

2016-06-01

To investigate the roles of TRPV1 and TRPA1 channels in baseline and allyl isothiocyanate (AITC)-evoked nociceptive responses by comparing wild-type and gene-deficient mice. In contrast to conventional methods of thermonociception measuring reflex latencies, we used our novel methods to determine the noxious heat threshold. It was revealed that the heat threshold of the tail measured by an increasing-temperature water bath is significantly higher in TRPV1(-/-), but not TRPA1(-/-), mice compared to respective wild-types. There was no difference between the noxious heat thresholds of the hind paw as measured by an increasing-temperature hot plate in TRPV1(-/-), TRPA1(-/-) and the corresponding wild-type mice. The withdrawal latency of the tail from 0°C water was prolonged in TRPA1(-/-), but not TRPV1(-/-), mice compared to respective wild-types. In wild-type animals, dipping the tail or paw into 1% AITC induced an 8-14°C drop of the noxious heat threshold (heat allodynia) of both the tail and paw, and 40-50% drop of the mechanonociceptive threshold (mechanical allodynia) of the paw measured by dynamic plantar esthesiometry. These AITC-evoked responses were diminished in TRPV1(-/-), but not TRPA1(-/-), mice. Tail withdrawal latency to 1% AITC was significantly prolonged in both gene-deleted strains. Different heat sensors determine the noxious heat threshold in distinct areas: a pivotal role for TRPV1 on the tail is contrasted with no involvement of either TRPV1 or TRPA1 on the hind paw. Noxious heat threshold measurement appears appropriate for preclinical screening of TRP channel ligands as novel analgesics. Copyright © 2016 Elsevier Inc. All rights reserved.

Triboelectrification of active pharmaceutical ingredients: week acids and their salts.

Science.gov (United States)

Fujinuma, Kenta; Ishii, Yuji; Yashihashi, Yasuo; Yonemochi, Estuo; Sugano, Kiyohiko; Tarada, Katsuhide

2015-09-30

The effect of salt formulation on the electrostatic property of active pharmaceutical ingredients was investigated. The electrostatic property of weak acids (carboxylic acids and amide-enole type acid) and their sodium salts was evaluated by a suction-type Faraday cage meter. Free carboxylic acids showed negative chargeability, whereas their sodium salts showed more positive chargeability than the free acids. However, no such trend was observed for amide-enole type acids. Copyright © 2015 Elsevier B.V. All rights reserved.

Carbons and carbon supported catalysts in hydroprocessing

Energy Technology Data Exchange (ETDEWEB)

Furimsky, Edward

2009-07-01

This book is a comprehensive summary of recent research in the field and covers all areas of carbons and carbon materials. The potential application of carbon supports, particularly those of carbon black (CB) and activated carbon (AC) in hydroprocessing catalysis are covered. Novel carbon materials such as carbon fibers and carbon nano tubes (CNT) are also covered, including the more recent developments in the use of fullerenes in hydroprocessing applications. Although the primary focus of this book is on carbons and carbon supported catalysts, it also identifies the difference in the effect of carbon supports compared with the oxidic supports, particularly that of the Al{sub 2}O{sub 3}. The difference in catalyst activity and stability was estimated using both model compounds and real feeds under variable conditions. The conditions applied during the preparation of carbon supported catalysts are also comprehensively covered and include various methods of pretreatment of carbon supports to enhance catalyst performance. The model compounds results consistently show higher hydrodesulfurization and hydrodeoxygenation activities of carbon supported catalysts than that of the Al{sub 2}O{sub 3} supported catalysts. Also, the deactivation of the former catalysts by coke deposition was much less evident. Chapter 6.3.1.3 is on carbon-supported catalysts: coal-derived liquids.

Inhibition of Listeria monocytogenes on cooked cured chicken breasts by acidified coating containing allyl isothiocyanate or deodorized Oriental mustard extract.

Science.gov (United States)

Olaimat, Amin N; Holley, Richard A

2016-08-01

Ready-to-eat meats are considered foods at high risk to cause life-threatening Listeria monocytogenes infections. This study screened 5 L. monocytogenes strains for their ability to hydrolyze sinigrin (a glucosinolate in Oriental mustard), which formed allyl isothiocyanate (AITC) and reduced L. monocytogenes viability on inoculated vacuum-packed, cooked, cured roast chicken slices at 4 °C. Tests involved incorporation of 25-50 μl/g AITC directly or 100-250 mg/g Oriental mustard extract in 0.5% (w/v) κ-carrageenan/2% (w/v) chitosan-based coatings prepared using 1.5% malic or acetic acid. L. monocytogenes strains hydrolyzed 33.6%-48.4% pure sinigrin in MH broth by 21 d at 25 °C. Acidified κ-carrageenan/chitosan coatings containing 25-50 μl/g AITC or 100-250 mg/g mustard reduced the viability of L. monocytogenes and aerobic bacteria on cooked, cured roast chicken slices by 4.1 to >7.0 log10 CFU/g compared to uncoated chicken stored at 4 °C for 70 d. Coatings containing malic acid were significantly more antimicrobial than those with acetic acid. During storage for 70 d, acidified κ-carrageenan/chitosan coatings containing 25-50 μl/g AITC or 250 mg/g mustard extract reduced lactic acid bacteria (LAB) numbers 3.8 to 5.4 log10 CFU/g on chicken slices compared to uncoated samples. Acidified κ-carrageenan/chitosan-based coatings containing either AITC or Oriental mustard extract at the concentrations tested had the ability to control L. monocytogenes viability and delay growth of potential spoilage bacteria on refrigerated, vacuum-packed cured roast chicken. Copyright © 2016. Published by Elsevier Ltd.

Theoretical investigation of the photophysics of methyl salicylate isomers

Science.gov (United States)

Massaro, Richard D.; Blaisten-Barojas, Estela

2011-10-01

The photophysics of methyl salicylate (MS) isomers has been studied using time-dependent density functional theory and large basis sets. First electronic singlet and triplet excited states energies, structure, and vibrational analysis were calculated for the ketoB, enol, and ketoA isomers. It is demonstrated that the photochemical pathway involving excited state intramolecular proton transfer (ESIPT) from the ketoB to the enol tautomer agrees well with the dual fluorescence in near-UV (from ketoB) and blue (from enol) wavelengths obtained from experiments. Our calculation confirms the existence of a double minimum in the excited state pathway along the O-H-O coordinate corresponding to two preferred energy regions: (1) the hydrogen belongs to the OH moiety and the structure of methyl salicylate is ketoB; (2) the hydrogen flips to the closest carboxyl entailing electronic rearrangement and tautomerization to the enol structure. This double well in the excited state is highly asymmetric. The Franck-Condon vibrational overlap is calculated and accounts for the broadening of the two bands. It is suggested that forward and backward ESIPT through the barrier separating the two minima is temperature-dependent and affects the intensity of the fluorescence as seen in experiments. When the enol fluoresces and returns to its ground state, a barrier-less back proton transfer repopulates the ground state of methyl salicylate ketoB. It is also demonstrated that the rotamer ketoA is not stable in an excited state close to the desired emission wavelength. This observation eliminates the conjecture that the near-UV emission of the dual fluorescence originates from the ketoA rotamer. New experimental results for pure MS in the liquid state are reported and theoretical results compared to them.

Carbon/Carbon Pistons for Internal Combustion Engines

Science.gov (United States)

Taylor, A. H.

1986-01-01

Carbon/carbon piston performs same function as aluminum pistons in reciprocating internal combustion engines while reducing weight and increasing mechanical and thermal efficiencies of engine. Carbon/carbon piston concept features low piston-to-cylinder wall clearance - so low piston rings and skirts unnecessary. Advantages possible by negligible coefficient of thermal expansion of carbon/carbon.

Carbon dioxide conversion over carbon-based nanocatalysts.

Science.gov (United States)

Khavarian, Mehrnoush; Chai, Siang-Piao; Mohamed, Abdul Rahman

2013-07-01

The utilization of carbon dioxide for the production of valuable chemicals via catalysts is one of the efficient ways to mitigate the greenhouse gases in the atmosphere. It is known that the carbon dioxide conversion and product yields are still low even if the reaction is operated at high pressure and temperature. The carbon dioxide utilization and conversion provides many challenges in exploring new concepts and opportunities for development of unique catalysts for the purpose of activating the carbon dioxide molecules. In this paper, the role of carbon-based nanocatalysts in the hydrogenation of carbon dioxide and direct synthesis of dimethyl carbonate from carbon dioxide and methanol are reviewed. The current catalytic results obtained with different carbon-based nanocatalysts systems are presented and how these materials contribute to the carbon dioxide conversion is explained. In addition, different strategies and preparation methods of nanometallic catalysts on various carbon supports are described to optimize the dispersion of metal nanoparticles and catalytic activity.

Toxic effects of a horseradish extract and allyl isothiocyanate in the urinary bladder after 13-week administration in drinking water to F344 rats.

Science.gov (United States)

Hasumura, Mai; Imai, Toshio; Cho, Young-Man; Ueda, Makoto; Hirose, Masao; Nishikawa, Akiyoshi; Ogawa, Kumiko

2011-01-01

Subchronic toxicity of a horseradish extract (HRE), consisting mainly of a mixture of allyl isothiocyanate (AITC) and other isothiocyanates, was investigated with administration at concentrations of 0, 0.0125, 0.025 and 0.05% of HRE in drinking water for 13 weeks to male and female F344 rats. For comparison, treatment with 0.0425% of AITC was similarly performed. Body weight gain was reduced in the 0.05% HRE and AITC males as compared to the 0% controls, and the cause was considered at least partly related to decreased water consumption due to the acrid smell of the test substance and decreased food consumption. Serum biochemistry demonstrated increased urea nitrogen in 0.025 and 0.05% HRE and AITC males and 0.0125-0.05% HRE and AITC females, along with decreased total cholesterol in 0.0125-0.05% HRE females. On histopathological assessment, papillary/nodular hyperplasia of bladder mucosa was observed in 0.05% HRE and AITC males and females, in addition to simple mucosal hyperplasia found in all treated groups. Based on the above findings, no-observed-adverse-effect levels (NOAELs) were estimated to be below 0.0125% of HRE for both males and females, corresponding to 9.4 and 8.0 mg/kg body weight/day, respectively, and there appeared to be comparable toxicological properties of HRE to AITC, such as the inductive effect of significant proliferative lesions in the urinary bladder.

Cathode spot movements along the carbon fibres in carbon/carbon composites

International Nuclear Information System (INIS)

Zhang Chengyu; Qiao Shengru; Yang Zhimao; Ding Bingjun

2007-01-01

The cathode spot movements on a polyacrilonitrile (PAN)-based carbon felt reinforced C/C composite and a three dimensional PAN-based carbon fibre reinforced C/C composite (3D-C/C) were investigated by a scanning electron microscope and a digital high-speed video camera. It was found that the carbon fibres have a higher ability to withstand the vacuum arc erosion than the carbon matrix. The cathode spot walks on the matrix, rather than on the carbon fibres. The cathode spot motion is controlled by the architecture of carbon fibres in C/C. The cathode spots move along the carbon fibres by a step-by-step manner rather than a random walk. The cathode spot tracks spread over a wide zone on the 3D-C/C surface parallel to the carbon fibre. The average arc spreading velocity is estimated to be about 0.9 m s -1 and the transient arc spreading velocity is in the range of 0.54-4.5 m s -1

Radiation damage in carbon-carbon composites

International Nuclear Information System (INIS)

Burchell, T.D.; Eartherly, W.P.; Nelson, G.E.

1992-01-01

Graphite and carbon-carbon composite materials are widely used in plasma facing applications in current Tokamak devices such as TFTR and DIIID in the USA, JET, Tore Supra and TEXTOR in Europe, and JT-60U in Japan. Carbon-carbon composites are attractive choices for Tokamak limiters and diverters because of their low atomic number, high thermal shock resistance, high melting point, and high thermal conductivity. Next generation machines such as the International Thermonuclear Experimental Reactor (ITER) will utilize carbon-carbon composites in their first wall and diverter. ITER will be an ignition machine and thus will produce substantial neutron fluences from the D-T fusion reaction. The resultant high energy neutrons will cause carbon atom displacements in the plasma facing materials which will markedly affect their structure and physical properties. The effect of neutron damage on graphite has been studied for over forty years. Recently the effects of neutron irradiation on the fusion relevant graphite GraphNOL N3M was reviewed. In contrast to graphite, relatively little work has been performed to elucidate the effects of neutron irradiation on carbon-carbon composites. The results of our previous irradiation experiments have been published elsewhere. Here the irradiation induced dimensional changes in 1D, 2D, and 3D carbon-carbon composites are reported for fluences up to 4.7 dpa at an irradiation temperature of 600 degree C

How does the long G·G* Watson-Crick DNA base mispair comprising keto and enol tautomers of the guanine tautomerise? The results of a QM/QTAIM investigation.

Science.gov (United States)

Brovarets', Ol'ha O; Hovorun, Dmytro M

2014-08-14

The double proton transfer (DPT) in the long G·G* Watson-Crick base mispair (|C6N1(G*)N1C6(G)| = 36.4°; C1 symmetry), involving keto and enol tautomers of the guanine (G) nucleobase, along two intermolecular neighboring O6H···O6 (8.39) and N1···HN1 (6.14 kcal mol(-1)) H-bonds that were established to be slightly anti-cooperative, leads to its transformation into the G*·G base mispair through a single transition state (|C6N1N1C6| = 37.1°; C1), namely to the interconversion into itself. It was shown that the G·G* ↔ G*·G tautomerisation via the DPT is assisted by the third specific contact, that sequentially switches along the intrinsic reaction coordinate (IRC) in an original way: (G)N2H···N2(G*) H-bond (-25.13 to -10.37) → N2···N2 van der Waals contact (-10.37 to -9.23) → (G)N2···HN2(G*) H-bond (-9.23 to 0.79) → (G*)N2···HN2(G) H-bond (0.79 to 7.35 Bohr). The DPT tautomerisation was found to proceed through the asynchronous concerted mechanism by employing the QM/QTAIM approach and the methodology of the scans of the geometric, electron-topological, energetic, polar and NBO properties along the IRC. Nine key points, that can be considered as part of the tautomerisation repertoire, have been established and analyzed in detail. Furthermore, it was shown that the G·G* or G*·G base mispair is a thermodynamically and dynamically stable structure with a lifetime of 8.22 × 10(-10) s and all 6 low-frequency intermolecular vibrations are able to develop during this time span. Lastly, our results highlight the importance of the G·G* ↔ G*·G DPT tautomerisation, which can have implications for biological and chemical sensing applications.

Enantioselective N-Heterocyclic Carbene Catalysis via the Dienyl Acyl Azolium.

Science.gov (United States)

Gillard, Rachel M; Fernando, Jared E M; Lupton, David W

2018-04-16

Herein we report the enantioselective N-heterocyclic carbene catalyzed (4+2) annulation of the dienyl acyl azolium with enolates. The reaction exploits readily accessible acyl fluorides and TMS enol ethers to give a range of highly enantio- and diastereo-enriched cyclohexenes (most >97:3 er and >20:1 dr). The reaction was found to require high nucleophilicity NHC catalysts with mechanistic studies supporting a stepwise 1,6-addition/β-lactonization. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

NIOSH Manual of Analytical Methods (third edition). Fourth supplement

Energy Technology Data Exchange (ETDEWEB)

1990-08-15

The NIOSH Manual of Analytical Methods, 3rd edition, was updated for the following chemicals: allyl-glycidyl-ether, 2-aminopyridine, aspartame, bromine, chlorine, n-butylamine, n-butyl-glycidyl-ether, carbon-dioxide, carbon-monoxide, chlorinated-camphene, chloroacetaldehyde, p-chlorophenol, crotonaldehyde, 1,1-dimethylhydrazine, dinitro-o-cresol, ethyl-acetate, ethyl-formate, ethylenimine, sodium-fluoride, hydrogen-fluoride, cryolite, sodium-hexafluoroaluminate, formic-acid, hexachlorobutadiene, hydrogen-cyanide, hydrogen-sulfide, isopropyl-acetate, isopropyl-ether, isopropyl-glycidyl-ether, lead, lead-oxide, maleic-anhydride, methyl-acetate, methyl-acrylate, methyl-tert-butyl ether, methyl-cellosolve-acetate, methylcyclohexanol, 4,4'-methylenedianiline, monomethylaniline, monomethylhydrazine, nitric-oxide, p-nitroaniline, phenyl-ether, phenyl-ether-biphenyl mixture, phenyl-glycidyl-ether, phenylhydrazine, phosphine, ronnel, sulfuryl-fluoride, talc, tributyl-phosphate, 1,1,2-trichloro-1,2,2-trifluoroethane, trimellitic-anhydride, triorthocresyl-phosphate, triphenyl-phosphate, and vinyl-acetate.

Composition, characterization and atherogenic potential of oils, fats and other by products produced or marketed in Costa Rica

International Nuclear Information System (INIS)

Castro Bolanos, Monserrat; Herrera Ramirez, Carlos H.; Lutz Cruz, Giselle

2005-01-01

Cardiovascular diseases are very common among Costa Rican people. They are related to diets high in lipids that cause arterial damage. The present study was undertaken to determine the quality of fats and oils consumed more frequently in our country. 15 different brands of butter and margarines (A, B, D1 to D11), 7 types of vegetable fat (E1 to E7) and 14 different brands of sunflower oil (EG1 to EG3), corn oil (EM1 to EM3), olive oil (EO1 to EO4), soy oil (ES1 to ES3) and palm oil (EV) were collected and identified. 67 percent of the products were made in Costa Rica, 33% were imported products. Using gas chromatography and nuclear magnetic resonance techniques, fatty acid composition, iodine and saponification number, average molecular weight, carbon-carbon double bond number, allyl and double aryl hydrogens were determined in the lipid fraction of the 36 different products. Two types of butter and one type of oil were found adulterated with triacylglycerols of different kind or source. Susceptibility of the products to lipid oxidation was determined only in terms of double bond number and allyl and double alryl hydrogens. Sunflower, corn and olive oils were the most susceptible products. Through polyunsaturated fatty acids / saturated fatty acids relation and atherogenic index the atherogenic potential of the products was evaluated. The findings were that 2 types of butter and 5 types of vegetable fat were the most injurious ones. (author) [es

Proton Tracks and Formation of Pores in Poly[Diethylene Glycol Bis-(Allyl Carbonate)

CERN Document Server

Oganesyan, V R; Danziger, M; Hermsdorf, D; Orelovich, O L

2004-01-01

Modern dosimetry needs effective detectors to register light ions, especially those having energies down to 10 MeV/a.m.u. That is why in the research in hand we pay attention to development of materials for such a task. In this work the most effective detector CR-39 irradiated with low-energy protons was applied. A full analysis from opening to final formation of a pore was made with the help of sensitive electrolytic ething and electron scanning microscopy. Successive process of track breakthroughs was observed. The shape of the pore and corresponding parameters of its formation provide simulation of the process. Etching rates and factor of selectivity were determined. The influence of energy losses on geometry was noted.

Proton tracks and formation of pores in poly[diethylene glycol bis-(allyl carbonate)

International Nuclear Information System (INIS)

Oganesyan, V.R.; Trofimov, V.V.; Orelovich, O.L.; Danziger, M.; Hermsdorf, D.

2004-01-01

Modern dosimetry needs effective detectors to register light ions, especially those having energies down to 10 MeV/a.m.a. That is why in the research in hand we pay attention to development of materials for such a task. In this work the most effective detector CR-39 irradiated with low-energy protons was applied. A full analysis from opening to final formation of a pore was made with the help of sensitive electrolytic etching and electron scanning microscopy. Successive process of track breakthroughs was observed. The shape of the pore and corresponding parameters of its formation provide simulation of the process. Etching rates and factor of selectivity were determined. The influence of energy losses on geometry was noted

Ruthenium Catalyzed Diastereo- and Enantioselective Coupling of Propargyl Ethers with Alcohols: Siloxy-Crotylation via Hydride Shift Enabled Conversion of Alkynes to π-Allyls.

Science.gov (United States)

Liang, Tao; Zhang, Wandi; Chen, Te-Yu; Nguyen, Khoa D; Krische, Michael J

2015-10-14

The first enantioselective carbonyl crotylations through direct use of alkynes as chiral allylmetal equivalents are described. Chiral ruthenium(II) complexes modified by Josiphos (SL-J009-1) catalyze the C-C coupling of TIPS-protected propargyl ether 1a with primary alcohols 2a-2o to form products of carbonyl siloxy-crotylation 3a-3o, which upon silyl deprotection-reduction deliver 1,4-diols 5a-5o with excellent control of regio-, anti-diastereo-, and enantioselectivity. Structurally related propargyl ethers 1b and 1c bearing ethyl- and phenyl-substituents engage in diastereo- and enantioselective coupling, as illustrated in the formation of adducts 5p and 5q, respectively. Selective mono-tosylation of diols 5a, 5c, 5e, 5f, 5k, and 5m is accompanied by spontaneous cyclization to deliver the trans-2,3-disubstituted furans 6a, 6c, 6e, 6f, 6k, and 6m, respectively. Primary alcohols 2a, 2l, and 2p were converted to the siloxy-crotylation products 3a, 3l, and 3p, which upon silyl deprotection-lactol oxidation were transformed to the trans-4,5-disubstituted γ-butyrolactones 7a, 7l, and 7p. The formation of 7p represents a total synthesis of (+)-trans-whisky lactone. Unlike closely related ruthenium catalyzed alkyne-alcohol C-C couplings, deuterium labeling studies provide clear evidence of a novel 1,2-hydride shift mechanism that converts metal-bound alkynes to π-allyls in the absence of intervening allenes.

Aldol Reactions of Axially Chiral 5-Methyl-2-(o-arylimino-3-(o-aryl-thiazolidine-4-ones

Directory of Open Access Journals (Sweden)

Sule Erol Gunal

2016-06-01

Full Text Available Axially chiral 5-methyl-2-(o-arylimino-3-(o-aryl-thiazolidine-4-ones have been subjected to aldol reactions with benzaldehyde to produce secondary carbinols which have been found to be separable by HPLC on a chiral stationary phase. Based on the reaction done on a single enantiomer resolved via a chromatographic separation from a racemic mixture of 5-methyl-2-(α-naphthylimino-3-(α-naphthyl-thiazolidine-4-one by HPLC on a chiral stationary phase, the aldol reaction was shown to proceed via an enolate intermediate. The axially chiral enolate of the thiazolidine-4-one was found to shield one face of the heterocyclic ring rendering face selectivity with respect to the enolate. The selectivities observed at C-5 of the ring varied from none to 11.5:1 depending on the size of the ortho substituent. Although the aldol reaction proceeded with a lack of face selectivity with respect to benzaldehyde, recrystallization returned highly diastereomerically enriched products.

NMR and IR Investigations of Strong Intramolecular Hydrogen Bonds

Directory of Open Access Journals (Sweden)

Poul Erik Hansen

2017-03-01

Full Text Available For the purpose of this review, strong hydrogen bonds have been defined on the basis of experimental data, such as OH stretching wavenumbers, νOH, and OH chemical shifts, δOH (in the latter case, after correction for ring current effects. Limits for O–H···Y systems are taken as 2800 > νOH > 1800 cm−1, and 19 ppm > δOH > 15 ppm. Recent results as well as an account of theoretical advances are presented for a series of important classes of compounds such as β-diketone enols, β-thioxoketone enols, Mannich bases, proton sponges, quinoline N-oxides and diacid anions. The O···O distance has long been used as a parameter for hydrogen bond strength in O–H···O systems. On a broad scale, a correlation between OH stretching wavenumbers and O···O distances is observed, as demonstrated experimentally as well as theoretically, but for substituted β-diketone enols this correlation is relatively weak.

Integral Ring Carbon-Carbon Piston

Science.gov (United States)

Northam, G. Burton (Inventor)

1999-01-01

An improved structure for a reciprocating internal combustion engine or compressor piston fabricate from carbon-carbon composite materials is disclosed. An integral ring carbon-carbon composite piston, disclosed herein, reduces the need for piston rings and for small clearances by providing a small flexible, integral component around the piston that allows for variation in clearance due to manufacturing tolerances, distortion due to pressure and thermal loads, and variations in thermal expansion differences between the piston and cylinder liner.

Novel derivatives of aclacinomycin A block cancer cell migration through inhibition of farnesyl transferase.

Science.gov (United States)

Magi, Shigeyuki; Shitara, Tetsuo; Takemoto, Yasushi; Sawada, Masato; Kitagawa, Mitsuhiro; Tashiro, Etsu; Takahashi, Yoshikazu; Imoto, Masaya

2013-03-01

In the course of screening for an inhibitor of farnesyl transferase (FTase), we identified two compounds, N-benzyl-aclacinomycin A (ACM) and N-allyl-ACM, which are new derivatives of ACM. N-benzyl-ACM and N-allyl-ACM inhibited FTase activity with IC50 values of 0.86 and 2.93 μM, respectively. Not only ACM but also C-10 epimers of each ACM derivative failed to inhibit FTase. The inhibition of FTase by N-benzyl-ACM and N-allyl-ACM seems to be specific, because these two compounds did not inhibit geranylgeranyltransferase or geranylgeranyl pyrophosphate (GGPP) synthase up to 100 μM. In cultured A431 cells, N-benzyl-ACM and N-allyl-ACM also blocked both the membrane localization of H-Ras and activation of the H-Ras-dependent PI3K/Akt pathway. In addition, they inhibited epidermal growth factor (EGF)-induced migration of A431 cells. Thus, N-benzyl-ACM and N-allyl-ACM inhibited EGF-induced migration of A431 cells by inhibiting the farnesylation of H-Ras and subsequent H-Ras-dependent activation of the PI3K/Akt pathway.

Photoinduced azidohydroperoxidation of myrtenyl hydroperoxide with semiconductor particles and lucigenin as PET-catalysts.

Science.gov (United States)

Griesbeck, Axel G; Reckenthäler, Melissa; Uhlig, Johannes

2010-06-01

The allylic hydroperoxide 2 (myrtenyl hydroperoxide), available from singlet oxygen photooxygenation of beta-pinene (1), is converted into the azido bis-hydroperoxide 3 by an electron-transfer induced azidyl radical formation and trapping of the initial tertiary carbon radical by triplet oxygen. The azido bis-hydroperoxide 3 is reduced to the azido 1,2-diol 4 or the amino diol 5, respectively. Beside classical fluorescent PET sensitizers such as rhodamines, also nanosized semiconductor particles as well as lucigenin were applied as catalysts. The electron transfer rate of azide oxidation was determined for lucigenin by fluorescence quenching analysis.

Synthesis of O- and C-glycosides derived from β-(1,3)-D-glucans.

Science.gov (United States)

Marca, Eduardo; Valero-Gonzalez, Jessika; Delso, Ignacio; Tejero, Tomás; Hurtado-Guerrero, Ramon; Merino, Pedro

2013-12-15

A series of β-(1,3)-d-glucans have been synthesized incorporating structural variations specifically on the reducing end of the oligomers. Both O- and C-glucosides derived from di- and trisaccharides have been obtained in good overall yields and with complete selectivity. Whereas the O-glycosides were obtained via a classical Koenigs-Knorr glycosylation, the corresponding C-glycosides were obtained through allylation of the anomeric carbon and further cross-metathesis reaction. Finally, the compounds were evaluated against two glycosidases and two endo-glucanases and no inhibitory activity was observed. Copyright © 2013 Elsevier Ltd. All rights reserved.

Synthesis of sn-1 functionalized phospholipids as substrates for secretory phospholipase A₂

DEFF Research Database (Denmark)

Linderoth, Lars; Peters, Günther H.J.; Jørgensen, K.

2007-01-01

Secretory phospholipase A2 (sPLA2) represents a family of small water-soluble enzymes that catalyze the hydrolysis of phospholipids in the sn-2 position liberating free fatty acids and lysophospholipids. Herein we report the synthesis of two new phospholipids (1 and 2) with bulky allyl-substituen......Secretory phospholipase A2 (sPLA2) represents a family of small water-soluble enzymes that catalyze the hydrolysis of phospholipids in the sn-2 position liberating free fatty acids and lysophospholipids. Herein we report the synthesis of two new phospholipids (1 and 2) with bulky allyl...... of the allyl-substituents by a zinc mediated allylation. Small unilamellar liposomes composed of phospholipids 1 and 2 were subjected to sPLA2 activity measurements. Our results show that only phospholipid 1 is hydrolyzed by the enzyme. Molecular dynamics simulations revealed that the lack of hydrolysis...

Acid Rearrangement of Secoiridoids Related to Oleuropein and Secologanin

DEFF Research Database (Denmark)

Bianco, Armandodoriano; Jensen, Søren Rosendal; Olesen, Jens

2003-01-01

Acid treatment of an iridoid glycoside results in the cleavage of the acetal bond between the sugar unit and the monoterpenoid aglycon. Iridoids possessing non-conjugated enol ether systems, however, undergo the hydration of the iridoid enol ether functionality in acid medium, as well as the hydr...... as the hydrolysis of the bond. We examined the acid rearrangement of secoiridoids such as oleuropein (1) and secologanin (2) and their reduction products oleuropeinol (3) and secologaninol (4), to examine whether similar behaviour also occurs in this case....

Chelate-size effects on the structures, chemical behavior, properties, and catalytic activity of the new palladium(II)-allyl complexes [Pd(eta(3)-1-R-1-C3H4){FcCH=N-CH2-(CH2)(n)-NMe2}][PF6] {Fc = (eta(5)-C5H5)Fe(eta(5)-C5H4), n=2 or 1, and R-1 = h or ph}

NARCIS (Netherlands)

Pérez, S.; López, C.; Bosque, R.; Solans, X.; Font-Bardía, M.; Roig, A.; Molins, E.; van Leeuwen, P.W.N.M.; van Strijdonck, G.P.F.; Freixa, Z.

2008-01-01

The synthesis, X-ray crystal structures, and the study of the solution behavior of the palladium(II) allyl complexes [Pd(eta(3)-1R(1)-C3H4){FcCH=N-CH2-(CH2)(n)-NMe2}][PF6] {with Fc = (eta(5)-C5H5)Fe(eta(5)-C5H4), R-1 = H, and n = 2 (4) or 1 (5) or R-1 = Ph and n = 2 (6) or 1 (7)} are described. The

Hierarchical carbon nanostructure design: ultra-long carbon nanofibers decorated with carbon nanotubes

International Nuclear Information System (INIS)

El Mel, A A; Achour, A; Gautron, E; Angleraud, B; Granier, A; Le Brizoual, L; Djouadi, M A; Tessier, P Y; Xu, W; Choi, C H

2011-01-01

Hierarchical carbon nanostructures based on ultra-long carbon nanofibers (CNF) decorated with carbon nanotubes (CNT) have been prepared using plasma processes. The nickel/carbon composite nanofibers, used as a support for the growth of CNT, were deposited on nanopatterned silicon substrate by a hybrid plasma process, combining magnetron sputtering and plasma-enhanced chemical vapor deposition (PECVD). Transmission electron microscopy revealed the presence of spherical nanoparticles randomly dispersed within the carbon nanofibers. The nickel nanoparticles have been used as a catalyst to initiate the growth of CNT by PECVD at 600 deg. C. After the growth of CNT onto the ultra-long CNF, SEM imaging revealed the formation of hierarchical carbon nanostructures which consist of CNF sheathed with CNTs. Furthermore, we demonstrate that reducing the growth temperature of CNT to less than 500 deg. C leads to the formation of carbon nanowalls on the CNF instead of CNT. This simple fabrication method allows an easy preparation of hierarchical carbon nanostructures over a large surface area, as well as a simple manipulation of such material in order to integrate it into nanodevices.

Sol-gel coatings on carbon/carbon composites

International Nuclear Information System (INIS)

Sim, S.M.; Krabill, R.M.; Dalzell, W.J. Jr.; Chu, P.Y.; Clark, D.E.

1986-01-01

The need for structural materials that can withstand severe environments up to 4000 0 F has promulgated the investigation of sol-gel derived ceramic and composite coatings on carbon/carbon composite materials. Alumina and zirconia sols have been deposited via thermophoresis on carbon/carbon substrates

Carbon K-edge spectra of carbonate minerals.

Science.gov (United States)

Brandes, Jay A; Wirick, Sue; Jacobsen, Chris

2010-09-01

Carbon K-edge X-ray spectroscopy has been applied to the study of a wide range of organic samples, from polymers and coals to interstellar dust particles. Identification of carbonaceous materials within these samples is accomplished by the pattern of resonances in the 280-320 eV energy region. Carbonate minerals are often encountered in the study of natural samples, and have been identified by a distinctive resonance at 290.3 eV. Here C K-edge and Ca L-edge spectra from a range of carbonate minerals are presented. Although all carbonates exhibit a sharp 290 eV resonance, both the precise position of this resonance and the positions of other resonances vary among minerals. The relative strengths of the different carbonate resonances also vary with crystal orientation to the linearly polarized X-ray beam. Intriguingly, several carbonate minerals also exhibit a strong 288.6 eV resonance, consistent with the position of a carbonyl resonance rather than carbonate. Calcite and aragonite, although indistinguishable spectrally at the C K-edge, exhibited significantly different spectra at the Ca L-edge. The distinctive spectral fingerprints of carbonates provide an identification tool, allowing for the examination of such processes as carbon sequestration in minerals, Mn substitution in marine calcium carbonates (dolomitization) and serpentinization of basalts.

Carbon K-edge Spectra of Carbonate Minerals

Energy Technology Data Exchange (ETDEWEB)

Brandes, J.; Wirick, S; Jacobsen, C

2010-01-01

Carbon K-edge X-ray spectroscopy has been applied to the study of a wide range of organic samples, from polymers and coals to interstellar dust particles. Identification of carbonaceous materials within these samples is accomplished by the pattern of resonances in the 280-320 eV energy region. Carbonate minerals are often encountered in the study of natural samples, and have been identified by a distinctive resonance at 290.3 eV. Here C K-edge and Ca L-edge spectra from a range of carbonate minerals are presented. Although all carbonates exhibit a sharp 290 eV resonance, both the precise position of this resonance and the positions of other resonances vary among minerals. The relative strengths of the different carbonate resonances also vary with crystal orientation to the linearly polarized X-ray beam. Intriguingly, several carbonate minerals also exhibit a strong 288.6 eV resonance, consistent with the position of a carbonyl resonance rather than carbonate. Calcite and aragonite, although indistinguishable spectrally at the C K-edge, exhibited significantly different spectra at the Ca L-edge. The distinctive spectral fingerprints of carbonates provide an identification tool, allowing for the examination of such processes as carbon sequestration in minerals, Mn substitution in marine calcium carbonates (dolomitization) and serpentinization of basalts.

Preparation and characterization of carbon/SiC nanowire/Na-doped carbonated hydroxyapatite multilayer coating for carbon/carbon composites

International Nuclear Information System (INIS)

Leilei, Zhang; Hejun, Li; Kezhi, Li; Shouyang, Zhang; Qiangang, Fu; Yulei, Zhang; Jinhua, Lu; Wei, Li

2014-01-01

Highlights: • CSH coatings were prepared by combination of magnetron sputter ion plating, CVD and UECD. • Na + and CO 3 2− were developed to co-substitute hydroxyapatite. • SiC nanowires were introduced into Na-doped carbonated hydroxyapatite. • CSH coatings showed excellent cell activity and cell proliferation behavior. - Abstract: A carbon/SiC nanowire/Na-doped carbonated hydroxyapatite multilayer coating (CSH coating) was prepared on carbon/carbon composites using a combination method of magnetron sputter ion plating, chemical vapor deposition and ultrasound-assisted electrochemical deposition procedure. The morphology, microstructure and chemical composition of the coating were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The results showed that the CSH coating was consisted of three components: carbon layer, SiC nanowires and Na-doped carbonated hydroxyapatite. The carbon layer provided a dense and uniform surface structure for the growth of SiC nanowires. The SiC nanowires exhibited a porous structure, favoring the infiltration of Na-doped carbonated hydroxyapatite crystals. The Na-doped carbonated hydroxyapatite could infiltrate into the pores of SiC nanowires and finally cover the SiC nanowires entirely with a needle shape. The osteoblast-like MG63 cells were employed to assess the in vitro biocompatibility of the CSH coating. The MG63 cells favorably spread and grew well across the CSH coating surface with plenty of filopods and microvilli, exhibiting excellent cell activity. Moreover, the CSH coating elicited higher cell proliferation as compared to bare carbon/carbon composites. In conclusion, the CSH offers great potential as a coating material for future medical application in hard tissue replacement

Preparation and characterization of carbon/SiC nanowire/Na-doped carbonated hydroxyapatite multilayer coating for carbon/carbon composites

Energy Technology Data Exchange (ETDEWEB)

Leilei, Zhang, E-mail: zhangleilei1121@aliyun.com; Hejun, Li; Kezhi, Li; Shouyang, Zhang; Qiangang, Fu; Yulei, Zhang; Jinhua, Lu; Wei, Li

2014-09-15

Highlights: • CSH coatings were prepared by combination of magnetron sputter ion plating, CVD and UECD. • Na{sup +} and CO{sub 3}{sup 2−} were developed to co-substitute hydroxyapatite. • SiC nanowires were introduced into Na-doped carbonated hydroxyapatite. • CSH coatings showed excellent cell activity and cell proliferation behavior. - Abstract: A carbon/SiC nanowire/Na-doped carbonated hydroxyapatite multilayer coating (CSH coating) was prepared on carbon/carbon composites using a combination method of magnetron sputter ion plating, chemical vapor deposition and ultrasound-assisted electrochemical deposition procedure. The morphology, microstructure and chemical composition of the coating were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The results showed that the CSH coating was consisted of three components: carbon layer, SiC nanowires and Na-doped carbonated hydroxyapatite. The carbon layer provided a dense and uniform surface structure for the growth of SiC nanowires. The SiC nanowires exhibited a porous structure, favoring the infiltration of Na-doped carbonated hydroxyapatite crystals. The Na-doped carbonated hydroxyapatite could infiltrate into the pores of SiC nanowires and finally cover the SiC nanowires entirely with a needle shape. The osteoblast-like MG63 cells were employed to assess the in vitro biocompatibility of the CSH coating. The MG63 cells favorably spread and grew well across the CSH coating surface with plenty of filopods and microvilli, exhibiting excellent cell activity. Moreover, the CSH coating elicited higher cell proliferation as compared to bare carbon/carbon composites. In conclusion, the CSH offers great potential as a coating material for future medical application in hard tissue replacement.

Carbon and carbon-14 in lunar soil 14163

International Nuclear Information System (INIS)

Fireman, E.L.; Stoenner, R.W.

1981-01-01

Carbon is removed from the surface of lunar soil 14163 size fractions by combustions at 500 and 1000 0 C in an oxygen stream and the carbon contents and the carbon-14 activities are measured. The carbon contents are inversely correlated with grain size. A measured carbon content of 198 ppM for bulk 14163, obtained by combining the size fraction results, is modified to 109 +- 12 ppM by a carbon contamination correction. This value is in accord with a previous determination, 110 ppM, for bulk 14163. The small ( 53 μ) grains, 11.2 +- 2.0 dpm/kg. The combusted carbon and carbon-14 are attributed mainly to solar-wind implantation. Melt extractions of carbon-14 from the combusted soil samples gave essentially identical activities, 21.0 +- 1.5 and 19.2 +- 2.0 dpm/kg for the small and large grains, and are attributed to cosmic-ray spallation-produced carbon-14

Zinc mediated domino elimination-alkylation of methyl 5-iodopentofuranosides

DEFF Research Database (Denmark)

Hyldtoft, Lene; Poulsen, Carina Storm; Madsen, Robert

1999-01-01

5-Iodopentofuranosides are converted with zinc and allyl/propargyl bromide into dienes/enynes which are further used in carbohydrate annulation reactions.......5-Iodopentofuranosides are converted with zinc and allyl/propargyl bromide into dienes/enynes which are further used in carbohydrate annulation reactions....

Carbon black vs. black carbon and other airborne materials containing elemental carbon: Physical and chemical distinctions

International Nuclear Information System (INIS)

Long, Christopher M.; Nascarella, Marc A.; Valberg, Peter A.

2013-01-01

Airborne particles containing elemental carbon (EC) are currently at the forefront of scientific and regulatory scrutiny, including black carbon, carbon black, and engineered carbon-based nanomaterials, e.g., carbon nanotubes, fullerenes, and graphene. Scientists and regulators sometimes group these EC-containing particles together, for example, interchangeably using the terms carbon black and black carbon despite one being a manufactured product with well-controlled properties and the other being an undesired, incomplete-combustion byproduct with diverse properties. In this critical review, we synthesize information on the contrasting properties of EC-containing particles in order to highlight significant differences that can affect hazard potential. We demonstrate why carbon black should not be considered a model particle representative of either combustion soots or engineered carbon-based nanomaterials. Overall, scientific studies need to distinguish these highly different EC-containing particles with care and precision so as to forestall unwarranted extrapolation of properties, hazard potential, and study conclusions from one material to another. -- Highlights: •Major classes of elemental carbon-containing particles have distinct properties. •Despite similar names, carbon black should not be confused with black carbon. •Carbon black is distinguished by a high EC content and well-controlled properties. •Black carbon particles are characterized by their heterogenous properties. •Carbon black is not a model particle representative of engineered nanomaterials. -- This review demonstrates the significant physical and chemical distinctions between elemental carbon-containing particles e.g., carbon black, black carbon, and engineered nanomaterials

Carbon/carbon composite materials

International Nuclear Information System (INIS)

Thebault, J.; Orly, P.

2006-01-01

Carbon/carbon composites are singular materials from their components, their manufacturing process as well as their characteristics. This paper gives a global overview of these particularities and applications which make them now daily used composites. (authors)

Synthesis of carbon nanorods by reduction of carbon bisulfide

International Nuclear Information System (INIS)

Lou Zhengsong; He Minglong; Zhao Dejian; Li Zhongchun; Shang Tongming

2010-01-01

Research highlights: Our manuscript is a concise preliminary account of original and of significant research, which illuminates carbon nanorods and variously shaped Y-junction carbon nanorods are successfully fabricated on a large scale through a carbon bisulfide thermal reduction process. Various shaped Y-junction carbon nanorods can be used as studying the electronic and transport properties of the nano-meter carbon material. - Abstract: Carbon nanorods are synthesized at large scale by the reduction of carbon bisulfide at 600 o C. Moreover, novel Y-junction carbon nanorods are detected in the samples. The X-ray power diffraction pattern indicates that the products are hexagonal graphite. Scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and N 2 physisorption studies show that carbon nanorods predominate in the product. Based on the supercritical carbon bisulfide system, the possible growth mechanism of the carbon nanorods was discussed. This method provides a simple and cheap route to large-scale synthesis of carbon nanorods.

Carbon dioxide sequestration by mineral carbonation

NARCIS (Netherlands)

Huijgen, W.J.J.

2007-01-01

The increasing atmospheric carbon dioxide (CO2) concentration, mainly caused by fossil fuel combustion, has lead to concerns about global warming. A possible technology that can contribute to the reduction of carbon dioxide emissions is CO2 sequestration by mineral carbonation. The basic concept

Activation of the microsomal glutathione-S-transferase and reduction of the glutathione dependent protection against lipid peroxidation by acrolein

NARCIS (Netherlands)

Haenen, G R; Vermeulen, N P; Tai Tin Tsoi, J N; Ragetli, H M; Timmerman, H; Blast, A

1988-01-01

Allyl alcohol is hepatotoxic. It is generally believed that acrolein, generated out of allyl alcohol by cytosolic alcohol dehydrogenase, is responsible for this toxicity. The effect of acrolein in vitro and in vivo on the glutathione (GSH) dependent protection of liver microsomes against lipid

40 CFR 116.4 - Designation of hazardous substances.

Science.gov (United States)

2010-07-01

... acetic acid, vinegar acid Acetic anhydride 108247 Acetic oxide, acetyl oxide Acetone cyanohydrin 75865 2... Allyl alcohol 107186 2-propen-1-ol, 1-propenol-3, vinyl carbinol Allyl chloride 107051 3-chloropropene..., mercaptomethane, methyl sulfhydrate, thiomethyl alcohol Methyl methacrylate 80626 Methacrylic acid methyl ester...

Investigation of the O+allyl addition/elimination reaction pathways from the OCH2CHCH2 radical intermediate

International Nuclear Information System (INIS)

FitzPatrick, Benjamin L.; Lau, K.-C.; Butler, Laurie J.; Lee, S.-H.; Lin, Jim Jr-Min

2008-01-01

These experiments study the preparation of and product channels resulting from OCH 2 CHCH 2 , a key radical intermediate in the O+allyl bimolecular reaction. The data include velocity map imaging and molecular beam scattering results to probe the photolytic generation of the radical intermediate and the subsequent pathways by which the radicals access the energetically allowed product channels of the bimolecular reaction. The photodissociation of epichlorohydrin at 193.3 nm produces chlorine atoms and c-OCH 2 CHCH 2 radicals; these undergo a facile ring opening to the OCH 2 CHCH 2 radical intermediate. State-selective resonance-enhanced multiphoton ionization (REMPI) detection resolves the velocity distributions of ground and spin-orbit excited state chlorine independently, allowing for a more accurate determination of the internal energy distribution of the nascent radicals. We obtain good agreement detecting the velocity distributions of the Cl atoms with REMPI, vacuum ultraviolet (VUV) photoionization at 13.8 eV, and electron bombardment ionization; all show a bimodal distribution of recoil kinetic energies. The dominant high recoil kinetic energy feature peaks near 33 kcal/mol. To elucidate the product channels resulting from the OCH 2 CHCH 2 radical intermediate, the crossed laser-molecular beam experiment uses VUV photoionization and detects the velocity distribution of the possible products. The data identify the three dominant product channels as C 3 H 4 O (acrolein)+H, C 2 H 4 +HCO (formyl radical), and H 2 CO (formaldehyde)+C 2 H 3 . A small signal from C 2 H 2 O (ketene) product is also detected. The measured velocity distributions and relative signal intensities at m/e=27, 28, and 29 at two photoionization energies show that the most exothermic product channel, C 2 H 5 +CO, does not contribute significantly to the product branching. The higher internal energy onset of the acrolein+H product channel is consistent with the relative barriers en route to

Investigation of the O+allyl addition/elimination reaction pathways from the OCH2CHCH2 radical intermediate

Science.gov (United States)

Fitzpatrick, Benjamin L.; Lau, Kai-Chung; Butler, Laurie J.; Lee, Shih-Huang; Lin, Jim-Min, Jr.

2008-08-01

These experiments study the preparation of and product channels resulting from OCH2CHCH2, a key radical intermediate in the O+allyl bimolecular reaction. The data include velocity map imaging and molecular beam scattering results to probe the photolytic generation of the radical intermediate and the subsequent pathways by which the radicals access the energetically allowed product channels of the bimolecular reaction. The photodissociation of epichlorohydrin at 193.3 nm produces chlorine atoms and c-OCH2CHCH2 radicals; these undergo a facile ring opening to the OCH2CHCH2 radical intermediate. State-selective resonance-enhanced multiphoton ionization (REMPI) detection resolves the velocity distributions of ground and spin-orbit excited state chlorine independently, allowing for a more accurate determination of the internal energy distribution of the nascent radicals. We obtain good agreement detecting the velocity distributions of the Cl atoms with REMPI, vacuum ultraviolet (VUV) photoionization at 13.8 eV, and electron bombardment ionization; all show a bimodal distribution of recoil kinetic energies. The dominant high recoil kinetic energy feature peaks near 33 kcal/mol. To elucidate the product channels resulting from the OCH2CHCH2 radical intermediate, the crossed laser-molecular beam experiment uses VUV photoionization and detects the velocity distribution of the possible products. The data identify the three dominant product channels as C3H4O (acrolein)+H, C2H4+HCO (formyl radical), and H2CO (formaldehyde)+C2H3. A small signal from C2H2O (ketene) product is also detected. The measured velocity distributions and relative signal intensities at m/e=27, 28, and 29 at two photoionization energies show that the most exothermic product channel, C2H5+CO, does not contribute significantly to the product branching. The higher internal energy onset of the acrolein+H product channel is consistent with the relative barriers en route to each of these product channels

Response ofMeteorus leviventris, (Hymenoptera: Braconidae) to mustard oils in field trapping experiments.

Science.gov (United States)

Pivnick, K A

1993-09-01

Trapping experiments were carried out near Saskatoon, Canada, from May through August 1990 to assess the response of the braconid wasp,Meteorus leviventris, to four selected mustard oils or isothiocyanates (IC) at a release rate of 4 mg/day, and for allyl IC only, at 40 mg/day. Only allyl IC at 4 mg/day was significantly attractive when trap captures were compared to the captures in the control traps. The others (n-propyl IC, 2-phenylethyl IC., and ethyl IC) were not attractive, nor was allyl IC at the higher dose, although trap captures with the latter bait were the second highest.

Carbon Micronymphaea: Graphene on Vertically Aligned Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Jong Won Choi

2013-01-01

Full Text Available This paper describes the morphology of carbon nanomaterials such as carbon nanotube (CNT, graphene, and their hybrid structure under various operating conditions during a one-step synthesis via plasma-enhanced chemical vapor deposition (PECVD. We focus on the synthetic aspects of carbon hybrid material composed of heteroepitaxially grown graphene on top of a vertical array of carbon nanotubes, called carbon micronymphaea. We characterize the structural features of this unique nanocomposite by uses of electron microscopy and micro-Raman spectroscopy. We observe carbon nanofibers, poorly aligned and well-aligned vertical arrays of CNT sequentially as the growth temperature increases, while we always discover the carbon hybrids, called carbon micronymphaea, at specific cooling rate of 15°C/s, which is optimal for the carbon precipitation from the Ni nanoparticles in this study. We expect one-pot synthesized graphene-on-nanotube hybrid structure poses great potential for applications that demand ultrahigh surface-to-volume ratios with intact graphitic nature and directional electronic and thermal transports.

Carbon Impact Analytics - Designing low carbon indices based on Carbon Impact Analytics indicators

International Nuclear Information System (INIS)

2016-01-01

Investors are increasingly exposed to carbon risks and now face the challenge of managing these risks and developing climate-resilient investment strategies. Carbon Impact Analytics (CIA), an innovative methodology for analyzing the full carbon impact of a portfolio or index, equips investors and asset managers with the tools necessary to reduce their climate-related risks but also to seize the opportunities offered by the ongoing energy transition. Investors, asset managers and other financial institutions may use CIA results to: - measure and manage risks, - optimize their contribution to the energy transition, - seize opportunities associated with climate change mitigation, - report on GHG emissions and savings (for regulatory purposes or voluntarily), - engage in dialogue with companies, - reallocate investment portfolios, - and build new low-carbon indices. In this report, Carbone 4 offers a detailed look into how CIA indicators can be used to either 1) reallocate an existing portfolio or index to achieve maximal carbon performance or 2) build new low carbon indices from the ground up, drawn from Carbone 4's ever-growing database of CIA-analyzed firms. Two main levers were used to optimize CIA output: 1. Sectorial reallocation: exclusion of fossil fuel-related sectors or insertion of low carbon pure players; 2. Intra-sectorial reallocation: best-in-class approach within a sector. Sectorial and intra-sectorial methods may be applied in conjunction with one another to maximize results. For example, a best-in-class + fossil fuel-free index may be constructed by first excluding the fossil fuel sector and then applying a CIA best-in-class approach to all remaining sectors. This report offers a detailed look into how CIA indicators can be used to rework portfolios or indices to maximize carbon performance or to build low carbon indices from the ground up. These methods are illustrated via two preliminary examples of indices designed by Carbone 4: the reallocated

Carbon tetrachloride desorption from activated carbon

International Nuclear Information System (INIS)

Jonas, L.A.; Sansone, E.B.

1981-01-01

Carbon tetrachloride was desorbed from a granular activated carbon subsequent to its adsorption under various vapor exposure periods. The varied conditions of exposure resulted in a range of partially saturated carbon beds which, when followed by a constant flow rate for desorption, generated different forms of the desorbing concentration versus time curve. A method of analyzing the desorption curves is presented which permits extraction of the various desorbing rates from the different desorption and to relate this to the time required for such regeneration. The Wheeler desorption kinetic equation was used to calculate the pseudo first order desorption rate constant for the carbon. The desorption rate constant was found to increase monotonically with increasing saturation of the bed, permitting the calculation of the maximum desorption rate constant for the carbon at 100% saturation. The Retentivity Index of the carbon, defined as the dimensionless ratio of the adsorption to the desorption rate constant, was found to be 681

Rh(V) -Nitrenoid as a Key Intermediate in Rh(III) -Catalyzed Heterocyclization by C-H Activation: A Computational Perspective on the Cycloaddition of Benzamide and Diazo Compounds.

Science.gov (United States)

Zhou, Tao; Guo, Wei; Xia, Yuanzhi

2015-06-15

A mechanistic study of the substituent-dependent ring formations in Rh(III) -catalyzed C-H activation/cycloaddition of benzamide and diazo compounds was carried out by using DFT calculations. The results indicated that the decomposition of the diazo is facilitated upon the formation of the five-membered rhodacycle, in which the Rh(III) center is more electrophilic. The insertion of carbenoid into Rh-C(phenyl) bond occurs readily and forms a 6-membered rhodacycle, however, the following C-N bond formation is difficult both kinetically and thermodynamically by reductive elimination from the Rh(III) species. Instead, the Rh(V) -nitrenoid intermediate could be formed by migration of the pivalate from N to Rh, which undergoes the heterocyclization much more easily and complementary ring-formations could be modulated by the nature of the substituent at the α-carbon. When a vinyl is attached, the stepwise 1,3-allylic migration occurs prior to the pivalate migration and the 8-membered ring product will be formed. On the other hand, the pivalate migration becomes more favorable for the phenyl-contained intermediate because of the difficult 1,3-allylic migration accompanied by dearomatization, thus the 5-membered ring product was formed selectively. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carbon-carbon mirrors for exoatmospheric and space applications

Science.gov (United States)

Krumweide, Duane E.; Wonacott, Gary D.; Woida, Patrick M.; Woida, Rigel Q.; Shih, Wei

2007-09-01

The cost and leadtime associated with beryllium has forced the MDA and other defense agencies to look for alternative materials with similar structural and thermal properties. The use of carbon-carbon material, specifically in optical components has been demonstrated analytically in prior SBIR work at San Diego Composites. Carbon-carbon material was chosen for its low in-plane and through-thickness CTE (athermal design), high specific stiffness, near-zero coefficient of moisture expansion, availability of material (specifically c-c honeycomb for lightweight substrates), and compatibility with silicon monoxide (SiO) and silicon dioxide (SiO II) coatings. Subsequent development work has produced shaped carbon-carbon sandwich substrates which have been ground, polished, coated and figured using traditional optical processing. Further development has also been done on machined monolithic carbon-carbon mirror substrates which have also been processed using standard optical finishing techniques.

The enantioselective total synthesis of (+)-clusianone.

Science.gov (United States)

Horeischi, Fiene; Guttroff, Claudia; Plietker, Bernd

2015-02-11

(+)-Clusianone, an exo-type B PPAP with reported anti-HIV and chemoprotective activities, was synthesized in eleven steps with 97% ee starting from acetylacetone. An enantioselective decarboxylative Tsuji-Trost-allylation and a Ru-catalyzed ring-closing metathesis-decarboxylative allylation were used to control both diastereo- and enantioselectivity.

Carbon Sequestered, Carbon Displaced and the Kyoto Context

International Nuclear Information System (INIS)

Marland, G.; Schlamadinger, B.

1999-01-01

The integrated system that embraces forest management, forest products, and land-use change impacts the global carbon cycle - and hence the net emission of the greenhouse gas carbon dioxide - in four fundamental ways. Carbon is stored in living and dead biomass, carbon is stored in wood products and landfills, forest products substitute in the market place for products made from other materials, and forest harvests can be used wholly or partially to displace fossil fuels in the energy sector. Implementation of the Kyoto Protocol to the United Nations Framework Convention on Climate Change would result in the creation of international markets for carbon dioxide emissions credits, but the current Kyoto text does not treat all carbon identically. We have developed a carbon accounting model, GORCAM, to examine a variety of scenarios for land management and the production of forest products. In this paper we explore, for two simple scenarios of forest management, the carbon flows that occur and how these might be accounted for under the Kyoto text. The Kyoto protocol raises questions about what activities can result in emissions credits, which carbon reservoirs will be counted, who will receive the credits, and how much credit will be available? The Kyoto Protocol would sometimes give credits for carbon sequestered, but it would always give credits when fossil-fuel carbon dioxide emissions are displaced

Antioxidant capacity of eugenol derivatives

Directory of Open Access Journals (Sweden)

María E. Hidalgo

2009-01-01

Full Text Available Toxicity and antioxidant capacity of eugenol derivatives (E2 = 2-Methoxy-4-[1-propenylphenyl]acetate, E3 = 4-Allyl-2-methoxyphenylacetate, E4 = 4-Allyl-2-methoxy-4-nitrophenol, E5 = 5-Allyl-3-nitrobenzene-1,2-diol, E6 = 4-Allyl-2-methoxy-5-nitrophenyl acetate were evaluated in order to determine the influence of the sustituents. E2-E6 were synthesized from eugenol (E1. E1 was extracted from cloves oil, and E2-E6 were obtained through acetylation and nitration reactions. Antioxidant capacity evaluated by DPPH (1, 1-Diphenyl-2-picrylhydrazil and ORAC fluorescein demonstrated that E1 and E5 have a higher capacity and the minor toxicity evaluated by red blood cells haemolysis and the Artemia saline test. In accordance with our results, the compound's (E1-E5 use in the pharmaceutical, cosmetic and or food industries could be suggested.

Synthesis and Characterization Carbon Nanotubes Doped Carbon Aerogels

Science.gov (United States)

Xu, Yuelong; Yan, Meifang; Liu, Zhenfa

2017-12-01

Polycondensation of phloroglucinol, resorcinol and formaldehyde with carbon nanotube (CNT) as the additives, using sodium carbonate as the catalyst, leads to the formation of CNT - doped carbon aerogels. The structure of carbon aerogels (CAs) with carbon nanotubes (CNTs) were characterized by X-ray diffraction and scanning electron microscopy. The specific surface area, pore size distribution and pore volume were measured by surface area analyzer. The results show that when the optimum doping dosage is 5%, the specific surface area of CNT - doped carbon aerogel is up to 665 m2 g-1 and exhibit plentiful mesoporous.

Carbon Management In the Post-Cap-and-Trade Carbon Economy

Science.gov (United States)

DeGroff, F. A.

2013-12-01

This abstract outlines an economic model that integrates carbon externalities seamlessly into the national and international economies. The model incorporates a broad carbon metric used to value all carbon in the biosphere, as well as all transnational commerce. The model minimizes the cost associated with carbon management, and allows for the variation in carbon avidity between jurisdictions. When implemented over time, the model reduces the deadweight loss while minimizing social cost, thus maximizing the marginal social benefit commonly associated with Pigouvian taxes. Once implemented, the model provides a comprehensive economic construct for governments, industry and consumers to efficiently weigh the cost of carbon, and effectively participate in helping to reduce their direct and indirect use of carbon, while allowing individual jurisdictions to decide their own carbon value, without the need for explicit, express agreement of all countries. The model uses no credits, requires no caps, and matches climate changing behavior to costs. The steps to implement the model for a particular jurisdiction are: 1) Define the Carbon Metric to value changes in Carbon Quality. 2) Apply the Carbon Metric to assess the Carbon Toll a) for all changes in Carbon Quality and b) for imports and exports. This economic model has 3 clear advantages. 1) The carbon pricing and cost scheme use existing and generally accepted accounting methodologies to ensure the veracity and verifiability of carbon management efforts with minimal effort and expense using standard auditing protocols. Implementing this economic model will not require any special training, tools, or systems for any entity to achieve their minimum carbon target goals within their jurisdictional framework. 2) Given the spectrum of carbon affinities worldwide, the model recognizes and provides for flexible carbon pricing regimes, but does not penalize domestic carbon-consuming producers subject to imports from exporters in

Measurement of carbon capture efficiency and stored carbon leakage

Science.gov (United States)

Keeling, Ralph F.; Dubey, Manvendra K.

2013-01-29

Data representative of a measured carbon dioxide (CO.sub.2) concentration and of a measured oxygen (O.sub.2) concentration at a measurement location can be used to determine whether the measured carbon dioxide concentration at the measurement location is elevated relative to a baseline carbon dioxide concentration due to escape of carbon dioxide from a source associated with a carbon capture and storage process. Optionally, the data can be used to quantify a carbon dioxide concentration increase at the first location that is attributable to escape of carbon dioxide from the source and to calculate a rate of escape of carbon dioxide from the source by executing a model of gas-phase transport using at least the first carbon dioxide concentration increase. Related systems, methods, and articles of manufacture are also described.

Vasorelaxing effects and inhibition of nitric oxide in macrophages by new iron-containing carbon monoxide-releasing molecules (CO-RMs).

Science.gov (United States)

Motterlini, Roberto; Sawle, Philip; Hammad, Jehad; Mann, Brian E; Johnson, Tony R; Green, Colin J; Foresti, Roberta

2013-02-01

Carbon monoxide-releasing molecules (CO-RMs) are a class of organometallo carbonyl complexes capable of delivering controlled quantities of CO gas to cells and tissues thus exerting a broad spectrum of pharmacological effects. Here we report on the chemical synthesis, CO releasing properties, cytotoxicity profile and pharmacological activities of four novel structurally related iron-allyl carbonyls. The major difference among the new CO-RMs tested was that three compounds (CORM-307, CORM-308 and CORM-314) were soluble in dimethylsulfoxide (DMSO), whereas a fourth one (CORM-319) was rendered water-soluble by reacting the iron-carbonyl with hydrogen tetrafluoroborate. We found that despite the fact all compounds liberated CO, CO-RMs soluble in DMSO caused a more pronounced toxic effect both in vascular and inflammatory cells as well as in isolated vessels. More specifically, iron carbonyls soluble in DMSO released CO with a fast kinetic and displayed a marked cytotoxic effect in smooth muscle cells and RAW 247.6 macrophages despite exerting a rapid and pronounced vasorelaxation ex vivo. In contrast, CORM-319 that is soluble in water and liberated CO with a slower rate, preserved smooth muscle cell viability, relaxed aortic tissue and exerted a significant anti-inflammatory effect in macrophages challenged with endotoxin. These data suggest that iron carbonyls can be used as scaffolds for the design and synthesis of pharmacologically active CO-RMs and indicate that increasing water solubility and controlling the rate of CO release are important parameters for limiting their potential toxic effects. Copyright © 2012 Elsevier Ltd. All rights reserved.

Neutron scattering investigation of carbon/carbon composites

International Nuclear Information System (INIS)

Prem, M.; Krexner, G.; Peterlik, H.

2005-01-01

Full text: Carbon/Carbon (C/C) composites, built up from bi-directionally woven fabrics from PAN based carbon fibers, pre-impregnated with phenolic resin followed by pressure curing and carbonization at 1000 o C and a final heat treatment at either 1800 o C or 2400 o C, were investigated by means of small-angle as well as wideangle elastic neutron scattering. Sample orientations arranging the carbon fibers parallel and perpendicular to the incoming beam were examined. Structural features of the composites, i.e. of the fibers as well as the inherently existing pores, are presented and the influence of the heat treatment on the structural properties is discussed. (author)

Fabrication and bonding of thiol-ene-based microfluidic devices

International Nuclear Information System (INIS)

Sikanen, Tiina M; Moilanen, Maria-Elisa; Lafleur, Josiane P; Zhuang, Guisheng; Jensen, Thomas G; Kutter, Jörg P

2013-01-01

In this work, the bonding strength of microchips fabricated by thiol-ene free-radical polymerization was characterized in detail by varying the monomeric thiol/allyl composition from the stoichiometric ratio (1:1) up to 100% excess of thiol (2:1) or allyl (1:2) functional groups. Four different thiol-ene to thiol-ene bonding combinations were tested by bonding: (i) two stoichiometric layers, (ii) two layers bearing complementary excess of thiols and allyls, (iii) two layers both bearing excess of thiols, or (iv) two layers both bearing excess of allyls. The results showed that the stiffness of the cross-linked polymer plays the most crucial role regarding the bonding strength. The most rigid polymer layers were obtained by using the stoichiometric composition or an excess of allyls, and thus, the bonding combinations (i) and (iv) withstood the highest pressures (up to the cut-off value of 6 bar). On the other hand, excess of thiol monomers yielded more elastic polymer layers and thus decreased the pressure tolerance for bonding combinations (ii) and (iii). By using monomers with more thiol groups (e.g. tetrathiol versus trithiol), a higher cross-linking ratio, and thus, greater stiffness was obtained. Surface characterization by infrared spectroscopy confirmed that the changes in the monomeric thiol/allyl composition were also reflected in the surface chemistry. The flexibility of being able to bond different types of thiol-enes together allows for tuning of the surface chemistry to yield the desired properties for each application. Here, a capillary electrophoresis separation is performed to demonstrate the attractive properties of stoichiometric thiol-ene microchips. (technical note)