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Sample records for aromatic rings synthesis

  1. Synthesis of Carbazole Alkaloids by Ring-Closing Metathesis and Ring Rearrangement-Aromatization.

    Science.gov (United States)

    Dhara, Kalyan; Mandal, Tirtha; Das, Joydeb; Dash, Jyotirmayee

    2015-12-21

    Aprocess for the assembly of carbazole alkaloids has been developed on the basis of ring-closing metathesis (RCM) and ringrearrangement-aromatization (RRA) as the key steps. This method is based on allyl Grignard addition to isatin derivatives to provide smooth access to 2,2-diallyl 3-oxindole derivatives through a 1,2-allyl shift. The diallyl derivatives were used as RCM precursors to afford a novel class of spirocyclopentene-3-oxindole derivatives, which underwent a novel RRA reaction to afford carbazole derivatives. The synthetic sequence to carbazoles was shortened by combining the RCM and RRA steps in an orthogonal tandem catalytic process. The utility of this methodology was further demonstrated by the straightforward synthesis of carbazole alkaloids, including amukonal derivative, girinimbilol, heptaphylline, and bis(2-hydroxy-3-methylcarbazole). PMID:26768698

  2. 1 alpha,25-dihydroxyvitamin D3 analogs featuring aromatic and heteroaromatic rings: design, synthesis, and preliminary biological testing.

    Science.gov (United States)

    Posner, G H; Li, Z; White, M C; Vinader, V; Takeuchi, K; Guggino, S E; Dolan, P; Kensler, T W

    1995-10-27

    Aromatic compounds 2a-c, analogs of 1 alpha, 25-dihydroxyvitamin (calcitriol, 1), and heteroaromatic compounds 4a-c and 5a-c, analogs of 19-nor-1 alpha, 25-dihydroxyvitamin D3 (3), were designed to simulate the topology of their biologically potent parent compounds while avoiding previtamin D equilibrium. Convergent and facile total syntheses of the analogs (+)-2b, (+)-2c, (-)-4b, and (-)-5b were achieved via carbonyl addition of regiospecifically formed organolithium nucleophiles to the enantiomerically pure C,D-ring ketone (+)-17, characteristic of natural calcitriol (1). Likewise, hybrid analogs 20a-c were prepared to determine whether incorporation of a known potentiating side chain would lead to increased biological activity. Preliminary in vitro biological testing showed that aromatic analogs (+)-2b, (+)-2c, and 20a-c as well as heteroaromatic analogs (-)-4b and (-)-5b have very low affinities for the calf thymus vitamin D receptor but considerable antiproliferative activities in murine keratinocytes at micromolar concentration. No biological advantage was observed in this keratinocyte assay for the doubly modified hybrid analogs 20a-c over the singly modified parent (+)-2b. Analog (+)-2b, but surprisingly not the corresponding analog 20b differing from (+)-2b only in the side chain, showed considerable activity in nongenomic opening of calcium channels in rat osteosarcoma cells. PMID:7473581

  3. Electronic Aromaticity Index for Large Rings

    CERN Document Server

    Matito, Eduard

    2015-01-01

    We introduce a new electronic aromaticity index, AV1245, consisting in the average of the 4-center MCI values along the ring that keep a positional relationship of 1,2,4,5. AV1245 measures the extent of transferability of the delocalized electrons between bonds 1-2 and 4-5, which is expected to be large in conjugated circuits and, therefore, in aromatic molecules. A new algorithm for the calculation of MCI for large rings is also introduced and used to produce the data for the calibration of the new aromaticity index. AV1245 does not rely on reference values, does not suffer from large numerical precision errors, and it does not present any limitation on the nature of atoms, the molecular geometry or the level of calculation. It is a size-extensive measure with a small computational cost that grows linearly with the number of ring members. Therefore, it is specially suitable to study the aromaticity of large molecular rings as those occurring in belt-shaped M\\"obius structures or porphyrins.

  4. Optimization of low ring polycylic aromatic biodegradation

    Science.gov (United States)

    Othman, N.; Abdul-Talib, S.; Tay, C. C.

    2016-07-01

    Polycyclic aromatic hydrocarbons (PAHs) are recalcitrance and persistence that finally turn into problematic environmental contaminants. Microbial degradation is considered to be the primary mechanism of PAHs removal from the environment due to its organic criteria. This study is carried out to optimize degradation process of low ring PAHs. Bacteria used in this study was isolated from sludge collected from Kolej Mawar, Universiti Teknologi MARA, Shah Alam, Selangor. Working condition namely, substrate concentration, bacteria concentration, pH and temperature were optimized. PAHs in the liquid sample was extracted by using solid phase microextractio equipped with a 7 µm polydimethylsiloxane (PDMS) SPME fibr. Removal of PAHs were assessed by measuring PAHs concentration using GC-FID. Results from the optimization study of biodegradation indicated that maximum rate of PAHs removal occurred at 100 mgL-1 of PAHs, 10% bacteria concentration, pH 7.0 and 30°C. These working condition had proved the effectiveness of using bacteria in biodegradation process of PAHs.

  5. Six-Membered Aromatic Polyazides: Synthesis and Application

    Directory of Open Access Journals (Sweden)

    Sergei V. Chapyshev

    2015-10-01

    Full Text Available Aromatic polyazides are widely used as starting materials in organic synthesis and photochemical studies, as well as photoresists in microelectronics and as cross-linking agents in polymer chemistry. Some aromatic polyazides possess high antitumor activity, while many others are of considerable interest as high-energy materials and precursors of high-spin nitrenes and C3N4 carbon nitride nanomaterials. The use of aromatic polyazides in click-reactions may be a new promising direction in the design of various supramolecular systems possessing interesting chemical, physical and biological properties. This review is devoted to the synthesis, properties and applications of six-membered aromatic compounds containing three and more azido groups in the ring.

  6. Six-Membered Aromatic Polyazides: Synthesis and Application.

    Science.gov (United States)

    Chapyshev, Sergei V

    2015-10-21

    Aromatic polyazides are widely used as starting materials in organic synthesis and photochemical studies, as well as photoresists in microelectronics and as cross-linking agents in polymer chemistry. Some aromatic polyazides possess high antitumor activity, while many others are of considerable interest as high-energy materials and precursors of high-spin nitrenes and C₃N₄ carbon nitride nanomaterials. The use of aromatic polyazides in click-reactions may be a new promising direction in the design of various supramolecular systems possessing interesting chemical, physical and biological properties. This review is devoted to the synthesis, properties and applications of six-membered aromatic compounds containing three and more azido groups in the ring.

  7. [Laser Induced Fluorescence Spectroscopic Analysis of Aromatics from One Ring to Four Rings].

    Science.gov (United States)

    Zhang, Peng; Liu, Hai-feng; Yue, Zong-yu; Chen, Bei-ling; Yao, Ming-fa

    2015-06-01

    In order to distinguish small aromatics preferably, a Nd : YAG Laser was used to supply an excitation laser, which was adjusted to 0.085 J x cm(-2) at 266 nm. Benzene, toluene, naphthalene, phenanthrene, anthracene, pyrene and chrysene were used as the representative of different rings aromatics. The fluorescence emission spectra were researched for each aromatic hydrocarbon and mixtures by Laser induced fluorescence (LIF). Results showed that the rings number determined the fluorescence emission spectra, and the structure with same rings number did not affect the emission fluorescence spectrum ranges. This was due to the fact that the absorption efficiency difference at 266 nm resulted in that the fluorescence intensities of each aromatic hydrocarbon with same rings number were different and the fluorescence intensities difference were more apparently with aromatic ring number increasing. When the absorption efficiency was similar at 266 nm and the concentrations of each aromatic hydrocarbon were same, the fluorescence intensities were increased with aromatic ring number increasing. With aromatic ring number increasing, the fluorescence spectrum and emission peak wavelength were all red-shifted from ultraviolet to visible and the fluorescence spectrum range was also wider as the absorption efficiency was similar. The fluorescence emission spectra from one to four rings could be discriminated in the following wavelengths, 275 to 320 nm, 320 to 375 nm, 375 to 425 nm, 425 to 556 nm, respectively. It can be used for distinguish the type of the polycyclic aromatic hydrocarbons (PAHs) as it exists in single type. As PAHs are usually exist in a variety of different rings number at the same time, the results for each aromatic hydrocarbon may not apply to the aromatic hydrocarbon mixtures. For the aromatic hydrocarbon mixtures, results showed that the one- or two-ring PAHs in mixtures could not be detected by fluorescence as three- or four-ring PAHs existed in mixture

  8. Solid Phase Synthesis of Helically Folded Aromatic Oligoamides.

    Science.gov (United States)

    Dawson, S J; Hu, X; Claerhout, S; Huc, I

    2016-01-01

    Aromatic amide foldamers constitute a growing class of oligomers that adopt remarkably stable folded conformations. The folded structures possess largely predictable shapes and open the way toward the design of synthetic mimics of proteins. Important examples of aromatic amide foldamers include oligomers of 7- or 8-amino-2-quinoline carboxylic acid that have been shown to exist predominantly as well-defined helices, including when they are combined with α-amino acids to which they may impose their folding behavior. To rapidly iterate their synthesis, solid phase synthesis (SPS) protocols have been developed and optimized for overcoming synthetic difficulties inherent to these backbones such as low nucleophilicity of amine groups on electron poor aromatic rings and a strong propensity of even short sequences to fold on the solid phase during synthesis. For example, acid chloride activation and the use of microwaves are required to bring coupling at aromatic amines to completion. Here, we report detailed SPS protocols for the rapid production of: (1) oligomers of 8-amino-2-quinolinecarboxylic acid; (2) oligomers containing 7-amino-8-fluoro-2-quinolinecarboxylic acid; and (3) heteromeric oligomers of 8-amino-2-quinolinecarboxylic acid and α-amino acids. SPS brings the advantage to quickly produce sequences having varied main chain or side chain components without having to purify multiple intermediates as in solution phase synthesis. With these protocols, an octamer could easily be synthesized and purified within one to two weeks from Fmoc protected amino acid monomer precursors. PMID:27586338

  9. Aromaticity in Polyacene Analogues of Inorganic Ring Compounds

    CERN Document Server

    Chattaraj, P K; Chattaraj, Pratim Kumar; Roy, Debesh Ranjan

    2006-01-01

    The aromaticity in the polyacene analogues of several inorganic ring compounds (BN-acenes, CN-acenes, BO-acenes and Na6-acenes) is reported here for the first time. Conceptual density functional theory based reactivity descriptors and the nucleus independent chemical shift (NICS) values are used in this analysis.

  10. Aromatic rings in chemical and biological recognition: energetics and structures.

    Science.gov (United States)

    Salonen, Laura M; Ellermann, Manuel; Diederich, François

    2011-05-16

    This review describes a multidimensional treatment of molecular recognition phenomena involving aromatic rings in chemical and biological systems. It summarizes new results reported since the appearance of an earlier review in 2003 in host-guest chemistry, biological affinity assays and biostructural analysis, data base mining in the Cambridge Structural Database (CSD) and the Protein Data Bank (PDB), and advanced computational studies. Topics addressed are arene-arene, perfluoroarene-arene, S⋅⋅⋅aromatic, cation-π, and anion-π interactions, as well as hydrogen bonding to π systems. The generated knowledge benefits, in particular, structure-based hit-to-lead development and lead optimization both in the pharmaceutical and in the crop protection industry. It equally facilitates the development of new advanced materials and supramolecular systems, and should inspire further utilization of interactions with aromatic rings to control the stereochemical outcome of synthetic transformations. PMID:21538733

  11. Synthesis of aromatic cytokinins for plant biotechnology.

    Science.gov (United States)

    Plíhalová, Lucie; Vylíčilová, Hana; Doležal, Karel; Zahajská, Lenka; Zatloukal, Marek; Strnad, Miroslav

    2016-09-25

    Cytokinins represent an important group of plant growth regulators that can modulate several biotechnological processes owing to their ability to influence almost all stages of plant development and growth. In addition, the use of purine based cytokinins with aromatic substituent in C6 position of the purine moiety in tissue culture techniques is currently experiencing a surge in interest, made possible by the ongoing systematic synthesis and study of these compounds. This review article outlines progress in the synthesis of aromatic cytokinins, the in vitro and in vivo effects of these substances and insights gleaned from their synthesis. As the purine moiety in these compounds can be substituted at several positions, we examine each of the substitution possibilities in relation to the derivatives prepared so far. The discussion highlights the gradual simplification of their preparation in relation to their application in practice and summarizes the relevant organic chemistry literature and published patents. PMID:26703810

  12. Coulomb pairing resonances in multiple-ring aromatic molecules

    CERN Document Server

    Huber, D L

    2015-01-01

    We present an analysis of the Coulomb pairing resonances observed in photo-double-ionization studies of CnHm aromatic molecules with multiple benzene-like rings. It is applied to naphthalene, anthracene, phenanthrene, pyrene and coronene, all of which have six-member rings, and azulene which is comprised of a five-member and a seven-member ring. There is a high energy resonance at ~ 40 eV that is found in all of the molecules cited and is associated with paired electrons localized on carbon sites on the perimeter of the molecule, each of which having two carbon sites as nearest neighbors. The low energy resonance at 10 eV, which is found only in pyrene and coronene, is attributed to the formation of paired electrons localized on arrays of interior carbon atoms that have the point symmetry of the molecule with each carbon atom having three nearest neighbors. The origin of the anomalous increase in the doubly charged to singly charged parent-ion ratio that is found above the 40 eV resonance in all of the cited ...

  13. Synthesis of azaphenanthridines via anionic ring closure

    DEFF Research Database (Denmark)

    Hansen, Henriette Møller; Lysén, M.; Begtrup, M.;

    2005-01-01

    A new and convergent synthesis of azaphenanthridines via an anionic ring closure is reported. Ortho-lithiation/in situ borylation of cyanopyridines produces the corresponding cyanopyridylboronic esters, which undergo a Suzuki-Miyaura cross-coupling to give the key intermediates. Addition of lithi...

  14. Stereoselective Arene-Forming Aldol Condensation: Synthesis of Axially Chiral Aromatic Amides.

    Science.gov (United States)

    Fäseke, Vincent C; Sparr, Christof

    2016-06-13

    The increasing awareness of the importance of amide atropisomers prompts the development of novel strategies for their selective preparation. Described herein is a method for the enantioselective synthesis of atropisomeric aromatic amides by an amine-catalyzed arene-forming aldol condensation. The high reactivity of the glyoxylic amide substrates enables a remarkably efficient construction of a new aromatic ring, which proceeds within minutes at ambient temperature to afford products with excellent stereoselectivity. The high rotational barriers of the reduced products highlight the utility of this stable, spatially organized chiral scaffold. PMID:27166995

  15. Linkage of Aromatic Ring Structures in Saturates, Aromatics, Resins and Asphaltenes Fractions of Vacuum Residues Determined by Collision-Induced Dissociation Technology

    Institute of Scientific and Technical Information of China (English)

    Wang Wei; Liu Yingrong; Liu Zelong; Hou Huandi; Tian Songbai

    2016-01-01

    The linkage of aromatic ring structures in vacuum residues was important for the reifning process. The Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) combined with collision-induced dissociation (CID) is a powerful method to characterize the molecular structure of petroleum fractions. In this work, model compounds with differ-ent aromatic ring structures were measured by CID FT-ICR MS. The cracking of the parent ions and the generated fragment ions were able to distinguish different linkage of the model compounds. Then, vacuum residues were separated into saturates, aromat-ics, resins and asphaltenes fractions (SARA), and each fraction was characterized by CID technology. According to the experi-mental results, the aromatic rings in saturates and aromatics fractions were mainly of the island-type structures, while the aromatic rings in resins and asphaltenes fractions had a signiifcant amount of archipelago-type structures.

  16. A new aromatic probe - The ring stretching vibration Raman spectroscopy frequency

    Science.gov (United States)

    Guo, Yan-bo; Liu, Zi-zhong; Liu, Hong-xia; Zhang, Feng-ying; Yin, Jun-qing

    2016-07-01

    A new aromatic criterion is presented to determine the aromatic degree of the high symmetric molecules. Group theory is used to explain the correlation between the aromatic degree and the value of Ring Stretching Vibration Raman Spectroscopic Frequency (RSVRSF). The calculations of the geometrical optimization, nucleus-independent chemical shifts (NICS) and values of the Raman Spectroscopy for the aromatic molecules-LnHn (L = C, Si, Ge, n = 3, 5-8) were performed using the Density Functional Theory (DFT) Method, as well as the correlations between the values of their RSVRSF and NICS values by Statistic Package for Social Science (SPSS17.0). There are high positive correlations between the theoretical calculated the NICS values and the value of the RSVRSF (A1g/A1‧) of the LnHn (L = C, Si, Ge, n = 3, 5-8). The bigger the aromatic degree, the bigger the RSVRSF is. The value of the RSVRSF is a new probe of aromaticity. Expectedly, it is predicted that the experimental determination of the aromatic degree can be achieved by the determination of the ring stretching vibration (A1g/A1‧) Raman spectrum frequencies for the aromatic target molecules.

  17. Condensation reactions of glucose and aromatic ring; Glucose to hokokan tono shukugo hanno

    Energy Technology Data Exchange (ETDEWEB)

    Komano, T.; Mashimo, K.; Wainai, T.; Tanaka, C.; Yoshioka, T. [Nihon University, Tokyo (Japan). College of Science and Technology; Sugimoto, Y.; Miki, Y. [National Institute of Materials and Chemical Research, Tsukuba (Japan)

    1996-10-28

    For artificial coalification, condensation reactions of aromatic ring and activated compounds produced by dehydrating reaction of glucose were studied experimentally. In heat treatment experiment in water, three reaction specimens such as glucose, glucose and phenol, and glucose and benzaldehyde were fed into an autoclave together with distilled water, and subjected to reaction at 180{degree}C under spontaneous pressure for 50 hours. In hydrogenation experiment, the specimens were fed into an autoclave together with tetradecane and sulfurization catalyst, and subjected to reaction at 350{degree}C under initial pressure of 9.8MPa for 2 hours for gas chromatography (GC) analysis of products. As the experimental result, the reaction between glucose and aromatic ring in heat treatment in water occurred between aromatic ring and active fragment with a mean carbon number of 4-5 produced by decomposition of glucose. The reactivity was higher in benzaldehyde addition than phenol addition. 3 refs., 4 figs., 1 tab.

  18. Synthesis, structure, and fullerene-complexing property of azacalix[6]aromatics.

    Science.gov (United States)

    Fa, Shi-Xin; Wang, Li-Xia; Wang, De-Xian; Zhao, Liang; Wang, Mei-Xiang

    2014-04-18

    Synthesis, structure, and fullerene-binding property of azacalix[6]aromatics were systematically studied. By means of [3 + 3] and [2 + 2 + 2] fragment coupling protocols, a number of azacalix[6]aromatics containing different combinations of benzene, pyridine, and pyrimidine rings and various substituents on the bridging nitrogen atoms were synthesized conveniently in moderate to good yields. The resulting macrocycles adopt in the solid state symmetric and heavily distorted 1,3,5-alternate conformations depending on the aromatic building units, whereas, in solution, they exist as a mixture of conformers that undergo rapid interchanges relative to the NMR time scale. All macrocycles were able to form 1:1 complexes with C60 and C70 in toluene with the association constants up to 7.28 × 10(4) M(-1). In the crystalline state, azacalix[6]aromatics form complexes with C60 and C70 with 2:1, 1:1, and 1:2 stoichiometric ratios between host and guest. Azacalix[6]aromatics interact with fullerene by forming mainly the sandwich structure in which C60 or C70 is sandwiched by two macrocycles. X-ray molecular structures revealed that multiple π-π and CH-π interactions between concave azacalix[6]aromatics and convex fullerenes C60 and C70 contribute a joint driving force to the formation of host-guest complexes.

  19. Electron correlation in C (4N+2) carbon rings aromatic vs. dimerized structures

    CERN Document Server

    Torelli, T; Torelli, Tommaso; Mitas, Lubos

    2000-01-01

    The electronic structure of C_(4N+2) carbon rings exhibits competing many-body effects of Huckel aromaticity, second-order Jahn-Teller and Peierls instability at large sizes. This leads to possible ground state structures with aromatic, bond angle or bond length alternated geometry. Highly accurate quantum Monte Carlo results indicate the existence of a crossover between C_10 and C_14 from bond angle to bond length alternation. The aromatic isomer is always a transition state. The driving mechanism is the second-order Jahn-Teller effect which keeps the gap open at all sizes.

  20. Microwave-assisted synthesis of α-hydroxy aromatic ketones from α-bromo aromatic ketones in water

    Institute of Scientific and Technical Information of China (English)

    Xiang Liu; Hai Bo Chen; Zheng Guang Pan; Jian He Xu; He Xing Li

    2011-01-01

    A reaction of α-bromo aromatic ketones in water with microwave irradiation gave the corresponding α-hydroxy aromatic ketones in good yields.The use of microwaves was found to significantly improve yields and shorten the reaction time.This reaction afforded a very clean,convenient method for the synthesis of α-hydroxy aromatic ketones.

  1. Plasmids and aromatic degradation in Sphingomonas for bioremediation : Aromatic ring cleavage genes in soil and rhizosphere

    OpenAIRE

    SipilÀ, Timo

    2009-01-01

    Microbial degradation pathways play a key role in the detoxification and the mineralization of polyaromatic hydrocarbons (PAHs), which are widespread pollutants in soil and constituents of petroleum hydrocarbons. In microbiology the aromatic degradation pathways are traditionally studied from single bacterial strains with capacity to degrade certain pollutant. In soil the degradation of aromatics is performed by a diverse community of micro-organisms. The aim of this thesis was to study biode...

  2. Aromaticity in benzene-like rings - An experimental electron density investigation

    Indian Academy of Sciences (India)

    Anupama Ranganathan; G U Kulkarni

    2003-10-01

    An experimental charge density study has been carried out on perylene based on X-ray diffraction measurements at 130 K. The electron density and its associated properties have been evaluated at the bond and the ring critical points for the naphthalene residues as well as for the central ring. The variation of the Laplacian along the axis, above and below the ring plane, is found to be symmetric for the central ring while for the naphthalene rings, the Laplacian values are enhanced under the bow-shaped region. A plot of the Laplacian versus density evaluated at various points along the axis above the ring plane, shows a steep variation in the case of the central ring implying that the -density is smeared out compared to that over the naphthalene rings. Similar data extracted from a quinoid ring and a regular phenyl ring (both based on earlier reports from this laboratory) exhibit increasingly shallower trends and indicate, by contrast, that the central ring of perylene is much less aromatic.

  3. Aromatic A-ring analogues of orobanchol, new germination stimulants for seeds of parasitic weeds

    NARCIS (Netherlands)

    Malik, H.; Kohlen, W.; Jamil, M.; Rutjes, F.P.J.T.; Zwanenburg, B.

    2011-01-01

    Strigolactones are signaling compounds in plants of increasing importance. In this paper the focus is on their activity as germinating agents for seeds of parasitic weeds. The syntheses of aromatic A-ring analogues of the germination stimulant orobanchol have been described. Starting substrate is th

  4. Argentation chromatography for the separation of polycyclic aromatic compounds according to ring number.

    Science.gov (United States)

    Nocun, Margarete; Andersson, Jan T

    2012-01-01

    Crude oils are the most complex mixtures known and every speciation method relies on a simplification of their complexity. Argentation chromatography is shown to be superior to traditional liquid chromatographic ways of separating aromatic compounds based on the number of aromatic carbon atoms. A silver(I) mercaptopropano silica gel allows an efficient group separation of polycyclic aromatic compounds to be achieved. The usefulness of this phase is demonstrated for SRM 1582 Wilmington crude oil and a diesel fuel. Furthermore, the phase can also be used for semi-preparative purposes to collect fractions for further analysis with high resolution mass spectrometry. Orbitrap mass spectra are obtained here for the polycyclic aromatic sulfur heterocycles and it is demonstrated that they can contain one to five naphtheno rings.

  5. [Asymmetric synthesis of aromatic L-amino acids catalyzed by transaminase].

    Science.gov (United States)

    Xia, Wenna; Sun, Yu; Min, Cong; Han, Wei; Wu, Sheng

    2012-11-01

    Aromatic L-Amino acids are important chiral building blocks for the synthesis of many drugs, pesticides, fine chemicals and food additives. Due to the high activity and steroselectivity, enzymatic synthesis of chiral building blocks has become the main research direction in asymmetric synthesis field. Guided by the phylogenetic analysis of transaminases from different sources, two representative aromatic transaminases TyrB and Aro8 in type I subfamily, from the prokaryote Escherichia coli and eukaryote Saccharomyces cerevisia, respectively, were applied for the comparative study of asymmetric transamination reaction process and catalytic efficiency of reversely converting keto acids to the corresponding aromatic L-amino acid. Both TyrB and Aro8 could efficiently synthesize the natural aromatic amino acids phenylalanine and tyrosine as well as non-natural amino acid phenylglycine. The chiral HPLC analysis showed the produced amino acids were L-configuration and the e.e value was 100%. L-alanine was the optimal amino donor, and the transaminase TyrB and Aro8 could not use D-amino acids as amino donor. The optimal molar ratio of amino donor (L-alanine) and amino acceptor (aromatic alpha-keto acids) was 4:1. Both of the substituted group on the aromatic ring and the length of fatty acid carbon chain part in the molecular structure of aromatic substrate alpha-keto acid have the significant impact on the enzyme-catalyzed transamination efficiency. In the experiments of preparative-scale transamination synthesis of L-phenylglycine, L-phenylalanine and L-tyrosine, the specific production rate catalyzed by TryB were 0.28 g/(g x h), 0.31 g/(g x h) and 0.60 g/(g x h) and the specific production rate catalyzed by Aro8 were 0.61 g/(g x h), 0.48 g/(g x h) and 0.59 g/(g x h). The results obtained here were useful for applying the transaminases to asymmetric synthesis of L-amino acids by reversing the reaction balance in industry.

  6. Identification of vitamin d3-based hedgehog pathway inhibitors that incorporate an aromatic a-ring isostere.

    Science.gov (United States)

    DeBerardinis, Albert M; Banerjee, Upasana; Hadden, M Kyle

    2013-07-11

    Previous structure-activity relationship studies for vitamin D3 (VD3) inhibition of Hedgehog (Hh) signaling directed the design, synthesis, and evaluation of a series of VD3-based analogues that contain an aromatic A-ring mimic. Characterization of these compounds in a series of cellular assays demonstrated their ability to potently and selectively down-regulate Hh pathway signaling. The most active of these, 17, inhibited pathway signaling in Hh-dependent mouse fibroblasts (IC50 = 0.74 ± 0.1 μM) and cultured cancer cells (IC50 values 3.8 ± 0.1 to 5.2 ± 0.2 μM). In addition, 17 demonstrated reduced activation of the vitamin D receptor (VDR) compared to VD3 in these cellular models. These results suggest that VD3-based analogues with an aromatic A-ring are a valid scaffold for the development of more selective and potent Hh pathway inhibitors and identify 17 as an intriguing lead from this class of compounds for further development. In addition, our analysis of Hh pathway inhibitors in cancer cells suggests that the murine basal cell carcinoma cell line ASZ001 and the human medulloblastoma cell line DAOY are appropriate in vitro cancer models for early stage evaluation of pathway inhibition. PMID:24900716

  7. Novel synthetic methodologies for the synthesis of heterocyclic rings

    OpenAIRE

    Oswald, Magalie Florence

    2010-01-01

    Part 1. Synthesis of Stereodefined Heterocyclic Rings. We wish to report the development of novel methodology for the synthesis of stereodefined heterocyclic rings, which could be used for the synthesis of natural products containing for example tetrahydrofuran motifs, such as members of the pamamycin family. Due to their ambivalent properties, organoaluminium reagents can easily react with acetals by transfering an alkyl group after prior coordination with the substrates. This work has led t...

  8. Structural variations in aromatic 2-electron three-membered rings of the main group elements

    Indian Academy of Sciences (India)

    Dibyendu Mallick; Eluvathingal D Jemmis

    2015-02-01

    Structural variations of different 2-aromatic three-membered ring systems of main group elements, especially group 14 and 13 elements as compared to the classical description of cyclopropenyl cation has been reviewed in this article. The structures of heavier analogues as well as group 13 analogues of cyclopropenyl cation showed an emergence of dramatic structural patterns which do not conform to the generalnorms of carbon chemistry. Isolobal analogies between the main group fragments have been efficiently used to explain the peculiarities observed in these three-membered ring systems.

  9. An efficient and versatile synthesis of aromatic nitriles from aldehydes

    Institute of Scientific and Technical Information of China (English)

    Maryam Hajjami; Arash Ghorbani-Choghamarani; Mohammad Ali Zolfigol; Fatemeh Gholamian

    2012-01-01

    A simple and direct method has been developed for synthesis of nitriles based on one-pot reaction of aromatic aldehydes with three different kind of reagents:CeCl3·7H2O/KI/H2O2,CeCl3·7H2O/KI/UHP and (NH4)2Ce(NO3)6/KI/H2O2 in aqueous ammonia.

  10. Aromaticity of rings-in-molecules (RIMs) from electron localization-delocalization matrices (LDMs)

    Science.gov (United States)

    Sumar, Ismat; Cook, Ronald; Ayers, Paul W.; Matta, Chérif F.

    2016-01-01

    A new and powerful molecular descriptor termed the LDM (localization-delocalization matrix) has recently been proposed as a molecular fingerprinting tool and has been shown to yield robust quantitative-structure-to-activity/property-relationships (QSAR/QSPR). An LDM lists the average number of electrons localized within an atom in a molecule along its diagonal while the off-diagonal elements are the pair-wise average number of electrons shared between every pair of atoms in the molecule, bonded or not. Hence, the LDM is a representation of a fuzzy molecular graph that accounts for the whereabouts of all electron(s) in the molecule and can be expected to encode for several facets of its chemistry at once. We show that the LDM captures the aromatic character of a ring-in-a-molecule by comparing the aromaticity ranking based on the LDMs and their eigenvalues of 6-membered carbon rings within (polycyclic) benzenoid hydrocarbons with the ranking based on four well-established local aromaticity measures (harmonic oscillator model of aromaticity, acromatic fluctuation index, para delocalization index, and nucleus independent chemical shift(0)). This paper is dedicated to the memory of Professor Paul von Ragué Schleyer (1930-2014).

  11. Role of aromatic rings in the molecular recognition of aminoglycoside antibiotics: implications for drug design.

    Science.gov (United States)

    Vacas, Tatiana; Corzana, Francisco; Jiménez-Osés, Gonzalo; González, Carlos; Gómez, Ana M; Bastida, Agatha; Revuelta, Julia; Asensio, Juan Luis

    2010-09-01

    Aminoglycoside antibiotics participate in a large variety of binding processes involving both RNA and proteins. The description, in recent years, of several clinically relevant aminoglycoside/receptor complexes has greatly stimulated the structural-based design of new bioactive derivatives. Unfortunately, design efforts have frequently met with limited success, reflecting our incomplete understanding of the molecular determinants for the antibiotic recognition. Intriguingly, aromatic rings of the protein/RNA receptors seem to be key actors in this process. Indeed, close inspection of the structural information available reveals that they are frequently involved in CH/pi stacking interactions with sugar/aminocyclitol rings of the antibiotic. While the interaction between neutral carbohydrates and aromatic rings has been studied in detail during past decade, little is known about these contacts when they involve densely charged glycosides. Herein we report a detailed experimental and theoretical analysis of the role played by CH/pi stacking interactions in the molecular recognition of aminoglycosides. Our study aims to determine the influence that the antibiotic polycationic character has on the stability, preferred geometry, and dynamics of these particular contacts. With this purpose, different aminoglycoside/aromatic complexes have been selected as model systems. They varied from simple bimolecular interactions to the more stable intramolecular CH/pi contacts present in designed derivatives. The obtained results highlight the key role played by electrostatic forces and the desolvation of charged groups in the molecular recognition of polycationic glycosides and have clear implications for the design of improved antibiotics.

  12. Comparison of Intramolecular Forces in Dipeptides with Two Aromatic Rings: does Dispersion Dominate?

    Science.gov (United States)

    Thomas, Jessica A.

    2015-06-01

    IR/UV double resonance spectroscopy has shown that the structure of the capped dipeptide Ac-Trp-Tyr-NH2 is dominated by a hydrophobic interaction between the aromatic rings on the side chains. Using the same method, a similar molecule, Ac-Phe-Phe-NH2, had three experimentally observed conformers including one similar to that of Ac-Trp-Tyr-NH2. In this work, calculations were performed on additional dipeptides containing two aromatic rings to determine if the dispersion-dominated structure was among the lowest energy structures in all such cases. The B3LYP-DCP method developed by DiLabio and Torres was used to calculate the conformations of each dipeptide. Appending dispersion correction potentials (DCP) to B3LYP input files improves results for systems containing dispersion interactions without significantly increasing the calculation time. This method was used first on Ac-Trp-Tyr-NH2 and Ac-Phe-Phe-NH2 to confirm that it successfully identified the experimentally observed structures among the lowest energy results and was then applied to other capped dipeptides containing two aromatic rings including Ac-Phe-Tyr-NH2 and Ac-Tyr-Phe-NH2.

  13. Synthesis and characterization of organosoluble aromatic copolyimids

    Institute of Scientific and Technical Information of China (English)

    YANG Jintian; HUANG Wei; ZHOU Yongfeng; YAN Deyue

    2007-01-01

    A series of aromatic copolyimides was success fully synthesized from the commercial pyromellitic dianhy dride (PMDA) with a commercial diamine p-phenyldiamine (PDA) and a diamine 4,4'-methylenebis-(2-tert-butylaniline)(MBTBA) specially designed by the authors.The copoly imides were characterized by Infra-red (IR),Nuclear Magnetic Resonance (NMR),Gel Permeation Chromato graphy (GPC),Ultraviolet Visual (UV-Vis),Thermogra vimetic Analysis (TGA) and Dynamic Mechanical Analysis (DMA).The copolyimide was precipitated in m-cresol in the polymerization process when the molar ratio of MBTBA and PDA was lower than 6/4.The number-average molecular weight of the soluble copolyimides measured by GPC was larger than 4.0 x 104,and the polydispersity index was higher than 1.5.Only one glass transition temperature of these copolyimdies was detected around 360℃ by DMA.The copolyimides did not show appreciable decomposition up to 500℃ under N2,and the thermal stability of the copolyimide increased a little with the introduction of PDA into the polyimide main chain.

  14. Aromaticity Competition in Differentially Fused Borepin-Containing Polycyclic Aromatics.

    Science.gov (United States)

    Messersmith, Reid E; Siegler, Maxime A; Tovar, John D

    2016-07-01

    This report describes the synthesis and characterization of a series of borepin-based polycyclic aromatics bearing two different arene fusions. The borepin synthesis features streamlined Ti-mediated alkyne reduction, leading to Z-olefins, followed by direct lithiation and borepin formation. These molecules allow for an assessment of aromatic competition between the fused rings and the central borepin core. Crystallographic, magnetic, and computational studies yielded insights about the aromaticity of novel, differentially fused [b,f]borepins and allowed for comparison to literature compounds. Multiple borepin motifs were also incorporated into polycyclic aromatics with five or six rings in the main backbone, and their properties were also evaluated.

  15. Substitution patterns in aromatic rings by increment analysis. Model development and application to natural organic matter.

    Science.gov (United States)

    Perdue, E M; Hertkorn, N; Kettrup, A

    2007-02-01

    The aromatic region of two-dimensional heteronuclear 1H, 13C NMR spectra of natural organic matter and related materials (e.g., 1H and 13C chemical shifts ranging from approximately 5 to 10 and 80 to 140 ppm, respectively) is highly complex and difficult to interpret using conventional approaches. In principle, this region of the NMR spectrum should be amenable to detailed analysis, because the effects of many common substituents on the chemical shifts of aromatic carbon and hydrogen are well documented. This paper describes the development of a model for prediction of substitution patterns in aromatic rings by increment analysis (SPARIA). In the forward mode, SPARIA is used to predict the chemical shifts of 1H and 13C on aromatic moieties containing every possible combination of eight common substituents that are likely to be representative of substituents on aromatic moieties in natural organic matter. The accuracy of SPARIA in the forward mode is evaluated for 29 aromatic compounds (100 peaks) by comparison of predicted chemical shifts for 1H and 13C with experimental values and with predictions of commercially available software for prediction of NMR spectra. The most important development in this paper is the inverse mode that is built into SPARIA. Given chemical shifts for 1H and 13C (such as may be obtained from a two-dimensional, heteronuclear NMR spectrum), the inverse mode of SPARIA calculates all possible combinations of the eight selected substituents that yield chemical shifts within a specified window of chemical shift for both 1H and 13C. Both the distribution of possible substitution patterns and simple descriptive statistics of the distribution are thus obtained. The inverse mode of SPARIA has been tested on the 29 aromatic compounds (100 peaks) that were used to evaluate its forward mode, and the dependence of the inverse process on the size of the chemical shift window has been evaluated. Finally, the inverse mode of SPARIA has been applied to

  16. Positioning a Carbon-Fluorine Bond over the π Cloud of an Aromatic Ring: A Different Type of Arene Activation.

    Science.gov (United States)

    Holl, Maxwell Gargiulo; Struble, Mark D; Singal, Prakhar; Siegler, Maxime A; Lectka, Thomas

    2016-07-11

    It is known that the fluoro group has only a small effect on the rates of electrophilic aromatic substitutions. Imagine instead a carbon-fluorine (C-F) bond positioned tightly over the π cloud of an aryl ring-such an orthogonal, noncovalent arrangement could instead stabilize a positively charged arene intermediate or transition state, giving rise to novel electrophilic aromatic substitution chemistry. Herein, we report the synthesis and study of molecule 1, containing a rigid C-F⋅⋅⋅Ar interaction that plays a prominent role in both its reaction chemistry and spectroscopy. For example, we established that the C-F⋅⋅⋅Ar interaction can bring about a >1500 fold increase in the relative rate of an aromatic nitration reaction, affording functionalization on the activated ring exclusively. Overall, these results establish fluoro as a through-space directing/activating group that complements the traditional role of fluorine as a slightly deactivating aryl substituent in nitrations. PMID:27145463

  17. Computer-aided rational design of novel EBF analogues with an aromatic ring.

    Science.gov (United States)

    Wang, Shanshan; Sun, Yufeng; Du, Shaoqing; Qin, Yaoguo; Duan, Hongxia; Yang, Xinling

    2016-06-01

    Odorant binding proteins (OBPs) are important in insect olfactory recognition. These proteins bind specifically to insect semiochemicals and induce their seeking, mating, and alarm behaviors. Molecular docking and molecular dynamics simulations were performed to provide computational insight into the interaction mode between AgamOBP7 and novel (E)-β-farnesene (EBF) analogues with an aromatic ring. The ligand-binding cavity in OBP7 was found to be mostly hydrophobic due to the presence of several nonpolar residues. The interactions between the EBF analogues and the hydrophobic residues in the binding cavity increased in strength as the distance between them decreased. The EBF analogues with an N-methyl formamide or ester linkage had higher docking scores than those with an amide linkage. Moreover, delocalized π-π and electrostatic interactions were found to contribute significantly to the binding between the ligand benzene ring and nearby protein residues. To design new compounds with higher activity, four EBF analogues D1-D4 with a benzene ring were synthesized and evaluated based on their docking scores and binding affinities. D2, which had an N-methyl formamide group linkage, exhibited stronger binding than D1, which had an amide linkage. D4 exhibited particularly strong binding due to multiple hydrophobic interactions with the protein. This study provides crucial foundations for designing novel EBF analogues based on the OBP structure. Graphical abstract The design strategy of new EBF analogues based on the OBP7 structure.

  18. Writing with ring currents: selectively hydrogenated polycyclic aromatics as finite models of graphene and graphane.

    Science.gov (United States)

    Fowler, Patrick W; Gibson, Christopher M; Bean, David E

    2014-03-01

    Alternating partial hydrogenation of the interior region of a polycyclic aromatic hydrocarbon gives a finite model system representing systems on the pathway from graphene to the graphane modification of the graphene sheet. Calculations at the DFT and coupled Hartree-Fock levels confirm that sp(2) cycles of bare carbon centres isolated by selective hydrogenation retain the essentially planar geometry and electron delocalization of the annulene that they mimic. Delocalization is diagnosed by the presence of ring currents, as detected by ipsocentric calculation and visualization of the current density induced in the π system by a perpendicular external magnetic field. These induced 'ring' currents have essentially the same sense, strength and orbital origin as in the free hydrocarbon. Subjected to the important experimental proviso of the need for atomic-scale control of hydrogenation, this finding predicts the possibility of writing single, multiple and concentric diatropic and/or paratropic ring currents on the graphene/graphane sheet. The implication is that pathways for free flow of ballistic current can be modelled in the same way.

  19. Computer-aided rational design of novel EBF analogues with an aromatic ring.

    Science.gov (United States)

    Wang, Shanshan; Sun, Yufeng; Du, Shaoqing; Qin, Yaoguo; Duan, Hongxia; Yang, Xinling

    2016-06-01

    Odorant binding proteins (OBPs) are important in insect olfactory recognition. These proteins bind specifically to insect semiochemicals and induce their seeking, mating, and alarm behaviors. Molecular docking and molecular dynamics simulations were performed to provide computational insight into the interaction mode between AgamOBP7 and novel (E)-β-farnesene (EBF) analogues with an aromatic ring. The ligand-binding cavity in OBP7 was found to be mostly hydrophobic due to the presence of several nonpolar residues. The interactions between the EBF analogues and the hydrophobic residues in the binding cavity increased in strength as the distance between them decreased. The EBF analogues with an N-methyl formamide or ester linkage had higher docking scores than those with an amide linkage. Moreover, delocalized π-π and electrostatic interactions were found to contribute significantly to the binding between the ligand benzene ring and nearby protein residues. To design new compounds with higher activity, four EBF analogues D1-D4 with a benzene ring were synthesized and evaluated based on their docking scores and binding affinities. D2, which had an N-methyl formamide group linkage, exhibited stronger binding than D1, which had an amide linkage. D4 exhibited particularly strong binding due to multiple hydrophobic interactions with the protein. This study provides crucial foundations for designing novel EBF analogues based on the OBP structure. Graphical abstract The design strategy of new EBF analogues based on the OBP7 structure. PMID:27251400

  20. Influence of chemical structure on hypersensitivity reactions induced by antiepileptic drugs: the role of the aromatic ring.

    NARCIS (Netherlands)

    Handoko, K.B.; Puijenbroek, E.P. van; Bijl, A.H.; Hermens, W.A.; Rijkom, JE Zwart-van; Hekster, Y.A.; Egberts, T.C.G.

    2008-01-01

    OBJECTIVE: Antiepileptic drugs (AEDs) can cause various 'idiosyncratic' hypersensitivity reactions, i.e. the mechanism by which AEDs induce hypersensitivity is unknown. The aim of this study was to assess whether the presence of an aromatic ring as a commonality in chemical structures of AEDs can ex

  1. Influence of chemical structure on hypersensitivity reactions induced by antiepileptic drugs : the role of the aromatic ring

    NARCIS (Netherlands)

    Handoko, Kim B; van Puijenbroek, Eugène P; Bijl, Annemarie H; Hermens, Walter A J J; Zwart-van Rijkom, Jeannette E F; Hekster, Yechiel A; Egberts, Toine C G

    2008-01-01

    OBJECTIVE: Antiepileptic drugs (AEDs) can cause various 'idiosyncratic' hypersensitivity reactions, i.e. the mechanism by which AEDs induce hypersensitivity is unknown. The aim of this study was to assess whether the presence of an aromatic ring as a commonality in chemical structures of AEDs can ex

  2. Studies of the Intramolecular Aromatic-ring Stacking Interactions in the Ternary Platinum(Ⅱ) Complexes

    Institute of Scientific and Technical Information of China (English)

    SUN Hong-liang

    2005-01-01

    The stability constants of some ternary mixed-ligand complexes, Pt(Phen)(CA)+, where Phen=1,10-phenanthroline and CA- =carboxylate, were determined by means of potentiometric pH titration in aqueous solutions(I=0.1 mol/L, KNO3; 25 ℃), and the stability of them was compared with that of the corresponding binary complexes. It was revealed that the ternary complexes containing phenylalkane carboxylates ligands(PCA-) are much more stable than those formed with formate and acetate. The results indicate that there exist the intramolecular aromatic-ring interactions between the phenanthroline ring of Phen and the phenyl moiety of ligand PCA- in the ternary mixed-ligand Pt(Phen)(PCA)- complexes. The extent of the stacking interactions, which depends on the number of methylene groups between the phenyl moieties and the coordinated phenylalkane carboxylate groups, was calculated. The best-fitted stack was obtained for the complexes with 2-phenylacetate and 3-phenylpropionate as the ligands.

  3. Synthesis of Heterocyclic Ring Systems Using Organometallic Reagents

    Institute of Scientific and Technical Information of China (English)

    Sameer Agarwal; Jan Kn(o)ll; Micha P. Krahl; Hans-Joachim Kn(o)lker

    2005-01-01

    @@ 1Introduction We developed novel synthetic routes to heterocyclic ring systems by using transition metal-mediated or -catalyzed reactions. A Lewis acid-promoted addition of the propargyl Grignard reagent 2 to the Schiff base 1 followed by a silvermediated oxidative cyclization of the homopropargylamine 3 provided the aryl-substituted pyrrole 4. Combined with a chemoselective hydrogenation of the pyrrole ring, this method has been applied to the total synthesis of the biologically active fused indolizidine alkaloids ( ± )-harmicine and ( ± )-crispine A[1]. See Fig. 1.

  4. Synthesis of Heteroaromatic Compounds by Oxidative Aromatization Using an Activated Carbon/Molecular Oxygen System

    Directory of Open Access Journals (Sweden)

    Masahiko Hayashi

    2009-08-01

    Full Text Available A variety of heteroaromatic compounds, such as substituted pyridines, pyrazoles, indoles, 2-substituted imidazoles, 2-substituted imidazoles, 2-arylbenzazoles and pyrimidin-2(1H-ones are synthesized by oxidative aromatization using the activated carbon and molecular oxygen system. Mechanistic study focused on the role of activated carbon in the synthesis of 2-arylbenzazoles is also discussed. In the final section, we will disclose the efficient synthesis of substituted 9,10-anthracenes via oxidative aromatization.

  5. Novel aromatic ring-hydroxylating dioxygenase genes from coastal marine sediments of Patagonia

    Directory of Open Access Journals (Sweden)

    Ferrero Marcela A

    2008-03-01

    Full Text Available Abstract Background Polycyclic aromatic hydrocarbons (PAHs, widespread pollutants in the marine environment, can produce adverse effects in marine organisms and can be transferred to humans through seafood. Our knowledge of PAH-degrading bacterial populations in the marine environment is still very limited, and mainly originates from studies of cultured bacteria. In this work, genes coding catabolic enzymes from PAH-biodegradation pathways were characterized in coastal sediments of Patagonia with different levels of PAH contamination. Results Genes encoding for the catalytic alpha subunit of aromatic ring-hydroxylating dioxygenases (ARHDs were amplified from intertidal sediment samples using two different primer sets. Products were cloned and screened by restriction fragment length polymorphism analysis. Clones representing each restriction pattern were selected in each library for sequencing. A total of 500 clones were screened in 9 gene libraries, and 193 clones were sequenced. Libraries contained one to five different ARHD gene types, and this number was correlated with the number of PAHs found in the samples above the quantification limit (r = 0.834, p nahAc-like genes, phnAc-like genes as identified in Alcaligenes faecalis AFK2, and phnA1-like genes from marine PAH-degraders from the genus Cycloclasticus. Conclusion These results show the presence of hitherto unidentified ARHD genes in this sub-Antarctic marine environment exposed to anthropogenic contamination. This information can be used to study the geographical distribution and ecological significance of bacterial populations carrying these genes, and to design molecular assays to monitor the progress and effectiveness of remediation technologies.

  6. A dissected ring current model for assessing magnetic aromaticity: a general approach for both organic and inorganic rings.

    Science.gov (United States)

    Foroutan-Nejad, Cina; Shahbazian, Shant; Feixas, Ferran; Rashidi-Ranjbar, Parviz; Solà, Miquel

    2011-08-01

    A model based on classical electrodynamics is used to measure the strength of ring currents of different molecular orbitals, i.e., σ- and π-orbitals, and characteristics of ring current loops, i.e., ring current radii and height of current loops above/below the ring planes, among a number of organic as well as inorganic molecules. For the π-current, the present model represents an improvement of previous approaches to determine ring current intensity. It is proven that the present model is more precise than previous models as they could not explain presence of the minimum in the plot of NICS(πzz) versus distance close to the ring plane. Variations in the charge of molecules and the types of constituent atoms of each species affect the ring current radii of both σ- and π-current loops as well as the height of π-current loops above/below the ring plane. It is suggested that variation in the distribution of the one-electron density in different systems is the main source of differences of the ring current characteristics. PMID:21598277

  7. [1,2]-Wittig Rearrangement of THP Acetal Compounds: Facile Synthesis of Aromatic Tertiary Alcohols

    Directory of Open Access Journals (Sweden)

    Feng-Lei Gu

    2011-01-01

    Full Text Available Several sec-aromatic THP acetal compounds have been found to be suitable substrates for the [1,2]-Wittig rearrangement in the absence of an external electrophile, which resulted in the generation of new carbon-carbon bond and the facile synthesis of aromatic tertiary alcohols. More interestingly, an unexpected effect of chlorotrimethylsilane on this [1,2]-Wittig rearrangement of sec-aromatic THP acetal compounds was found, in which two different products involving oxidative procedure were obtained due to the competitive [1,4]-Sigmatropic rearrangement versus [1,2]-Wittig rearrangement

  8. Application of aromatization catalyst in synthesis of carbon nanotubes

    Indian Academy of Sciences (India)

    Song Rongjun; Yang Yunpeng; Ji Qing; Li Bin

    2012-02-01

    In a typical chemical vapour deposition (CVD) process for synthesizing carbon nanotubes (CNTs), it was found that the aromatization catalysts could promote effectively the formation of CNT. The essence of this phenomenon was attributed to the fact that the aromatization catalyst can accelerate the dehydrogenation–cyclization and condensation reaction of carbon source, which belongs to a necessary step in the formation of CNTs. In this work, aromatization catalysts, H-beta zeolite, HZSM-5 zeolite and organically modified montmorillonite (OMMT) were chosen to investigate their effects on the formation of multi-walled carbon nanotubes (MWCNTs) via pyrolysis method when polypropylene and 1-hexene as carbon source and Ni2O3 as the charring catalyst. The results demonstrated that the combination of those aromatization catalysts with nickel catalyst can effectively improve the formation of MWCNTs.

  9. π-Conjugated aromatics based on truxene: synthesis, self-assembly, and applications.

    Science.gov (United States)

    Shi, Ke; Wang, Jie-Yu; Pei, Jian

    2015-02-01

    Recently, many efforts have been devoted to developing novel polycyclic aromatics due to their unique optical and electronic properties and broad applications, such as in organic field-effect transistors, organic photovoltaics, and organic light-emitting diodes. Among various π-conjugated molecules, many truxene derivatives have interesting characteristics such as C3 -symmetry, strong blue emission, and a planar rigid structure. Moreover, compared with many other π-conjugated aromatics, the synthesis and modification of truxene are particularly facile and diverse. In this account, we summarize investigations into truxene derivatives from synthesis and physical properties to applications in organic electronics.

  10. Synthesis and Characterization of Aliphatic-Aromatic Hyperbranched Polyesters

    Institute of Scientific and Technical Information of China (English)

    唐黎明; 张晓龙; 邱藤; 刘德山

    2002-01-01

    Hyperbranched polymers possess special architectures and have potential applications in various areas. In this study, two AB2 monomers, dipropyl 5-(hydroxyethoxy) isophthalate (I) and 5-hydroxyethoxyisophthaic acid (II), were prepared. By bulk polycondensation of each monomer, two aliphatic-aromatic hyperbranched polyesters were prepared and characterized by 1H-nuclear magnetic resonance (1H-NMR), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), and scanning electron microscopy (SEM). Compared with all-aromatic hyperbranched polyesters, the prepared polymers showed lower glass transition temperatures in connection with the moderate decrease in their decomposition temperatures.

  11. Natural occurrence, biological activities and synthesis of eight-, nine-, and eleven-membered ring lactones

    OpenAIRE

    Helena M. C. Ferraz; Fernanda I. Bombonato; Myrian K. Sano; Luiz S. Longo Jr.

    2008-01-01

    The natural occurrence, biological activities and synthetic approaches to natural eight-, nine-, and eleven-membered lactones is reviewed. These medium ring lactones are grouped according to ring size, and their syntheses are discussed. The structures of some natural products early identified as medium-ring lactones were revised after total synthesis.

  12. Natural occurrence, biological activities and synthesis of eight-, nine-, and eleven-membered ring lactones

    Directory of Open Access Journals (Sweden)

    Helena M. C. Ferraz

    2008-01-01

    Full Text Available The natural occurrence, biological activities and synthetic approaches to natural eight-, nine-, and eleven-membered lactones is reviewed. These medium ring lactones are grouped according to ring size, and their syntheses are discussed. The structures of some natural products early identified as medium-ring lactones were revised after total synthesis.

  13. Aromaticity of strongly bent benzene rings : persistence of a diatropic ring current and its shielding cone in [5]paracyclophane

    NARCIS (Netherlands)

    Jenneskens, Leonardus W.; Havenith, Remco W. A.; Soncini, Alessandro; Fowler, Patrick W.

    2011-01-01

    Direct evaluation of the induced pi current density in [5]paracyclophane (1) shows that, despite the significant non-planarity (alpha = 23.2 degrees) enforced by the pentamethylene bridge, there is only a modest (ca. 17%) reduction in the pi ring current, justifying the use of shielding-cone argumen

  14. Reaction of benzoxasilocines with aromatic aldehydes: Synthesis of homopterocarpans

    Directory of Open Access Journals (Sweden)

    Rodríguez-García Ignacio

    2007-02-01

    Full Text Available Abstract Condensation of 2H-benzo[g][1,2]oxasilocines with aromatic aldehydes in the presence of boron trifluoride affords mixtures of cis/trans 2-phenyl-3-vinylchromans with moderate yields. These can be transformed into homopterocarpans, a synthetic group of substances homologous to the natural isoflavonoid pterocarpans.

  15. Synthesis of Triarylmethane and Xanthene Dyes Using Electrophilic Aromatic Substitution Reactions

    Science.gov (United States)

    McCullagh, James V.; Daggett, Kelly A.

    2007-01-01

    The synthesis of dyes has long been a popular topic in organic chemistry laboratory experiments because it allows students to see first hand that reactions learned in class can be used to make compounds with useful applications. In this experiment electrophilic aromatic substitution reactions are used to synthesize several triarylmethane and…

  16. Synthesis of a Fluorescent Acridone Using a Grignard Addition, Oxidation, and Nucleophilic Aromatic Substitution Reaction Sequence

    Science.gov (United States)

    Goodrich, Samuel; Patel, Miloni; Woydziak, Zachary R.

    2015-01-01

    A three-pot synthesis oriented for an undergraduate organic chemistry laboratory was developed to construct a fluorescent acridone molecule. This laboratory experiment utilizes Grignard addition to an aldehyde, alcohol oxidation, and iterative nucleophilic aromatic substitution steps to produce the final product. Each of the intermediates and the…

  17. Synthesis of aromatic glycoconjugates. Building blocks for the construction of combinatorial glycopeptide libraries

    Directory of Open Access Journals (Sweden)

    Markus Nörrlinger

    2014-10-01

    Full Text Available New aromatic glycoconjugate building blocks based on the trifunctional 3-aminomethyl-5-aminobenzoic acid backbone and sugars linked to the backbone by a malonyl moiety were prepared via peptide coupling. The orthogonally protected glycoconjugates, bearing an acetyl-protected glycoside, were converted into their corresponding acids which are suitable building blocks for combinatorial glycopeptide synthesis.

  18. Enantioselective synthesis of the predominant AB ring system of the Schisandra nortriterpenoid natural products.

    Science.gov (United States)

    Gockel, Birgit; Goh, Shermin S; Puttock, Emma J; Baars, Hannah; Chaubet, Guilhem; Anderson, Edward A

    2014-09-01

    An enantioselective synthesis of the AB ring system common to the majority of the Schisandra nortriterpenoid natural products is reported. Key steps include a stereospecific ring opening of a trisubstituted epoxide and the use of a β-lactone to enable installation of the gem-dimethyl functionality of the B ring. An acetalization strategy played a key role in a late-stage biomimetic AB ring bicyclization.

  19. Diels-Alder addition of some 6-and 5-member ring aromatic compounds on the Si(001)-2×1 surface: dependence of the binding energy on the resonance energy of the aromatic compounds

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    An energy decomposition scheme is proposed for understanding of the relative lowbinding energy of the [4+2] cycloaddition of benzene on the Si(001)-2×1 surface. By means ofdensity functional cluster model calculations, this scheme is demonstrated to be applicable tosome other 6-and 5-member ring aromatic compounds, giving a trend that the binding energy ofthe [4+2] cycloaddition products of those aromatic compounds on the Si(001) surface dependsstrongly on their resonance energy.

  20. Green Synthesis of Benzylated Aromatics Using Iron Loaded Mesoporous Materials

    OpenAIRE

    Preethi, Muthuraj Esther Leena; Revathi, Shanmugam; Sivakumar, Thiripuranthagan

    2008-01-01

    Syntheses of benzylated aromatics like diphenylmethane and its derivatives by the condensation of benzene or toluene or o-xylene with benzylchloride or 4-methylbenzylchloride in the presence of a catalytic amount of various iron loaded mesoporous solid acid catalysts such as Fe/Al-MCM-41 (Si/Al=25), Fe/Al-MCM-41 (Si/Al=50) and Fe/Al-MCM-41 (Si/Al=100) are reported.

  1. On the Importance of the Aromatic Ring Parameter in Studies of the Solvolyses of Cinnamyl and Cinnamoyl Halides

    Directory of Open Access Journals (Sweden)

    Malcolm J. D'Souza

    2010-01-01

    Full Text Available In solvolysis studies using Grunwald-Winstein plots, dispersions were observed for substrates with aromatic rings at the α-carbon. Several examples for the unimolecular solvolysis of monoaryl benzylic derivatives and related diaryl- or naphthyl-substituted derivatives have now been reported, where the application of the aromatic ring parameter (I removes this dispersion. A recent claim suggesting the presence of an appreciable nucleophilic component to the I scale has now been shown, in a review of the solvolysis of highly-hindered alkyl halides, to be unlikely to be correct. Attention is now focused on the application of the hI term for the solvolysis of compounds containing a double bond in the vicinity of any developing carbocation. Available specific rates of solvolysis (plus some new values at 25°C of cinnamyl chloride, cinnamyl bromide, cinnamoyl chloride, p-chlorocinnamoyl chloride, and p-nitrocinnamoyl chloride are analyzed using the simple and extended (including the hI term Grunwald-Winstein equations.

  2. Functional characterization of diverse ring-hydroxylating oxygenases and induction of complex aromatic catabolic gene clusters in Sphingobium sp. PNB

    Directory of Open Access Journals (Sweden)

    Pratick Khara

    2014-01-01

    Full Text Available Sphingobium sp. PNB, like other sphingomonads, has multiple ring-hydroxylating oxygenase (RHO genes. Three different fosmid clones have been sequenced to identify the putative genes responsible for the degradation of various aromatics in this bacterial strain. Comparison of the map of the catabolic genes with that of different sphingomonads revealed a similar arrangement of gene clusters that harbors seven sets of RHO terminal components and a sole set of electron transport (ET proteins. The presence of distinctly conserved amino acid residues in ferredoxin and in silico molecular docking analyses of ferredoxin with the well characterized terminal oxygenase components indicated the structural uniqueness of the ET component in sphingomonads. The predicted substrate specificities, derived from the phylogenetic relationship of each of the RHOs, were examined based on transformation of putative substrates and their structural homologs by the recombinant strains expressing each of the oxygenases and the sole set of available ET proteins. The RHO AhdA1bA2b was functionally characterized for the first time and was found to be capable of transforming ethylbenzene, propylbenzene, cumene, p-cymene and biphenyl, in addition to a number of polycyclic aromatic hydrocarbons. Overexpression of aromatic catabolic genes in strain PNB, revealed by real-time PCR analyses, is a way forward to understand the complex regulation of degradative genes in sphingomonads.

  3. Concise synthesis of the A/BCD-ring fragment of gambieric acid A

    Science.gov (United States)

    Fuwa, Haruhiko; Fukazawa, Ryo; Sasaki, Makoto

    2014-01-01

    Gambieric acid A (GAA) and its congeners belong to the family of marine polycyclic ether natural products. Their highly complex molecular architecture and unique biological activities have been of intense interest within the synthetic community. We have previously reported the first total synthesis, stereochemical reassignment, and preliminary structure–activity relationships of GAA. Here we disclose a concise synthesis of the A/BCD-ring fragment of GAA. The synthesis started from our previously reported synthetic intermediate that represents the A/B-ring. The C-ring was synthesized via an oxiranyl anion coupling and a 6-endo cyclization, and the D-ring was forged by means of an oxidative lactonization and subsequent palladium-catalyzed functionalization of the lactone ring. In this manner, the number of linear synthetic steps required for the construction of the C- and D-rings was reduced from 22 to 11. PMID:25629027

  4. Polycyclic Aromatic Compounds as Anticancer Agents: Synthesis and Biological Evaluation of Methoxy Dibenzofluorene Derivatives

    Directory of Open Access Journals (Sweden)

    Bimal Krishna Banik

    2014-08-01

    Full Text Available Synthesis of a new methoxy dibenzofluorene through alkylation, cyclodehydration and aromatization in a one-pot operation is achieved for the first time. Using this hydrocarbon, a few derivatives are prepared through aromatic nitration, catalytic hydrogenation, coupling reaction with a side chain and reduction. The benzylic position of this hydrocarbon with the side chain is oxidized and reduced. Some of these derivatives have demonstrated excellent antitumor activities in vitro. This study confirms antitumor activity depends on the structures of the molecules.

  5. One-Pot Synthesis of Tetraphene and Construction of Expanded Conjugated Aromatics.

    Science.gov (United States)

    Wang, Jianbo; Yao, Jinzhong; Wang, Hailong; Chen, Hao; Dong, Jingcheng; Zhou, Hongwei

    2016-06-17

    Acene derivatives as a class of polycyclic aromatic hydrocarbons have attracted considerable interest because of their outstanding semiconductor properties. We developed a one-pot synthesis for fully conjugated tetraphene via a sequence of propargyl-allenyl isomerization, phosphine addition, intramolecular Wittig reactions, and Diels-Alder cyclization reactions. The derivative-conjugated aromatic compounds including carbazole or triphenylamine have been constructed via Pd-catalyzed coupling reaction with dibromotetraphene. These compounds show superior photophysical and electrochemical properties, which make them possible candidates for optoelectronic conjugated materials.

  6. SYNTHESIS OF AN EPOXY-TERMINATED HYPERBRANCHED AROMATIC POLYESTER

    Institute of Scientific and Technical Information of China (English)

    Xia Wang; W.J. Feast

    2002-01-01

    An epoxy-terminated hyperbranched aromatic polyester (P3) was synthesized from a hyperbranched aromaticpolyester containing carboxylic acid end groups (P1), which was derived from the condensation polymerization of the AB2monomer, 5-acetoxyisophthalic acid. Polymer P1 was converted into the polymeric acid chloride by reaction with thionylchloride. The acid chloride was reacted with ethanol and glycidol to form a poly(ethyl ester) (P2) and an epoxy terminatedmaterial (P3), respectively. The reaction conditions in each step of these processes had to be controlled very carefully toavoid unwanted cross-linking reactions. The characterization of products and intermediates, including molecular weightdistributions and thermal properties, are reported.

  7. Ih Symmetrical (4,6)-Fullerenes and Their Local Ring Aromaticity: A First Principle Study

    OpenAIRE

    Jing Wang; Haigang Lu; Yingfang Fan; Si-Dian Li

    2015-01-01

    As the natural extension of carbon fullerene, a series of Ih symmetrical (4,6)-fullerenes were constructed and investigated using first principle methods. These Ih (4,6)-fullerenes consist of many four- and six-membered rings and are classified into two types: (1) those with isolated four- and six-membered rings and (2) those with connected four- and/or six-membered rings. Though these (4,6)-fullerenes are less stable than Ih C60 and C240 (5,6)-fullerene, it is possible to synthesize them fro...

  8. Aromatic polyesters with photosensitive side chains: Synthesis, characterization and properties

    Directory of Open Access Journals (Sweden)

    Nechifor Marioara

    2016-01-01

    Full Text Available New aromatic polyesters with photosensitive groups in their pendant chains were prepared from a diphenol carrying as substituent a cinnamoyl group extended with a flexible oxyethyleneoxy spacer and different aromatic dicarboxylic acids via direct polyesterification reaction in the presence of tosyl chloride/pyridine/dimethylformamide system as condensing agent. The resulting polyesters were characterized using Fourier-transform IR, proton and carbon nuclear magnetic resonance and ultraviolet spectroscopy, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffractometry, gel permeation chromatography, viscosity measurement and solubility test. These polyarylates had moderate inherent viscosities ranging from 0.37 to 0.54 dL g-1, good solubility in polar aprotic solvents, and afforded transparent, colorless and apparently tough films by casting from their solutions. Their glass-transition temperatures ranged from 136 to 154°C. All of them did not show significant decomposition below 320°C and retained 38-47 % weight at 700°C in nitrogen atmosphere. The presence of cinnamoyl chromophore endowed these polymers with the ability to react to ultraviolet light which resulted in photodimerization between cinnamoyl side groups upon irradiation at l = 365 nm and cross-linking the polymers chains in the absence of photo-initiators or photo-sensitizers. As a consequence, the polymer films became insoluble in organic solvents.

  9. Effect of aromatic ring fluorination on CHπ interactions: microwave spectrum and structure of the 1,2-difluorobenzeneacetylene dimer.

    Science.gov (United States)

    Akmeemana, Anuradha G; Kang, Justin M; Dorris, Rachel E; Nelson, Rebecca D; Anderton, Ashley M; Peebles, Rebecca A; Peebles, Sean A; Seifert, Nathan A; Pate, Brooks H

    2016-09-21

    Rotational spectra for the normal isotopic species and for six additional isotopologues of the 1,2-difluorobenzeneacetylene (C6H4F2HCCH) weakly bound dimer have been assigned in the 6-18 GHz region using chirped-pulse Fourier-transform microwave spectroscopy. This is the third complex in a series of fluorinated benzeneacetylene dimers. In 1,2-difluorobenzeneHCCH, the Hπ distance (2.725(28) Å) is longer by about 0.23 Å, and the estimated binding energy (EB = 2.3(6) kJ mol(-1)) is weaker by about 1.8 kJ mol(-1), than in the previously studied fluorobenzeneHCCH complex. In addition, in 1,2-difluorobenzeneacetylene, HCCH tips ∼46(3)° away from perpendicular to the aromatic ring, with the H nearest the ring moving away from the fluorine atoms along the C2 axis of the monomer, while in the fluorobenzene and benzene complexes HCCH is perpendicular (benzeneHCCH) or nearly perpendicular (fluorobenzeneHCCH, ∼7° tilt) to the ring plane. Results from ab initio and DFT calculations will be compared to an experimental structure determined from rotational constants for the DCCD and five unique (13)C substituted isotopologues. PMID:27530245

  10. Evidence for transport intermediates in aromatic amino acid synthesis of non-green tissues

    International Nuclear Information System (INIS)

    Quinate (QA) is the predominant pre-aromatic compound formed at high rates in leaves of many plants at the early vegetation stage and transported through the phloem. The transfer of 3-dehydroquinate, 3-dehydroshikimate and (SkA) across the plastidial membranes has been evidenced. The question was whether the rate of QA uptake is comparable to that of the 3 SkA-pathway intermediates. To demonstrate this, /U-14C/QA and /U-14C/SkA were applied to Brassica rapa roots. Both compounds were uptaken at considerable rates and incorporated into aromatic amino acids (Phe + Tyr + Trp formation, in nmol/g fresh wt x h: applying 145 μmol QA: 21.2; applying 156 μmol Ska: 31.8). Thus, QA is a possible candidate for transport into non-green tissues for aromatic amino acid synthesis

  11. Evidence for transport intermediates in aromatic amino acid synthesis of non-green tissues

    Energy Technology Data Exchange (ETDEWEB)

    Leuschner, C.; Schultz, G. (Botanisches Institut, Hannover (West Germany))

    1990-05-01

    Quinate (QA) is the predominant pre-aromatic compound formed at high rates in leaves of many plants at the early vegetation stage and transported through the phloem. The transfer of 3-dehydroquinate, 3-dehydroshikimate and (SkA) across the plastidial membranes has been evidenced. The question was whether the rate of QA uptake is comparable to that of the 3 SkA-pathway intermediates. To demonstrate this, /U-{sup 14}C/QA and /U-{sup 14}C/SkA were applied to Brassica rapa roots. Both compounds were uptaken at considerable rates and incorporated into aromatic amino acids (Phe + Tyr + Trp formation, in nmol/g fresh wt x h: applying 145 {mu}mol QA: 21.2; applying 156 {mu}mol Ska: 31.8). Thus, QA is a possible candidate for transport into non-green tissues for aromatic amino acid synthesis.

  12. Exploring mild enzymatic sustainable routes for the synthesis of bio-degradable aromatic-aliphatic oligoesters.

    Science.gov (United States)

    Pellis, Alessandro; Guarneri, Alice; Brandauer, Martin; Acero, Enrique Herrero; Peerlings, Henricus; Gardossi, Lucia; Guebitz, Georg M

    2016-05-01

    The application of Candida antarctica lipase B in enzyme-catalyzed synthesis of aromatic-aliphatic oligoesters is here reported. The aim of the present study is to systematically investigate the most favorable conditions for the enzyme catalyzed synthesis of aromatic-aliphatic oligomers using commercially available monomers. Reaction conditions and enzyme selectivity for polymerization of various commercially available monomers were considered using different inactivated/activated aromatic monomers combined with linear polyols ranging from C2 to C12 . The effect of various reaction solvents in enzymatic polymerization was assessed and toluene allowed to achieve the highest conversions for the reaction of dimethyl isophthalate with 1,4-butanediol and with 1,10-decanediol (88 and 87% monomer conversion respectively). Mw as high as 1512 Da was obtained from the reaction of dimethyl isophthalate with 1,10-decanediol. The obtained oligomers have potential applications as raw materials in personal and home care formulations, for the production of aliphatic-aromatic block co-polymers or can be further functionalized with various moieties for a subsequent photo- or radical polymerization. PMID:26762794

  13. Exploring mild enzymatic sustainable routes for the synthesis of bio-degradable aromatic-aliphatic oligoesters.

    Science.gov (United States)

    Pellis, Alessandro; Guarneri, Alice; Brandauer, Martin; Acero, Enrique Herrero; Peerlings, Henricus; Gardossi, Lucia; Guebitz, Georg M

    2016-05-01

    The application of Candida antarctica lipase B in enzyme-catalyzed synthesis of aromatic-aliphatic oligoesters is here reported. The aim of the present study is to systematically investigate the most favorable conditions for the enzyme catalyzed synthesis of aromatic-aliphatic oligomers using commercially available monomers. Reaction conditions and enzyme selectivity for polymerization of various commercially available monomers were considered using different inactivated/activated aromatic monomers combined with linear polyols ranging from C2 to C12 . The effect of various reaction solvents in enzymatic polymerization was assessed and toluene allowed to achieve the highest conversions for the reaction of dimethyl isophthalate with 1,4-butanediol and with 1,10-decanediol (88 and 87% monomer conversion respectively). Mw as high as 1512 Da was obtained from the reaction of dimethyl isophthalate with 1,10-decanediol. The obtained oligomers have potential applications as raw materials in personal and home care formulations, for the production of aliphatic-aromatic block co-polymers or can be further functionalized with various moieties for a subsequent photo- or radical polymerization.

  14. Sandwich Complexes of the As42-Aromatic Ring with Some Transition Metals

    Institute of Scientific and Technical Information of China (English)

    LI Zhi-Wei; ZHAO Cun-Yuan; WU Wen-Sheng; CHEN Liu-Ping

    2008-01-01

    The equilibrium geometries, energies, harmonic vibrational frequencies, and nuc- leus independent chemical shifts (NICS) of the new type sandwich structures [As4MAs4]n- (M = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt; n = 0, 1 or 2) are investigated at the B3LYP level.All the [As4MAs4]n- species adopt staggered (D4d) conformations as their stable structures and eclipsed (D4h) conformations as their transition states, and once the sandwich complexes are formed, the As42- square properties remain unchanged.The NICS calculation confirms that the complexes of Fe, Co, and Ni are aromatic with negative NICS values, and those of Ru, Rh, and Ir exhibit slight aromaticity, while those of Pd, Os, and Pt show slight antiaromaticity.

  15. Synthesis of alkenyl boronates from allyl-substituted aromatics using an olefin cross-metathesis protocol.

    Science.gov (United States)

    Hemelaere, Rémy; Carreaux, François; Carboni, Bertrand

    2013-07-01

    An efficient synthesis of 3-aryl-1-propenyl boronates from pinacol vinyl boronic ester and allyl-substituted aromatics by cross metathesis is reported. Although the allylbenzene derivatives are prone to isomerization reaction under metathesis conditions, we found that some ruthenium catalysts are effective for this methodology. This strategy thus provides an interesting alternative approach to alkyne hydroboration, leading to the preparation of unknown compounds. Moreover, the boron substituent can be replaced by various functional groups in good yields.

  16. Synthesis, Characterization, and Pharmacological Evaluation of Selected Aromatic Amines

    Directory of Open Access Journals (Sweden)

    Hammad Ismail

    2015-01-01

    Full Text Available Aromatic amines 1-amino-4-phenoxybenzene (A-1A, 2-(4-aminophenoxy naphthalene (A-2A, and 1-(4-aminophenoxy naphthalene (A-3A were synthesized by the reduction of corresponding nitroaromatics with hydrazine monohydrate and Pd/C 5% (w/w. The newly synthesized compounds were characterized by FTIR, 1H NMR, 13C NMR, UV-visible spectrophotometer, and mass spectrometry and their biological activities were investigated along with structurally similar 4-(4-aminophenyloxy biphenyl (A-A. Results of brine shrimp cytotoxicity assay showed that almost all of the compounds had LD50 values <1 μg/mL. The compounds also showed significant antitumor activity with IC50 values ranging from 67.45 to 12.2 µgmL−1. The cytotoxicity and antitumor studies correlate the results which suggests the anticancerous nature of compounds. During the interaction study of these compounds with DNA, all of the compounds showed hyperchromic effect indicating strong interaction through binding with the grooves of DNA. Moreover, A-3A also showed decrease in λmax confirming higher propensity for DNA groove binding. In DPPH free radical scavenging assay, all the compounds showed potential antioxidant capability. The compounds were highly active in protecting DNA against hydroxyl free radicals. DNA interaction and antioxidant results back up each other indicating that these compounds have potential to be used as cancer chemopreventive agents. Additionally, one compound (A-1A showed significant antibacterial and antifungal activity as well.

  17. SYNTHESIS AND CHARACTERIZATION OF HIGHLY SOLUBLE AROMATIC POLYIMIDES

    Institute of Scientific and Technical Information of China (English)

    Xiao-hua Huang; Wei Huang; Yong-feng Zhou; De-yue Yan

    2011-01-01

    Two highly soluble aromatic polyimides were synthesized successfully from a diamine with two tert-butyl groups (MBTBA) and dianhydrides with a thioether or sulfone moiety (DTDA and DSDA). Both of them showed excellent solubility in common solvents such as chloroform, tetrahydrofuran and dioxane at the room temperature. The numberaverage molecular weight was 6.0 × 104 and 8.3 × 104 according to gel permeation chromatography relative to a polystyrene standard, and the polydispersity index was 1.80 and 1.82 respectively. The glass-transition temperatures of them were 286℃and 314℃ (or 315℃ and 358℃) respectively, as measured by differential scanning calorimetry (or dynamic mechanical analysis). The 5% weight loss temperature of both was near 490℃ in N2 by thermogravimetric analysis. These results indicated that the tert-butyl pendent groups reduced the interactions among polymer chains and the thioether or sulfone moiety was flexible which may improve their solubility in conventional organic solvents without the loss of thermal stability.Transparent and flexible films of the two polyimides were obtained via solution casting. The MBTBA-DTDA membrane had higher storage moduli than those of the MBTBA-DSDA membrane.

  18. Advance in the synthesis of aromatic amine via direct amination

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Arylamines are very common and important organic molecules. Acting as important intermediates in medical and chemical industry, they are widely used in the synthesis of pharmaceuticals, dyes, pesticides, rubber additives, isocyanates and heterocyclic compounds. The traditional methods for the synthesis of arylamines include several steps. The production of aniline, for example, includes the following steps: the production of nitro-benzene by the nitration of benzene, and the reduction of the resulting nitro-benzene by catalytic hydrogenation or other reduction ways[1-6]; or the substitution of phenol or chlorbenzene by amino groups, etc.[7-10]. There are several disadvantages for these methods: low atom utilization, strict operation condition, large amount of by-products and serious environmental pollution, which could not afford for the needs of a sustainable civilization. So there has been growing interest in the direct amination to produce arylamines recently. With the direct methods, the multi- step reaction may change into one step, the atom utilization can be evidently improved, and the by-products H2 or/and H2O are harmless to the environment.

  19. Recent applications of ring-rearrangement metathesis in organic synthesis.

    Science.gov (United States)

    Kotha, Sambasivarao; Meshram, Milind; Khedkar, Priti; Banerjee, Shaibal; Deodhar, Deepak

    2015-01-01

    Ring-rearrangement metathesis (RRM) involves multiple metathesis processes such as ring-opening metathesis (ROM)/ring-closing metathesis (RCM) in a one-pot operation to generate complex targets. RRM delivers complex frameworks that are difficult to assemble by conventional methods. The noteworthy point about this type of protocol is multi-bond formation and it is an atom economic process. In this review, we have covered literature that appeared during the last seven years (2008-2014). PMID:26664603

  20. Recent applications of ring-rearrangement metathesis in organic synthesis

    Directory of Open Access Journals (Sweden)

    Sambasivarao Kotha

    2015-10-01

    Full Text Available Ring-rearrangement metathesis (RRM involves multiple metathesis processes such as ring-opening metathesis (ROM/ring-closing metathesis (RCM in a one-pot operation to generate complex targets. RRM delivers complex frameworks that are difficult to assemble by conventional methods. The noteworthy point about this type of protocol is multi-bond formation and it is an atom economic process. In this review, we have covered literature that appeared during the last seven years (2008–2014.

  1. Efficient oxidative dechlorination and aromatic ring cleavage of chlorinated phenols catalyzed by iron sulfophthalocyanine

    Energy Technology Data Exchange (ETDEWEB)

    Sorokin, A.; Meunier, B. [Laboratoire de Chimie de Coordination du CNRS, Toulouse (France); Seris, J.L. [Elf-Aquitaine, Artix (France)

    1995-05-26

    An efficient method has been developed for the catalytic oxidation of pollutants that are not easily degraded. The products of the hydrogen peroxide (H{sub 2}O{sub 2}) oxidation of 2,4,6-trichlorophenol (TCP) catalyzed by the iron complex 2,9,16,23-tetrasulfophthalocyanine (FePcS) were observed to be chloromaleic, chlorofumaric, maleic, and fumaric acids from dechlorination and aromatic cycle cleavage, as well as additional products that resulted from oxidative coupling. Quantitative analysis of the TCP oxidation reaction revealed that up to two chloride ions were released per TCP molecule. This chemical system, consisting of an environmentally safe oxidant (H{sub 2}O{sub 2}) and an easily accessible catalyst (FePcS), can perform several key steps in the oxidative mineralization of TCP, a paradigm of recalcitrant pollutants. 20 refs., 4 figs., 2 tabs.

  2. Improved Size-Tunable Synthesis of Monodisperse Gold Nanorods through the Use of Aromatic Additives

    Energy Technology Data Exchange (ETDEWEB)

    Ye, XC; Jin, LH; Caglayan, H; Chen, J; Xing, GZ; Zheng, C; Doan-Nguyen, V; Kang, YJ; Engheta, N; Kagan, CR; Murray, CB

    2012-03-01

    We report an improved synthesis of colloidal gold nanorods (NRs) by using aromatic additives that reduce the concentration of hexadecyltrimethylammonium bromide surfactant to similar to 0.05 M as opposed to 0.1 M in well-established protocols. The method optimizes the synthesis for each of the 11 additives studied, allowing a rich array of monodisperse gold NRs with longitudinal surface plasmon resonance tunable from 627 to 1246 nm to be generated. The gold NRs form large-area ordered assemblies upon slow evaporation of NR solution, exhibiting liquid crystalline ordering and several distinct local packing motifs that are dependent upon the NR's aspect ratio. Tailored synthesis of gold NRs with simultaneous improvements in monodispersity and dimensional tunability through rational introduction of additives will not only help to better understand the mechanism of seed-mediated growth of gold NRs but also advance the research on plasmonic metamaterials incorporating anisotropic metal nanostructures.

  3. Efficient synthesis of enantiopure conduritols by ring-closing metathesis

    DEFF Research Database (Denmark)

    Jørgensen, Morten; Iversen, Erik Høgh; Paulsen, Andreas Lundtang;

    2001-01-01

    Two short synthetic approaches to enantiopure conduritols are described starting from the chiral pool. In both cases, the cyclohexene ring is assembled via ring-closing olefin metathesis. The terminal diene precursers for the metathesis reaction are prepared either from octitols or from tartaric...

  4. Synthesis and accumulation of aromatic aldehydes in an engineered strain of Escherichia coli.

    Science.gov (United States)

    Kunjapur, Aditya M; Tarasova, Yekaterina; Prather, Kristala L J

    2014-08-20

    Aromatic aldehydes are useful in numerous applications, especially as flavors, fragrances, and pharmaceutical precursors. However, microbial synthesis of aldehydes is hindered by rapid, endogenous, and redundant conversion of aldehydes to their corresponding alcohols. We report the construction of an Escherichia coli K-12 MG1655 strain with reduced aromatic aldehyde reduction (RARE) that serves as a platform for aromatic aldehyde biosynthesis. Six genes with reported activity on the model substrate benzaldehyde were rationally targeted for deletion: three genes that encode aldo-keto reductases and three genes that encode alcohol dehydrogenases. Upon expression of a recombinant carboxylic acid reductase in the RARE strain and addition of benzoate during growth, benzaldehyde remained in the culture after 24 h, with less than 12% conversion of benzaldehyde to benzyl alcohol. Although individual overexpression results demonstrated that all six genes could contribute to benzaldehyde reduction in vivo, additional experiments featuring subset deletion strains revealed that two of the gene deletions were dispensable under the conditions tested. The engineered strain was next investigated for the production of vanillin from vanillate and succeeded in preventing formation of the byproduct vanillyl alcohol. A pathway for the biosynthesis of vanillin directly from glucose was introduced and resulted in a 55-fold improvement in vanillin titer when using the RARE strain versus the wild-type strain. Finally, synthesis of the chiral pharmaceutical intermediate L-phenylacetylcarbinol (L-PAC) was demonstrated from benzaldehyde and glucose upon expression of a recombinant mutant pyruvate decarboxylase in the RARE strain. Beyond allowing accumulation of aromatic aldehydes as end products in E. coli, the RARE strain expands the classes of chemicals that can be produced microbially via aldehyde intermediates. PMID:25076127

  5. A Porous Aromatic Framework Constructed from Benzene Rings Has a High Adsorption Capacity for Perfluorooctane Sulfonate

    Science.gov (United States)

    Luo, Qin; Zhao, Changwei; Liu, Guixia; Ren, Hao

    2016-02-01

    A low-cost and easily constructed porous aromatic framework (PAF-45) was successfully prepared using the Scholl reaction. PAF-45 was, for the first time, used to remove perfluorooctane sulfonate (PFOS) from aqueous solution. Systematic experiments were performed to determine the adsorption capacity of PAF-45 for PFOS and to characterize the kinetics of the adsorption process. The adsorption of PFOS onto PAF-45 reached equilibrium in 30 min, and the adsorption capacity of PAF-45 for PFOS was excellent (5847 mg g-1 at pH 3). The amount of PFOS adsorbed by PAF-45 increased significantly as the cation (Na+, Mg2+, or Fe3+) concentration increased, which probably occurred because the cations enhanced the interactions between the negatively charged PFOS molecules and the positively charged PAF-45 surface. The cations Na+, Mg2+, and Fe3+ were found to form complexes with PFOS anions in solution. Density functional theory was used to identify the interactions between PFOS and Na+, Mg2+, and Fe3+. We expect that materials of the same type as PAF-45 could be useful adsorbents for removing organic pollutants from industrial wastewater and contaminated surface water.

  6. A short designed semi-aromatic organic nanotube – synthesis, chiroptical characterization, and host properties

    DEFF Research Database (Denmark)

    Wixe, Torbjörn; Christensen, Niels Johan; Lidin, Sven;

    2014-01-01

    The first generation of an organic nanotube based on the enantiomerically pure bicyclo[3.3.1]nonane framework is presented. The helical tube synthesised is the longest to date having its aromatic systems oriented parallel to the axis of propagation (length 26 Å and inner diameter 11 Å according...... to molecular dynamics simulations in chloroform). The synthesis of the tube, a heptamer, is based on a series of Friedländer condensations and the use of pyrido[3,2-d]pyrimidine units as masked 2-amino aldehydes, as a general means to propagate organic tubular structures and the introduction of a methoxy group...

  7. Synthesis and Evaluation of Novel Aromatic Substrates and Competitive Inhibitors of GABA Aminotransferase

    OpenAIRE

    Clift, Michael D.; Silverman, Richard B.

    2007-01-01

    The design, synthesis, and evaluation of novel γ-aminobutyric acid aminotransferase (GABA-AT) inhibitors and inactivators can lead to the discovery of new GABA-related therapeutics. To this end, a series of aromatic amino acid compounds was synthesized to aid in the design of new inhibitors and inactivators of GABA-AT. All compounds were tested as competitive inhibitors of GABA-AT. The amino acids with benzylic amines were also tested as substrates for GABA-AT. It was found that these compoun...

  8. Unravelling airborne polycyclic aromatic hydrocarbons (PAHs in southern China using tree-rings of 100-yr old Pinus Kwangtungensis

    Directory of Open Access Journals (Sweden)

    L. B. Huang

    2011-10-01

    Full Text Available Reliable perennial biomonitoring of airborne polycyclic aromatic hydrocarbons (PAHs is urgently necessary to detect long-term impacts of anthropogenic emission, in response to industrial policies and combustion technology adoption. One hundred records of airborne PAHs were novelly demonstrated by analyzing the tree-rings of Kwangtung pine (Pinus kwangtungensis formed from 1883 to 2007 at Naling Mountains of southern China. The total concentrations of PAHs (∑PAHs detected in the tree xylem did not progressively increase against the time. Temporal increase of high molecular-weight PAHs (HMW-PAHs coincided well to the historical-socioeconomic status in China, suggesting HMW-PAHs in old trees growing at high mountains were more indicative of regionally historical changes in airborne PAHs compared with ∑PAHs. Compositional analysis indicated airborne PAHs absorbed and accumulated in tree tissues were pyrogenic origination. Principal component analysis revealed PAHs inputs were quite historically diversiform and unevenly distributed in the atmosphere of Nanling Mountains of southern China. Dendroanalysis of old trees grown at geographically sink locations could be a useful biomonitoring technique for unravelling historical changes in PAHs composition and intensity in the atmosphere, in relation to regional industrial development and fuel consumptions.

  9. Ring Walking/Oxidative Addition Reactions for the Controlled Synthesis of Conjugated Polymers

    Energy Technology Data Exchange (ETDEWEB)

    Bazan, Guillermo C

    2012-04-03

    Power conversion efficiencies of plastic solar cells depend strongly on the molecular weight characteristics of the semiconducting polymers used for their fabrication. The synthesis of these materials typically relies on transition metal mediated catalytic reactions. In many instances, the ideal structures cannot be attained because of deficiencies in these reactions, particularly when it comes to being able to achieve high number average molecular weights and narrow molecular weight distributions. Another important conjugated polymer structure of interest is one in which a single functional group is attached at the end group of the chain. Such systems would be ideal for modifying surface properties at interfaces and for labeling biomolecular probes used in fluorescent biosensors. To respond to the challenges above, our efforts have centered on the design of homogenous transition metal complexes that are easy to prepare and effective in carrying out living, or quasi-living, condensative chain polymerization reactions. The key mechanistic challenge for the success of this reaction is to force the insertion of one monomer unit at a time via a process that involves migration of the transition metal-containing fragment to one terminus of the polymer chain. Chain growth characteristics are therefore favored when the metal does not dissociate from the newly formed reductive elimination product. We have proposed that dissociation is disfavored by the formation of a -complex, in which the metal can sample various locations of the electronically delocalized framework, a process that we term ring-walking , and find the functionality where oxidative addition takes place. Success has been achieved in the nickel-mediated cross coupling reaction of Grignard reagents with aromatic halides by using bromo[1,2-bis(diphenylphosphino)ethane]phenylnickel. This reagent can yield poly(thiophene)s (one of the most widely used type of polymer in plastic solar cells) with excellent

  10. Nano-rings with a handle – Synthesis of substituted cycloparaphenylenes

    Directory of Open Access Journals (Sweden)

    Anne-Florence Tran-Van

    2014-08-01

    Full Text Available The research of cycloparaphenylenes (CPPs, the smallest armchair carbon nanotube, has been a quest for the past decades which experienced a revival in 2008 when the first synthesis was achieved. Since then CPPs with various ring sizes have been realized. The incorporation of substituents and the synthesis of CPPs with building blocks different from phenyl rings bear challenges of their own. Such structures, however, are highly interesting, as they allow for an incorporation of CPPs as defined nano-objects for other applications. Therefore, this review provides a status report about the current efforts in synthesizing CPPs beyond the parent unsubstituted oligo-phenylene structure.

  11. (Thio)urea-mediated synthesis of functionalized six-membered rings with multiple chiral centers

    Science.gov (United States)

    Koutoulogenis, Giorgos; Kaplaneris, Nikolaos

    2016-01-01

    Summary Organocatalysis, now running its second decade of life, is being considered one of the main tools a synthetic chemist has to perform asymmetric catalysis. In this review the synthesis of six-membered rings, that contain multiple chiral centers, either by a ring closing process or by a functionalization reaction on an already existing six-membered ring, utilizing bifunctional (thio)ureas will be summarized. Initially, the use of primary amine-thioureas as organocatalysts for the above transformation is being discussed, followed by the examples employing secondary amine-thioureas. Finally, the use of tertiary amine-thioureas and miscellaneous examples are presented. PMID:27340441

  12. Copper Causes Regiospecific Formation of C4F8-Containing Six-Membered Rings and their Defluorination/Aromatization to C4F4-Containing Rings in Triphenylene/1,4-C4F8I2 Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Rippy, Kerry C.; Bukovsky, Eric V.; Clikeman, Tyler T.; Chen, Yu-Sheng; Hou, Gao-Lei; Wang, Xue B.; Popov, Alexey; Boltalina, Olga V.; Strauss, Steven H.

    2016-01-18

    The presence of Cu in reactions of triphenylene (TRPH) and 1,4-C4F8I2 at 360 °C led to regiospecific substitution of TRPH ortho C(β) atoms to form C4F8-containing rings, completely suppressing substitution on C(α) atoms. In addition, Cu caused selective reductive-defluorination/aromatization (RD/A) to form C4F4- containing aromatic rings. Without Cu, the reactions of TRPH and 1,4- C4F8I2 were not regiospecific and no RD/A was observed. These results, supported by DFT calculations, are the first examples of Cupromoted (i) regiospecific perfluoroannulation, (ii) preparative C–F activation, and (iii) RD/A. HPLC-purified products were characterized by X-ray diffraction, low-temperature PES, and 1H/19F NMR.

  13. Secondary Structures in a Freeze-Dried Lignite Humic Acid Fraction Caused by Hydrogen-Bonding of Acidic Protons with Aromatic Rings.

    Science.gov (United States)

    Cao, Xiaoyan; Drosos, Marios; Leenheer, Jerry A; Mao, Jingdong

    2016-02-16

    A lignite humic acid (HA) was separated from inorganic and non-HA impurities (i.e., aluminosilicates, metals) and fractionated by a combination of dialysis and XAD-8 resin. Fractionation revealed a more homogeneous structure of lignite HA. New and more specific structural information on the main lignite HA fraction is obtained by solid-state nuclear magnetic resonance (NMR) spectroscopy. Quantitative (13)C multiple cross-polarization (multiCP) NMR indicated oxidized phenyl propane structures derived from lignin. MultiCP experiments, conducted on potassium HA salts titrated to pH 10 and pH 12, revealed shifts consistent with carboxylate and phenolate formation, but structural changes associated with enolate formation from aromatic beta keto acids were not detected. Two-dimensional (1)H-(13)C heteronuclear correlation (2D HETCOR) NMR indicated aryl-aliphatic ketones, aliphatic and aromatic carboxyl groups, phenol, and methoxy phenyl ethers. Acidic protons from carboxyl groups in both the lignite HA fraction and a synthetic HA-like polycondensate were found to be hydrogen-bonded with electron-rich aromatic rings. Our results coupled with published infrared spectra provide evidence for the preferential hydrogen bonding of acidic hydrogens with electron-rich aromatic rings rather than adjacent carbonyl groups. These hydrogen-bonding interactions likely result from stereochemical arrangements in primary structures and folding.

  14. Synthesis of ring-13C-labelled and ring-demethylated retinals

    International Nuclear Information System (INIS)

    Efficient synthetic schemes are described for the preparation of the required mono- and di-13C labelled retinals based on simple 13C labelled starting materials. Results from solid-state 13C-NMR spectroscopic studies of the various ring-13C labelled bacteriorhodopsins and rhodopsins are discussed. 404 refs.; 74 figs.; 16 tabs

  15. Synthetic studies on maitotoxin. 1. Stereoselective synthesis of the C'D'E'F'-ring system having a side chain.

    Science.gov (United States)

    Morita, Masayuki; Ishiyama, Seishi; Koshino, Hiroyuki; Nakata, Tadashi

    2008-05-01

    The stereoselective synthesis of the maitotoxin C'D'E'F'-ring system having a side chain has been accomplished through a convergent strategy. The key reactions include Horner-Wadsworth-Emmons coupling of the C'D'E'-ring and the side chain and subsequent construction of the F'-ring by silane reduction of dihydropyran.

  16. Synthesis of Gabosine A and N from Ribose by the Use of Ring-Closing Metathesis

    DEFF Research Database (Denmark)

    Monrad, Rune Nygaard; Fanefjord, Mette; Hansen, Flemming Gundorph;

    2009-01-01

    -methylallyl bromide. The functionalized octa-1,7-diene, thus obtained, is converted into the six-membered gabosine skeleton by ring-closing olefin metathesis. Subsequent protective group manipulations and oxidation gives rise to gabosine N in a total of 8 steps from ribose while the synthesis of gabosine...

  17. Synthesis and Structure of 1D Na6 Cluster Chain with Short Na-Na Distance: Organic like Aromaticity in Inorganic Metal Cluster

    CERN Document Server

    Khatua, S; Chattaraj, P K; Roy, D R; Bhattacharjee*, Manish; Chattaraj*, Pratim K.; Khatua, Snehadrinarayan; Roy, Debesh R.

    2006-01-01

    A unique 1D chain of sodium cluster containing (Na6) rings stabilized by a molybdenum containing metalloligand has been synthesized and characterized. DFT calculations show striking resemblance in their aromatic behaviour with the corresponding hydrocarbon analogues

  18. Selective synthesis of Rh5 carbonyl clusters within a polyamine dendrimer for chemoselective reduction of nitro aromatics.

    Science.gov (United States)

    Maeno, Zen; Mitsudome, Takato; Mizugaki, Tomoo; Jitsukawa, Koichiro; Kaneda, Kiyotomi

    2014-06-21

    The selective synthesis of the [Rh5(CO)15](-) cluster within the PPI dendrimer was successfully demonstrated. The dendrimer-encapsulated [Rh5(CO)15](-) was resistant to decomposition under the catalytic reaction conditions and exhibited extremely high selectivity for the chemoselective reduction of nitro groups of various nitro aromatics with other reducible groups using CO/H2O as a reductant.

  19. Controlled synthesis of monodisperse gold nanorods with different aspect ratios in the presence of aromatic additives

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yun; Wang, Feihu [Shanghai Jiao Tong University, School of Pharmacy (China); Guo, Yuan [University of Leeds, School of Chemistry and Astbury Centre for Structural Molecular Biology (United Kingdom); Chen, Rongjun, E-mail: rongjun.chen@imperial.ac.uk [Imperial College London, Department of Chemical Engineering (United Kingdom); Shen, Yuanyuan; Guo, Aijie; Liu, Jieying; Zhang, Xiao [Shanghai Jiao Tong University, School of Pharmacy (China); Zhou, Dejian, E-mail: d.zhou@leeds.ac.uk [University of Leeds, School of Chemistry and Astbury Centre for Structural Molecular Biology (United Kingdom); Guo, Shengrong, E-mail: srguo@sjtu.edu.cn [Shanghai Jiao Tong University, School of Pharmacy (China)

    2014-12-15

    This paper reports the synthesis of monodisperse gold nanorods (GNRs) via a simple seeded growth approach in the presence of different aromatic additives, such as 7-bromo-3-hydroxy-2-naphthoic acid (7-BrHNA), 3-hydroxy-2-naphthoic acid (HNA), 5-bromosalicylic acid (5-BrSA), salicylic acid (SA), or phenol (PhOH). Effects of the aromatic additives and hydrochloric acid (HCl) on the structure and optical properties of the synthesized GNRs were investigated. The longitudinal surface plasmon resonance (LSPR) peak wavelength of the resulting GNRs was found to be dependent on the aromatic additive in the following sequence: 5-BrSA (778 nm) > 7-BrHNA (706 nm) > SA (688 nm) > HNA (676 nm) > PhOH (638 nm) without the addition of HCl, but this was changed to 7-BrHNA (920 nm) > SA (890 nm) > HNA (872 nm) > PhOH (858 nm) > 5-BrSA (816 nm) or 7-BrHNA (1,005 nm) > PhOH (995 nm) > SA (990 nm) > HNA (980 nm) > 5-BrSA (815 nm) with the addition of HCl or HNO{sub 3}, respectively. The LSPR peak wavelength was increased with the increasing concentration of 7-BrHNA without HCl addition; however, there was a maximum LSPR peak wavelength when HCl was added. Interestingly, the LSPR peak wavelength was also increased with the amount of HCl added. The results presented here thus established a simple approach to synthesize monodisperse GNRs of different LSPR wavelengths.

  20. Synthesis and stereochemistry of 6-membered ring phosphonates

    Directory of Open Access Journals (Sweden)

    Michael D. Pungente

    2012-03-01

    Full Text Available Background: Organophosphorus compounds have important industrial and biomedical applications as pharmaceutical and agrochemical agents, as well as transition state analogs for the production of monoclonal antibodies. Methods: Two diastereomers of a 6-membered ring, cyclic phenyl phosphonate were synthesized in 8 steps from 1,3-butanediol. Results: The stereochemistry of the diastereomers was elucidated on the basis of H NMR nuclear Overhauser effects (NOE difference experiments. Conclusions: Such cyclic phosphonates may have utility serving as transition state analogs for the production of monoclonal antibodies.

  1. Synthesis of 4-Methylene-2-cyclohexenones and Their Aromatization Reaction toward para-Methoxylmethyl Anisole Derivatives

    International Nuclear Information System (INIS)

    We and other groups have reported the selective introduction of nucleophiles at the secondary benzylic position of the Baylis-Hillman acetates via the corresponding DABCO salts. Thus, we envisioned that we could prepare 4-methylene- 2-cyclohexenone skeleton and para-methoxymethyl anisoles by combining the DABCO salt concept and the aromatization reaction with iodine in methanol. Suitably substituted anisoles are useful as the starting materials for the fragrances, dyes and pesticides, as antioxidants in oils and fats, or as stabilizers of plastics. Moreover, paramethoxymethyl anisoles have been used for the kinetic acetalization of diol or amino alcohol systems in the presence of DDQ5 during the synthesis of (+)-FR900482, taxotere side chain,5c cyclopropyl lactone oxylipins, and erythromycin A.

  2. Synthesis of the ABCDEFG ring system of maitotoxin.

    Science.gov (United States)

    Nicolaou, K C; Aversa, Robert J; Jin, Jian; Rivas, Fatima

    2010-05-19

    Maitotoxin (1) continues to fascinate scientists not only because of its size and potent neurotoxicity but also due to its molecular architecture. To provide further support for its structure and facilitate fragment-based biological studies, we developed an efficient chemical synthesis of the ABCDEFG segment 3 of maitotoxin. (13)C NMR chemical shift comparisons of synthetic 3 with the corresponding values for the same carbons of maitotoxin revealed a close match, providing compelling evidence for the correctness of the originally assigned structure to this polycyclic system of the natural product. The synthetic strategy for the synthesis of 3 relied heavily on our previously developed furan-based technology involving sequential Noyori asymmetric reduction and Achmatowicz rearrangement for the construction of the required tetrahydropyran building blocks, and employed a B-alkyl Suzuki coupling and a Horner-Wadsworth-Emmons olefination to accomplish their assembly and elaboration to the final target molecule. PMID:20415445

  3. Synthesis and non-covalent functionalization of carbon nanotubes rings: new nanomaterials with lectin affinity

    Science.gov (United States)

    Assali, Mohyeddin; Pernía Leal, Manuel; Fernández, Inmaculada; Khiar, Noureddine

    2013-03-01

    We present a mild and practical carbon nanotubes rings (CNRs) synthesis from non-covalent functionalized and water-soluble linear single-wall carbon nanotubes. The hemi-micellar-supramolecular self-organization of lactose-based glycolipid 1 on the ring surface, followed by photo-polymerization of the diacetylenic function triggered by UV light afforded the first water-soluble and biocompatible CNRs. The obtained donut-like nanoconstructs expose a high density of lactose moieties on their surface, and are able to engage specific interactions with Arachis hypogea lectin similar to glycoconjugates on the cell membrane.

  4. Practical synthesis of the C-ring precursor of paclitaxel from 3-methoxytoluene.

    Science.gov (United States)

    Fukaya, Keisuke; Yamaguchi, Yu; Watanabe, Ami; Yamamoto, Hiroaki; Sugai, Tomoya; Sugai, Takeshi; Sato, Takaaki; Chida, Noritaka

    2016-04-01

    The practical synthesis of the C-ring precursor of paclitaxel starting from 3-methoxytoluene is described. Lipase-catalyzed kinetic resolution of a substituted cyclohexane-1,2-diol, derived from 3-methoxytoluene in three steps, successfully afforded a desired enantiomer with >99% ee, which was transformed to a cyclohexenone. 1,4-Addition of a vinyl metal species, followed by Mukaiyama aldol reaction with formalin in the presence of a Lewis acid provided the known C-ring precursor of paclitaxel in a 10 g scale. PMID:26860468

  5. Two-dimensional inorganic–organic hybrid semiconductors composed of double-layered ZnS and monoamines with aromatic and heterocyclic aliphatic rings: Syntheses, structures, and properties

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Sujing; Li, Jing, E-mail: jingli@rutgers.edu

    2015-04-15

    As an addition to the II–VI based inorganic–organic hybrid semiconductor family, five new two-dimensional (2D) double-layered structures have been synthesized employing monoamines with different aromatic or heterocyclic aliphatic rings. Zn{sub 2}S{sub 2}(bza) (1), Zn{sub 2}S{sub 2}(mbza) (2), Zn{sub 2}S{sub 2}(fbza) (3), Zn{sub 2}S{sub 2}(pca) (4), and Zn{sub 2}S{sub 2}(thfa) (5) (bza=benzylamine, mbza=4-methoxybenzylamine, fbza=4-flurobenzylamine, pca=3-picolylamine, and thfa=tetrahydrofurfurylamine) are prepared by solvothermal reactions and characterized by different analytical methods, including powder X-ray diffraction, optical diffuse reflection, thermogravimetric analysis and photoluminescence spectroscopy. The powder X-ray diffraction patterns show that all five compounds adopt 2D double-layered structures. Optical diffuse reflectance spectra of these compounds suggest that they have notably lower band gaps than those of the similar compounds composed of aliphatic alkyl amines. Their photoluminescence properties and thermal stability are also analyzed. - Graphical abstract: Five new members of two-dimensional double-layered 2D-Zn{sub 2}S{sub 2}(L) (L=Ligand) structures employing monoamines with different aromatic or heterocyclic aliphatic rings have been designed, synthesized, and characterized. - Highlights: • A new sub-family of II-VI based hybrid semiconductors are designed, synthesized, and structurally characterized using amines with aromatic or aliphatic cyclic rings. • These compounds have notably lower band gaps than those made of aliphatic alkyl amines, greatly broadening the range of band gaps of this material family. • They emit strongly with systematically tunable emission intensity and energy.

  6. Synthesis and Radiolabeling of Modified Peptides Attached to Heterocyclic Rings and Their Possible Medical Applications

    International Nuclear Information System (INIS)

    Keeping in mind the pharmacological potential of heterocyclic rings as well as the advantage of biodegradability and biocompatibility of amino acids/peptides, in this thesis we were prompted for the following: 1. Synthesis of novel dipeptide derivatives coupled with different heterocyclic rings (pyridine, 1,2,4-triazol-pyridine, 1,3,4-oxadiazolpyridine and tetrazol-pyridine rings). 2. Characterization of the synthesized compounds on the basis of their spectral data (IR, Mass and 1 H-NMR spectra). 3. Study their antimicrobial activity as one of their expected biological activities. 4. Study the radioiodination of some synthesized dipeptide derivatives. 5. Study the biodistribution of the radiolabeled compounds in normal mice as preliminary studies for the possibility of using them as agents for imaging and treatment.

  7. A stereoselective synthesis of (+)-physoperuvine using a tandem aza-Claisen rearrangement and ring closing metathesis reaction.

    Science.gov (United States)

    Zaed, Ahmed M; Swift, Michael D; Sutherland, Andrew

    2009-07-01

    A stereoselective synthesis of (+)-physoperuvine, a tropane alkaloid from Physalis peruviana Linne has been developed using a one-pot tandem aza-Claisen rearrangement and ring closing metathesis reaction to form the key amino-substituted cycloheptene ring. PMID:19532981

  8. Pioneering Metal-Free Oxidative Coupling Strategy of Aromatic Compounds Using Hypervalent Iodine Reagents.

    Science.gov (United States)

    Kita, Yasuyuki; Dohi, Toshifumi

    2015-10-01

    We started our hypervalent iodine research about 30 years ago in the mid-1980s. We soon successfully developed the single-electron-transfer oxidation ability of a hypervalent iodine reagent, specifically, phenyliodine(III) bis(trifluoroacetate) (PIFA), toward aromatic rings of phenyl ethers for forming aromatic cation radicals. This was one of the exciting and unexpected events in our research studies so far, and the discovery was reported in 1991. It also led to the next challenge, developing the metal-free oxidative couplings for C-H functionalizations and direct couplings between the C-H bonds of valuable aromatic compounds in organic synthesis. In order to realize the effective oxidative coupling, pioneering new aromatic ring activations was essential and several useful methodologies have been found for oxidizable arenes. The achievements regarding this objective obtained in our continuous research are herein summarized with classification of the aromatic ring activation strategies.

  9. Novel Easy Preparations of Some Aromatic Iodine(I, III, and V) Reagents, Widely Applied in Modern Organic Synthesis

    OpenAIRE

    Lech Skulski

    2003-01-01

    We report our novel (or considerably improved) methods for the synthesis of aromatic iodides, (dichloroiodo)arenes, (diacetoxyiodo)arenes, [bis(trifluoroacetoxy)-iodo]arenes, iodylarenes and diaryliodonium salts, as well as some facile, oxidative anion metatheses in crude diaryliodonium or tetraalkylammonium halides and, for comparison, potassium halides. All our formerly published papers were discussed and explained in our review “Organic Iodine(I, III, and V) Chemistry: 10 Years of Dev...

  10. Synthesis, double-helix formation, and higher-assembly formation of chiral polycyclic aromatic compounds: conceptual development of polyketide aldol synthesis.

    Science.gov (United States)

    Yamaguchi, Masahiko; Shigeno, Masanori; Saito, Nozomi; Yamamoto, Koji

    2014-02-01

    Polycyclic aromatic compounds are an important group of substances in chemistry, and the study of their properties is a subject of interest in the development of drugs and materials. We have been conducting studies to develop chiral polycyclic aromatic compounds, i.e., helicenes and equatorenes. These helical molecules showed notable aggregate-forming properties and the capability for chiral recognition exerted by noncovalent bond interactions, which were not observed in compounds with central chirality. Homo- and hetero-double-helix-forming helicene oligomers were developed, and the latter self-assembled to form gels and vesicles. In this article, we describe such hierarchical studies of polycyclic aromatic compounds, which were started from polyketide aldol synthesis.

  11. Sapindus mukorossi mediated green synthesis of some manganese oxide nanoparticles interaction with aromatic amines

    Science.gov (United States)

    Jassal, Vidhisha; Shanker, Uma; Gahlot, Sweta; Kaith, B. S.; Kamaluddin; Iqubal, Md Asif; Samuel, Pankaj

    2016-04-01

    A green route was successfully used to synthesize some manganese oxides (MO) nanoparticles like MnO2, Mn2O3 and Mn3O4 with varied Mn/O ratio. This approach involved utilization of Sapindus mukorossi (raw reetha)-water as a natural surfactant-solvent system. The most important feature of present work was that during the synthesis of nanoparticles, no harmful toxic solvent or chemicals were used in order to follow the principles of green chemistry. The size of nanoparticles was recorded below 100 nm with different shapes and morphologies. MnO2 nanoparticles were found to have needle shape, Mn2O3: spherical and Mn3O4: cubic shape. The synthesized nanoparticles were characterized by powder X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The synthesized MO nanoparticles were found to act as a solid support cum catalysts for the oxidation and polymerization of some aromatic amines like p-anisidine, p-toluidine, p-chloroaniline and aniline.

  12. Synthesis, Structure and Noncovalent Interactions of Palladium(Ⅱ) Complexes with N-Benzoyl-β-phenylalaninate Dianion and Aromatic Diimine

    Institute of Scientific and Technical Information of China (English)

    CHEN,Yao-Feng(陈耀峰); GONG,Yu-Qiu(龚钰秋); ZHANG,Hua-Song(张华松)

    2002-01-01

    Two palladiun(Ⅱ) complexes, [Pd(bipy)(BzPhe-N,O) ] and [Pd(phen) (BzPhe-N,O) ] @4H2O were synthesized by reactions between Pd(bipy)Cl2 and BzPheH2 ( N-benzoyl- β-phenylalanine), Pd(phen) Cla and BzPheH2 in water at pH ~ 9, with their structrues determined by X-ray diffraction analysis. The Pd atom is coordinated by two nitrogen atoms of bipy (or phen), the deprotonated amido type nitrogen atom and one of the carboxylic oxygens of BzPhe (BzPhe = N-benzoyl-β-phenylalaninate dianion). In the complex [Pd(phen)(BzPhe-N,O)]@ 4H2O, the side chain of phenvlalanine is located above and approximately parallels to the coordination plane. Both the aromic-aromatic stacking interaction between the phenyl ring of phenylalanine and phen, and the metal ion-aromatic interaction between the phenyi ring of phenylalanine and Pd(Ⅱ) were observed. [Pd(bipy)(BzPhe-N,O) ] has the phenylalanyl side chain oriented outwards from the coordination plane, which is mainly due to the interaction between the carbonyl oxygen atom of the amido group and the phenyl ring of phenylalanine. The reason for the different orientation of phenylalanyl side chain in the complexes was suggested.

  13. Decarboxylative and direct functionalisations of aromatic compounds

    OpenAIRE

    Seo, Sangwon

    2014-01-01

    Aromatic rings are privileged structures found in a diverse range of natural and synthetic compounds, thus synthetic methods for their functionalisations are important in organic synthesis. Despite significant advancements made, especially in the field of transition metal catalysis, work still continues for the development of milder, more efficient, and more atom economical reactions. We describe here our efforts towards the development of decarboxylative/direct C(aryl)–N and C(aryl)–C bond f...

  14. A Novel Approach in Cinnamic Acid Synthesis: Direct Synthesis of Cinnamic Acids from Aromatic Aldehydes and Aliphatic Carboxylic Acids in the Presence of Boron Tribromide

    Directory of Open Access Journals (Sweden)

    M. Onciu

    2005-02-01

    Full Text Available Cinnamic acids have been prepared in moderate to high yields by a new direct synthesis using aromatic aldehydes and aliphatic carboxylic acids, in the presence of boron tribromide as reagent, 4-dimethylaminopyridine (4-DMAP and pyridine (Py as bases and N-methyl-2-pyrolidinone (NMP as solvent, at reflux (180-190°C for 8-12 hours.

  15. Efficient synthesis of biflavones having a ring-A ring of two flavone units using Suzuki cross-coupling reactions

    OpenAIRE

    KOHARI, Yoshihito; HOSHINO, Yukio; MATSUYAMA, Haruo; NAKANO, Hiroto

    2010-01-01

    Biflavones having a A ring-A ring of two flavone units were easily prepared by using Suzuki cross-coupling reaction of borylated flavones with bromoflavones or flavone-5-triflate in good to excellent yields.

  16. A highly sensitive monoclonal antibody based biosensor for quantifying 3–5 ring polycyclic aromatic hydrocarbons (PAHs in aqueous environmental samples

    Directory of Open Access Journals (Sweden)

    Xin Li

    2016-03-01

    Full Text Available Immunoassays based on monoclonal antibodies (mAbs are highly sensitive for the detection of polycyclic aromatic hydrocarbons (PAHs and can be employed to determine concentrations in near real-time. A sensitive generic mAb against PAHs, named as 2G8, was developed by a three-step screening procedure. It exhibited nearly uniformly high sensitivity against 3-ring to 5-ring unsubstituted PAHs and their common environmental methylated PAHs, with IC50 values between 1.68 and 31 μg/L (ppb. 2G8 has been successfully applied on the KinExA Inline Biosensor system for quantifying 3–5 ring PAHs in aqueous environmental samples. PAHs were detected at a concentration as low as 0.2 μg/L. Furthermore, the analyses only required 10 min for each sample. To evaluate the accuracy of the 2G8-based biosensor, the total PAH concentrations in a series of environmental samples analyzed by biosensor and GC–MS were compared. In most cases, the results yielded a good correlation between methods. This indicates that generic antibody 2G8 based biosensor possesses significant promise for a low cost, rapid method for PAH determination in aqueous samples.

  17. Synthesis and Thermal Behavior of a Fused, Tricyclic 1,2,3,4-Tetrazine Ring System.

    Science.gov (United States)

    Chavez, David E; Bottaro, Jeffery C; Petrie, Mark; Parrish, Damon A

    2015-10-26

    This study presents the synthesis and characterization of a fused, tricyclic 1,2,3,4-tetrazine ring system. The molecule is synthesized in a three-step process from 5,5'-dinitro-bis,1,2,4-triazole via a di-N-amino compound. Oxidation to form the azo-coupled fused tricyclic 1,2,3,4-tetrazine is achieved using tert-butyl hypochlorite as the oxidant. The di-N-amino compound and the desired fused tricyclic 1,2,3,4-triazine display interesting thermal behavior and are predicted to be high-performance energetic materials.

  18. Convergent solid-phase and solution approaches in the synthesis of the cysteine-rich Mdm2 RING finger domain.

    Science.gov (United States)

    Vasileiou, Zoe; Barlos, Kostas; Gatos, Dimitrios

    2009-12-01

    The RING finger domain of the Mdm2, located at the C-terminus of the protein, is necessary for regulation of p53, a tumor suppressor protein. The 48-residues long Mdm2 peptide is an important target for studying its interaction with small anticancer drug candidates. For the chemical synthesis of the Mdm2 RING finger domain, the fragment condensation on solid-phase and the fragment condensation in solution were studied. The latter method was performed using either protected or free peptides at the C-terminus as the amino component. Best results were achieved using solution condensation where the N-component was applied with the C-terminal carboxyl group left unprotected. The developed method is well suited for large-scale synthesis of Mdm2 RING finger domain, combining the advantages of both solid-phase and solution synthesis. PMID:19824037

  19. Enantioselective synthesis of angularly substituted 1-azabicylic rings: coupled dynamic kinetic epimerization and chirality transfer.

    Science.gov (United States)

    Aron, Zachary D; Ito, Tatsuya; May, Tricia L; Overman, Larry E; Wang, Jocelyn

    2013-10-01

    A new strategy for enantioselective synthesis of azacyclic molecules in which dynamic kinetic equilibration of diastereomeric iminium ions precedes a stereochemistry-determining sigmatropic rearrangement is reported. The method is illustrated by the synthesis, in high enantiomeric purity (generally 95-99% ee), of a variety of 1-azabicyclic molecules containing angular allyl or 3-substituted 2-propenyl side chains adjacent to nitrogen and up to three stereogenic centers. In these products, the size of the carbocyclic ring is varied widely (5-12 membered); however, useful yields are obtained in forming 1-azabicyclic products containing only fused pyrrolidine and piperidine rings. Chirality transfer from substituents at carbons 1 and 2 of the 3-butenylamine fragment of the starting material is investigated, with methyl and phenyl substituents at the allylic position shown to provide exquisite stereocontrol (generally 98-99% chirality transfer). An attractive feature of the method is the ability to carry out the key transformation in the absence of solvent. Illustrated also is the high yielding conversion of four such products to a new family of bicyclic β-amino acids of high enantiomeric purity.

  20. Efficient Synthesis of 2-Ethyl-A-ring Analogues of 19-Nor-1α,25-dihydroxy Vitamin D3

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The novel 19-nor-lα,25-dihydroxy vitamin D3 analogues possessing an ethyl at the 2-position(4 and 5), were synthesized by coupling 25-hydroxy Windaus-Grundmann ketone derivative 20 with A-ring synthons(15 and 19) respectively. The enantioselective synthesis of substituted bicyclic[3,1,0] hexanes structure A-ring synthons, started from all-cis-3,5-dihydroxy-4-ethyl-1-(methoxycarbonyl)cyclohexane via lipase-catalyzd asymmetrization, was demonstrated.

  1. Recoupled long-range C-H dipolar dephasing in solid-state NMR, and its use for spectral selection of fused aromatic rings

    Science.gov (United States)

    Mao, J.-D.; Schmidt-Rohr, K.

    2003-05-01

    This work introduces a simple new solid-state 13C NMR method for distinguishing various types of aromatic residues, e.g. those of lignin from fused rings of charcoal. It is based on long-range dipolar dephasing, which is achieved by recoupling of long-range C-H dipolar interactions, using two 1H 180° pulses per rotation period. This speeds up dephasing of unprotonated carbon signals approximately threefold compared to standard dipolar dephasing without recoupling and thus provides much more efficient differential dephasing. It also reduces the effects of spinning-speed dependent effective proton-proton dipolar couplings on the heteronuclear dephasing. Signals of unprotonated carbons with two or more protons at a two-bond distance dephase to wood charcoal, and even slower for inorganic carbonate. Direct 13C polarization is used on these structurally complex samples to prevent loss of the signals of interest, which by design originate from carbons that are distant from protons and therefore crosspolarize poorly. In natural organic matter such as humic acids, this combination of recoupled dipolar dephasing and direct polarization at 7-kHz MAS enables selective observation of signals from fused rings that are characteristic of charcoal.

  2. Novel Easy Preparations of Some Aromatic Iodine(I, III, and V Reagents, Widely Applied in Modern Organic Synthesis

    Directory of Open Access Journals (Sweden)

    Lech Skulski

    2003-01-01

    Full Text Available We report our novel (or considerably improved methods for the synthesis of aromatic iodides, (dichloroiodoarenes, (diacetoxyiodoarenes, [bis(trifluoroacetoxy-iodo]arenes, iodylarenes and diaryliodonium salts, as well as some facile, oxidative anion metatheses in crude diaryliodonium or tetraalkylammonium halides and, for comparison, potassium halides. All our formerly published papers were discussed and explained in our review “Organic Iodine(I, III, and V Chemistry: 10 Years of Development at the Medical University of Warsaw, Poland” (1990-2000 [1]. Our newest results are discussed below.

  3. Synthesis of o-Carboxyarylacrylic Acids by Room Temperature Oxidative Cleavage of Hydroxynaphthalenes and Higher Aromatics with Oxone.

    Science.gov (United States)

    Parida, Keshaba Nanda; Moorthy, Jarugu Narasimha

    2015-08-21

    A simple procedure for the synthesis of a variety of o-carboxyarylacrylic acids has been developed with Oxone (2KHSO5·KHSO4·K2SO4); the oxidation reaction involves the stirring of methoxy/hydroxy-substituted naphthalenes, phenanthrenes, anthracenes, etc. with Oxone in an acetonitrile-water mixture (1:1, v/v) at rt. Mechanistically, the reaction proceeds via initial oxidation of naphthalene to o-quinone, which undergoes cleavage to the corresponding o-carboxyarylacrylic acid. The higher aromatics are found to yield carboxymethyl lactones derived from the initially formed o-carboxyarylacrylic acids.

  4. Gaining Control over Radiolytic Synthesis of Uniform Sub-3-nanometer Palladium Nanoparticles: Use of Aromatic Liquids in the Electron Microscope.

    Science.gov (United States)

    Abellan, Patricia; Parent, Lucas R; Al Hasan, Naila; Park, Chiwoo; Arslan, Ilke; Karim, Ayman M; Evans, James E; Browning, Nigel D

    2016-02-16

    Synthesizing nanomaterials of uniform shape and size is of critical importance to access and manipulate the novel structure-property relationships arising at the nanoscale, such as catalytic activity. In this work, we synthesize Pd nanoparticles with well-controlled size in the sub-3 nm range using scanning transmission electron microscopy (STEM) in combination with an in situ liquid stage. We use an aromatic hydrocarbon (toluene) as a solvent that is very resistant to high-energy electron irradiation, which creates a net reducing environment without the need for additives to scavenge oxidizing radicals. The primary reducing species is molecular hydrogen, which is a widely used reductant in the synthesis of supported metal catalysts. We propose a mechanism of particle formation based on the effect of tri-n-octylphosphine (TOP) on size stabilization, relatively low production of radicals, and autocatalytic reduction of Pd(II) compounds. We combine in situ STEM results with insights from in situ small-angle X-ray scattering (SAXS) from alcohol-based synthesis, having similar reduction potential, in a customized microfluidic device as well as ex situ bulk experiments. This has allowed us to develop a fundamental growth model for the synthesis of size-stabilized Pd nanoparticles and demonstrate the utility of correlating different in situ and ex situ characterization techniques to understand, and ultimately control, metal nanostructure synthesis. PMID:26741639

  5. Gaining Control over Radiolytic Synthesis of Uniform Sub-3-nanometer Palladium Nanoparticles: Use of Aromatic Liquids in the Electron Microscope.

    Science.gov (United States)

    Abellan, Patricia; Parent, Lucas R; Al Hasan, Naila; Park, Chiwoo; Arslan, Ilke; Karim, Ayman M; Evans, James E; Browning, Nigel D

    2016-02-16

    Synthesizing nanomaterials of uniform shape and size is of critical importance to access and manipulate the novel structure-property relationships arising at the nanoscale, such as catalytic activity. In this work, we synthesize Pd nanoparticles with well-controlled size in the sub-3 nm range using scanning transmission electron microscopy (STEM) in combination with an in situ liquid stage. We use an aromatic hydrocarbon (toluene) as a solvent that is very resistant to high-energy electron irradiation, which creates a net reducing environment without the need for additives to scavenge oxidizing radicals. The primary reducing species is molecular hydrogen, which is a widely used reductant in the synthesis of supported metal catalysts. We propose a mechanism of particle formation based on the effect of tri-n-octylphosphine (TOP) on size stabilization, relatively low production of radicals, and autocatalytic reduction of Pd(II) compounds. We combine in situ STEM results with insights from in situ small-angle X-ray scattering (SAXS) from alcohol-based synthesis, having similar reduction potential, in a customized microfluidic device as well as ex situ bulk experiments. This has allowed us to develop a fundamental growth model for the synthesis of size-stabilized Pd nanoparticles and demonstrate the utility of correlating different in situ and ex situ characterization techniques to understand, and ultimately control, metal nanostructure synthesis.

  6. Total Synthesis of Flocoumafen via Knoevenagel Condensation and Intramolecular Ring Cyclization: General Access to Natural Products

    Directory of Open Access Journals (Sweden)

    Mankil Jung

    2012-02-01

    Full Text Available The total synthesis and structure determination of cis- and trans-flocoumafen was described. The key synthetic steps involve Knoevenagel condensation with p-methoxybenzaldehyde, in situ decarboxylation and intramolecular ring cyclization to construct the tetralone skeleton. Stereospecific reduction of the O-alkylated ketone 13 afforded good yield of precusor alcohol 5. Final coupling of alcohol 5 with 4-hydroxy-coumarin yielded flocoumafen (1. Separation and structure determination of cis- and trans-flocoumafen through 2D NMR analyses-assisted computer simulation techniques for the evaluation of anticoagulant activities are reported for the first time. This method is useful for generating the core tetralone skeleton of 4-hydroxycoumarin derivatives and provides a generalized access to various warfarin type anticoagulants.

  7. Synthesis and Properties of Some polyurethane/ Partially Aromatic Polyester Casting Samples

    International Nuclear Information System (INIS)

    A series of partially aromatic terephthalate polyesters were synthesized by melt transesterification of dimethyl terephthalate with various types of aliphatic diol compounds in 1:1.1 molar ratio. Ethylene-, di-, tri-, tetra ethylene glycol and polyethylene glycol with different molecular weights 1000, 4000, 6000 as well as the prepared dihydroxy natural rubber were used. Another series of partially aromatic adipate and sebacate polyesters based on the prepared bisphenol A and its tetrabromo derivative were also synthesized by direct polycondensation esterification with adipic and sebacic acid. Polyurethane with NCO/OH ratio equal 4 was prepared from the reaction of 2,4 toluene diisocyanate with polyethylene glycol 1000. The prepared polyurethane was mixed with different weight percentages (2, 4, 6, 8, 10 or 12 % w/w) of the prepared partially aromatic polyesters to give polyurethane/polyester compositions. Mechanical and electrical properties as well as water and chemical resistance of the prepared film samples with thickness 3-4 mm were determined and compared with those of polyurethane film sample without polyester. The data indicate that 10 % w/w of the added partially aromatic polyester increases polyurethane tensile strength, improves its insulation properties and hydrolytic stability as well as its chemical resistance. Film samples based on bisphenol A impart excellent properties as compared with those based on aliphatic glycol species and dihydroxy natural rubber. Keywords: Partially aromatic polyesters, Dimethyl terephthalate, Glycols, Bisphenol A, Tetrabromo bisphenol A, Natural rubber, Adipic acid, Sebacic acid, Polyurethane, Casting

  8. Synthesis of novel amphiphilic hyaluronan containing-aromatic fatty acids for fabrication of polymeric micelles.

    Science.gov (United States)

    Matelová, Alena; Huerta-Angeles, Gloria; Šmejkalová, Daniela; Brůnová, Zdislava; Dušek, Jan; Vícha, Robert; Velebný, Vladimír

    2016-10-20

    Novel hydrophobized hyaluronan (HA) derivatives, containing ω-phenylalkanoic acids (ω-PAA, 4-phenylbutyric acid, 6-phenylhexanoic, 8-phenyloctanoic or 11-tolylundecanoic acids) were prepared by esterification. Mixed anhydrides obtained after reaction of the carboxyl acid moiety and benzoyl chloride were found to be active acylating agents, affording hydrophobized HA in good yield and under mild conditions. The reactivity of the aromatic fatty acids towards esterification has decreased with the increasing length of the aliphatic spacer between the aromatic substituent and carboxylic acid moiety. The novel HA derivatives self-assembled from very low concentrations and were found to be non-cytotoxic. The potential use of ω-phenylalkanoic acids grafted-HA towards drug delivery applications was demonstrated by hydrophobic drugs (resveratrol and retinyl palmitate) encapsulation. The drug loading capacity of the novel HA derivatives was significantly improved most likely because of π⋯π interactions between the micelle core and loaded hydrophobic aromatic compound. PMID:27474668

  9. Recent advances in the ruthenium-catalyzed hydroarylation of alkynes with aromatics: synthesis of trisubstituted alkenes.

    Science.gov (United States)

    Manikandan, Rajendran; Jeganmohan, Masilamani

    2015-11-14

    The hydroarylation of alkynes with substituted aromatics in the presence of a metal catalyst via chelation-assisted C-H bond activation is a powerful method to synthesize trisubstituted alkenes. Chelation-assisted C-H bond activation can be done by two ways: (a) an oxidative addition pathway and (b) a deprotonation pathway. Generally, a mixture of cis and trans stereoisomeric as well as regioisomeric trisubstituted alkenes was observed in an oxidative addition pathway. In the deprotonation pathway, the hydroarylation reaction can be done in a highly regio- and stereoselective manner, and enables preparation of the expected trisubstituted alkenes in a highly selective manner. Generally, ruthenium, rhodium and cobalt complexes are used as catalysts in the reaction. In this review, a ruthenium-catalyzed hydroarylation of alkynes with substituted aromatics is covered completely. The hydroarylation reaction of alkynes with amide, azole, carbamate, phosphine oxide, amine, acetyl, sulfoxide and sulphur directed aromatics is discussed.

  10. Automated synthesis of transmission lines loaded with complementary split ring resonators (CSRRs) and open complementary split ring resonators (OCSRRs) through aggressive space mapping (ASM)

    Science.gov (United States)

    Selga, Jordi; Rodríguez, Ana; Orellana, Marco; Boria, Vicente; Martín, Ferran

    2014-09-01

    This paper is focused on the application of space mapping optimization to the automated synthesis of transmission lines loaded with complementary split ring resonators (CSRRs) and open complementary split ring resonators (OCSRRs). These structures are of interest for the implementation of resonant-type metamaterial transmission lines and for the design of planar microwave circuits based on such complementary resonators. The paper presents a method to generate the layouts of CSRR- and OCSRR-loaded microstrip lines from the elements of their equivalent circuit models. Using the so-called aggressive space mapping, a specific implementation that uses quasi-Newton type iteration, we have developed synthesis algorithms that are able to provide the topology of these CSRR- and OCSRR-loaded lines in few steps. The most relevant aspect, however, is that this synthesis process is completely automatic, i.e., it does not require any action from the designers, other than initiating the algorithm. Moreover, this technique can be translated to other electrically small planar elements described by lumped element equivalent circuit models.

  11. Synthesis of Fluoroalkoxy Substituted Arylboronic Esters by Iridium-Catalyzed Aromatic C–H Borylation

    KAUST Repository

    Batool, Farhat

    2015-08-17

    The preparation of fluoroalkoxy arylboronic esters by iridium-catalyzed aromatic C–H borylation is described. The fluoroalkoxy groups employed include trifluoromethoxy, difluoromethoxy, 1,1,2,2-tetrafluoroethoxy, and 2,2-difluoro-1,3-benzodioxole. The borylation reactions were carried out neat without the use of a glovebox or Schlenk line. The regioselectivities available through the iridium-catalyzed C–H borylation are complementary to those obtained by the electrophilic aromatic substitution reactions of fluoroalkoxy arenes. Fluoroalkoxy arylboronic esters can serve as versatile building blocks.

  12. A Novel Synthesis of N-Methyl-N-aryl Carbamates from Aromatic Amines and Dimethyl Carbonate Catalyzed by K2CO3/Bu4NBr

    Institute of Scientific and Technical Information of China (English)

    Zhen Lu SHEN; Xuan Zhen JIANG

    2004-01-01

    A facile synthesis of N-methyl-N-aryl carbamates from aromatic amines and dimethyl carbonate (DMC) has been achieved with high yields in the presence of potassium carbonate (K2CO3) and tetrabutylammonium bromide (Bu4NBr) under solvent-free conditions.

  13. Synthesis of Aryl-Substituted 2,4-Dinitrophenylamines: Nucleophilic Aromatic Substitution as a Problem-Solving and Collaborative-Learning Approach

    Science.gov (United States)

    Santos, Elvira Santos; Garcia, Irma Cruz Gavilan; Gomez, Eva Florencia Lejarazo; Vilchis-Reyes, Miguel Angel

    2010-01-01

    A series of experiments based on problem-solving and collaborative-learning pedagogies are described that encourage students to interpret results and draw conclusions from data. Different approaches including parallel library synthesis, solvent variation, and leaving group variation are used to study a nucleophilic aromatic substitution of…

  14. Cardiac toxicity of 5-ring polycyclic aromatic hydrocarbons is differentially dependent on the aryl hydrocarbon receptor 2 isoform during zebrafish development

    Energy Technology Data Exchange (ETDEWEB)

    Incardona, John P., E-mail: john.incardona@noaa.gov; Linbo, Tiffany L.; Scholz, Nathaniel L.

    2011-12-15

    Petroleum-derived compounds, including polycyclic aromatic hydrocarbons (PAHs), commonly occur as complex mixtures in the environment. Recent studies using the zebrafish experimental model have shown that PAHs are toxic to the embryonic cardiovascular system, and that the severity and nature of this developmental cardiotoxicity varies by individual PAH. In the present study we characterize the toxicity of the relatively higher molecular weight 5-ring PAHs benzo[a]pyrene (BaP), benzo[e]pyrene (BeP), and benzo[k]fluoranthene (BkF). While all three compounds target the cardiovascular system, the underlying role of the ligand-activated aryl hydrocarbon receptor (AHR2) and the tissue-specific induction of the cytochrome p450 metabolic pathway (CYP1A) were distinct for each. BaP exposure (40 {mu}M) produced AHR2-dependent bradycardia, pericardial edema, and myocardial CYP1A immunofluorescence. By contrast, BkF exposure (4-40 {mu}M) caused more severe pericardial edema, looping defects, and erythrocyte regurgitation through the atrioventricular valve that were AHR2-independent (i.e., absent myocardial or endocardial CYP1A induction). Lastly, exposure to BeP (40 {mu}M) yielded a low level of CYP1A+ signal in the vascular endothelium of the head and trunk, without evident toxic effects on cardiac function or morphogenesis. Combined with earlier work on 3- and 4-ring PAHs, our findings provide a more complete picture of how individual PAHs may drive the cardiotoxicity of mixtures in which they predominate. This will improve toxic injury assessments and risk assessments for wild fish populations that spawn in habitats altered by overlapping petroleum-related human impacts such as oil spills, urban stormwater runoff, or sediments contaminated by legacy industrial activities. -- Highlights: Black-Right-Pointing-Pointer PAH compounds with 5 rings in different arrangements caused differential tissue-specific patterns of CYP1A induction in zebrafish embryos. Black

  15. Synthesis of Aromatic Retinoids and Curcuminoids and Evaluation of their Antiproliferative, Antiradical, and Anti-inflammatory Activities.

    Science.gov (United States)

    Morzycki, Jacek W; Rárová, Lucie; Grúz, Jiři; Sawczuk, Tomasz; Kiełczewska, Urszula; Siergiejczyk, Leszek; Wojtkielewicz, Agnieszka

    2016-08-01

    Natural retinoids and curcuminoids are known for their broad spectrum of biological properties, such as antioxidant, anti-inflammatory, antitumor, and so forth. In this work, a convenient synthesis of aromatic retinoids and curcuminoids from vinyl or allyl ketones, and the corresponding alcohols, using olefin metathesis as a key reaction, was elaborated. The best yields and diastereoselectivities were obtained from allylic or homoallylic alcohols by employing the two-step cross-metathesis/oxidation procedure. The synthesized analogues were tested for their antiproliferative activity on human cancer cell lines of various origin (leukemia CEM, adenocarcinoma MCF7, cervical carcinoma HeLa) as well as for their antioxidant and anti-inflammatory activity in vitro. All examined derivatives exhibited strong anti-inflammatory activity in vitro without affecting cell viability. They also showed strong cytotoxicity against leukemia cell line CEM, except for 18 and 35. The antioxidant activity of the tested compounds was rather weak. PMID:27547644

  16. Cu(II AND Zn(II COMPLEX COMPOUNDS WITH BIGUANIDES AROMATIC DERIVATIVES. SYNTHESIS, CHARACTERIZATION, BIOLOGICAL ACTIVITY

    Directory of Open Access Journals (Sweden)

    Ticuţa Negreanu-Pîrjol

    2011-05-01

    Full Text Available In this paper we report the synthesis, physical-chemical characterization and antimicrobial activity of some new complex compounds of hetero-aromatic biguanides ligands, chlorhexidine base (CHX and chlorhexidine diacetate (CHXac2 with metallic ions Cu(II and Zn(II, in different molar ratio. The synthesized complexes were characterized by elemental chemical analysis and differential thermal analysis. The stereochemistry of the metallic ions was determined by infrared spectra, UV-Vis, EPR spectroscopy and magnetic susceptibility in the aim to establish the complexes structures. The biological activity of the new complex compounds was identified in solid technique by measuring minimum inhibition diameter of bacterial and fungal culture, against three standard pathogen strains, Escherichia coli ATCC 25922, Staphilococcus aureus ATCC 25923 and Candida albicans ATCC 10231. The results show an increased specific antimicrobial activity for the complexes chlorhexidine:Cu(II 1:1 and 1:2 compared with the one of the Zn(II complexes.

  17. Synthesis of Aromatic Retinoids and Curcuminoids and Evaluation of their Antiproliferative, Antiradical, and Anti‐inflammatory Activities

    Science.gov (United States)

    Morzycki, Jacek W.; Rárová, Lucie; Grúz, Jiři; Sawczuk, Tomasz; Kiełczewska, Urszula; Siergiejczyk, Leszek

    2016-01-01

    Abstract Natural retinoids and curcuminoids are known for their broad spectrum of biological properties, such as antioxidant, anti‐inflammatory, antitumor, and so forth. In this work, a convenient synthesis of aromatic retinoids and curcuminoids from vinyl or allyl ketones, and the corresponding alcohols, using olefin metathesis as a key reaction, was elaborated. The best yields and diastereoselectivities were obtained from allylic or homoallylic alcohols by employing the two‐step cross‐metathesis/oxidation procedure. The synthesized analogues were tested for their antiproliferative activity on human cancer cell lines of various origin (leukemia CEM, adenocarcinoma MCF7, cervical carcinoma HeLa) as well as for their antioxidant and anti‐inflammatory activity in vitro. All examined derivatives exhibited strong anti‐inflammatory activity in vitro without affecting cell viability. They also showed strong cytotoxicity against leukemia cell line CEM, except for 18 and 35. The antioxidant activity of the tested compounds was rather weak. PMID:27547644

  18. Asymmetric synthesis of a functionalized tricyclo[6.2.0.02,6]decane ring system present in kelsoene and poduran

    Indian Academy of Sciences (India)

    Amrita Ghosh; Subrata Ghosh

    2014-11-01

    Synthesis of a functionalized tricyclo[6.2.0.02,6]decane derivative in enantiomerically pure form, the core structure present in the natural products kelsoene and poduran, is described. The key steps involve a stereocontrolled copper (I)-catalyzed intramolecular [2+2] photocycloaddition of a 1, 6-diene prepared from D-mannitol to form a substituted bicyclo[3.2.0]heptane derivative and a ring closing olefin metathesis involving the vicinal substituents on the five-membered ring of the bicyclo[3.2.0]heptane derivative.

  19. A New Membrane Protein Sbg1 Links the Contractile Ring Apparatus and Septum Synthesis Machinery in Fission Yeast

    Science.gov (United States)

    Sethi, Kriti; Palani, Saravanan; Cortés, Juan C. G.; Sato, Mamiko; Sevugan, Mayalagu; Ramos, Mariona; Vijaykumar, Shruthi; Osumi, Masako; Naqvi, Naweed I.; Ribas, Juan Carlos; Balasubramanian, Mohan

    2016-01-01

    Cytokinesis in many organisms requires a plasma membrane anchored actomyosin ring, whose contraction facilitates cell division. In yeast and fungi, actomyosin ring constriction is also coordinated with division septum assembly. How the actomyosin ring interacts with the plasma membrane and the plasma membrane-localized septum synthesizing machinery remains poorly understood. In Schizosaccharomyces pombe, an attractive model organism to study cytokinesis, the β-1,3-glucan synthase Cps1p / Bgs1p, an integral membrane protein, localizes to the plasma membrane overlying the actomyosin ring and is required for primary septum synthesis. Through a high-dosage suppressor screen we identified an essential gene, sbg1+ (suppressor of beta glucan synthase 1), which suppressed the colony formation defect of Bgs1-defective cps1-191 mutant at higher temperatures. Sbg1p, an integral membrane protein, localizes to the cell ends and to the division site. Sbg1p and Bgs1p physically interact and are dependent on each other to localize to the division site. Loss of Sbg1p results in an unstable actomyosin ring that unravels and slides, leading to an inability to deposit a single contiguous division septum and an important reduction of the β-1,3-glucan proportion in the cell wall, coincident with that observed in the cps1-191 mutant. Sbg1p shows genetic and / or physical interaction with Rga7p, Imp2p, Cdc15p, and Pxl1p, proteins known to be required for actomyosin ring integrity and efficient septum synthesis. This study establishes Sbg1p as a key member of a group of proteins that link the plasma membrane, the actomyosin ring, and the division septum assembly machinery in fission yeast. PMID:27749909

  20. Synthesis and thermal studies of some epoxy systems cured with aromatic diamines

    International Nuclear Information System (INIS)

    Some aromatic diamines having flexible ether linkages with variable aliphatic and aromatic character were synthesized via Williamson's method and used as curing agents in their solution phase and/or molten state for a commercially available epoxy resin; diglycidyl ether of bisphenol-A (DGEBA) (n = 0.03, epoxy equivalent = 174.5 g/mol). The resulting polymeric systems were characterized by their physical properties and FT-IR-spectral studies. The thermal behaviour of the synthesized epoxy polymers were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). The optimum curing temperature of these polymers was found to be proportional to 150 deg. C. The polymers were stable up to 270 deg. C with maximum weight loss at proportional to 400 deg. C. (author)

  1. Synthesis and Properties of Novel Aromatic Azo Compounds from Hydroxyazobenzene and Cyanuric Chloride

    Institute of Scientific and Technical Information of China (English)

    李巍巍; 徐冬梅; 张志兰; 徐颖

    2012-01-01

    A new series of aromatic azo compounds with one, two, three and five azobenzene units were facilely constructed by dehydrochlorination reaction between p-hydroxyazobenzene, 4,4'-dihydroxyazobenzene and cyanuric chloride under very mild conditions. Their solubility, crystallinity, thermostability, UV-vis absorption properties and photoisomerization behaviors were carefully examined. When the number of azobenzene unit grew, the solubility of the synthesized compounds basically decreased, the crystallinity of the synthesized compounds firstly rose then dropped, while the thermostability and UV-vis absorption ability of the synthesized compounds greatly im- proved. All the aromatic azo compounds exhibited typical reversible photoisomerization behaviors and were expected to be applied in photosensitive material areas.

  2. Heptaphyrins: Expanded porphyrins with seven heterocyclic rings

    Indian Academy of Sciences (India)

    Venkataramanarao G Anand; Simi K Pushpan; Sundararaman Venkatraman; Tavarekere K Chandrashekar

    2003-10-01

    Expanded porphyrins containing seven pyrrole/heterocyclic rings linked in a cyclic fashion are termed heptaphyrins. The number of -electrons in heptaphyrins depends on the number of meso carbon bridges used to link the heterocyclic rings, accordingly heptaphyrins with 28-electrons and 30 -electrons are reported to date. Both condensation reactions of the appropriate precursors and acid-catalysed oxidative coupling reactions have been utilized to synthesise the heptaphyrins. The 30 heptaphyrins exhibit rich structural diversity where some of the heterocyclic rings in the macrocycle undergo a 180° ring flipping. An overview of the synthetic methods employed for the synthesis of heptaphyrins, their spectroscopic properties, structural behaviour and aromatic properties are highlighted in this paper.

  3. Four-component synthesis of 1,3,4-oxadiazole derivatives from N-isocyaniminotriphenylphosphorane, aromatic carboxylic acids, aromatic bis-aldehydes, and secondary amines

    OpenAIRE

    Ramazani, Ali; Karimi, Zahra; SOULDOZI, Ali; AHMADI, Yavar

    2012-01-01

    The 1:1 iminium intermediate generated by the addition of a secondary amine to aromatic bis-aldehydes (isophthalaldehyde and terphthalaldehyde) is trapped by the N-isocyaniminotriphenylphosphorane in the presence of a aromatic carboxylic acid derivative, which leads to the formation of corresponding iminophosphorane intermediate. Then disubstituted 1,3,4-oxadiazole derivatives are formed via intramolecular aza-Wittig reaction of the iminophosphorane intermediates. The reactions were ...

  4. Synthesis and Nonlinear Optical Property of a Series of New Chromophores Containing Furan Ring as the Only Conjugation Bridge

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper reports the synthesis and the nonlinear optical property of a series of new chromophores which contain furan ring as the only conjugation bridge for the first time. They are characterized by UV-VIS, FT-IR, 1H NMR, MS and elemental analysis. Their dipole moment and the first-order molecular hyperpolarizability (β) are calculated and compared with those of the analogues containing either benzene or thiophene as the conjugation bridge.

  5. Recent applications in natural product synthesis of dihydrofuran and -pyran formation by ring-closing alkene metathesis.

    Science.gov (United States)

    Jacques, Reece; Pal, Ritashree; Parker, Nicholas A; Sear, Claire E; Smith, Peter W; Ribaucourt, Aubert; Hodgson, David M

    2016-07-01

    In the past two decades, alkene metathesis has risen in prominence to become a significant synthetic strategy for alkene formation. Many total syntheses of natural products have used this transformation. We review the use, from 2003 to 2015, of ring-closing alkene metathesis (RCM) for the generation of dihydrofurans or -pyrans in natural product synthesis. The strategies used to assemble the RCM precursors and the subsequent use of the newly formed unsaturation will also be highlighted and placed in context. PMID:27108941

  6. One-pot three-component synthesis of quinoxaline and phenazine ring systems using Fischer carbene complexes

    Directory of Open Access Journals (Sweden)

    Priyabrata Roy

    2010-05-01

    Full Text Available One-pot three-component coupling of o-alkynylheteroaryl carbonyl derivatives with Fischer carbene complexes and dienophiles leading to the synthesis of quinoxaline and phenazine ring systems has been investigated. This involves the generation of furo[3,4-b]pyrazine and furo[3,4-b]quinoxaline as transient intermediates, which were trapped with Diels–Alder dienophiles. This is the first report on furo[3,4-b]pyrazine intermediates.

  7. Unexpected lateral-lithiation-induced alkylative ring opening of tetrahydrofurans in deep eutectic solvents: synthesis of functionalised primary alcohols.

    Science.gov (United States)

    Sassone, Francesca C; Perna, Filippo M; Salomone, Antonio; Florio, Saverio; Capriati, Vito

    2015-06-11

    o-Tolyl-substituted tetrahydrofurans undergo highly regioselective ring opening with the concomitant formation of new C-C bonds as the result of a lateral lithiation reaction. This reaction provides a new method for the synthesis of functionalised primary alcohols and can be run directly in protic eutectic mixtures as benign reaction media at 0 °C and under air, competitively with protonolysis. PMID:25959580

  8. Ring-Contraction Strategy for the Practical, Scalable, Catalytic Asymmetric Synthesis of Versatile γ-Quaternary Acylcyclopentenes

    KAUST Repository

    Hong, Allen Y.

    2011-02-24

    Contraction action! A simple protocol for the catalytic asymmetric synthesis of highly functionalized γ-quaternary acylcyclopentenes (see schematic) in up to 91 % overall yield and 92 % ee has been developed. The reaction sequence employs a palladium-catalyzed enantioselective alkylation reaction and exploits the unusual stability of β-hydroxy cycloheptanones to achieve a general and robust method for performing two-carbon ring contractions.

  9. Second generation benzofuranone ring substituted noscapine analogs: synthesis and biological evaluation.

    Science.gov (United States)

    Mishra, Ram Chandra; Karna, Prasanthi; Gundala, Sushma Reddy; Pannu, Vaishali; Stanton, Richard A; Gupta, Kamlesh Kumar; Robinson, M Hope; Lopus, Manu; Wilson, Leslie; Henary, Maged; Aneja, Ritu

    2011-07-15

    Microtubules, composed of α/β tubulin heterodimers, represent a validated target for cancer chemotherapy. Thus, tubulin- and microtubule-binding antimitotic drugs such as taxanes and vincas are widely employed for the chemotherapeutic management of various malignancies. Although quite successful in the clinic, these drugs are associated with severe toxicity and drug resistance problems. Noscapinoids represent an emerging class of microtubule-modulating anticancer agents based upon the parent molecule noscapine, a naturally occurring non-toxic cough-suppressant opium alkaloid. Here we report in silico molecular modeling, chemical synthesis and biological evaluation of novel analogs derived by modification at position-7 of the benzofuranone ring system of noscapine. The synthesized analogs were evaluated for their tubulin polymerization activity and their biological activity was examined by their antiproliferative potential using representative cancer cell lines from varying tissue-origin [A549 (lung), CEM (lymphoma), MIA PaCa-2 (pancreatic), MCF-7 (breast) and PC-3 (prostate)]. Cell-cycle studies were performed to explore their ability to halt the cell-cycle and induce subsequent apoptosis. The varying biological activity of these analogs that differ in the nature and bulk of substituent at position-7 was rationalized utilizing predictive in silico molecular modeling. PMID:21501599

  10. Clean Synthesis in Water:Darzens Condensation Reaction of Aromatic Aldehydes with Phenacyl Chloride

    Institute of Scientific and Technical Information of China (English)

    史达清; 张姝; 庄启亚; 王香善; 屠树江; 胡宏纹

    2003-01-01

    The Darzens condensation reaction of aromatic aldehydes with phenacyl chloride proceeded very efficiently in a water suspension medium in the presence of triethylbenzylammonium chloride and only trans-2,3-epoxy-1,3-diaryl-1-propanones were formed which can be isolated simply by filtration.The structures of these compounds were confirmed by elemental analysis,IR and 1H NMR spectra.Therir configurations are in agreement with that of the same compounds reported in the literature.Compared to the classical Darzens condensation,this new method has the advantages of good yields,high stereoselectivity,low running cost inexpensive and environmentally benign procedure.

  11. Synthesis and antifungal activity of halogenated aromatic bis-γ-lactones analogous to avenaciolide

    International Nuclear Information System (INIS)

    Here we describe the total syntheses and characterization by elemental analyses, infrared and NMR spectroscopy of three new compounds analogous to avenaciolide, a bis-g-lactone isolated from Aspergillus avenaceus that possesses antifungal activity, where the octyl group of the natural product was replaced by aromatic groups containing chlorine and fluorine atoms. The effects of the avenaciolide, the novel compounds and their synthetic precursors on mycelia development and conidia germination of Colletotrichum gloeosporioides and Fusarium solani were evaluated in vitro. The title compounds were almost as active as avenaciolide. The absolute structures of the chlorinated analogs were determined by X-ray diffraction analysis. (author)

  12. Combining the [2,3] Sigmatropic Rearrangement and Ring-Closing Metathesis Strategies for the Synthesis of Spirocyclic Alkaloids. A Short and Efficient Route to (+/-)-Perhydrohistrionicotoxin

    DEFF Research Database (Denmark)

    Tanner, David Ackland; Hagberg, Lars; Poulsen, Anders

    1999-01-01

    This paper describes the use of selenium-based [2,3] sigmatropic rearrangement in combination with ruthenium-catalyzed ring-closing metathesis (RCM) for the synthesis of azaspiro ring systems, as exemplified by the reactions of model substrates 5 and 6. The methodology has been applied to a short...

  13. SYNTHESIS AND ANALYSIS OF SOME N-AROMATIC DERIVATIVES OF 4- OXOPYRIMIDINE

    Directory of Open Access Journals (Sweden)

    T. Yu. Archinova

    2015-01-01

    Full Text Available We have carried out preliminary analysis of foreseeable biological activity of some compounds derivants of 4-oxopyrimidine with a use of PASS program. We have established that they should have anti-inflammatory, benzothiazepine, analgesic, hypotensive, nootropic activity.Molecular docking method (Autodock 4.0 allowed modeling of interaction of 4-oxopyrimidine derivatives with GABA, dopamine and benzothiazepine receptors. On the basis of the data received we forecasted structures of N-aromatic derivatives of 4-oxopyrimidine. The derivatives of 4-xopyrimidine we received with a reaction of cyclocondensation of N-acyl-β-ketamides with aromatic amines. We have synthesized five compounds. Using IR, UV and NMR spectrometry we have established its presumable structure as well as some physical and optical parameters. We have elaborated methods of quantitative spectrophotometric determination of two synthesized compounds and made its validation estimation.

  14. C-shaped diastereomers containing cofacial thiophene-substituted quinoxaline rings: synthesis, photophysical properties, and X-ray crystallography.

    Science.gov (United States)

    DeBlase, Catherine R; Finke, Ryan T; Porras, Jonathan A; Tanski, Joseph M; Nadeau, Jocelyn M

    2014-05-16

    Synthesis and characterization of two diastereomeric C-shaped molecules containing cofacial thiophene-substituted quinoxaline rings are described. A previously known bis-α-diketone was condensed with an excess of 4-bromo-1,2-diaminobenzene in the presence of zinc acetate to give a mixture of two C-shaped diastereomers with cofacial bromine-substituted quinoxaline rings. After chromatographic separation, thiophene rings were installed by a microwave-assisted Suzuki coupling reaction, resulting in highly emissive diastereomeric compounds that were studied by UV-vis, fluorescence, and NMR spectroscopy, as well as X-ray crystallography. The unique symmetry of each diastereomer was confirmed by NMR spectroscopy. NMR data indicated that the syn isomer has restricted rotation about the bond connecting the thiophene and quinoxaline rings, which was also observed in the solid state. The spectroscopic properties of the C-shaped diastereomers were compared to a model compound containing only a single thiophene-substituted quinoxaline ring. Ground state intramolecular π-π interactions in solution were detected by NMR and UV-vis spectroscopy. Red-shifted emission bands, band broadening, and large Stokes shifts were observed, which collectively suggest excited state π-π interactions that produce excimer-like emissions, as well as a remarkable positive emission solvatochromism, indicating charge-transfer character in the excited state.

  15. Polish turpentine as source of raw material for synthesis of aromatic substances

    Energy Technology Data Exchange (ETDEWEB)

    Wizner, I.

    1980-01-01

    This paper provides data on the volume of world-wide use of turpentine (Sk), essential directions of Sk utilization and trends in this area. The significant interest toward turpentine as a raw material for deriving aromatic substances, including linalool, geraniol, citronellol, verbenol, isoborneol, ionones, citrals, irone and menthol. Reaction schemes are provided for deriving from Poland's production of turpentine and its basic components the following: ..cap alpha..-pinene ( about54%), ..beta..-pinene ( about2.2%), and 3-carene ( about-40%) which are at the present time imported. Such use of turpentine, by providing the most valuable and high-demand production of its derivatives will be extremely efficient for Poland.

  16. Synthesis of Oxygen Heterocycles via Aromatic C-O Bond Formation Using Arynes

    Directory of Open Access Journals (Sweden)

    Hideto Miyabe

    2015-07-01

    Full Text Available Most of the synthetic approaches to the benzo-fused heterocycles containing an oxygen atom have involved the use of phenol derivatives as a starting material. This review highlights the new synthetic approaches involving the aromatic C-O bond-forming process using arynes. The insertion of arynes into the C=O bond gives the unstable intermediates, [2 + 2] cycloaddition-type adducts, which can be easily converted into a variety of oxygen atom-containing heterocycles in a single operation. In this review, the syntheses of oxygen heterocycles, such as coumarin, chromene, xanthene, dihydrobenzofuran and benzofuran derivatives, via the insertion of arynes into the C=O bond of aldehydes or formamides are summarized.

  17. Synthesis, Fluorescence Properties and Biological Activity of 8-Hydroxyquinoline Conjugate Bonded Aromatic Heterocyclic Derivatives

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Four kinds of 8-hydroxyquinoline conjugate bonded aromatic heterocyclic derivatives were designed and syn-thesized for potential use in the emission and electron conduction layers in organic light emitting devices, and as luminescent probes for metal ions. These novel compounds were characterized by IR, 1H NMR,13C NMR, Mass and UV-visible spectra. The photoluminescent properties of the new compounds including the spectra (shape of bands,λex, λem), quantum yield (pf) and lifetime (t) were investigated. Moreover, density functional theory method was used to study the relationship between the geometric configuration and emission wavelength. MTT assays of cell proliferation of rMSC and DPPH radical-scavenging tests suggested that the new compounds generate a sig-nificant increase of rMSC and demonstrate a good antioxidant activity.

  18. Synthesis of Methyl-substituted Phthalazinone-based Aromatic Poly(amide imide)s

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A series of novel aromatic poly ( amide imide)s containing phthalazinone moieties were prepared from 2-(4-aminophenyl)-4-[3-methyl-4-(4-aminophenoxy)-2,3-phthalazinone-1], a novel diamine 1 with four diimide-dicarboxylic acids by Yamazaki phosphorylation method with the inherent viscosity of 0.360.65 dL/g. These polymers had high glass transition temperatures above 300(C and they lost 10% weight between 426~475℃ in N2. The structure of diamine 1 and the polymers was confirmed by IR, 1H NMR and MS. The obtained polymers were readily soluble in polar solvents such as NMP, m-cresol etc. and easily cast into tough, flexible films. The X-ray indicated that they are all amorphous.

  19. Synthesis and liquid crystalline properties of hyperbranched aromatic polyesters consisting of azoxybenzene mesogens and polymethylene spacers

    International Nuclear Information System (INIS)

    A new series of hyperbranched aromatic polyesters containing azoxybenzene mesogens and polymethylene spacers were prepared by polymerizing AB2 type monomers that have the isophthaloyl dicarboxylic acid terminal at one end and the p-oxyphenol terminal at the other end. The monomers contain a built-in azoxybenzene mesogen that is linked to the terminal groups through polymethylene spacers. The polyesters prepared were characterized by solution viscosity , differential scanning calorimetry, X-ray diffractometry and polarizing microscopy. All of the polyesters were found to be thermotropic (nematic). Their glass-transition temperatures and mesophase temperature ranges were very sensitive to the length of the two spacers existing in the repeating unit. The degree of branching of one of the polyesters was determined by the NMR spectroscopy and found to be 0.56

  20. Asymmetric synthesis of aromatic β-amino acids using ω-transaminase: Optimizing the lipase concentration to obtain thermodynamically unstable β-keto acids.

    Science.gov (United States)

    Mathew, Sam; Jeong, Seong-Su; Chung, Taeowan; Lee, Sang-Hyeup; Yun, Hyungdon

    2016-01-01

    Synthesized aromatic β-amino acids have recently attracted considerable attention for their application as precursors in many pharmacologically relevant compounds. Previous studies on asymmetric synthesis of aromatic β-amino acids using ω-transaminases could not be done efficiently due to the instability of β-keto acids. In this study, a strategy to circumvent the instability problem of β-keto acids was utilized to generate β-amino acids efficiently via asymmetric synthesis. In this work, thermodynamically stable β-ketoesters were initially converted to β-keto acids using lipase, and the β-keto acids were subsequently aminated using ω-transaminase. By optimizing the lipase concentration, we successfully overcame the instability problem of β-keto acids and enhanced the production of β-amino acids. This strategy can be used as a general approach to efficiently generate β-amino acids from β-ketoesters.

  1. Allenylphosphonates with a 1,3,2-dioxaphosphorinane ring: Synthesis, structures, stability and utility

    Indian Academy of Sciences (India)

    N N Bhuvan Kumar; Manab Chakravarty; N Satish Kumar; K V Sajna; K C Kumara Swamy

    2009-01-01

    Synthesis, structures and stability (thermal and air) of allenylphosphonates of the type (OCH2CMe2CH2O)P(O)C(R)=C=CR'R" and [R"R'C=C=C(R)P(O)(OCH2)2]2C are discussed. Thermally activated dimerization (cycloaddition) of (OCH2CMe2CH2O)P(O)C(H)=C=CMe2 leads to the phosphonocyclobutane [(OCH2CMe2CH2O)P(O)C(H)=]2[C-CMe2]2 (18). Many of these allenes undergo addition of diethylamine to lead to enaminophosphonates that are readily hydrolysed by water to lead to -ketophosphonates. The latter compounds are useful as Horner-Wadsworth-Emmons (HWE) reagents. Molecular structures of (OCH2CMe2CH2O)P(O)C(CH2OH)=C=CH2 (6), [H2C=C=C(H)P(O)(OCH2)2]2C (9), (OCH2CMe2CH2O)P(O)CH=C=CH2 (12), [(OCH2CMe2CH2O)P(O)C(H)=]2[C-CMe2]2 (18), and the -ketophosphonate (OCH2CMe2CH2O)P(O)CH2)-C(O)CHMe2 (24) have been determined. In compound 6, intermolecular hydrogen bonding between the phosphoryl oxygen and the hydroxyl group leading to an infinite chain is observed. In 6, there is a significant deviation (ca 7°) from the orthogonality expected between the planes containing 4 atoms of (a) H2C=C and (b) C=C(H)P in the allene part. In 9, weak C-H…O interaction between the phosphoryl oxygen atom and a CH2 proton of the six-membered ring is present.

  2. Synthesis and characterization of a three-ring bent-core compound

    Institute of Scientific and Technical Information of China (English)

    TANG Yanhong; MEI Chongyu; LI Shaojun; WANG Yan; WANG Xingdong; WANG Lixiang; YAN Donghang; YE Cheng

    2005-01-01

    To investigate the vacuum-deposited films of the banana-shaped mesogens, we prepared a three-ring bent-core (that is, banana-shaped) compound m-bis(4-p- octoxysryrenyl)benzene (m-OSB) and used it as a prototype for studying the related film physics. Herein the synthesis and the structural characterization of m-OSB are reported. 13C and 1H NMR spectra and IR spectrum confirm that m-OSB has a symmetric and all-trans conformation. The results of differential scanning calorimetry, polarizing optical microscopy and X-ray diffractometry indicate that no liquid crystalline phase but two crystalline phases are present in this material: phase I (T<66℃) and phase II (66℃

  3. One-step synthesis of α,β-unsaturated arylsulfones by a novel multicomponent reaction of aromatic aldehydes,chloroacetonitrile, benzenesulfinic acid sodium salt

    Institute of Scientific and Technical Information of China (English)

    Lei Zhang; Mao Hua Ding; Hong Yun Guo

    2012-01-01

    A new and green method for the synthesis of α,β-unsaturated arylsulfones had been achieved through the condensation of aromatic aldehydes,chloroacetonitrile,benzenesulfinic acid sodium salt in the presence of 1-butyl-3-methyl imidazolium hydroxide ([bmim]OH) in EtOH under reflux.The ionic liquid was recovered and recycled for subsequent reactions.The advantages of this protocol were non-toxic,easy work-up and good yields.

  4. PhI(OAc)2-mediated one-pot oxidative decarboxylation and aromatization of tetrahydro-β-carbolines: synthesis of norharmane, harmane, eudistomin U and eudistomin I.

    Science.gov (United States)

    Kamal, Ahmed; Tangella, Yellaiah; Manasa, Kesari Lakshmi; Sathish, Manda; Srinivasulu, Vunnam; Chetna, Jadala; Alarifi, Abdullah

    2015-08-28

    Iodobenzene diacetate was employed as a mild and efficient reagent for one-pot oxidative decarboxylation of tetrahydro-β-carboline acids and dehydrogenation of tetrahydro-β-carbolines to access the corresponding aromatic β-carbolines. To the best of our knowledge this is the first synthesis of β-carbolines via a one-pot oxidative decarboxylation at ambient temperature. The utility of this protocol has been demonstrated in the synthesis of β-carboline alkaloids norharmane (2o), harmane (2p), eudistomin U (9) and eudistomin I (12). PMID:26099113

  5. Synthesis and Evaluation of Changes Induced by Solvent and Substituent in Electronic Absorption Spectra of New Azo Disperse Dyes Containig Barbiturate Ring

    Directory of Open Access Journals (Sweden)

    Hooshang Hamidian

    2013-01-01

    Full Text Available Six azo disperse dyes were prepared by diazotizing 4-amino hippuric acid and coupled with barbituric acid and 2-thiobarbituric acid. Then, the products were reacted with aromatic aldehyde, sodium acetate, and acetic anhydride, and oxazolone derivatives were formed. Characterization of the dyes was carried out by using UV-Vis, FT-IR, 1H NMR and 13C NMR, and mass spectroscopic techniques. The solvatochromic behavior of azo disperse dyes was evaluated in various solvents. The effects of substituents of aromatic aldehyde, barbiturate, and thiobarbiturate ring on the color of dyes were investigated.

  6. Dissipation of polycyclic aromatic hydrocarbons (PAHs) in the rhizosphere: Synthesis through meta-analysis

    International Nuclear Information System (INIS)

    Polycyclic aromatic hydrocarbons (PAHs) are widespread and persistent organic pollutants with high carcinogenic effect and toxicity; their behavior and fate in the soil-plant system have been widely investigated. In the present paper, meta-analysis was used to explore the interaction between plant growth and dissipation of PAHs in soil based on the large body of published literature. Plants have a promoting effect on PAH dissipation in soils. There was no difference in PAH dissipation between soils contaminated with single and mixed PAHs. However, plants had a more obvious effect on PAH dissipation in freshly-spiked soils than in long-term field-polluted soils. Additionally, a positive effect of the number of microbial populations capable of degrading PAHs was observed in the rhizosphere compared with the bulk soil. Our meta-analysis established the importance of the rhizosphere effect on PAH dissipation in variety of the soil-plant systems. - The meta-analysis provides the first quantitative evidence of the positive effect of rhizosphere processes on PAH dissipation.

  7. Synthesis of MDIPA, an aromatic diamine curative for polyurethane adhesives. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, F.N.

    1980-09-01

    The compound 4,4'-methylene bis-(2,6-diisopropylaniline), or MDIPA, has shown good thermal stability, high butt tensile strength, and excellent compatibility with salt when used as a curative for LLL's Halthane 87 prepolymer. Laboratory-scale synthesis of MDIPA by condensation of commercially-available 2,6-diisopropylaniline and formaldehyde has been accomplished, using the amine sulfate as an intermediate. Polymer Pilot Plant scale-up has been achieved; kilogram quantities at acceptable purity levels (98+ percent) have been produced.

  8. Straightforward synthesis of deuterated precursors to demonstrate the biogenesis of aromatic thiols in wine.

    Science.gov (United States)

    Roland, Aurélie; Schneider, Rémi; Razungles, Alain; Le Guernevé, Christine; Cavelier, Florine

    2010-10-13

    Straightforward synthesis of labeled S-3-(hexan-1-ol)-glutathione and S-4-(4-methylpentan-2-one)-glutathione has been developed through a conjugate addition optimization study. Sauvignon blanc fermentation experiments with the [(2)H(10)] S-4-(4-methylpentan-2-one)-glutathione used as a tracer released the corresponding deuterated thiol, thus proving the direct relationship with the 4-mercapto-4-methylpentan-2-one under enological conditions. The conversion yield of such transformation was estimated to be close to 0.3%, opening an avenue for additional study on varietal thiol biogenesis. PMID:20825191

  9. Orthogonal ring-closing alkyne and olefin metathesis for the synthesis of small GTPase-targeting bicyclic peptides.

    Science.gov (United States)

    Cromm, Philipp M; Schaubach, Sebastian; Spiegel, Jochen; Fürstner, Alois; Grossmann, Tom N; Waldmann, Herbert

    2016-01-01

    Bicyclic peptides are promising scaffolds for the development of inhibitors of biological targets that proved intractable by typical small molecules. So far, access to bioactive bicyclic peptide architectures is limited due to a lack of appropriate orthogonal ring-closing reactions. Here, we report chemically orthogonal ring-closing olefin (RCM) and alkyne metathesis (RCAM), which enable an efficient chemo- and regioselective synthesis of complex bicyclic peptide scaffolds with variable macrocycle geometries. We also demonstrate that the formed alkyne macrocycle can be functionalized subsequently. The orthogonal RCM/RCAM system was successfully used to evolve a monocyclic peptide inhibitor of the small GTPase Rab8 into a bicyclic ligand. This modified peptide shows the highest affinity for an activated Rab GTPase that has been reported so far. The RCM/RCAM-based formation of bicyclic peptides provides novel opportunities for the design of bioactive scaffolds suitable for the modulation of challenging protein targets. PMID:27075966

  10. Synthesis, Characterization, and Electropolymerization of Extended Fused-Ring Thieno[3,4-b]pyrazine-Based Terthienyls

    Directory of Open Access Journals (Sweden)

    Kristine L. Konkol

    2016-05-01

    Full Text Available The synthesis, characterization, and electropolymerization of a series of extended fused-ring thieno[3,4-b]pyrazine-based terthienyls are reported. The target terthienyls contain a central extended thieno[3,4-b]pyrazine analogue containing 2-thienyl units at the reactive α-positions of the central thiophene. The extended fused-ring thieno[3,4-b]pyrazine analogues studied include acenaphtho[1,2-b]thieno[3,4-e]pyrazine, dibenzo[f,h]thieno[3,4-b]quinoxaline, and thieno[3′,4′:5,6]-pyrazino[2,3-f][1,10]phenanthroline. Comparison of the electrochemical and photophysical properties to simple thieno[3,4-b]pyrazine-based terthienyls and their polymeric analogues are reported in order to provide structure-function relationships within this series of compounds and materials.

  11. Orthogonal ring-closing alkyne and olefin metathesis for the synthesis of small GTPase-targeting bicyclic peptides.

    Science.gov (United States)

    Cromm, Philipp M; Schaubach, Sebastian; Spiegel, Jochen; Fürstner, Alois; Grossmann, Tom N; Waldmann, Herbert

    2016-04-14

    Bicyclic peptides are promising scaffolds for the development of inhibitors of biological targets that proved intractable by typical small molecules. So far, access to bioactive bicyclic peptide architectures is limited due to a lack of appropriate orthogonal ring-closing reactions. Here, we report chemically orthogonal ring-closing olefin (RCM) and alkyne metathesis (RCAM), which enable an efficient chemo- and regioselective synthesis of complex bicyclic peptide scaffolds with variable macrocycle geometries. We also demonstrate that the formed alkyne macrocycle can be functionalized subsequently. The orthogonal RCM/RCAM system was successfully used to evolve a monocyclic peptide inhibitor of the small GTPase Rab8 into a bicyclic ligand. This modified peptide shows the highest affinity for an activated Rab GTPase that has been reported so far. The RCM/RCAM-based formation of bicyclic peptides provides novel opportunities for the design of bioactive scaffolds suitable for the modulation of challenging protein targets.

  12. Synthesis of the ABCD and ABCDE ring systems of azaspiracid-1†‡

    OpenAIRE

    Zhou, Xiao-Ti; Carter, Rich G.

    2004-01-01

    The efficient syntheses of the ABCD ring system of the originally proposed structure of azaspiracid-1 and the ABCDE ring system of the revised structure of azaspiracid-1 containing the correct stereochemistry at C6, C10, C13, C14, C16, C17, C19, C21, C22, C24 and C25 have been achieved.

  13. Efficient synthesis of the C/D rings of atisine-type C20-diterpenoid alkaloids

    Institute of Scientific and Technical Information of China (English)

    De Lin Chen; Feng Peng Wang

    2012-01-01

    A bicyclo[2.2.2]octane C/D ring system,with a lactonic ring at C-8 and C-9,of the atisine-type C20-diterpenoid alkaloids,was successfully synthesized,using an oxidative dearomatization/intramolecular Diels-Alder reaction.

  14. New Multi-1,2,3-Selenadiazole Aromatic Derivatives

    Directory of Open Access Journals (Sweden)

    S. Ratrout

    2005-09-01

    Full Text Available The aromatic polyketones 3a-d are versatile compounds for the synthesis of the multi-1,2,3-selenadiazole aromatic derivatives 1a-d. The preparation starts with the reaction between the multi-bromomethylene benzene derivatives 2a-d and 4-hydroxy- acetophenone to give compounds 3a-d which are transformed through the reaction with semicarbazide hydrochloride or ethyl hydrazine carboxylate into the corresponding semicarbazones derivatives 4a-d or hydrazones 5a-d. The reaction with selenium dioxide leads to regiospecific ring closure of semicarbazones or hydrazones to give the multi- 1,2,3-selenadiazole aromatic derivatives in high yield.

  15. Synthesis and characterization of aromatic and aliphatic ether bridged polymers containing carbazole moieties

    Energy Technology Data Exchange (ETDEWEB)

    Kaya, İsmet, E-mail: kayaismet@hotmail.com; Temizkan, Kevser; Aydın, Aysel

    2013-08-01

    Graphical abstract: Novel ether bridged polymers containing carbazole moieties were synthesized via elimination of HBr. Fluorescence measurements of the polymers were performed using N,N′-dimethyl formamide solutions. The morphologic properties of the polymers were investigated by using Scanning Electron Microscopy. Thermal stabilities were determined TGA measurements. -- Highlights: • Novel ether bridged polymers containing carbazole moieties were synthesized via elimination of HBr. • Fluorescence measurements of the polymers were performed using DMF solutions. • The morphologic properties of the polymers were investigated by using Scanning Electron Microscopy. • Thermal stabilities were determined TGA measurements. -- Abstract: In this study, the polymers were synthesized ether bridged containing carbazole moieties via HBr elimination. Also, these polymers include the aliphatic chains at the different lengths and aromatic groups in their structures. However, the polymers were characterized by FT-IR, NMR and UV–vis spectroscopy, and their thermal stabilities were determined via TGA measurements. Fluorescence measurements were performed using N,N′-dimethyl formamide solutions and also, the optimization of the concentrations to obtain maximal emission intensity was investigated in N,N′-dimethyl formamide. The morphologic properties of the polymers were investigated at different particle sizes by using Scanning Electron Microscopy (SEM). Additionally, the number average molecular weight (M{sub n}), weight average molecular weight (M{sub w}) and polydispersity index (PDI) values of the polymers were determined by size exclusion chromatography (SEC) technique. Resultantly, the remarkable properties related to the fluorescence and thermal measurements of the polymers were obtained. Therefore, these polymers could be used in various application fields because of the fluorescent and thermal properties.

  16. Reactivity umpolung in intramolecular ring closure of 3,4-disubstituted butenolides: diastereoselective total synthesis of paeonilide.

    Science.gov (United States)

    Deore, Prashant S; Argade, Narshinha P

    2013-11-15

    Remarkable reactivity reversal stratagem in 3,4-disubstituted butenolides under acidic conditions is described. Design of a suitably substituted multifunctional butenolide followed by an acid-catalyzed chemo- and diastereoselective intramolecular ring closure via the reactivity umpolung has been demonstrated to accomplish a concise total synthesis of paeonilide. Overall, the present protocol involves one-pot reduction of an α,β-unsaturated carbon-carbon double bond and intramolecular nucleophilic insertion of oxygen function at the electron-rich γ-position of butenolide. The involved mechanistic aspects have also been discussed. PMID:24175675

  17. Synthesis and Ring-Opening Metathesis Polymerization of Second-Generation Dendronized Poly(ether Monomers Initiated by Ruthenium Carbenes

    Directory of Open Access Journals (Sweden)

    Guzmán Pablo E.

    2016-03-01

    Full Text Available The Ring-Opening Metathesis Polymerization (ROMP of second-generation dendronized monomers is described. Using the highly active and fast-initiating third-generation ruthenium complex [(H2IMes(pyr2Cl2RuCHPh], moderate to high molecular weight polymers (430-2230 kDa are efficiently synthesized with low dispersities (Ð = 1.01-1.17. This study highlights the power of the metathesis approach toward polymer synthesis in a context where monomer structure can significantly impede polymerization.

  18. Synthesis, characterization and thermal properties of new aromatic quaternary ammonium bromides: precursors for ionic liquids and complexation studies

    Science.gov (United States)

    Busi, Sara; Lahtinen, Manu; Ropponen, Jarmo; Valkonen, Jussi; Rissanen, Kari

    2004-10-01

    Series of new aromatic R2R‧2N+Br- (R=benzyl, 4-methylbenzyl, 2-phenylethyl, 3-phenylpropyl; R‧=ethyl, methyl, isopropyl) or RR‧2NH+Br--type (R=benzyl, R‧=isopropyl) quaternary ammonium bromides were prepared by using novel synthetic route in which a formamide (N,N-diethylformamide, N,N-dimethylformamide, N,N-diisopropylformamide) is treated with aralkyl halide in presence of a weak base. The compounds were characterized by 1H-NMR and 13C-NMR spectroscopy and mass spectrometry. Structures of the crystalline compounds were determined by X-ray single crystal diffraction, and in addition the powder diffraction method was used to study the structural similarities between the single crystal and microcrystalline bulk material. Three of the compounds crystallized in monoclinic, two in orthorhombic and one in triclinic crystal system, showing ion pairs, which are interconnected by weak hydrogen bonds and weak π - π interactions between the phenyl rings. Three of the compounds appeared as viscous oil or waxes. Finally, TG/DTA and DSC methods were used to analyze thermal properties of the prepared compounds. The lowest melting points were obtained for diethyldi-(2-phenylethyl)ammonium bromide (122.2 °C) and for diethyldi-(3-phenylpropyl)-ammonium bromide (109.1 °C). In general, decomposition of the compounds started at 170-190 °C without identifiable cleavages, thus liquid ranges of 30-70 °C were observed for some of the compounds.

  19. Design and synthesis of aromatic molecules for probing electric-fields at the nanoscale

    CERN Document Server

    Faez, Sanli; Markoulides, Marios; Buda, Francesco; Gourdon, André; Orrit, Michel

    2015-01-01

    We propose using halogenated organic dyes as nanoprobes for electric field and show their greatly enhanced Stark coefficients using density functional theory (DFT) calculations. We analyse halogenated variants of three molecules that have been of interest for cryogenic single molecule spectroscopy, perylene, terrylene, and dibenzoterrylene, with the zero-phonon optical transitions at blue, red, and near infrared. Out of all the combinations of halides and binding sites that are calculated, we have found that fluorination of the optimum binding site induces a dipole difference between ground and excited states larger than 0.5 D for all three molecules with the highest value of 0.69 D for fluoroperylene. We also report on synthesis of 3-fluoroterrylene and bulk spectroscopy of this compound in liquid and solid organic environments.

  20. Pyrazine motif containing hexagonal macrocycles: synthesis, characterization, and host-guest chemistry with nitro aromatics.

    Science.gov (United States)

    Bhowmick, Sourav; Chakraborty, Sourav; Das, Atanu; Nallapeta, Sivaramaiah; Das, Neeladri

    2015-09-21

    The synthesis and characterization of cationic two-dimensional metallamacrocycles having a hexagonal shape and cavity are described. Both macrocycles utilize a pyrazine motif containing an organometallic acceptor tecton with platinum(II) centers along with different donor ligands. While one macrocycle is a relatively larger [6 + 6], the other is a relatively smaller [2 + 2] polygon. A unique feature of the smaller ensemble is that it is an irregular polygon in which all six edges are not of equal length. Molecular modeling of these macrocycles confirmed the presence of hexagonal cavities. The ability of these π-electron rich macrocycles to act as potential hosts for relatively electron deficient nitroaromatics (DNT = 2,4-dinitrotoluene and PA = picric acid) has been studied using isothermal titration calorimetry (ITC) as a tool. Molecular dynamics simulation studies were subsequently performed to gain critical insight into the binding interactions between the nitroaromatic guest molecules (PA/DNT) and the ionic macrocycles reported herein.

  1. Synthesis, structure, redox and spectra of green iridium complexes of tridentate azo-aromatic ligands

    Indian Academy of Sciences (India)

    Manashi Panda; Chayan Das; Chen-Hsiung Hung; Sreebrata Goswami

    2007-01-01

    Reactions of IrCl3$\\cdot$ H2O with the ligands, 2-[(phenylamino)phenylazo]pyridine (HL1a) and 2-[(-tolylamino)phenylazo]pyridine (HL1b) produce [Ir(L1)2]Cl (L1 = L1a, [1]Cl and L1 = L1b, [2]Cl) along with many unidentified products. The iridium complexes have been characterized by various techniques such as X-ray crystallography, mass spectrometry, 1H and 13C NMR, cyclic voltammetry and absorption studies. The complex [1]ClO4 crystallises in triclinic space group. The crystallographic data have been determined. Notably, the Ir-N (azo) lengths are short (av. 1.9875(4) Å) as compared to the remaining four Ir-N lengths (av. 2.052(5) Å). There is significant degree of ligand backbone conjugation in the coordinated ligands, which result in shortening of the C-N lengths on the other side of the middle phenyl ring and also in lengthening of the diazo (N=N) lengths. The complexes display multiple low energy transitions ranging between 1010 and 450 nm. These are electro active and show three reversible redox responses in the potential range, +1.5 V to -1.5 V. The cathodic potential responses are ascribed as ligand reductions, while the redox process at the anodic potential occurs at a mixed metal-ligand (HOMO) orbital.

  2. From lignin to cycloparaffins and aromatics: directional synthesis of jet and diesel fuel range biofuels using biomass.

    Science.gov (United States)

    Bi, Peiyan; Wang, Jicong; Zhang, Yajing; Jiang, Peiwen; Wu, Xiaoping; Liu, Junxu; Xue, He; Wang, Tiejun; Li, Quanxin

    2015-05-01

    The continual growth in commercial aviation fuels and more strict environmental legislations have led to immense interest in developing green aviation fuels from biomass. This paper demonstrated a controllable transformation of lignin into jet and diesel fuel range hydrocarbons, involving directional production of C8-C15 aromatics by the catalytic depolymerization of lignin into C6-C8 low carbon aromatic monomers coupled with the alkylation of aromatics, and the directional production of C8-C15 cycloparaffins by the hydrogenation of aromatics. The key step, the production of the desired C8-C15 aromatics with the selectivity up to 94.3%, was achieved by the low temperature alkylation reactions of the lignin-derived monomers using ionic liquid. The synthetic biofuels basically met the main technical requirements of conventional jet fuels. The transformation potentially provides a useful way for the development of cycloparaffinic and aromatic components in jet fuels using renewable lignocellulose biomass. PMID:25710678

  3. From lignin to cycloparaffins and aromatics: directional synthesis of jet and diesel fuel range biofuels using biomass.

    Science.gov (United States)

    Bi, Peiyan; Wang, Jicong; Zhang, Yajing; Jiang, Peiwen; Wu, Xiaoping; Liu, Junxu; Xue, He; Wang, Tiejun; Li, Quanxin

    2015-05-01

    The continual growth in commercial aviation fuels and more strict environmental legislations have led to immense interest in developing green aviation fuels from biomass. This paper demonstrated a controllable transformation of lignin into jet and diesel fuel range hydrocarbons, involving directional production of C8-C15 aromatics by the catalytic depolymerization of lignin into C6-C8 low carbon aromatic monomers coupled with the alkylation of aromatics, and the directional production of C8-C15 cycloparaffins by the hydrogenation of aromatics. The key step, the production of the desired C8-C15 aromatics with the selectivity up to 94.3%, was achieved by the low temperature alkylation reactions of the lignin-derived monomers using ionic liquid. The synthetic biofuels basically met the main technical requirements of conventional jet fuels. The transformation potentially provides a useful way for the development of cycloparaffinic and aromatic components in jet fuels using renewable lignocellulose biomass.

  4. Enzyme catalytic nitration of aromatic compounds.

    Science.gov (United States)

    Kong, Mingming; Wang, Kun; Dong, Runan; Gao, Haijun

    2015-06-01

    Nitroaromatic compounds are important intermediates in organic synthesis. The classic method used to synthesize them is chemical nitration, which involves the use of nitric acid diluted in water or acetic acid, both harmful to the environment. With the development of green chemistry, environmental friendly enzyme catalysis is increasingly employed in chemical processes. In this work, we adopted a non-aqueous horseradish peroxidase (HRP)/NaNO2/H2O2 reaction system to study the structural characteristics of aromatic compounds potentially nitrated by enzyme catalysis, as well as the relationship between the charges on carbon atoms in benzene ring and the nitro product distribution. Investigation of various reaction parameters showed that mild reaction conditions (ambient temperature and neutral pH), plus appropriate use of H2O2 and NaNO2 could prevent inactivation of HRP and polymerization of the substrates. Compared to aqueous-organic co-solvent reaction media, the aqueous-organic two-liquid phase system had great advantages in increasing the dissolved concentration of substrate and alleviating substrate inhibition. Analysis of the aromatic compounds' structural characteristics indicated that substrates containing substituents of NH2 or OH were readily catalyzed. Furthermore, analysis of the relationship between natural bond orbital (NBO) charges on carbon atoms in benzene ring, as calculated by the density functional method, and the nitro product distribution characteristics, demonstrated that the favored nitration sites were the ortho and para positions of substituents in benzene ring, similar to the selectivity of chemical nitration.

  5. RING Dimerization Links Higher-Order Assembly of TRIM5α to Synthesis of K63-Linked Polyubiquitin

    Directory of Open Access Journals (Sweden)

    Zinaida Yudina

    2015-08-01

    Full Text Available Members of the tripartite motif (TRIM protein family of RING E3 ubiquitin (Ub ligases promote innate immune responses by catalyzing synthesis of polyubiquitin chains linked through lysine 63 (K63. Here, we investigate the mechanism by which the TRIM5α retroviral restriction factor activates Ubc13, the K63-linkage-specific E2. Structural, biochemical, and functional characterization of the TRIM5α:Ubc13-Ub interactions reveals that activation of the Ubc13-Ub conjugate requires dimerization of the TRIM5α RING domain. Our data explain how higher-order oligomerization of TRIM5α, which is promoted by the interaction with the retroviral capsid, enhances the E3 Ub ligase activity of TRIM5α and contributes to its antiretroviral function. This E3 mechanism, in which RING dimerization is transient and depends on the interaction of the TRIM protein with the ligand, is likely to be conserved in many members of the TRIM family and may have evolved to facilitate recognition of repetitive epitope patterns associated with infection.

  6. Synthesis of Poly(aryl ether ketone) Copolymers Containing Adamantyl-substituted Naphthalene Rings

    Institute of Scientific and Technical Information of China (English)

    ZHU Xiao-liang; ZHANG Shu-ling; REN Dian-fu; GUAN Shao-wei; WANG Gui-bin; JIANG Zhen-hua

    2009-01-01

    @@ 1 Introduction High performance polymers have received considerable attention over the past decade owing to their increased demands as replacements for metals or ceramics in automotive,aerospace,and microelectronic industries.Poly(aryl ether ketone)s(PAEKs) are a class of important high-performance aromatic polymers with excellent mechanical properties,good solvent resistance,size-accuracy,electrical characteristics,and superior thermal stability[1-3].

  7. Synthesis of Calystegine A(3) from Glucose by the Use of Ring-Closing Metathesis

    DEFF Research Database (Denmark)

    Monrad, Rune Nygaard; Pipper, Charlotte Bressen; Madsen, Robert

    2009-01-01

    and allylated in the same pot. The functionalized nona-1,8-diene, thus obtained, is converted into the seven-membered carbon skeleton in calystegine A(3) by ring-closing olefin metathesis. Subsequent deoxygenation by the Barton-McCombie protocol, hydroboration and oxidative workup followed by hydrogenolysis...

  8. Synthesis and Cytotoxicity of Derivatives of Fluorouracil Conjugated with Three-membered Ring

    Institute of Scientific and Technical Information of China (English)

    WANG, Le; ZHANG, Yunxiao; TAO, Jingchao

    2009-01-01

    A novel series of 3-membered ring fluorouracil conjugates including cyclopropylmethyl fluorouracil and (2,3- epoxypropyl) fluorouracil conjugates were synthesized via selective protection, and their structures were confirmed by IR, 1H NMR and HRMS. Cytotoxicities in vitro of these conjugates were evaluated. Compounds 7, 8, 12 and 13 have shown cytotoxicities against Ec9706 cells in different degrees.

  9. Synthesis of the rice herbicide HW-52 [dichlorophenyl ring-14C(U)

    International Nuclear Information System (INIS)

    14C-labeled 2', 3'-dichloro-4-(ethoxymethoxy)benzanilide (HW-52) was synthesized in a total of 9 steps from 1,3-dinitrobenzene [14C(U)]. The key intermediate 2,3-dichloroaniline [14C(U)] was prepared from the starting material by a series of aromatic substitutions and functional group manipulations. Conversion to the final product was achieved in high yield by coupling and further functional group manipulations. The overall radiochemical yield was 1.88% and radiochemical purity of the product was greater than 98.8%. (author)

  10. Synthesis of cyclic 1-alkenylboronates via Zr-mediated double functionalization of alkynylboronates and sequential Ru-catalyzed ring-closing olefin metathesis.

    Science.gov (United States)

    Nishihara, Yasushi; Suetsugu, Masato; Saito, Daisuke; Kinoshita, Megumi; Iwasaki, Masayuki

    2013-05-17

    Synthesis of novel cyclic 1-alkenylboronates is accomplished through the zirconium-mediated regio- and stereoselective double functionalization of 1-alkynylboronates and the subsequent ruthenium-catalyzed ring-closing metathesis (RCM). The obtained substituted cyclic 1-alkenylboronates are transformed into o-terphenyl and triphenylene derivatives.

  11. Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products

    Directory of Open Access Journals (Sweden)

    Alexander O. Terent'ev

    2014-01-01

    Full Text Available The present review describes the current status of synthetic five and six-membered cyclic peroxides such as 1,2-dioxolanes, 1,2,4-trioxolanes (ozonides, 1,2-dioxanes, 1,2-dioxenes, 1,2,4-trioxanes, and 1,2,4,5-tetraoxanes. The literature from 2000 onwards is surveyed to provide an update on synthesis of cyclic peroxides. The indicated period of time is, on the whole, characterized by the development of new efficient and scale-up methods for the preparation of these cyclic compounds. It was shown that cyclic peroxides remain unchanged throughout the course of a wide range of fundamental organic reactions. Due to these properties, the molecular structures can be greatly modified to give peroxide ring-retaining products. The chemistry of cyclic peroxides has attracted considerable attention, because these compounds are used in medicine for the design of antimalarial, antihelminthic, and antitumor agents.

  12. Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products

    Science.gov (United States)

    Borisov, Dmitry A; Vil’, Vera A; Dembitsky, Valery M

    2014-01-01

    Summary The present review describes the current status of synthetic five and six-membered cyclic peroxides such as 1,2-dioxolanes, 1,2,4-trioxolanes (ozonides), 1,2-dioxanes, 1,2-dioxenes, 1,2,4-trioxanes, and 1,2,4,5-tetraoxanes. The literature from 2000 onwards is surveyed to provide an update on synthesis of cyclic peroxides. The indicated period of time is, on the whole, characterized by the development of new efficient and scale-up methods for the preparation of these cyclic compounds. It was shown that cyclic peroxides remain unchanged throughout the course of a wide range of fundamental organic reactions. Due to these properties, the molecular structures can be greatly modified to give peroxide ring-retaining products. The chemistry of cyclic peroxides has attracted considerable attention, because these compounds are used in medicine for the design of antimalarial, antihelminthic, and antitumor agents. PMID:24454562

  13. Synthesis and mesomorphic behaviour of achiral four-ring unsymmetrical bent-core liquid crystals: Nematic phases

    Science.gov (United States)

    Paul, Manoj Kumar; Kalita, Gayatri; Laskar, Atiqur Rahman; Debnath, Somen; Gude, Venkatesh; Sarkar, Dipika Debnath; Mohiuddin, Golam; Varshney, Sanjay Kumar; Nandiraju Rao, V. S.

    2013-10-01

    Achiral four ring unsymmetrical bent-core liquid crystals derived from 3-amino-2-methylbenzoic acid have been designed and synthesized with an imine, ester and photochromic azo linking moieties. These hockey-stick shape resembling bent molecules possess an alkoxy chain at one end of the molecule and methyl or methoxy group at the other end. The synthesis, phase transition temperatures and characterization of phase behaviour are discussed. The molecular structure characterization is consistent with data from elemental and spectroscopic analysis. The materials thermal behaviour and phase characterization have been investigated by differential scanning calorimetry and polarizing optical microscopy. All these compounds exhibit enantiotropic nematic phase over wide temperature range. Stable supercooling of nematic phase has been observed in methoxy homologues. The density functional theory (DFT) calculations were performed to obtain the stable molecular conformation, polarizability, dipole moment, Highest occupied molecular orbital (HOMO), Lowest unoccupied molecular orbital (LUMO) energies and bending angle of the compound.

  14. Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products.

    Science.gov (United States)

    Terent'ev, Alexander O; Borisov, Dmitry A; Vil', Vera A; Dembitsky, Valery M

    2014-01-01

    The present review describes the current status of synthetic five and six-membered cyclic peroxides such as 1,2-dioxolanes, 1,2,4-trioxolanes (ozonides), 1,2-dioxanes, 1,2-dioxenes, 1,2,4-trioxanes, and 1,2,4,5-tetraoxanes. The literature from 2000 onwards is surveyed to provide an update on synthesis of cyclic peroxides. The indicated period of time is, on the whole, characterized by the development of new efficient and scale-up methods for the preparation of these cyclic compounds. It was shown that cyclic peroxides remain unchanged throughout the course of a wide range of fundamental organic reactions. Due to these properties, the molecular structures can be greatly modified to give peroxide ring-retaining products. The chemistry of cyclic peroxides has attracted considerable attention, because these compounds are used in medicine for the design of antimalarial, antihelminthic, and antitumor agents. PMID:24454562

  15. Synthesis, characterization and comparative evaluation of phenoxy ring containing long chain gemini imidazolium and pyridinium amphiphiles.

    Science.gov (United States)

    Bhadani, Avinash; Kataria, Hardeep; Singh, Sukhprit

    2011-09-01

    Two series of phenoxy ring containing long chain imidazolium and pyridinium based gemini amphiphiles have been synthesized from renewable cardanol oil having different spacers (i. e. -S-(CH(2))(n)-S-, where n is 2, 3, 4 & 6). Critical micelle concentration (cmc) of these new gemini amphiphiles has been determined by conductivity method. Further, these new cationic amphiphiles have been evaluated for their DNA binding capability by agarose gel electrophoresis, ethidium bromide exclusion experiments and transmission electron microscopy (TEM). The cytotoxicity of these new amphiphiles have been evaluated by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Comparative studies of these phenoxy ring containing long chain gemini imidazolium amphiphiles and their pyridinium analogues depicted low cmc values of the later but greater DNA interaction capability and low cytotoxicity of the former series of amphiphiles. PMID:21676409

  16. Synthesis of first row transition metal carboxylate complexes by ring opening reactions of cyclic anhydrides

    Indian Academy of Sciences (India)

    Jubaraj Bikash Baruah

    2011-03-01

    Hydrolytic and solvolytic ring opening reactions of phthalic anhydride, pyromellitic dianhydride and 2,3-pyridine dicarboxylic anhydride in the presence of various transition metal salts with or without a ancillary ligands were studied. The reactions were found to be dependent on stoichiometry of ligand and types of anhydride used. In the case of pyromellitic dianhydride selective ring opening reaction by cobalt(II) ions gave 1,3-benzene dicarboxylate derivatives, whereas use of copper(II) ions gave 1,4-benzene dicarboxylate derivatives. Preference for methanolysis was seen in the case of copper (II) promoted reactions of pyromellitic dianhydride in the presence of 1:1 metal to 1,10-phenanthroline ratio.

  17. Synthesis and action on the central nervous system of mescaline analogues containing piperazine or homopiperazine rings.

    Science.gov (United States)

    Majchrzak, M W; Kotełko, A; Guryn, R; Lambert, J B; Szadowska, A; Kowalczyk, K

    1983-03-01

    Structural juxtaposition of the 3,4,5-trimethoxyphenyl group in the same molecule with a piperazine or homopiperazine ring has been realized in a series of mescaline analogues (I-IV) as part of an investigation into the pharmacological properties of the seven-membered perhydro-1,4-diazepines (homopiperazines). The analogous six-membered piperazines were synthesized and tested as reference substances to determine whether the seven-membered ring conveyed special properties. A variety of pharmacological tests of action on the CNS showed that replacement of the amino group in mescaline by the heterocycles significantly alters the biological activity. In particular, both the piperazine and the homopiperazine derivatives displayed sedative activity to about the same extent.

  18. SYNTHESIS OF A NOVEL CHELATING RESIN WITH HETEROCYCLIC RING OF S AND N

    Institute of Scientific and Technical Information of China (English)

    QU Rongjun; SUN Changmei; JI Chunnuan; WANG Chunhua; CHENG Guoxiang

    2003-01-01

    By the reaction of poly(bromoacetyl styrene) (EBPS) with thiaurea (TU), a kind of novel chelating resin with heterocyaclic ring of sulfur and nitrogen, poly[4-(2-amino)thiazoleyl-4-vinylben=ene], was synthesized. Its structure was characterized by FTIR and elemental analysis. The factors which have influence on the reaction such as reaction time, solvents, and molar ratio of reactants were investigated.

  19. Synthesis of graft polyrotaxane by simultaneous capping of backbone and grafting from rings of pseudo-polyrotaxane

    Directory of Open Access Journals (Sweden)

    Kazuaki Kato

    2014-11-01

    Full Text Available Graft polyrotaxanes, with poly(ε-caprolactone (PCL graft chains on the ring components were synthesized by the simultaneous ring-opening polymerization of ε-caprolactone from both ends of the backbone polymer, an end-functionalized polyethylene glycol (PEG and the formation of inclusion complexes with α-cyclodextrin (α-CD. PEG with multiple functional groups at each end was prepared by the condensation of PEG-amine and D-gluconic acid; the PEG derivative formed an inclusion complex with α-CD. The polymerization of multiple hydroxy groups at the backbone ends resulted in a star-shaped end group, which served as a bulky capping group to prevent dethreading. In contrast, PEG with only one hydroxy group at each end did not produce polyrotaxanes, indicating that single PCL chains were too thin to confine α-CDs to the complex. In addition, the grafting polymerization proceeded properly only when robust hydrogen bonds formed between α-CDs were dissociated using a basic catalyst. Since the dissociation also induced dethreading, kinetic control of the polymerization and dissociation were crucial for producing graft polyrotaxanes. Consequently, this three-step reaction yielded graft polyrotaxanes in a good yield, demonstrating a significant simplification of the synthesis of graft polyrotaxanes.

  20. SYNTHESIS, CHARACTERIZATION AND RING-OPENING POLYMERIZATION OF CYCLIC (ARYLENE PHOSPHONATE) OLIGOMERS

    Institute of Scientific and Technical Information of China (English)

    Hong-ming Zhang; Qing-zhong Guo; Tian-lu Chen

    2004-01-01

    A series of cyclic (arylene phosphonate) oligomers were prepared by reaction of phenylphosphonic dichloride (PPD) with various bisphenols under pseudo-high dilution conditions via interfacial polycondensation. The yield of cyclic (arylenc phosphonate) oligomers is over 85% by using hexadecyltrimethylammonium bromide as phase transfer catalyst (PTC) at 0 ℃. The structures of the cyclic oligomers were confirmed by a combination of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and IR analysis. These cyclic oligomers undergo facile ring-opening polymerization in the melt by using potassium 4,4'-biphenoxide as the initiator to give linear polyphosphonate. Free-radical ring-opening polymerization of cyclic(arylene phosphonate) oligomers containing sulfur linkages was also performed in the melt using 2,2'-dithiobis(benzothiazole) (DTB) as the initiator at 270℃ and the resulting polymer had a Mw of 8 × 103 with a molecular weight distribution of 4. Ring-opening copolymerization of these cyclic oligomers with cyclic carbonate oligomers was also achieved. The average molecular weight of the resulting copolymer is higher than the corresponding homopolymer and the thermal stability of the copolymer is better than the corresponding homopolymer.

  1. Synthesis of Human Milk Oligosaccharides and Regioselective Ring Opening of Oxabicycles

    DEFF Research Database (Denmark)

    Jennum, Camilla Arboe

    the fucose is also attached in the same pot. In addition, pNP-neuraminic acid was synthesized for the purpose to perform activity studies on enzymes. The enzymes were designed to perform sialyl transfer reactions in the synthesis human milk oligosaccharides containing neuraminic acid. OH O HO HO O OH O HO O...

  2. Synthesis of 1-Bromo-3-methoxy-4-propoxy-5-iodobenzene-A Novel Efficient Process for the Synthesis of Brominated Aromatic Compound

    Institute of Scientific and Technical Information of China (English)

    Hong Xin SHI; Hui LIN; Gérard MANDVILLE

    2004-01-01

    The reaction of aromatic carboxylic acid with oxalyl chloride gives rise to the corres- ponding acid chloride which without purification is treated with the sodium salt of mercapto- pyridine oxide in the presence of 2,2-azo-bisisobutyronitrile (AIBN), radical initiator to give a brominated aromatic compound. After etherification and oxidation, 5-iodovaniline was converted to trisubstituted benzene carboxylic acid which give 1-bromo-3-methoxy-4-propoxy-5-iodo- benzene by this new brominating process with a yield of 74 %.

  3. Synthesis of aromatic (13)C/(2)H-α-ketoacid precursors to be used in selective phenylalanine and tyrosine protein labelling.

    Science.gov (United States)

    Lichtenecker, R J

    2014-10-14

    Recent progress in protein NMR spectroscopy revealed aromatic residues to be valuable information sources for performing structure and motion analysis of high molecular weight proteins. However, the applied NMR experiments require tailored isotope labelling patterns in order to regulate spin-relaxation pathways and optimize magnetization transfer. We introduced a methodology to use α-ketoacids as metabolic amino acid precursors in cell-based overexpression of phenylalanine and/or tyrosine labelled proteins in a recent publication, which we have now developed further by providing synthetic routes to access the corresponding side-chain labelled precursors. The target compounds allow for selective introduction of (13)C-(1)H spin systems in a highly deuterated chemical environment and feature alternating (12)C-(13)C-(12)C ring-patterns. The resulting isotope distribution is especially suited to render straightforward (13)C spin relaxation experiments possible, which provide insight into the dynamic properties of the corresponding labelled proteins.

  4. Synthesis and Biological Activity of New Pyrethroid Acid Oxime-esters Containing Pyrazole Ring

    Institute of Scientific and Technical Information of China (English)

    MA Jun-an; HUANG Run-qiu; FENG Lei; SONG Jian; QIU De-wen

    2003-01-01

    A series of compounds containing oxime-ester linkage and pyrazole ring(in place of the ester linkage and the alcohol moiety in pyrethroid ester) was designed and synthesized. The structures of all the compounds prepared were confirmed by 1H NMR and MS spectroscopy as well as elemental analyses. The bioassay data of those compounds against tobacco mosaic virus(TMV), cucumber mosaic virus(CMV), potato virus X(PVX) and potato virus Y(PVY) were presented. Among them compound 6i was found to possess significant plant antiviral activities. But all the compounds showed low insecticidal and acaricidal activities.

  5. Low Catalyst Loadings in Olefin Metathesis: Synthesis of Nitrogen Heterocycles by Ring Closing Metathesis

    Science.gov (United States)

    Kuhn, Kevin M.; Champagne, Timothy M.; Hong, Soon Hyeok; Wei, Wen-Hao; Nickel, Andrew; Lee, Choon Woo; Virgil, Scott C.; Grubbs, Robert H.; Pederson, Richard L.

    2010-01-01

    (eq 1) A series of ruthenium catalysts have been screened under ring closing metathesis (RCM) conditions to produce five-, six-, and seven-membered carbamate-protected cyclic amines. Many of these catalysts demonstrated excellent RCM activity and yields with as low as 500 ppm catalyst loadings. RCM of the five-membered carbamate-series could be run neat, the six-membered carbamate-series could be run at 1.0 M concentrations and the seven-membered carbamate-series worked best at 0.2 M to 0.05 M concentrations. PMID:20141172

  6. Synthesis of all-hydrocarbon stapled α-helical peptides by ring-closing olefin metathesis.

    Science.gov (United States)

    Kim, Young-Woo; Grossmann, Tom N; Verdine, Gregory L

    2011-06-01

    This protocol provides a detailed procedure for the preparation of stapled α-helical peptides, which have proven their potential as useful molecular probes and as next-generation therapeutics. Two crucial features of this protocol are (i) the construction of peptide substrates containing hindered α-methyl, α-alkenyl amino acids and (ii) the ring-closing olefin metathesis (RCM) of the resulting resin-bound peptide substrates. The stapling systems described in this protocol, namely bridging one or two turns of an α-helix, are highly adaptable to most peptide sequences, resulting in favorable RCM kinetics, helix stabilization and promotion of cellular uptake.

  7. Recent applications of ring-closing metathesis in the synthesis of lactams and macrolactams.

    Science.gov (United States)

    Hassan, Hani Mutlak A

    2010-12-28

    Lactams are an important class of compounds owing to their presence in numerous biologically active molecules of natural and unnatural nature. They are also highly versatile intermediates that can be elaborated into interesting compounds for potential use in organic and medicinal chemistry endeavors. In this feature article, the reader will be given a background to olefin metathesis followed by concise discussions (with selected examples) to report recent applications of ring-closing metathesis to form lactams and macrolactams from acyclic diene precursors, an area which continues to deposit attractive applications in the chemical literature en route or in the final step to the target molecules.

  8. Low catalyst loadings in olefin metathesis: synthesis of nitrogen heterocycles by ring-closing metathesis.

    Science.gov (United States)

    Kuhn, Kevin M; Champagne, Timothy M; Hong, Soon Hyeok; Wei, Wen-Hao; Nickel, Andrew; Lee, Choon Woo; Virgil, Scott C; Grubbs, Robert H; Pederson, Richard L

    2010-03-01

    A series of ruthenium catalysts have been screened under ring-closing metathesis (RCM) conditions to produce five-, six-, and seven-membered carbamate-protected cyclic amines. Many of these catalysts demonstrated excellent RCM activity and yields with as low as 500 ppm catalyst loadings. RCM of the five-membered carbamate series could be run neat, the six-membered carbamate series could be run at 1.0 M, and the seven-membered carbamate series worked best at 0.2-0.05 M.

  9. Drug-Initiated, Controlled Ring-Opening Polymerization for the Synthesis of Polymer-Drug Conjugates

    OpenAIRE

    Tong, Rong; Cheng, Jianjun

    2012-01-01

    Paclitaxel, a polyol chemotherapeutic agent, was covalently conjugated through its 2′-OH to polylactide with 100% regioselectivity via controlled polymerization of lactide mediated by paclitaxel/(BDI-II)ZnN(TMS)2 (BDI-II = 2-((2,6-diisopropylphenyl)amino)-4-((2,6-diisopropylphenyl)imino)-2-pentene). The steric bulk of the substituents on the N-aryl groups of the BDI ligand drastically affected the regiochemistry of coordination of the metal catalysts to paclitaxel and the subsequent ring-open...

  10. Efficient synthesis of novel glutamate homologues and investigation of their affinity and selectivity profile at ionotropic glutamate receptors.

    Science.gov (United States)

    Pinto, Andrea; Tamborini, Lucia; Mastronardi, Federica; Ettari, Roberta; Romano, Diego; Nielsen, Birgitte; De Micheli, Carlo; Conti, Paola

    2014-04-15

    A convenient synthesis of four new enantiomerically pure acidic amino acids is reported and their affinity at ionotropic glutamate receptors was determined. The new compounds are higher homologues of glutamic acid in which the molecular complexity has been increased by introducing an aromatic/heteroaromatic ring, that is a phenyl or a thiophene ring, that could give additional electronic interactions with the receptors. The results of the present investigation indicate that the insertion of an aromatic/heteroaromatic ring into the amino acid skeleton of glutamate higher homologues is well tolerated and this modification could be exploited to generate a new class of NMDA antagonists. PMID:24630559

  11. The application of catalytic ring-closing olefin metathesis to the synthesis of unsaturated oxygen heterocycles

    Energy Technology Data Exchange (ETDEWEB)

    Fu, G.C.; Grubbs, R.H. [California Institute of Technology, Pasadena, CA (United States)

    1992-06-17

    The development of general approaches to carbon-carbon bond formation represents an important ongoing challenge for synthetic organic chemists. One efficient method for constructing carbon-carbon double bonds, the transition metal alkylidene-catalyzed olefin metathesis reaction, has been the focus of intense interest in recent years from the standpoint of both mechanism and polymer synthesis, in contrast, use of this transformation in organic synthesis has been limited. As part of a broader program directed toward establishing transition metal alkylidenes as versatile reagents for organic chemistry, the authors report the successful application of catalytic olefin methathesis to the generation of a variety of unsaturated oxygen heterocycles. 13 refs., 1 fig., 1 tab.

  12. Peptide aromatic interactions modulated by fluorinated residues: Synthesis, structure and biological activity of Somatostatin analogs containing 3-(3',5'difluorophenyl)-alanine.

    Science.gov (United States)

    Martín-Gago, Pablo; Rol, Álvaro; Todorovski, Toni; Aragón, Eric; Martin-Malpartida, Pau; Verdaguer, Xavier; Vallès Miret, Mariona; Fernández-Carneado, Jimena; Ponsati, Berta; Macias, Maria J; Riera, Antoni

    2016-01-01

    Somatostatin is a 14-residue peptide hormone that regulates the endocrine system by binding to five G-protein-coupled receptors (SSTR1-5). We have designed six new Somatostatin analogs with L-3-(3',5'-difluorophenyl)-alanine (Dfp) as a substitute of Phe and studied the effect of an electron-poor aromatic ring in the network of aromatic interactions present in Somatostatin. Replacement of each of the Phe residues (positions 6, 7 and 11) by Dfp and use of a D-Trp8 yielded peptides whose main conformations could be characterized in aqueous solution by NMR. Receptor binding studies revealed that the analog with Dfp at position 7 displayed a remarkable affinity to SSTR2 and SSTR3. Analogs with Dfp at positions 6 or 11 displayed a π-π interaction with the Phe present at 11 or 6, respectively. Interestingly, these analogs, particularly [D-Trp8,L-Dfp11]-SRIF, showed high selectivity towards SSTR2, with a higher value than that of Octreotide and a similar one to that of native Somatostatin. PMID:27271737

  13. Peptide aromatic interactions modulated by fluorinated residues: Synthesis, structure and biological activity of Somatostatin analogs containing 3-(3′,5′difluorophenyl)-alanine

    Science.gov (United States)

    Martín-Gago, Pablo; Rol, Álvaro; Todorovski, Toni; Aragón, Eric; Martin-Malpartida, Pau; Verdaguer, Xavier; Vallès Miret, Mariona; Fernández-Carneado, Jimena; Ponsati, Berta; Macias, Maria J.; Riera, Antoni

    2016-01-01

    Somatostatin is a 14-residue peptide hormone that regulates the endocrine system by binding to five G-protein-coupled receptors (SSTR1–5). We have designed six new Somatostatin analogs with L-3-(3′,5′-difluorophenyl)-alanine (Dfp) as a substitute of Phe and studied the effect of an electron-poor aromatic ring in the network of aromatic interactions present in Somatostatin. Replacement of each of the Phe residues (positions 6, 7 and 11) by Dfp and use of a D-Trp8 yielded peptides whose main conformations could be characterized in aqueous solution by NMR. Receptor binding studies revealed that the analog with Dfp at position 7 displayed a remarkable affinity to SSTR2 and SSTR3. Analogs with Dfp at positions 6 or 11 displayed a π-π interaction with the Phe present at 11 or 6, respectively. Interestingly, these analogs, particularly [D-Trp8,L-Dfp11]-SRIF, showed high selectivity towards SSTR2, with a higher value than that of Octreotide and a similar one to that of native Somatostatin. PMID:27271737

  14. Synthesis, insecticidal activity, and structure-activity relationship (SAR) of anthranilic diamides analogs containing oxadiazole rings.

    Science.gov (United States)

    Li, Yuhao; Zhu, Hongjun; Chen, Kai; Liu, Rui; Khallaf, Abdalla; Zhang, Xiangning; Ni, Jueping

    2013-06-28

    A series of anthranilic diamides analogs (3–11, 16–24) containing 1,2,4- or 1,3,4-oxadiazole rings were synthesized and characterized by (1)H NMR, MS and elemental analyses. The structure of 3-bromo-N-(2-(3-(4-bromophenyl)-1,2,4-oxadiazol-5-yl)-4-chloro-6-methylphenyl)-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxamide (18, CCDC-) was determined by X-ray diffraction crystallography. The insecticidal activities against Plutella xylostella and Spodoptera exigua were evaluated. The results showed that most of title compounds displayed good larvicidal activities against P. xylostella, especially compound 3-bromo-N-(4-chloro-2-methyl-6-(5-(methylthio)-1,3,4-oxadiazol-2-yl)phenyl)-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxamide (6), which displayed 71.43% activity against P. xylostella at 0.4 μg mL(-1) and 33.33% against S. exigua at 1 μg mL(-1). The structure-activity relationship showed that compounds decorated with a 1,3,4-oxadiazole were more potent than compounds decorated with a 1,2,4-oxadiazole, and different substituents attached to the oxadiazole ring also affected the insecticidal activity. This work provides some hints for further structure modification and the enhancement of insecticidal activity.

  15. Synthesis, Structure Optimization and Antifungal Screening of Novel Tetrazole Ring Bearing Acyl-Hydrazones

    Directory of Open Access Journals (Sweden)

    Manzoor A. Malik

    2012-08-01

    Full Text Available Azoles are generally fungistatic, and resistance to fluconazole is emerging in several fungal pathogens. In an attempt to find novel azole antifungal agents with improved activity, a series of tetrazole ring bearing acylhydrazone derivatives were synthesized and screened for their in vitro antifungal activity. The mechanism of their antifungal activity was assessed by studying their effect on the plasma membrane using flow cytometry and determination of the levels of ergosterol, a fungal-specific sterol. Propidium iodide rapidly penetrated a majority of yeast cells when they were treated with the synthesized compounds at concentrations just above MIC, implying that fungicidal activity resulted from extensive lesions of the plasma membrane. Target compounds also caused a considerable reduction in the amount of ergosterol. The results also showed that the presence and position of different substituents on the phenyl ring of the acylhydrazone pendant seem to play a role on the antifungal activity as well as in deciding the fungistatic and fungicidal nature of the compounds.

  16. SYNTHESIS AND MAGNETIC PROPERTIES OF COMPLEXES OF A CONJUGATED HYPERBRANCHED POLYMER CONTAINING BITHIAZOLE RINGS

    Institute of Scientific and Technical Information of China (English)

    Neng-wen Ding; Wei-lin Sun; Yan Lin; Zhi-quan Shen

    2012-01-01

    A novel conjugated hyperbranched polymer containing bithiazole rings (PBTADB) was synthesized by polycondensation of 1,3,5-benzenetricarboxaldehyde and 2,2′-diamino-4,4′-bithiazole (DABT).The structure of the hyperbranched polymer was confirmed by FT-IR and 1H-NMR.PBTADB dissolved in organic polar solvents such as DMSO and NMP.Bithiazole rings were introduced to provide bidentate N-donor sites for binding metal ions.The metal complexes were prepared by chelation of the polymer with Co2+ and Sm3+.The magnetic behavior of coordination compounds was measured as a function of magnetic field strength (0-4.8 × l06 A/m) at 5 K and as a function of temperature (5-300 K) at magnetic field strength of 2.4 × 106 A/m.The magnetic hysteresis loops of PBTADB-Sm3+ and PBTADB-Co2+ showed the typical ‘S' shape at 5 K with the Curie-Weiss temperature Tθ =96 K and 41 K respectively.The results show that they exhibit properties of soft ferromagnetic materials.

  17. Synthesis, insecticidal activity, and structure-activity relationship (SAR) of anthranilic diamides analogs containing oxadiazole rings.

    Science.gov (United States)

    Li, Yuhao; Zhu, Hongjun; Chen, Kai; Liu, Rui; Khallaf, Abdalla; Zhang, Xiangning; Ni, Jueping

    2013-06-28

    A series of anthranilic diamides analogs (3–11, 16–24) containing 1,2,4- or 1,3,4-oxadiazole rings were synthesized and characterized by (1)H NMR, MS and elemental analyses. The structure of 3-bromo-N-(2-(3-(4-bromophenyl)-1,2,4-oxadiazol-5-yl)-4-chloro-6-methylphenyl)-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxamide (18, CCDC-) was determined by X-ray diffraction crystallography. The insecticidal activities against Plutella xylostella and Spodoptera exigua were evaluated. The results showed that most of title compounds displayed good larvicidal activities against P. xylostella, especially compound 3-bromo-N-(4-chloro-2-methyl-6-(5-(methylthio)-1,3,4-oxadiazol-2-yl)phenyl)-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxamide (6), which displayed 71.43% activity against P. xylostella at 0.4 μg mL(-1) and 33.33% against S. exigua at 1 μg mL(-1). The structure-activity relationship showed that compounds decorated with a 1,3,4-oxadiazole were more potent than compounds decorated with a 1,2,4-oxadiazole, and different substituents attached to the oxadiazole ring also affected the insecticidal activity. This work provides some hints for further structure modification and the enhancement of insecticidal activity. PMID:23657615

  18. 4-Trifluoromethyl-p-quinols as dielectrophiles: three-component, double nucleophilic addition/aromatization reactions

    Science.gov (United States)

    Dong, Jinhuan; Shi, Lou; Pan, Ling; Xu, Xianxiu; Liu, Qun

    2016-06-01

    In recent years, numerous methods have emerged for the synthesis of trifluoromethylated arenes based on the late-stage introduction of a trifluoromethyl group onto an aryl ring. In sharp comparison, the synthesis of trifluoromethylated arenes based on the pre-introduction of a trifluoromethyl group onto an “aromatic to be” carbon has rarely been addressed. It has been found that 4-trifluoromethyl-p-quinol silyl ethers, the readily available and relatively stable compounds, can act as dielectrophiles to be applied to multi-component reactions for the synthesis of various trifluoromethylated arenes. Catalyzed by In(OTf)3, 4-trifluoromethyl-p-quinol silyl ethers react with C-, N-, and S-nucleophiles, respectively, in a regiospecific 1,2-addition manner to generate the corresponding highly reactive electrophilic intermediates. Further reaction of the in-situ generated electrophiles with a C-nucleophile followed by spontaneous aromatization enables the construction of functionalized trifluoromethyl arenes. This three-component, double nucleophilic addition/aromatization reaction based on the pre-introduction of a trifluoromethyl group onto an “aromatic to be” carbon provides a divergent strategy for the synthesis of trifluoromethylated arenes under mild reaction conditions in a single operation.

  19. Combinatorial Solid-Phase Synthesis of Aromatic Oligoamides: A Research-Based Laboratory Module for Undergraduate Organic Chemistry

    Science.gov (United States)

    Fuller, Amelia A.

    2016-01-01

    A five-week, research-based experiment suitable for second-semester introductory organic laboratory students is described. Each student designs, prepares, and analyzes a combinatorial array of six aromatic oligoamides. Molecules are prepared on solid phase via a six-step synthetic sequence, and purities and identities are determined by analysis of…

  20. Charge migration in dicationic electrophiles and its application to the synthesis of aza-polycyclic aromatic compounds.

    Science.gov (United States)

    Li, Ang; Kindelin, Patrick J; Klumpp, Douglas A

    2006-03-16

    [reaction: see text] Superacid-promoted reactions of dicationic electrophiles have been studied, and the positive charge centers are found to migrate apart in a predictable manner. Using isotopic labeling the charge migration is found in one system to occur through successive deprotonation-reprotonation steps. The charge migration chemistry is the basis for new general synthetic route to aza-polycyclic aromatic compounds.

  1. Aromatic-Aromatic Interactions in Biological System: Structure Activity Relationships

    Energy Technology Data Exchange (ETDEWEB)

    Rajagopal, Appavu; Deepa, Mohan [Molecular Biophysics Unit, Indian Institute of Sciences-Bangalore, Karnataka (India); Govindaraju, Munisamy [Bio-Spatial Technology Research Unit, Department of Environmental Biotechnology, School of Environmental Sciences, Bharathidasan University, Tiruchirappalli, Tamil Nadu (India)

    2016-02-26

    While, intramolecular hydrogen bonds have attracted the greatest attention in studies of peptide conformations, the recognition that several other weakly polar interactions may be important determinants of folded structure has been growing. Burley and Petsko provided a comprehensive overview of the importance of weakly polar interactions, in shaping protein structures. The interactions between aromatic rings, which are spatially approximate, have attracted special attention. A survey of the proximal aromatic residue pairs in proteins, allowed Burley and Petsko to suggest that, “phenyl ring centroids are separated by a preferential distance of between 4.5 and 7 Å, and dihedral angles approximately 90° are most common”.

  2. Aromatic-Aromatic Interactions in Biological System: Structure Activity Relationships

    Directory of Open Access Journals (Sweden)

    Rajagopal Appavu

    2016-03-01

    Full Text Available While, intramolecular hydrogen bonds have attracted the greatest attention in studies of peptide conformations, the recognition that several other weakly polar interactions may be important determinants of folded structure has been growing. Burley and Petsko provided a comprehensive overview of the importance of weakly polar interactions, in shaping protein structures. The interactions between aromatic rings, which are spatially approximate, have attracted special attention. A survey of the proximal aromatic residue pairs in proteins, allowed Burley and Petsko to suggest that, “phenyl ring centroids are separated by a preferential distance of between 4.5 and 7 Å, and dihedral angles approximately 90° are most common”.

  3. Aromatic-Aromatic Interactions in Biological System: Structure Activity Relationships

    International Nuclear Information System (INIS)

    While, intramolecular hydrogen bonds have attracted the greatest attention in studies of peptide conformations, the recognition that several other weakly polar interactions may be important determinants of folded structure has been growing. Burley and Petsko provided a comprehensive overview of the importance of weakly polar interactions, in shaping protein structures. The interactions between aromatic rings, which are spatially approximate, have attracted special attention. A survey of the proximal aromatic residue pairs in proteins, allowed Burley and Petsko to suggest that, “phenyl ring centroids are separated by a preferential distance of between 4.5 and 7 Å, and dihedral angles approximately 90° are most common”

  4. Pendant triazole ring assisted mesogen containing side chain liquid crystalline polymethacrylates: Synthesis and characterization

    Indian Academy of Sciences (India)

    T Palani; C Saravanan; P Kannan

    2011-01-01

    Two series of click chemistry assisted alkoxymethyl-1H-[1,2,3]-triazol-1-yl containing sidechain liquid-crystalline polymethacrylates were synthesized by free radical polymerization technique. Mesogen was linked to backbone through various spacer units. Monomers and polymers were characterized by FT-IR, 1H and 13C-NMR spectral techniques. Thermal stability of polymers was confirmed by thermogravimetric analysis. Mesomorphic property and phase transition temperature of polymers were analysed by differential scanning calorimetry and polarized optical microscopy. Phase transition temperature and mesomorphic property of polymers with respect to insertion of polar alkoxy group on terminal triazole ring and spacer length between backbone and mesogen were investigated. Polymers exhibited grainy like textures under polarized optical microscopy. Spacer length between mesogen and backbone alters phase transition temperature of the polymers.

  5. Synthesis of Cobalt Containing Block Copolymers Via Ring Opening Metathesis Polymerizastion (ROMP)

    Institute of Scientific and Technical Information of China (English)

    Bongjin Moon; Minhyuk Kang

    2004-01-01

    In order to realize a metal containing nano-structure, a block-copolymer containing alkynyl groups in one block was designed and synthesized by living ring opening metathesis polymerization (ROMP) technique. The newly developed bis-3-bromopyridine complex of Grubbs catalyst was employed in the series of polymerization and it yielded the desired polymers with great molecular weight control and narrow polydispersities. The characteristics of the block copolymers were investigated by gel permeation chromatography, H- and 13H- NMR spectroscopy. Complexation of the alkynyl group containing block copolymers by treatment with dicobalt octacarbonyl occurred smoothly in 5 min at room temperature. GPC analysis before and after cobalt complexation indicated a significant increase of the hydrodynamic volume. AFM images of the films before and after the complexation also showed a noticeable change in its morphology where grain sizes become smaller and more regular upon complexation.

  6. Synthesis, Structure and Properties of Two Photochromic Compounds Containing A Pyrazolone-ring

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Two photochromic compounds with the pyrazolone-ring as the photochromic functional structure, 2-(1'-phenyl-3'-methyl-4'-benzoformyl-pyrazolone-5')-thiosemicarbazone(PMBP-TSC) and 2-(1'-phenyl-3'-methyl-4'-benzoformyl-pyrazolone-5')-S-methylthiosemicarbazone(PMBP-MTSC), were synthesized and characterized by elemental analysis, MS, IR spectra, NMR spectra. The crystal structure of the photocolored product of PMBP-TSC was determined by single crystal XRD analysis. The results show that the photochromic phenomenon is due to the photoisomerization from enol form to keto form. Their photochromic properties were studied by powder-UV reflectance spectra under the irradiation of 200-380 nm light. The first-order rate constants of the photocoloring reaction were found to be 7.80×10-3 s-1 for compound 1A and 1.03×10-3 s-1 for compound 2A.

  7. SYNTHESIS AND CHARACTERIZATION OF CELLULOSE-GRAFT-POLY (L-LACTIDE VIA RING-OPENING POLYMERIZATION

    Directory of Open Access Journals (Sweden)

    Shu Xiao,

    2012-02-01

    Full Text Available Cellulose-graft-poly (L-lactide (cellulose-g-PLLA was prepared under homogeneous mild conditions. Ring-opening polymerization (ROP was carried out successfully using 4-dimethylaminopyridine (DMAP as an organic catalyst in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl. The structure of the polymer was characterized by GPC, 1H NMR, 13C NMR, FT-IR, TGA, WAXD, and AFM. The results indicated that the grafting rate of the polymer reached 4.44, which was higher than that reported in AmimCl with Sn(oct2 as a catalyst. In addition, AFM showed that the polymer in solution could aggregate and self-assemble into an approximately spherical structure, which was different from the rod-like structure of cellulose and round-like polylactic acid particles.

  8. Efficient Synthesis of 2—Ethyl—A—ring Analogues of 19—Nor—1α,25—dihydroxy Vitamin D3

    Institute of Scientific and Technical Information of China (English)

    WangQiu-an; ZHAOYu-rui

    2003-01-01

    The novel 19-nor-1α,25-dihydroxy vitamin D3 analogues possessing an ethyl at the 2-position(4 and 5).were synthesized by coupling 25-hydroxy Windaus-Grundmann ketone derivative 20 with A-ring synthons(15 and 19)respectively.The enantioselective synthesis of substituted bicyclic[3,1,0]hexanes structure A-ring synthons,started from all-cis-3,5-dihydroxy-4-ethyl-1-(methoxycarbonyl)cyclohexane via lipase-catalyzd asymmetrization,was demonstratcd.

  9. Superconductivity in aromatic hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Kubozono, Yoshihiro, E-mail: kubozono@cc.okayama-u.ac.jp [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Research Center of New Functional Materials for Energy Production, Storage and Transport, Okayama University, Okayama 700-8530 (Japan); Japan Science and Technology Agency, ACT-C, Kawaguchi 332-0012 (Japan); Goto, Hidenori; Jabuchi, Taihei [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Yokoya, Takayoshi [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Research Center of New Functional Materials for Energy Production, Storage and Transport, Okayama University, Okayama 700-8530 (Japan); Kambe, Takashi [Department of Physics, Okayama University, Okayama 700-8530 (Japan); Sakai, Yusuke; Izumi, Masanari; Zheng, Lu; Hamao, Shino; Nguyen, Huyen L.T. [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Sakata, Masafumi; Kagayama, Tomoko; Shimizu, Katsuya [Center of Science and Technology under Extreme Conditions, Osaka University, Osaka 560-8531 (Japan)

    2015-07-15

    Highlights: • Aromatic superconductor is one of core research subjects in superconductivity. Superconductivity is observed in certain metal-doped aromatic hydrocarbons. Some serious problems to be solved exist for future advancement of the research. This article shows the present status of aromatic superconductors. - Abstract: ‘Aromatic hydrocarbon’ implies an organic molecule that satisfies the (4n + 2) π-electron rule and consists of benzene rings. Doping solid aromatic hydrocarbons with metals provides the superconductivity. The first discovery of such superconductivity was made for K-doped picene (K{sub x}picene, five benzene rings). Its superconducting transition temperatures (T{sub c}’s) were 7 and 18 K. Recently, we found a new superconducting K{sub x}picene phase with a T{sub c} as high as 14 K, so we now know that K{sub x}picene possesses multiple superconducting phases. Besides K{sub x}picene, we discovered new superconductors such as Rb{sub x}picene and Ca{sub x}picene. A most serious problem is that the shielding fraction is ⩽15% for K{sub x}picene and Rb{sub x}picene, and it is often ∼1% for other superconductors. Such low shielding fractions have made it difficult to determine the crystal structures of superconducting phases. Nevertheless, many research groups have expended a great deal of effort to make high quality hydrocarbon superconductors in the five years since the discovery of hydrocarbon superconductivity. At the present stage, superconductivity is observed in certain metal-doped aromatic hydrocarbons (picene, phenanthrene and dibenzopentacene), but the shielding fraction remains stubbornly low. The highest priority research area is to prepare aromatic superconductors with a high superconducting volume-fraction. Despite these difficulties, aromatic superconductivity is still a core research target and presents interesting and potentially breakthrough challenges, such as the positive pressure dependence of T{sub c} that is clearly

  10. Nine-step synthesis of (/sup 14/C)flupirtine maleate labeled in the pyridine ring

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Y.M.; Kucharczyk, N.; Sofia, R.D.

    1987-01-01

    A nine-step procedure for microscale synthesis of ethyl 2-amino-6-brace((4-fluorophenyl)methyl)aminobrace-3-pyridinyl-2,6-/sup 14/C carbamate maleate, (/sup 14/C)flupirtine maleate, was developed. The synthesis started with potassium cyanide-/sup 14/C and 1,3-dibromopropane making the following intermediates: glutarontrile-/sup 14/C, glutarimide-/sup 14/C, 2,6-dichloropyridine-2,6-/sup 14/C, 2,6-dichloro-3-nitro-pyridine-2,6-/sup 14/C, 2-amino-3-nitro-6-chloropyridine-2,6-/sup 14/C, 2-amino-3-nitro-6-(p-fluorobenzylamino)pyridine-2,6-/sup 14/C, 2,3-diamino-6-(p-fluorobenzylamino)pyridine-2,6-/sup 14/C, and ethyl 2-amino-6-brace((4-fluorophenyl)-methyl)aminobrace-3-pyridinyl-2,6-/sup 14/C carbamic acid ester hydrochloride. The overall yield was 6.3% (5.4 mCi), and the radioactivity was 99.8% as determined by high performance liquid chromatography and liquid scintillation counting.

  11. A nine-step synthesis of [14C]flupirtine maleate labeled in the pyridine ring

    International Nuclear Information System (INIS)

    A nine-step procedure for microscale synthesis of ethyl 2-amino-6-brace[(4-fluorophenyl)methyl]aminobrace-3-pyridinyl-2,6-14C carbamate maleate, [14C]flupirtine maleate, was developed. The synthesis started with potassium cyanide-14C and 1,3-dibromopropane making the following intermediates: glutarontrile-14C, glutarimide-14C, 2,6-dichloropyridine-2,6-14C, 2,6-dichloro-3-nitro-pyridine-2,6-14C, 2-amino-3-nitro-6-chloropyridine-2,6-14C, 2-amino-3-nitro-6-(p-fluorobenzylamino)pyridine-2,6-14C, 2,3-diamino-6-(p-fluorobenzylamino)pyridine-2,6-14C, and ethyl 2-amino-6-brace[(4-fluorophenyl)-methyl)aminobrace-3-pyridinyl-2,6-14C carbamic acid ester hydrochloride. The overall yield was 6.3% (5.4 mCi), and the radioactivity was 99.8% as determined by high performance liquid chromatography and liquid scintillation counting. (author)

  12. Diels-Alder addition of some 6-and 5-member ring aromatic compounds on the Si(001)-2×1 surface: dependence of the binding energy on the resonance energy of the aromatic compounds

    Institute of Scientific and Technical Information of China (English)

    LuXin

    2001-01-01

    [1]Onganer, Y., Saglam, M., Turut, A. et al., High barrier metallic polymer p-type silicon Schottky diodes, Solid State Electron, 1996, 39: 677.[2]Lonergan, M. C., A tunable diode based on an inorganic semiconductor vertical bar conjugated polymer interface, Science,1997, 278: 2103.[3]Wolkow, R. A., Moffatt, D. J., The frustrated motion of benzene on the surface of Si(l11), J. Chem. Phys., 1995,103: 10696.[4]MacPherson, C. D., Leung, K. T., Electron-induced chemistry of pyridine on Si(l 11)7x7 An LEED and TDS study,Surf. Sci., 1995, 324: 202.[5]MacPherson, C. D., Hu, D. Q., Leung, K. T., Room-temperature adsorption of thiophene and related 5-membered cyclicolefins on Si( 111)7x7 by thermal-desorption spectrometry, Surf. Sci., 1992, 276:156.[6]Cao, Y.. Wang, Z., Deng, J. F. et al., Evidence for dangling bond mediated dimerization of furan on the silicon (111 )-(7x7) surface, Angew Chem. Int. Ed., 2000, 39: 2740-2743.[7]Cao, Y., Yong, K. S., Wang, Z. Q. et al., Dry thienylation of the silicon (111)-(7x7) surface, J. Am. Chem. Soc., 2000, 112:1812.[8]Taguchi, Y., Fujisawa, M., Takaoka, T. et al., Adsorbed state of benzene on the Si(100) surface-thermal-desorption and electron-energy loss spectroscopy studies, J. Chem. Phys., 1991,95: 6870.[9]Lopinski, G. P., Fortier, T M., Moffatt, D. J. et al., Multiple bonding geometries and binding state conversion of benzene/Si(100), J. Vac. Sci. Technol., 1998, Al6: 1037.[10]Ellison, M. D., Hamers, R. J., Reactions of substituted aromatic hydrocarbons with the Si(001) surface, J. Vac. Sci.Technol., 2000, Al8: 1965.[11]Qiao, M. H., Cao, Y., Deng, J. F. et al, Formation of covalent Si-N linkages on pyrrole functionalized Si(100)-(2×l),Chem. Phys. Lett., 2000, 325: 508.[12]Konecny, R., Doren, D. J., Cycloaddition reactions of unsaturated hydrocarbons on the Si(100)-(2×1) surface: theoretical predictions, Surf. Sci., 1998, 417: 169.[13]Birkenheuer, U., Gutdeutsch, U., Rosch, N

  13. Ring-closing metathesis as key step in the synthesis of Luffarin I, 16-epi-Luffarin I and Luffarin A.

    Science.gov (United States)

    Urosa, Aitor; Marcos, Isidro S; Díez, David; Plata, Gabriela B; Padrón, José M; Basabe, Pilar

    2016-05-01

    Natural sesterterpenolides, luffarin I and luffarin A, from Luffariella geometrica have been synthesized, and this is the first reported synthesis of luffarin A. The Yamaguchi esterification of the nor-diterpenic fragment, obtained from 2.8-15μM, with the appropriate furane alcohols yielded the necessary diene intermediates for the synthesis of the target molecules. The key strategic step in this synthesis was the ring-closing metathesis (RCM) reaction of the diene intermediates. This strategy allowed for the synthesis of 16-epi-luffarin I and analogues for structure-activity relationship (SAR) studies. The most active compound exhibited antiproliferative activity against a panel of six human solid tumour cell lines with [Formula: see text] values in the range 2.8-15 M. PMID:26486134

  14. An Expeditious and Safe Synthesis of Some Exocyclic α,β-Unsaturated Ketones by Microwave-Assisted Condensation of Cyclic Ketones with Aromatic Aldehydes over Anhydrous Potassium Carbonate

    Directory of Open Access Journals (Sweden)

    Rina Mondal

    2012-01-01

    Full Text Available A rapid, efficient, and solvent-free methodology for synthesis of exocyclic α,β-unsaturated ketones of the categories E-3-arylidene-4-chromanones, E-2-arylidene-1-tetralones, E-2-arylidene-1-indanones, E-3-cinnamylidene-4-chromanones, E-2-cinnamylidene-1-tetralones, E-2-cinnamylidene-1-indanones, α,α′-(E,E-bis(arylidene-cycloalkanones, and α,α′-(E,E-bis(cinnamylidene-cycloalkanones has been developed through cross-aldol condensation of the constituent cyclic ketones and aldehydes by microwave irradiation over anhydrous potassium carbonate. However, for condensation of 1-thio-4-chromanones with aromatic aldehydes by this method, the initially formed exocyclic α,β-unsaturated ketone has been found to undergo isomerization yielding 3-(arylmethylthiochromones.

  15. Practical synthesis and cytotoxic evaluation of the pyrazino[1,2-b]-isoquinoline ring system.

    Science.gov (United States)

    Hernández-Vázquez, Eduardo; Miranda, Luis D

    2016-06-01

    A practical three-step protocol for the synthesis of pyrazino[1,2-b]isoquinolines is reported. This approach includes a one-pot parallel cyclization/cyclization parallel process followed by a non-common 6-endo Heck cyclization that transformed previously constructed Ugi adducts into diversely decorated tricyclic systems. Compounds bearing a t-butyl or 2,6-dimethylphenyl substituent showed significant cytotoxic activity. The most active analogue (6p) showed significant activity against HCT-15 and K562 (IC50 = 41.8 ± 3.3 and 57.7 ± 2.1 μM, respectively) with no cytotoxicity against human gingival fibroblasts. PMID:27161451

  16. A Simple, Rapid and Mild One Pot Synthesis of Benzene Ring Acylated and Demethylated Analogues of Harmine under Solvent-free Conditions

    OpenAIRE

    Siddiqui, Bina S.; Syed Imran Hassan; Farhat Farhat; Syed Nawazish Ali; Sabira Begum

    2008-01-01

    A simple, rapid, solvent-free, room temperature one pot synthesis of benzene ring acylated and demethylated analogues of harmine using acyl halides/acid anhydrides and AlCl3 has been developed. Eight different acyl halides/acid anhydrides were used in the synthesis. The resulting mixture of products was separated by column chromatography to afford 10- and 12-monoacyl analogues, along with 10,12-diacyl-11-hydroxy products. In five cases the corresponding 10-acyl-11-hydroxy analogues were also ...

  17. A Simple, Rapid and Mild One Pot Synthesis of Benzene Ring Acylated and Demethylated Analogues of Harmine under Solvent-free Conditions

    Directory of Open Access Journals (Sweden)

    Bina S. Siddiqui

    2008-08-01

    Full Text Available A simple, rapid, solvent-free, room temperature one pot synthesis of benzene ring acylated and demethylated analogues of harmine using acyl halides/acid anhydrides and AlCl3 has been developed. Eight different acyl halides/acid anhydrides were used in the synthesis. The resulting mixture of products was separated by column chromatography to afford 10- and 12-monoacyl analogues, along with 10,12-diacyl-11-hydroxy products. In five cases the corresponding 10-acyl-11-hydroxy analogues were also obtained. Yields from the eight syntheses (29 products in total were in the 6-34% range and all compounds were fully characterized.

  18. SYNTHESIS OF NEW AROMATIC POLY(AMIDE IMIDE)S FROM UNSYMMETRICAL EXTENDED DIAMINE CONTAINING A PHTHALAZINONE MOIETY

    Institute of Scientific and Technical Information of China (English)

    Lin Cheng; Xi-gao Jian

    2004-01-01

    The direct polymerization of an unsymmetrical kink non-coplanar heterocyclic diarnine (1) with various aromatic bis(trimellitimide)s (2a-e) using triphenyl phosphite and pyridine as condensing agents could generate a series of new aromatic poly(amide imide)s (3a-e) containing the kink non-coplanar phthalazinone heterocyclic units in the polymer main chains with inherent viscosities of 0.58-0.66 dL/g. The polymers are readily soluble in a variety of solvents such as N,Ndimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methy1-2-pyrrolidinone, pyridine and m-cresol and can be cast to form flexible and tough films. The glass transition temperatures of polymers (Ts) are in the range of 301-327℃,and the temperatures for 5% weight loss in nitrogen are in the range of 498-521 ℃.

  19. Anéis aromáticos condensados e relação E4/E6: estudo de ácidos húmicos de gleissolos por RMN de 13C no estado sólido utilizando a técnica CP/MAS desacoplamento defasado Condensed aromatic rings and E4/E6 ratio: humic acids in gleysoils studied by NMR CP/MAS13C, and dipolar dephasing

    Directory of Open Access Journals (Sweden)

    Sérgio da Costa Saab

    2007-04-01

    Full Text Available In this work, seven samples of humic acids extracted from gleysoils were investigated. These studies, using NMR CP/MAS 13C techniques, did not show significant correlation between the E4/E6 ratio and the degree of aromaticity. However, dipolar dephasing (DD measurements of condensed aromatic or substituted carbons showed a negative correlation of 0.94. Also, there was a good correlation between the amount of semiquinone free radicals measured by the EPR technique and condensed aromatic rings measured by NMR CP/MAS 13C with the DD technique. The content of semiquinone free radicals was quantified by EPR spectroscopy and was correlated with the humification (degree of aromaticity of the humic substances. The results indicated that the E4/E6 ratio identifies the degree of aromatic rings condensation. It was also found that the degree of aromaticity, measured by NMR, as frequently presented in the literature (by conventional CP/MAS, underestimates aromatic rings in condensed structures.

  20. Synthesis of a Near-Infrared Emitting Squaraine Dye in an Undergraduate Organic Laboratory

    Science.gov (United States)

    Marks, Patrick; Levine, Mindy

    2012-01-01

    Squaraines are a class of organic fluorophores that possess unique photophysical properties, including strong near-infrared absorption and emission. The synthesis of many squaraines involves the condensation of an electron-rich aromatic ring with squaric acid. These reactions are generally refluxed overnight in a benzene-butanol solvent mixture.…

  1. Synthesis and biological activities of the respiratory chain inhibitor aurachin D and new ring versus chain analogues

    Directory of Open Access Journals (Sweden)

    Xu-Wen Li

    2013-07-01

    Full Text Available Aurachins are myxobacterial 3-farnesyl-4(1H-quinolone derived compounds initially described as respiratory chain inhibitors, more specifically as inhibitors of various cytochrome complexes. They are also known as potent antibiotic compounds. We describe herein the first synthesis of aurachin D through a key Conrad–Limpach reaction. The same strategy was used to reach some ring as opposed to chain analogues, allowing for the description of structure–activity relationships. Biological screening of the analogues showed antiparasitic, cytotoxic, antibacterial and antifungal activities, and depletion of the mitochondrial membrane potential. The strongest activity was found on Plasmodium falciparum with a selectivity index of 345, compared to Vero cells, for the natural product and its geranyl analogue. The loss of mitochondrial membrane potential induced by aurachins in human U-2 OS osteosarcoma cells was studied, showing the best activity for aurachin D and a naphthalene analogue, yet without totally explaining the observed cytotoxic activity of the compounds. Finally, a synthetic entry is given to the complete carboheterocyclic core of aurachin H through the N-oxidation/epoxidation of aurachin D and a shorter chain analogue, followed by subsequent biomimetic cyclization.

  2. Bidirectional cross metathesis and ring-closing metathesis/ring opening of a C2-symmetric building block: a strategy for the synthesis of decanolide natural products

    Directory of Open Access Journals (Sweden)

    Bernd Schmidt

    2013-11-01

    Full Text Available Starting from the conveniently available ex-chiral pool building block (R,R-hexa-1,5-diene-3,4-diol, the ten-membered ring lactones stagonolide E and curvulide A were synthesized using a bidirectional olefin-metathesis functionalization of the terminal double bonds. Key steps are (i a site-selective cross metathesis, (ii a highly diastereoselective extended tethered RCM to furnish a (Z,E-configured dienyl carboxylic acid and (iii a Ru–lipase-catalyzed dynamic kinetic resolution to establish the desired configuration at C9. Ring closure was accomplished by macrolactonization. Curvulide A was synthesized from stagonolide E through Sharpless epoxidation.

  3. Bidirectional cross metathesis and ring-closing metathesis/ring opening of a C 2-symmetric building block: a strategy for the synthesis of decanolide natural products.

    Science.gov (United States)

    Schmidt, Bernd; Kunz, Oliver

    2013-01-01

    Starting from the conveniently available ex-chiral pool building block (R,R)-hexa-1,5-diene-3,4-diol, the ten-membered ring lactones stagonolide E and curvulide A were synthesized using a bidirectional olefin-metathesis functionalization of the terminal double bonds. Key steps are (i) a site-selective cross metathesis, (ii) a highly diastereoselective extended tethered RCM to furnish a (Z,E)-configured dienyl carboxylic acid and (iii) a Ru-lipase-catalyzed dynamic kinetic resolution to establish the desired configuration at C9. Ring closure was accomplished by macrolactonization. Curvulide A was synthesized from stagonolide E through Sharpless epoxidation.

  4. Metabolic activation of N-hydroxy arylamines, N-hydroxy heterocyclic amines and ring-hydroxymethyl polycyclic aromatic hydrocarbons by human sulfotransferases

    Energy Technology Data Exchange (ETDEWEB)

    Chou, H.C.

    1993-01-01

    Arylamines and polycyclic aromatic hydrocarbons (PAHs) are two major classes of chemical carcinogens. N-Hydroxylation of arylamines is regarded to be a necessary process for their mutagenicity and carcinogenicity, while alkyl-hydroxylation is the major metabolic pathway for alkyl-substituted PAHs. Evidence has been presented that sulfation of several N-hydroxy arylamines and hydroxymethyl PAHs is an important pathway leading to the formation of ultimate carcinogens in experiment animals. Sulfation of these chemicals forms putative sulfuric acid ester intermediates that can rearrange to electrophilic nitrenium or carbenium ions capable of forming covalent adducts with important cellular macromolecules. In order to study the metabolic activation by sulfotransferase(s) in various human tissue preparations an in vitro enzymatic assay was established. A metabolic phenotyping method was also developed for thermostable phenolsulfotransferase (TS-PST) in platelet homogenates (correlated with TS-PST activity in other tissues) based on a simple colorimetric assay using 2-naphthol as substrate. By using a PAPS-regenerating system to supply the activated sulfate and calf thymus DNA to trap the reactive metabolites, we found that N-hydroxy derivatives of the carcinogens, 4-aminobiphenyl (4-ABP), 4,4[prime]-methylene-bis(2-chloroaniline) (MOCA), 2-acetylaminofluorene (2-AAF), 2-aminofluorene (2-AF), 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP), and 2-amino-6-methyldipyrido [1,2-1:3[prime],2[prime]-d]imidazole (Glu-P-1) were metabolically activated by human TS-PST. On the other hand, three methyl-hydroxylated derivatives (7-OH, 12-OH, and 7,12-diOH) of 7, 12-dimethylbenz[a]anthracene (DMBA) were metabolically activated by human steroid sulfotransferase. Human sulfotransferase(s)-mediated activation of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) or 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) was not observed.

  5. Synthesis of New Bifunctional Bis(oxazolines) and Their Application in the Asymmetric Cyanosilylation of Aromatic Ketones

    Institute of Scientific and Technical Information of China (English)

    LUO,Mei; DU,Da-Ming

    2004-01-01

    @@ Catalytic asymmetric synthesis of tertiary cyanohydrins by the addition of cyanide to a wide range of ketones has important synthetic utility, since the resulting optically active cyanohydrins are important intermediates for the synthesis of a variety of valuable classes of chiral compounds. The application of oxazoline in asymmetric cyanosilylation has seldom reported in comparation with other reactions.[1] Recently, polymer-supported pyridine-bis(oxazoline) ytterbium complex was reported to catalyze cyanosilylation of benzaldehyde.

  6. SYNTHESIS AND CHARACTERIZATION OF MAIN CHAIN AROMATIC LIQUID CRYSTAL COPOLYESTERS WITH X-SHAPED AND ROD-SHAPED MESOGENIC UNITS

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    A series of main chain liquid crystal aromatic copolyesters with X-shaped and rod-shaped mesogenic units were synthesized via solution condensation polymerizations of 4, 4'-(α,ω-octanedioyloxy)-dibenzoyl dichlorides with 2,5-bis(p-octanoxy benzoyloxy)-hydroquinone and diphenol. All of the copolyesters showed thermotropic liquid crystalline behaviors through observations using DSC, polarized microscopy and X-ray diffraction. The melting point (Tm) and the isotropization temperature (Ti) change regularly with varying the content of diphenol unit in the copolymers.

  7. New thermally stable polyesters based on 2,5-pyridinedicarbonyl dichloride and aromatic diols: Synthesis and characterization

    Institute of Scientific and Technical Information of China (English)

    Hossein Nasr Isfahani; Khalil Faghihi

    2009-01-01

    Six new thermally stable polyesters (4a-f) were synthesized through the solution polycondensation reaction of 2,5-pyridine dicarbonyldichloride (2) with six aromatic diols in N,N'-dimethyl acetamide (DMAc) solution and in the presence of pyridine as a base. The polycondensation reactions produce a series of new polyesters (4a-f) in high yields, and inherent viscosity between 0.30 and 0.55 dL/g. The resulting polyesters were characterized by elemental analysis, viscosity measurements, thermal gravimetric analysis (TGA and DTG), solubility test, Fourier transform infrared (FT-IR) spectroscopy and gel permeation chromatography (GPC).

  8. Bioassay of polycyclic aromatic hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Van Kirk, E.A.

    1980-08-01

    A positive relationship was found between the photodynamic activity of 24 polycyclic aromatic hydrocarbons versus published results on the mutagenicity, carcinogenicity, and initiation of unscheduled DNA synthesis. Metabolic activation of benzo(a)pyrene resulted in detection of increased mutagenesis in Paramecium tetraurelia as found also in the Ames Salmonella assay. The utility of P. tetraurelia as a biological detector of hazardous polycyclic aromatic hydrocarbons is discussed.

  9. Two novel series of allocolchicinoids with modified seven membered B-rings: design, synthesis, inhibition of tubulin assembly and cytotoxicity.

    Science.gov (United States)

    Büttner, Frank; Bergemann, Silke; Guénard, Daniel; Gust, Ronald; Seitz, Gunther; Thoret, Sylviane

    2005-05-16

    Two new attractive series of allocolchicinoids were designed as inhibitors of tubulin assembly using the potent ketone 4 and the tetracyclic, pyrazole annulated NCME variant 7 (NCME = N-acetyl colchinol-O-methylether (2)) as lead structures. The first group of inhibitors of type 6 with novel oxepine and azepine B-ring structures belongs to the NCME-series and was synthesized via a multistep total synthesis starting from simple and cheap 3-methoxybenzaldehyde (12) and 3,4,5-trimethoxybenzaldehyde (13). Biaryl-coupling of the starting materials 12 and 13 was accomplished via Ziegler-Ullmann-reaction to furnish the biphenyl 11 equipped with two carbaldehyde functions. The subsequent Cannizzaro reaction of this dicarbaldehyde 11 proceeded with high regioselectivity to yield almost exclusively the key compound, the hydroxymethyl carboxylic acid 9. Ring closure to the o,o'-bridged biphenyls was accomplished by two routes: on the one hand, treatment of 9 with aqueous hydrochloric acid yielded the lactone 15. On the other hand, a four step sequence starting from the isomeric mixture 9/10 furnished the constitutionally isomeric lactams 23 and 24; these could be converted to the corresponding thiolactams 25 and 26 and to the tetrazole annulated NCME-type derivatives 27 and 28. The second series of bioactive compounds are congeners of allocolchicine (3). The well known desacetyl allocolchicine (29) was easily oxidized to the oxime 30, which was further transformed to the corresponding ketone 31. This served as key precursor for the syntheses of various tetracyclic allocolchicine modifications 33-36 annulated with a pyrazole, isoxazole, pyrimidine or 2-aminopyrimidine heterocycle, respectively. Unexpectedly, all the NCME-variants with a substituent in position 7 like in NCME (2) inhibited the tubulin assembly only moderately. In contrast, the new series of allocolchicine modifications proved to be highly potent antimicrotubule agents. Inhibition of tubulin assembly occurred at

  10. Towards novel adsorptive nanomaterials: Synthesis of Co2+Mo6+ LDH for sulfur and aromatic removal from crude petrolatum

    Directory of Open Access Journals (Sweden)

    Mohsen S. Mostafa

    2016-06-01

    Full Text Available In the present work Co/Mo(CO32−-LDH material of highly energetic surface was prepared by controlled titration of ammonium carbonate and ammonium hydroxide against Co and Mo cations at elevated temperatures, while different analytical techniques were applied to proof the chemical constitution and surface features of the material as XPS (X-ray Photoelectric Spectroscopy in addition to XRF metal analysis, FT-IR, SEM, XRD, DSC-TGA and N2 adsorption–desorption isotherm. The highly energetic surface due to formation of 4+ surface charge in the brucite layer between Co and Mo as confirmed by XPS was practically ensured when the freshly prepared Co2+Mo6+-LDH dried at 60 °C overnight without any activation has been applied as a novel adsorbent for the removal of the undesirable compounds (sulfur and aromatics compounds from crude waxes. Suez crude petrolatum has been used during this study. Depending on the experimental data, we were successful to prepare a new type of LDHs showed high ability for removing the undesirable compounds (sulfur and aromatics from Suez crude petrolatum. Also, in the same trend it removed low melting waxes. This leads to isolation of microcrystalline waxes from petroleum wastes which used as a lubricant, rust preventive, in the manufacture of cosmetics, and in medicine as a protective dressing, emollient, and in a lot of industrial applications.

  11. Automated synthesis of n.c.a. [18F]FDOPA via nucleophilic aromatic substitution with [18F]fluoride

    International Nuclear Information System (INIS)

    An improved, automated synthesis of [18F]FDOPA including four synthetic steps (fluorination, reductive iodination, alkylation and hydrolysis) is reported with each step optimized individually. In a home-made automatic synthesizer, 9064±3076 MBq of [18F]FDOPA were produced within 120 min from EOB (n=5). Radiochemical purity and enantiomeric excess were both ≥95%. Specific activity was ca. 50 GBq/μmol at EOS. This automatically operable synthesis is well suited for the multi-patient-dose routine production of n.c.a. [18F]FDOPA.

  12. Synthesis 1-(5-oxohexyl)-3,7-dimethyl-xanthyne labelled with tritium into 8 position from purinic ring

    International Nuclear Information System (INIS)

    This paper presents the work on synthesis of 1-(5-oxohexyl)-3,7-dimethyl-xanthyne labelled with tritium into 8 position from purinic ring. The obtaining of tritium labelled compound is realized by initial labelling of theobromine with tritium into 8 position and by coupling the purinic derivative to 1-Br-5-hexanone. Theobromine-8- 3 H was obtained by the bromination of theobromine with elementary bromine and after that the bromine was substituted with tritium i.e.: C7H8O2N4 theobromine Br2/(-HBr) C7H7O2N4 Br (8-Br-theobromine) (3 H2/cat)/(-KOH) C7H73 HO2N4 (theobromine-8- 3 H). Theobromine-8- 3 H was purified by thin layer chromatography with a solvent system i.e. n-BuOH:AcOH:H2O (4:1:1, v/v/v) and characterized radiochemically. It was then diluted by unlabelled theobromine to specific activity of 50 mCi/g. After dilution, theobromine-8-3 H was coupled to 1-Br-5-hexanone i.e.: C7H73 HO2N4 (theobromine-8- 3 H) + Br-(CH2)4-CO-CH3 (1-Br-5-hexanone) (NaOH)/(CH3OH) C13 H173 HO3N4 (1-(5-oxohexyl)- 3,7-dimethyl-xanthine-8- 3 H). The raw compound was purified by recrystallization from 2-propanol and it was characterized radiochemically. (authors)

  13. A regioselective synthesis of benzopinacolones through aerobic dehydrogenative α-arylation of the tertiary sp3 C-H bond of 1,1-diphenylketones with aromatic and heteroaromatic compounds.

    Science.gov (United States)

    More, Nagnath Yadav; Jeganmohan, Masilamani

    2015-01-12

    A regioselective synthesis of symmetrical and unsymmetrical benzopinacolones through aerobic dehydrogenative α-arylation at the tertiary sp(3) C-H bond of substituted 1,1-diphenylketones with aromatic and heteroaromatic compounds, in the presence of K2S2O8 in CF3COOH at room temperature, is described. The reaction is proposed to go via a carbocation intermediate, which could be generated directly from cleavage of the sp(3) C-H bond of 1,1-diphenylketone. Subsequent α-arylation was achieved at the methene sp(3) carbon atom of the substituted ketone. A variety of substituted aromatic and heteroaromatic compounds were compatible with this reaction. In addition, benzopinacolones were converted into sterically hindered, tetrasubstituted alkenes and polycyclic aromatic compounds.

  14. Synthesis of benzyl chlorides and cycloveratrylene macrocycles using benzylic alcohols under homogeneous catalysis by HCl/dioxane

    Directory of Open Access Journals (Sweden)

    Yolanda Marina Vargas-Rodríguez

    2012-01-01

    Full Text Available The synthesis of benzyl chlorides, cyclic derivatives cyclotriveratrylene and cyclotripiperotrylene were carried out in using the HCl/dioxane system as a catalyst. The reaction proceeded with high selectivity and is sensitive to the number of alkyl and methoxy substituent on the aromatic ring.

  15. "Carbo-aromaticity" and novel carbo-aromatic compounds.

    Science.gov (United States)

    Cocq, Kévin; Lepetit, Christine; Maraval, Valérie; Chauvin, Remi

    2015-09-21

    While the concept of aromaticity is being more and more precisely delineated, the category of "aromatic compounds" is being more and more expanded. This is illustrated by an introductory highlight of the various types of "aromaticity" previously invoked, and by a focus on the recently proposed "aromatic character" of the "two-membered rings" of the acetylene and butatriene molecules. This serves as a general foundation for the definition of "carbo-aromaticity", the relevance of which is surveyed through recent results in the synthetic, physical, and theoretical chemistry of carbo-mers and in particular macrocyclic-polycyclic representatives constituting a natural family of "novel aromatic compounds". With respect to their parent molecules, carbo-mers are constitutionally defined as "carbon-enriched", and can also be functionally regarded as "π-electron-enriched". This is exemplified by recent experimental and theoretical results on functional, aromatic, rigid, σ,π-macrocyclic carbo-benzene archetypes of various substitution patterns, with emphasis on the quadrupolar pattern. For the purpose of comparison, several types of non-aromatic references of carbo-benzenes are then considered, i.e. freely rotating σ,π-acyclic carbo-n-butadienes and flexible σ-cyclic, π-acyclic carbo-cyclohexadienes, and to "pro-aromatic" congeners, i.e. rigid σ,π-macrocyclic carbo-quinoids. It is shown that functional carbo-mers are entering the field of "molecular materials" for properties such as linear or nonlinear optical properties (e.g. dichromism and two-photon absorption) and single molecule conductivity. Since total or partial carbo-mers of aromatic carbon-allotropes of infinite size such as graphene (graphynes and graphdiynes) and graphite ("graphitynes") have long been addressed at the theoretical or conceptual level, recent predictive advances on the electrical, optical and mechanical properties of such carbo-materials are surveyed. Very preliminary experimental results

  16. "Carbo-aromaticity" and novel carbo-aromatic compounds.

    Science.gov (United States)

    Cocq, Kévin; Lepetit, Christine; Maraval, Valérie; Chauvin, Remi

    2015-09-21

    While the concept of aromaticity is being more and more precisely delineated, the category of "aromatic compounds" is being more and more expanded. This is illustrated by an introductory highlight of the various types of "aromaticity" previously invoked, and by a focus on the recently proposed "aromatic character" of the "two-membered rings" of the acetylene and butatriene molecules. This serves as a general foundation for the definition of "carbo-aromaticity", the relevance of which is surveyed through recent results in the synthetic, physical, and theoretical chemistry of carbo-mers and in particular macrocyclic-polycyclic representatives constituting a natural family of "novel aromatic compounds". With respect to their parent molecules, carbo-mers are constitutionally defined as "carbon-enriched", and can also be functionally regarded as "π-electron-enriched". This is exemplified by recent experimental and theoretical results on functional, aromatic, rigid, σ,π-macrocyclic carbo-benzene archetypes of various substitution patterns, with emphasis on the quadrupolar pattern. For the purpose of comparison, several types of non-aromatic references of carbo-benzenes are then considered, i.e. freely rotating σ,π-acyclic carbo-n-butadienes and flexible σ-cyclic, π-acyclic carbo-cyclohexadienes, and to "pro-aromatic" congeners, i.e. rigid σ,π-macrocyclic carbo-quinoids. It is shown that functional carbo-mers are entering the field of "molecular materials" for properties such as linear or nonlinear optical properties (e.g. dichromism and two-photon absorption) and single molecule conductivity. Since total or partial carbo-mers of aromatic carbon-allotropes of infinite size such as graphene (graphynes and graphdiynes) and graphite ("graphitynes") have long been addressed at the theoretical or conceptual level, recent predictive advances on the electrical, optical and mechanical properties of such carbo-materials are surveyed. Very preliminary experimental results

  17. Influence of methoxy- and nitro-substitutions in the aromatic ring on proton donation ability in hydrogen bond and on the amino group parameters of free and H-bonded molecules of 2-aminopyrimidine

    Science.gov (United States)

    Borisenko, V. E.; Krekov, S. A.; Fomenko, M. Yu.; Koll, A.; Lipkovski, P.

    2008-06-01

    Amino- and imino- forms of pyrimidine are widely presented as part of antibiotics, corrective medications for heart failures and metabolic stimulators. Hydrogen bonding is one of the fundamental interactions between biologically active molecules. This type of interactions provides flexibility, speed and variety of the biochemical processes. Proton donation properties of aminopyrimidines significantly depend on the position, number and kind of the substituent in its aromatic ring. In present work we studied the influence of the methoxy- and nitro-substitutions in the phenyl radical of pyridine and pyrimidine cycles on the proton donation ability of the amino group in hydrogen bonds as well as on its geometrical, force, electro-optical and thermodynamical characteristics in free and H-bonded (1:1 and 1:2, with various proton acceptors) molecules of primary aromatic amines. Acetonitrile, dioxane, tetrahydrofourane, dimethylformamide, dimethylsulfoxide and hexamethylphosphoramide (whose proton accepting properties vary within a wide range) were used as proton acceptors in our research. In the region of the amino group stretching and deformation vibrations the IR spectra of free and H-bonded (1:1) molecules of 2-amino-4,6-dimethoxy- and 2-amino-5-nitropyrimidine were studied in complexes with proton acceptors in CCl 4 within the temperature range 288-328 K. The spectra of 1:2 complexes were studied in undiluted aprotic solvents. The following spectral characteristics of absorption bands in amino group stretching vibrations were determined: M(0) (zero spectral moment, integrated intensity B); M(1) (first spectral moment, band "centre of gravity"); effective half width, related to the second central moment (Δ ν1/2) eff = 2( M(2)) 1/2, frequencies of the deformation vibrations δ(HNH) of free and H-bonded molecules. It was shown that changes of the absorption band spectral characteristics of the amino group stretching and deformation vibrations in the analyzed

  18. Ring Theory

    CERN Document Server

    Jara, Pascual; Torrecillas, Blas

    1988-01-01

    The papers in this proceedings volume are selected research papers in different areas of ring theory, including graded rings, differential operator rings, K-theory of noetherian rings, torsion theory, regular rings, cohomology of algebras, local cohomology of noncommutative rings. The book will be important for mathematicians active in research in ring theory.

  19. New series of aromatic/ five-membered heteroaromatic butanesulfonyl hydrazones as potent biological agents: Synthesis, physicochemical and electronic properties

    Science.gov (United States)

    Hamurcu, Fatma; Mamaş, Serhat; Ozdemir, Ummuhan Ozmen; Gündüzalp, Ayla Balaban; Senturk, Ozan Sanlı

    2016-08-01

    The aromatic/five-membered heteroaromatic butanesulfonylhydrazone derivatives; 5-bromosalicylaldehydebutanesulfonylhydrazone(1), 2-hydroxy-1-naphthaldehydebutane sulfonylhydrazone(2), indole-3-carboxaldehydebutanesulfonylhydrazone (3), 2-acetylfuran- carboxyaldehydebutanesulfonylhydrazone(4), 2-acetylthiophenecarboxyaldehydebutane- sulfonylhydrazone(5) and 2-acetyl-5-chlorothiophenecarboxyaldehydebutanesulfonyl hydrazone (6) were synthesized by the reaction of butane sulfonic acid hydrazide with aldehydes/ketones and characterized by using elemental analysis, 1H NMR, 13C NMR and FT-IR technique. Their geometric parameters and electronic properties consist of global reactivity descriptors were also determined by theoretical methods. The electrochemical behavior of the butanesulfonylhydrazones were investigated by using cyclic voltammetry (CV), controlled potential electrolysis and chronoamperometry (CA) techniques. The number of electrons transferred (n), diffusion coefficient (D) and standard heterogeneous rate constants (ks) were determined by electrochemical methods.

  20. Synthesis of Acenaphthyl and Phenanthrene Based Fused-Aromatic Thienopyrazine Co-Polymers for Photovoltaic and Thin Film Transistor Applications

    KAUST Repository

    Mondal, Rajib

    2009-08-11

    Dithiophene and fluorene co-polymers containing fused aromatic thieno[3,4-b]pyrazine moieties were synthesized for organic thin film transistor (OTFT) and organic photovoltaic (OPV) applications. Suzuki and Stille polycondensation reactions were used for the polymerization. The band gap (Eg) of the polymers was tuned in the range of 1.15-1.6 eV to match the solar spectrum. Density functional theory calculations were carried out to rationalize the low band gaps. These polymers showed field effect mobility (μ) as high as 0.2 cm2/(V.s) with an on/off ratio as high as 106 in OTFT devices. Interestingly, one polymer in this class also showed ambipolar charge transport. Power conversion efficiency (PCE) up to 1.3% was achieved in bulk heterojunction solar cells, indicating that these materials are promising for OPV applications. © 2009 American Chemical Society.

  1. SYNTHESIS AND CHARACTERIZATION OF A SILICA-SUPPORTED CARBOXYMETHYLCELLULOSE PLATINUM COMPLEX AND ITS CATALYTIC BEHAVIORS FOR HYDROGENATION OF AROMATICS

    Institute of Scientific and Technical Information of China (English)

    TANG Liming; HUANG Meiyu; JIANG Yingyan

    1996-01-01

    A silica-supported carboxymethylcellulose platinum complex (abbreviated as SiO2-CMC-Pt) has been prepared and characterized by XPS. Its catalytic properties for hydrogenation of aromatic compounds were studied. The results showed that this catalyst could catalyze the hydrogenation of phenol, anisol, p-cresol, benzene and toluene to cyclohexanol, cyclohexyl methyl ether, p-methyl cyclohexanol, cyclohexane and methylcyclohexane, respectively in 100% yield at 30℃ and 1 atm. In the hydrogenation of phenol,COO/Pt ratio in SiO2-CMC-Pt has much influence on the initial hydrogenation rate and the selectivity for the intermediate product, cyclohexanone. The highest initial rate and the highest yield of cyclohexanone both occur at COO/Pt ratio of 6. The complex is stable during the reaction and can be used repeatedly.

  2. Total synthesis and evaluation of vinblastine analogues containing systematic deep-seated modifications in the vindoline subunit ring system: core redesign.

    Science.gov (United States)

    Schleicher, Kristin D; Sasaki, Yoshikazu; Tam, Annie; Kato, Daisuke; Duncan, Katharine K; Boger, Dale L

    2013-01-24

    The total synthesis of a systematic series of vinblastine analogues that contain deep-seated structural modifications to the core ring system of the lower vindoline subunit is described. Complementary to the vindoline 6,5 DE ring system, compounds with 5,5, 6,6, and the reversed 5,6 membered DE ring systems were prepared. Both the natural cis and unnatural trans 6,6-membered ring systems proved accessible, with the latter representing a surprisingly effective class for analogue design. Following Fe(III)-promoted coupling with catharanthine and in situ oxidation to provide the corresponding vinblastine analogues, their evaluation provided unanticipated insights into how the structure of the vindoline subunit contributes to activity. Two potent analogues (81 and 44) possessing two different unprecedented modifications to the vindoline subunit core architecture were discovered that matched the potency of the comparison natural products and both lack the 6,7-double bond whose removal in vinblastine leads to a 100-fold drop in activity.

  3. Gaining Control over Radiolytic Synthesis of Uniform Sub-3-nanometer Palladium Nanoparticles: Use of Aromatic Liquids in the Electron Microscope

    Energy Technology Data Exchange (ETDEWEB)

    Abellan Baeza, Patricia; Parent, Lucas R.; Al Hasan, Naila M.; Park, Chiwoo; Arslan, Ilke; Karim, Ayman M.; Evans, James E.; Browning, Nigel D.

    2016-01-07

    Synthesizing nanomaterials of uniform shape and size is of critical importance to access and manipulate the novel structure-property relationships arising at the nanoscale. In this work we synthesize Pd nanoparticles with well-controlled size using in situ liquid-stage scanning transmission electron microscopy (STEM) and demonstrate a match between the reaction kinetics and products of the radiolytic and chemical syntheses of size-stabilized Pd nanoparticles. We quantify the effect of electron dose on the nucleation kinetics, and compare these results with in situ small angle X-ray scattering (SAXS) experiments investigating the effect of temperature during chemical synthesis. This work introduces methods for precise control of nanoparticle synthesis in the STEM and provides a means to uncover the fundamental processes behind the size and shape stabilization of nanoparticles.

  4. SYNTHESIS OF POLY(5,5-DIMETHYL-1,3-DIOXAN-2-ONE) BY LIPASE-CATALYZED RING-OPENING POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Chi-fei Wu

    2003-01-01

    Porcine pancreas lipase (PPL) and PPL immobilized on narrow distributed micron-sized glass beads were employed successfully for the ring-opening polymerization of 5,5-dimethyl-1,3-dioxan-2-one (DTC) for the first time.Different polymerization conditions such as enzyme concentration and reaction temperature were studied. Immobilized PPL exhibits higher activity than native PPL. Along with the increasing enzyme concentration, the molecular weight of resulting PDTC decreases. PPL immobilized on narrow distributed micron-sized glass beads has outstanding recyclability. For the third recycle time, immobilized PPL exhibits the highest catalytic activity and with high activity even after the fifth recyle time for the synthesis of PDTC. The 1H-NMR spectra indicate that decarboxylation does not occur during the ring-opening polymerization.

  5. Novel Approach for Evaluating Secondary Organic Aerosol from Aromatic Hydrocarbons: Unified Method for Predicting Aerosol Composition and Formation.

    Science.gov (United States)

    Li, Lijie; Tang, Ping; Nakao, Shunsuke; Kacarab, Mary; Cocker, David R

    2016-06-21

    Innovative secondary organic aerosol (SOA) composition analysis methods normalizing aerosol yield and chemical composition on an aromatic ring basis are developed and utilized to explore aerosol formation from oxidation of aromatic hydrocarbons. SOA yield and chemical composition are revisited using 15 years of University of California, Riverside/CE-CERT environmental chamber data on 17 aromatic hydrocarbons with HC:NO ranging from 11.1 to 171 ppbC:ppb. SOA yield is redefined in this work by normalizing the molecular weight of all aromatic precursors to the molecular weight of the aromatic ring [Formula: see text], where i is the aromatic hydrocarbon precursor. The yield normalization process demonstrates that the amount of aromatic rings present is a more significant driver of aerosol formation than the vapor pressure of the precursor aromatic. Yield normalization also provided a basis to evaluate isomer impacts on SOA formation. Further, SOA elemental composition is explored relative to the aromatic ring rather than on a classical mole basis. Generally, four oxygens per aromatic ring are observed in SOA, regardless of the alkyl substitutes attached to the ring. Besides the observed SOA oxygen to ring ratio (O/R ∼ 4), a hydrogen to ring ratio (H/R) of 6 + 2n is observed, where n is the number of nonaromatic carbons. Normalization of yield and composition to the aromatic ring clearly demonstrates the greater significance of aromatic ring carbons compared with alkyl carbon substituents in determining SOA formation and composition. PMID:27177154

  6. A Molecular Precursor to Phosphaethyne and its Application in Synthesis of the Aromatic 1,2,3,4-Phosphatriazolate Anion

    Energy Technology Data Exchange (ETDEWEB)

    Transue, Wesley J.; Velian, Alexandra; Nava, Matthew; Martin-Drummel, Marie A.; Womack, Caroline C.; Jiang, Jun; Hou, Gao-Lei; Wang, Xue B.; McCarthy, Michael C.; Field, Robert W.; Cummins, Christopher C.

    2016-06-01

    Dibenzo-7-phosphanorbornadiene Ph3PC(H)PA (1, A = C14H10, anthracene) is reported as a molecular precursor to phosphaethyne (HC≡P), produced together with anthracene and triphenylphosphine. HCP generated by thermolysis of 1 has been characterized by molecular beam mass spectrometry (MBMS), laser-induced fluorescence (LIF), microwave spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. In toluene, fragmentation of 1 has been found to proceed with activation parameters of ΔH = 25.5 kcal/mol and ΔS = ₋2.43 e.u., and is accompanied by formation of an orange insoluble precipitate. Results from computational studies of the mechanism of HCP generation are in good agreement with experimental data. This high temperature method of HCP generation has pointed to new reaction chemistry with azide anion to produce the 1,2,3,4-phosphatriazolate anion, HCPN3- , for which structural data have been obtained in a single-crystal Xray diffraction study. Negative ion photoelectron spectroscopy has shown the adiabatic detachment energy for this anion to be 3.555(10) eV. The aromaticity of HCPN3- has been assessed using nucleus-independent chemical shift (NICS), quantum theory of atoms in molecules (QTAIM), and natural bond orbital (NBO) methods.

  7. A Molecular Precursor to Phosphaethyne and Its Application in Synthesis of the Aromatic 1,2,3,4-Phosphatriazolate Anion.

    Science.gov (United States)

    Transue, Wesley J; Velian, Alexandra; Nava, Matthew; Martin-Drumel, Marie-Aline; Womack, Caroline C; Jiang, Jun; Hou, Gao-Lei; Wang, Xue-Bin; McCarthy, Michael C; Field, Robert W; Cummins, Christopher C

    2016-06-01

    Dibenzo-7-phosphanorbornadiene Ph3PC(H)PA (1, A = C14H10, anthracene) is reported here as a molecular precursor to phosphaethyne (HC≡P), produced together with anthracene and triphenylphosphine. HCP generated by thermolysis of 1 has been observed by molecular beam mass spectrometry, laser-induced fluorescence, microwave spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. In toluene, fragmentation of 1 has been found to proceed with activation parameters of ΔH(⧧) = 25.5 kcal/mol and ΔS(⧧) = -2.43 eu and is accompanied by formation of an orange insoluble precipitate. Results from computational studies of the mechanism of HCP generation are in good agreement with experimental data. This high-temperature method of HCP generation has pointed to new reaction chemistry with azide anion to produce the 1,2,3,4-phosphatriazolate anion, HCPN3(-), for which structural data have been obtained in a single-crystal X-ray diffraction study. Negative-ion photoelectron spectroscopy has shown the adiabatic detachment energy for this anion to be 3.555(10) eV. The aromaticity of HCPN3(-) has been assessed using nucleus-independent chemical shift, quantum theory of atoms in molecules, and natural bond orbital methods. PMID:27171847

  8. SYNTHESIS OF NOVEL BI-FUNCTIONAL COPOLYMER BEA RING STERICALLY HINDERED PHENOL AND HINDERED AMINE GROUPS VIA RING-OPENING METATHESIS POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Bo-yong Xue; Kenichi Ogata; Akinori Toyota

    2008-01-01

    Norbornene derivatives exo,endo-2-[2-(3,5-di-tert-butyl-4-hydroxyphenoxy)-acetoxy]methyl-5-norbornene(M1) and 3,3,5,5-tetramethyl-4-piperidinyl 5-norbornene-exo,endo-2-carboxylate(M2)were synthesized and polymerized by RuCl2(=CHPh)(PCy3)2 to prepare a novel kind of bi-functional polymer bearing sterically hindered phenol (SHP) and hindered amine(HLAS)groups via ring-opening metathesis polymerization(ROMP).The resulting copolymers were characterized by gel permeation chromatography(GPC),'H-NMR and differential scanning calorimetry (DSC).The number average molecular weight(Mn)and functional unit content of the resulting copolymer could be regulated by varying the concentration of catalyst and monomer feed.

  9. Role of methyl group number on SOA formation from monocyclic aromatic hydrocarbons photooxidation under low-NOx conditions

    OpenAIRE

    Li, L.; Tang, P.; Nakao, S.; Chen, C.-L.; Cocker III, D. R.

    2016-01-01

    Substitution of methyl groups onto the aromatic ring determines the secondary organic aerosol (SOA) formation from the monocyclic aromatic hydrocarbon precursor (SOA yield and chemical composition). This study links the number of methyl groups on the aromatic ring to SOA formation from monocyclic aromatic hydrocarbons photooxidation under low-NOx conditions (HC/NO  >  10 ppbC : ppb). Monocyclic aromatic hydrocarbons with increasing numbers of methyl groups are systemat...

  10. Aromatic oligoamides with a rare ortho-connectivity

    DEFF Research Database (Denmark)

    Hjelmgaard, T.; Nielsen, John

    2013-01-01

    Even though aromatic oligoamides composed of aromatic amino acids in a "one-way sequence" attract ever increasing research interest, backbones connected through ortho-linked aromatics remain rare. Herein, we present the first synthesis and study of N-alkylated ortho-aminomethyl- benzamides termed...

  11. Highly Contorted 1,2,5-Thiadiazole-Fused Aromatics for Solution-Processed Field-Effect Transistors: Synthesis and Properties.

    Science.gov (United States)

    Shi, Xin; Liu, Shuli; Liu, Chunming; Hu, Yueming; Shi, Saihua; Fu, Nina; Zhao, Baomin; Wang, Zhaohui; Huang, Wei

    2016-08-01

    A straightforward strategy has been used to construct 1,2,5-thiadiazole-fused 12-ring π systems through twofold Stille coupling and subsequent cyclodehydrogenation by utilizing the building blocks of naphthodithiophene and 5,6-substituted benzo[b]-2,1,3-thiadidazole. Molecules 1 a and 1 b, which exhibit highly contorted π surfaces, show a butterfly-shaped conformation according to DFT calculations. Within the molecules, a plane-to-plane angle of 44.8° was found. UV/Vis absorption, thermogravimetric analysis, differential scanning calorimetry, and cyclic voltammetry (CV) were used to study their physical properties. Strong intermolecular interactions of the nonplanar molecules were also observed by concentration-dependent (1) H NMR spectroscopy measurements and thin-film XRD characterization. The low-lying LUMO and high-lying HOMO levels of the molecules are -3.73 and -5.48 eV, respectively, as estimated from CV measurements; this indicates their potential as semiconducting materials for solution-processed organic field-effect transistors (OFETS). A field-effect hole mobility of up to 0.035 cm(2)  V(-1)  s(-1) , a threshold voltage of 6.98 V, and a current on/off ratio of 8.65×10(5) in air for 1 a have been demonstrated with the top-contact bottom-gate field-effect transistor device structures; this represents an important step toward the solution-processed OFET application of contorted aromatics.

  12. 催化油浆重质芳烃制备沥青树脂%Synthesis asphalt resin from heavy aromatic of catalytic slurry

    Institute of Scientific and Technical Information of China (English)

    赵晓隆; 赵华; 李会鹏; 卢传竹; 李智超

    2015-01-01

    以催化油浆重质芳烃为原料,苯甲醛为交联剂,在浓硫酸作催化剂条件下,合成沥青树脂。采用FTIR探究了反应机理,采用TGA考察了合成树脂的热重反应性能。通过单因素实验,考察了合成条件对沥青树脂软化点、残炭量、收率的影响。结果表明,反应机理为质子催化下的缩聚反应;合成树脂的工艺条件为:交联剂用量70%,反应时间为5 h,反应温度为130℃,催化剂用量为6%。合成树脂的收率为83.2%,残炭量为27.6%,软化点为76.5℃。%Asphalt resin has been synthesized using heavy aromatic as monomer and benzaldehyde as cross-linking agent in the presence of concentrated sulfuric acid. FTIR was used to study the reaction mechanism. The thermal weight loss behavior of the synthesized resin was characterized by TGA. The effects of synthesis conditions on the softening point and carbon residue of the pitch resin as well as its yield were investigated by single factor experiments. The results showed that the reaction of heavy aromatic and benzaldehyde is a positive ion-typed condensation polymerization catalyzed by acid. The suitable con-ditions for synthesizing the asphalt resin were:the usage of crosslinkers 70%,the reaction time of 5 h, the reaction temperature of 130 ℃ and the usage of catalyst 6%. Under the optimal conditions, the asphalt resin exhibits the yield of 83. 2%,the carbon residue of 27. 6% and the softening point of 76. 5 ℃.

  13. Synthesis asphalt resin from heavy aromatic of catalytic slurry%催化油浆重质芳烃制备沥青树脂

    Institute of Scientific and Technical Information of China (English)

    赵晓隆; 赵华; 李会鹏; 卢传竹; 李智超

    2015-01-01

    Asphalt resin has been synthesized using heavy aromatic as monomer and benzaldehyde as cross-linking agent in the presence of concentrated sulfuric acid. FTIR was used to study the reaction mechanism. The thermal weight loss behavior of the synthesized resin was characterized by TGA. The effects of synthesis conditions on the softening point and carbon residue of the pitch resin as well as its yield were investigated by single factor experiments. The results showed that the reaction of heavy aromatic and benzaldehyde is a positive ion-typed condensation polymerization catalyzed by acid. The suitable con-ditions for synthesizing the asphalt resin were:the usage of crosslinkers 70%,the reaction time of 5 h, the reaction temperature of 130 ℃ and the usage of catalyst 6%. Under the optimal conditions, the asphalt resin exhibits the yield of 83. 2%,the carbon residue of 27. 6% and the softening point of 76. 5 ℃.%以催化油浆重质芳烃为原料,苯甲醛为交联剂,在浓硫酸作催化剂条件下,合成沥青树脂。采用FTIR探究了反应机理,采用TGA考察了合成树脂的热重反应性能。通过单因素实验,考察了合成条件对沥青树脂软化点、残炭量、收率的影响。结果表明,反应机理为质子催化下的缩聚反应;合成树脂的工艺条件为:交联剂用量70%,反应时间为5 h,反应温度为130℃,催化剂用量为6%。合成树脂的收率为83.2%,残炭量为27.6%,软化点为76.5℃。

  14. Facile solvothermal synthesis of abnormal growth of one-dimensional ZnO nanostructures by ring-opening reaction of polyvinylpyrrolidone

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Facile solvothermal synthesis of ZnO nanostructures in super high alkaline alcoholic condition. • The exact role and chemical transformations of PVP in solvothermal synthesis of ZnO nanostructures was revealed. • Mechanism of abnormal growth of ZnO nanopyramids was proposed based on ring-opening reaction of PVP. - Abstract: Abnormal growth of one-dimensional (1-D) ZnO nanostructures (NSs) have been accomplished with the assistance of polyvinylpyrrolidone (PVP) under a super high alkaline alcoholic solvothermal condition. The products were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (1H NMR) spectroscopy. The effect of synthetic conditions, such as reaction temperature and the addition of PVP, on the morphologies of ZnO products were investigated. The results show that PVP molecules had the significant role in the transformation of morphologies of ZnO NSs ranging from nanorods, nanoparticles to pyramids, as well as flower-like assembly features. The possible growth mechanism of ZnO pyramids was proposed based on ring-opening reaction of PVP

  15. Diastereoselective Ring-Closing Metathesis as a Means to Construct Medium-Sized Cyclic Ethers: Application to the Synthesis of a Photoactivatable Gambierol Derivative.

    Science.gov (United States)

    Onodera, Yu; Hirota, Kazuaki; Suga, Yuto; Konoki, Keiichi; Yotsu-Yamashita, Mari; Sasaki, Makoto; Fuwa, Haruhiko

    2016-09-16

    This paper describes a concise synthesis of six- to eight-membered α,α'-substituted cyclic ethers by exploiting diastereoselective ring-closing metathesis (RCM) of 1,4-pentadien-3-yl ether derivatives. The RCM precursors could be efficiently prepared via a vinylation of the corresponding α-acetoxy ether derivatives using divinylzinc. Diastereoselective RCM of 1,4-pentadien-3-yl ether derivatives afforded a series of six- to eight-membered α,α'-substituted cyclic ethers with moderate to good diastereoselectivity. The stereochemical consequence of the diastereoselective RCM appeared to be dependent on the structure of the ring being forged. The diastereoselectivity of six- and seven-membered cyclic ethers appeared to be largely under kinetic control irrespective of the catalyst reactivity, whereas that of an eight-membered cyclic ether could be controlled by the catalyst reactivity. Finally, the diastereoselective RCM chemistry was applied to the synthesis of a biotin-tagged photoactivatable derivative of gambierol. PMID:27529493

  16. Synthesis and biological evaluation of biaryl analogs of antitubulin compounds

    Energy Technology Data Exchange (ETDEWEB)

    Tozatti, Camila Santos Suniga; Khodyuk, Rejane Goncalves Diniz; Silva, Adriano Olimpio da; Santos, Edson dos Anjos dos; Amaral, Marcos Serrou do; Lima, Denis Pires de, E-mail: denis.lima@ufms.br [Centro de Ciencias Exatas e Tecnologia, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS (Brazil); Hamel, Ernest [Screening Technologies Branch, Division of Cancer Treatment and Diagnosis, National Cancer Institute at Frederick, MD (United States)

    2012-07-01

    This paper reports the synthesis of methanones and esters bearing different substitution patterns as spacer groups between aromatic rings. This series of compounds can be considered phenstatin analogs. Two of the newly synthesized compounds, 5a and 5c, strongly inhibited tubulin polymerization and the binding of [{sup 3}H] colchicine to tubulin, suggesting that, akin to phenstatin and combretastatin A-4, they can bind to tubulin at the colchicine site. (author)

  17. Synthesis and biological evaluation of biaryl analogs of antitubulin compounds

    Directory of Open Access Journals (Sweden)

    Camila Santos Suniga Tozatti

    2012-01-01

    Full Text Available This paper reports the synthesis of methanones and esters bearing different substitution patterns as spacer groups between aromatic rings. This series of compounds can be considered phenstatin analogs. Two of the newly synthesized compounds, 5a and 5c, strongly inhibited tubulin polymerization and the binding of [³H] colchicine to tubulin, suggesting that, akin to phenstatin and combretastatin A-4, they can bind to tubulin at the colchicine site.

  18. Synthesis and DPPH Radical Scavenging Activity of Prenylated Phenol Derivatives

    OpenAIRE

    Héctor Carrasco; Luis Espinoza; Marcela Carvajal; Cesar González; Alejandra Vergara; Lautaro Taborga; Evelyn Baeza; Karen Catalán; Mauricio Osorio; Jacqueline Aravena

    2012-01-01

    The synthesis of twenty six prenylated phenols derivatives is reported. These compounds were obtained under mild conditions via Electrophilic Aromatic Substitution (EAS) coupling reactions between phenol derivatives containing electron-donor subtituents and 3-methyl-2-buten-1-ol using BF3×OEt2. Dialkylations were also produced with this method. The formation of a chroman ring by intramolecular cyclization between a sp2 carbon from the prenyl group with the hydroxyl substituent in the ortho po...

  19. Critical analysis of the local aromaticity concept in polyaromatic hydrocarbons.

    Science.gov (United States)

    Bultinck, Patrick

    2007-01-01

    A large number of local aromaticity indices for the benzenoid rings in polyaromatic hydrocarbons is computed. The results are interpreted, supporting Clar's hypothesis, and mutual correlations are investigated. It is shown that there are good correlations between all indices that strictly allow comparing benzenoid character. Poor correlations are found with NICS. A rationale is offered, yielding the conclusion that NICS and ring current maps follow a fundamentally different path to local aromaticity. In this sense the lack of correlation is not due to a real multidimensional character of aromaticity but rather to confusion and vagueness of the aromaticity concept. PMID:17328438

  20. Metátese de olefinas aplicada ao fechamento de anéis: uma ferramenta poderosa para a síntese de macrociclos naturais Ring-closing olefin metathesis: a powerful tool for the synthesis of natural macrocycles

    Directory of Open Access Journals (Sweden)

    Anderson Rouge dos Santos

    2008-01-01

    Full Text Available For a quarter of a century, metathesis has become indispensable for the synthesis of natural and non-natural products, particularly of biologically active compounds. This review illustrates through a maximum of appropriate examples the power and the versatility of the metathesis ring-closure (RCM reaction as a key ring-closure methodology for the synthesis of natural macrocycles. Its high functional group compatibility as well as the possibility of further transformations makes this reaction a powerful tool in the cases where the structural framework and function requirements are difficult to meet.

  1. Luminescent Di- and Trinuclear Boron Complexes Based on Aromatic Iminopyrrolyl Spacer Ligands: Synthesis, Characterization, and Application in OLEDs.

    Science.gov (United States)

    Suresh, D; Gomes, Clara S B; Lopes, Patrícia S; Figueira, Cláudia A; Ferreira, Bruno; Gomes, Pedro T; Di Paolo, Roberto E; Maçanita, António L; Duarte, M Teresa; Charas, Ana; Morgado, Jorge; Vila-Viçosa, Diogo; Calhorda, Maria José

    2015-06-15

    New bis- and tris(iminopyrrole)-functionalized linear (1,2-(HNC4 H3 -C(H)N)2 -C6 H4 (2), 1,3-(HNC4 H3 -C(H)N)2 -C6 H4 (3), 1,4-(HNC4 H3 -C(H)N)2 -C6 H4 (4), 4,4'-(HNC4 H3 -C(H)N)2 -(C6 H4 -C6 H4 ) (5), 1,5-(HNC4 H3 C-(H)N)2 -C10 H6 (6), 2,6-(HNC4 H3 C-(H)N)2 -C10 H6 (7), 2,6-(HNC4 H3 C-(H)N)2 -C14 H8 (8)) and star-shaped (1,3,5-(HNC4 H3 -C(H)N-1,4-C6 H4 )3 -C6 H3 (9)) π-conjugated molecules were synthesized by the condensation reactions of 2-formylpyrrole (1) with several aromatic di- and triamines. The corresponding linear diboron chelate complexes (Ph2 B[1,3-bis(iminopyrrolyl)-phenyl]BPh2 (10), Ph2 B[1,4-bis(iminopyrrolyl)-phenyl]BPh2 (11), Ph2 B[4,4'-bis(iminopyrrolyl)-biphenyl]BPh2 (12), Ph2 B[1,5-bis(iminopyrrolyl)-naphthyl]BPh2 (13), Ph2 B[2,6-bis(iminopyrrolyl)-naphthyl]BPh2 (14), Ph2 B[2,6-bis(iminopyrrolyl)-anthracenyl]BPh2 (15)) and the star-shaped triboron complex ([4',4'',4'''-tris(iminopyrrolyl)-1,3,5-triphenylbenzene](BPh2 )3 (16)) were obtained in moderate to good yields, by the treatment of 3-9 with B(C6 H5 )3 . The ligand precursors are non-emissive, whereas most of their boron complexes are highly fluorescent; their emission color depends on the π-conjugation length. The photophysical properties of the luminescent polyboron compounds were measured, showing good solution fluorescence quantum yields ranging from 0.15 to 0.69. DFT and time-dependent DFT calculations confirmed that molecules 10 and 16 are blue emitters, because only one of the iminopyrrolyl groups becomes planar in the singlet excited state, whereas the second (and third) keeps the same geometry. Compound 13, in which planarity is not achieved in any of the groups, is poorly emissive. In the other examples (11, 12, 14, and 15), the LUMO is stabilized, narrowing the gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital (HOMO-LUMO), and the two iminopyrrolyl groups become planar, extending the size of the π-system, to

  2. Multicenter bond index analysis of influence of metal cations on the aromaticity of aromatic amino acids: Phenylalanine and tyrosine

    Science.gov (United States)

    Pakiari, A. H.; Farrokhnia, M.; Azami, S. M.

    2008-05-01

    In order to provide insight into the influence of metal cations on the aromaticity of amino acids, evaluation of six-center delocalization indices is accomplished in the context of quantum theory of atoms in molecules (QTAIM). Aromaticity of two amino acids, phenylalanine and tyrosine, is investigated as typical amino acids containing aromatic ring in their isolated state and complexed by some metal cations. The results showed that the metal cations affect the most important three connectivities differently. Also, it is shown that the existence of metal cations can increase two-center delocalization in certain parts of the aromatic rings.

  3. From small aromatic molecules to functional nanostructured carbon by pulsed laser-induced photochemical stitching

    Directory of Open Access Journals (Sweden)

    R. R. Gokhale

    2012-06-01

    Full Text Available A novel route employing UV laser pulses (KrF Excimer, 248 nm to cleave small aromatic molecules and stitch the generated free radicals into functional nanostructured forms of carbon is introduced. The process differs distinctly from any strategies wherein the aromatic rings are broken in the primary process. It is demonstrated that this pulsed laser-induced photochemical stitching (PLPS process when applied to routine laboratory solvents (or toxic chemical wastes when discarded Chlorobenzene and o-Dichlorobenzene yields Carbon Nanospheres (CNSs comprising of graphene-like sheets assembled in onion-like configurations. This room temperature process implemented under normal laboratory conditions is versatile and clearly applicable to the whole family of haloaromatic compounds without and with additions of precursors or other nanomaterials. We further bring out its applicability for synthesis of metal-oxide based carbon nanocomposites.

  4. Aromatic graphene

    Science.gov (United States)

    Das, D. K.; Sahoo, S.

    2016-04-01

    In recent years graphene attracts the scientific and engineering communities due to its outstanding electronic, thermal, mechanical and optical properties and many potential applications. Recently, Popov et al. [1] have studied the properties of graphene and proved that it is aromatic but without fragrance. In this paper, we present a theory to prepare graphene with fragrance. This can be used as scented pencils, perfumes, room and car fresheners, cosmetics and many other useful household substances.

  5. Dehalogenation of aromatics by nucleophilic aromatic substitution.

    Science.gov (United States)

    Sadowsky, Daniel; McNeill, Kristopher; Cramer, Christopher J

    2014-09-16

    Nucleophilic aromatic substitution has been implicated as a mechanism for both the biotic and abiotic hydrodehalogenation of aromatics. Two mechanisms for the aqueous dehalogenation of aromatics involving nucleophilic aromatic substitution with hydride as a nucleophile are investigated using a validated density functional and continuum solvation protocol. For chlorinated and brominated aromatics, nucleophilic addition ortho to carbon-halogen bonds via an anionic intermediate is predicted to be the preferred mechanism in the majority of cases, while concerted substitution is predicted to be preferred for most fluorinated aromatics. Nucleophilic aromatic substitution reactions with the hydroxide and hydrosulfide anions as nucleophiles are also investigated and compared.

  6. Synthesis of 4'α-C Phenyl-Branched Carbocyclic Nucleoside Using Ring-Closing Metathesis

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Joon Hee; Ko, Ok Hyun [Chosun University, Gwangju(Korea, Republic of)

    2003-09-15

    An efficient synthetic route for preparing novel 4'α-C phenyl branched carbocyclic nucleoside is described. The installation of phenyl group at the 4'-position of carbocyclic nucleoside was successfully accomplished via a sequential [3,3]-sigmatropic rearrangement and ring-closing metathesis (RCM) beginning from simple ketone such as 2-hydroxy acetophenone.

  7. Synthesis and Luminescent Properties of Two New Triphenylamine-based Compounds with Heterocyclic Ring as Conjugation Bridge

    Institute of Scientific and Technical Information of China (English)

    LI,Qian-Qian; DI,Chong-An; YU,Gui; LIU,Yun-Qi; LI,Zhen; QIN,Jin-Gui

    2008-01-01

    Two new "D-π-D" type triphenylamine-based compounds with a heterocyclic ring,furan or thiophene,as a conjugation bridge were synthesized through a normal Wittig reaction which exhibited good thermal stability and strong luminescence.The preliminary light-emitting diode results indicate that they are promising candidates for the practical application.

  8. Synthesis, spectral characterization and antihaemostatic activity of 1,2,4-triazoles incorporating 1,2,4-triazine rings

    Indian Academy of Sciences (India)

    Ravindra R Kamble; Belgur S Sudha

    2006-03-01

    A simple and high yielding method for the integration of a 1,2,4-triazole ring with 1,2,4-triazine- 5-one (4a-j) has been developed starting from 3-arylsydnones (1a-d). The structures were proved by their spectral data and screened for antihaemostatic activity.

  9. Synthesis of a novel uridine analogue and its use in attempts to form new cyclonucleosides using ring-closing metathesis

    Institute of Scientific and Technical Information of China (English)

    MONDON; Martine; LEN; Christophe

    2010-01-01

    One novel nucleoside analogue having a hex-5-enyl group and an allyl group in the 5’-C and 3-N position was synthesized regioand diastereoselectively from D-glucose in twelve steps.In order to reach a particular conformation of nucleosides the nucleoside formation of restricted cyclonucleoside analogues was studied via Ring-Closing Metathesis.

  10. Silicone elastomers with aromatic voltage stabilizers

    DEFF Research Database (Denmark)

    A Razak, Aliff Hisyam; Skov, Anne Ladegaard

    of electron-trapping by aromatic compounds grafted to silicone backbones in a crosslinked PDMS is illustrated in Fig. 1. The electrical breakdown strength, the storage modulus and the loss modulus of the elastomer were investigated, as well as the excitation energy from the collision between electron carriers...... and benzene rings in PDMS-PPMS copolymer was measured by UV-vis spectroscopy. The developed elastomers were inherently soft with enhanced electrical breakdown strength due to delocalized pi-electrons of aromatic rings attached to the silicone backbone. The dielectric relative permittivity of PDMS...

  11. Fluorescent aromatic sensors and their methods of use

    Science.gov (United States)

    Meador, Michael A. (Inventor); Tyson, Daniel S. (Inventor); Ilan, Ulvi F. (Inventor)

    2012-01-01

    Aromatic molecules that can be used as sensors are described. The aromatic sensors include a polycyclic aromatic hydrocarbon core with a five-membered imide rings fused to the core and at least two pendant aryl groups. The aromatic sensor molecules can detect target analytes or molecular strain as a result of changes in their fluorescence, in many cases with on-off behavior. Aromatic molecules that fluoresce at various frequencies can be prepared by altering the structure of the aromatic core or the substituents attached to it. The aromatic molecules can be used as sensors for various applications such as, for example, the detection of dangerous chemicals, biomedical diagnosis, and the detection of damage or strain in composite materials. Methods of preparing aromatic sensor molecules are also described.

  12. Hexacoordinate bonding and aromaticity in silicon phthalocyanine.

    Science.gov (United States)

    Yang, Yang

    2010-12-23

    Si-E bondings in hexacoordinate silicon phthalocyanine were analyzed using bond order (BO), energy partition, atoms in molecules (AIM), electron localization function (ELF), and localized orbital locator (LOL). Bond models were proposed to explain differences between hexacoordinate and tetracoordinate Si-E bondings. Aromaticity of silicon phthalocyanine was investigated using nucleus-independent chemical shift (NICS), harmonic oscillator model of aromaticity (HOMA), conceptual density functional theory (DFT), ring critical point (RCP) descriptors, and delocalization index (DI). Structure, energy, bonding, and aromaticity of tetracoordinate silicon phthalocyanine were studied and compared with hexacoordinate one. PMID:21105726

  13. Synthesis and Anti-tumor Evaluation of B-ring Modified Caged Xanthone Analogues of Gambogic Acid%Synthesis and Anti-tumor Evaluation of B-ring Modified Caged Xanthone Analogues of Gambogic Acid

    Institute of Scientific and Technical Information of China (English)

    李想; 张晓进; 汪小涧; 李念光; 林昌军; 高原; 于卓沁; 郭青龙; 尤启冬

    2012-01-01

    Gambogic acid (GA, 1), the most prominent member of Garcinia natural products, has been reported to be a promising anti-tumor agent. Previous studies have suggested that the planar B ring and the unique 4-oxa-tricyclo- [4.3.1.03.7]dec-2-one caged motif were essential for anti-tumor activity. To further explore the structure-activity relationship (SAR) of caged Garcinia xanthones, two new series of B-ring modified caged GA analogues 13a-13e and 15a-lge were synthesized utilizing a Claisen/Diel-Alder cascade reaction. Subsequently, these compounds were evaluated for their in vitro antitumor activities against A549, MCF-7, SMMC-7721 and BGC-823 cancer cell lines by MTT assay. Among them, 13b-13e exhibited micromolar inhibition against several cancer cell lines, being approximately 2-4 fold less potent in comparison to GA. SAR analysis revealed that the peripheral gem-dimethyl groups are essential for maintaining antitumor activity and substituent group on C1 position of B-ring has a significant effect on potency, while modifications at C-2, C-3 and C-4 positions are relatively tolerated. These findings will enhance our understanding of the SAR of Garcinia xanthones and lead to the development of simplified analogues as potential anti-tumor agents.

  14. Synthesis and Resolution of Ring-substituted phenylalanines%苯环取代苯丙氨酸的合成及拆分

    Institute of Scientific and Technical Information of China (English)

    梁远军; 刘克良; 于文胜; 赵玉芬

    2001-01-01

    Seven racemic aromatic ring modified phenylalanines wer e sy nthesized using aniline derivatives as raw materials. The amino acids were resol ved with α--chymotrypsin or subtilisin. D-and L-amino acids were separ ated from each other. The chemical structures of the amino acids were characteri zed by IR, 1 HNMR, EA and optical rotation. The procedure mentioned here coul d be scaled up for producing the amino acids.%以苯胺类化合物为起始原料,经重氮化、丙烯酸加成、氨解 等反应合成了7种消旋苯环取代苯丙氨酸类氨基酸,并采用α-糜蛋白酶或枯草杆菌蛋白酶 对所有氨基酸进行了拆分,其结构分别通过红外光谱、核磁共振、元素分析、熔点、旋光等 分析得到确证。该法可以较大规模合成此类氨基酸。

  15. Regioselective ring opening of epoxides using NH4SCN/silica sulfuric acid: An efficient approach for the synthesis of β-hydroxy thiocyanate under solvent-free conditions

    Institute of Scientific and Technical Information of China (English)

    Ali R. Kiasat; Maryam Zayadi; Mehdi Fallah Mehrjardi

    2008-01-01

    Silica sulfuric acid was developed as a stable and efficient heterogeneous catalyst in organic synthesis. This solid acid catalyzed the regioselective ring opening of epoxides by thiocyanate anion to give thiocyanohydrins as key intermediates in agricultural and pharmaceutical chemistry in high yields under solvent-free conditions.

  16. All-optically tunable waveform synthesis by a silicon nanowaveguide ring resonator coupled with a photonic-crystal fiber frequency shifter

    KAUST Repository

    Savvin, Aleksandr D.

    2011-03-01

    A silicon nanowaveguide ring resonator is combined with a photonic-crystal fiber (PCF) frequency shifter to demonstrate an all-optically tunable synthesis of ultrashort pulse trains, modulated by ultrafast photoinduced free-carrier generation in the silicon resonator. Pump-probe measurements performed with a 50-fs, 625-nm second-harmonic output of a Cr:forsterite laser, used as a carrier-injecting pump, and a 1.50-1.56-μm frequency-tunable 100-fs soliton output of a photonic-crystal fiber, serving as a probe, resolve tunable ultrafast oscillatory features in the silicon nanowaveguide resonator response. © 2010 Elsevier B.V. All rights reserved.

  17. Reproducible Synthesis and High Porosity of mer-Zn(Im)2 (ZIF-10): Exploitation of an Apparent Double-Eight Ring Template.

    Science.gov (United States)

    Ramirez, Joseph R; Yang, Haiyang; Kane, Christopher M; Ley, Amanda N; Holman, K Travis

    2016-09-21

    Reproducible synthesis of the elusive merlinoite (mer) topology of zinc imidazolate (mer-Zn(Im)2, or ZIF-10) has been achieved by employing a simple macrocyclic solute-MeMeCH2-as a kinetic template. The corresponding phase-pure material, mer-MeMeCH2@Zn16(Im)32, is confirmed to be porous and exhibits one of the highest experimental surface areas (1893 m(2)/g, BET) yet reported for any ZIF. The X-ray single crystal structure of mer-MeMeCH2@Zn16(Im)32·xsolvent reveals the role of the macrocyle as an 8-fold hydrogen bond acceptor in templating the requisite double-eight rings (d8r) of the mer framework.

  18. Assessing Uncertainty of Interspecies Correlation Estimation Models for Aromatic Compounds

    Science.gov (United States)

    We developed Interspecies Correlation Estimation (ICE) models for aromatic compounds containing 1 to 4 benzene rings to assess uncertainty in toxicity extrapolation in two data compilation approaches. ICE models are mathematical relationships between surrogate and predicted test ...

  19. Synthesis and Biological Evaluation of Novel Benzimidazole Derivatives Bearing a Heterocyclic Ring at 4/5 Position

    Energy Technology Data Exchange (ETDEWEB)

    Wubulikasimu, Reyila; Yang, Yanbing; Xue, Fei; Luo, Xianjin; Shao, Dongping [Shanghai Jiaotong Univ., Shanghai (China); Li, Yuhuan; Gao, Rongmei [Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing (China); Ye, Weidong [Zhejiang Medicine Co. Ltd., Zhejiang (China)

    2013-08-15

    A series of novel benzimidazole derivatives bearing a heterocyclic ring as oxadiazole (21-32), thiadiazole (33-34), triazole (35-36) were synthesized and evaluated for their activities against Coxsackie virus B3 and B6 in Vero cells. Compounds 21-26, 31-36 with moieties of 2'-pyridyl, 3'-pyridyl and 4'-pyridyl at the 2-position and oxadiazoles, thiadiazole, or triazole substituent at the 4- or 5-position generally displayed activities against CVB3 and CVB6. Especially compound 24 (IC{sub 50} = 1.08 μg/mL, SI = 61.7 against CVB3) was the promising candidate as lead compound for anti-enteroviral drug. It was observed in the incorporation of heterocyclic rings in benzimidazole at the 5-position could enhance their biological activities.

  20. Synthesis and Catalytic Activity of a Two-core Ruthenium Carbene Complex: a Unique Catalyst for Ring Closing Metathesis Reaction

    Institute of Scientific and Technical Information of China (English)

    SHAO Ming-bo; WANG Jian-hui

    2011-01-01

    The reaction of a ruthenium carbide complex RuCl2(C:)(PCy3)2 with [H(Et2O)x]+[BF4]- at a molar ratio of 1:2 produced a two-core ruthenium carbene complex,{[RuCl(=HPCy3)(PCy3)]2(μ-Cl)3}+[BF4]-,in the form of a yellow-green crystalline solid in a yield of 94%.This two-core ruthenium complex is a selective catalyst for ring closing metathesis of unsubstituted terminal dienes.More importantly,no isomerized byproduct was observed for N-substrates when the two-core ruthenium complex was used as the catalyst at an elevated temperature(137 ℃),indicating that the complex is a chemo-selective catalyst for ring closing metathesis reactions.

  1. Design and synthesis of fused polycycles via Diels–Alder reaction and ring-rearrangement metathesis as key steps

    Directory of Open Access Journals (Sweden)

    Sambasivarao Kotha

    2015-07-01

    Full Text Available Atom efficient processes such as the Diels–Alder reaction (DA and the ring-rearrangement metathesis (RRM have been used to design new polycycles. In this regard, ruthenium alkylidene catalysts are effective in realizing the RRM of bis-norbornene derivatives prepared by DA reaction and Grignard addition. Here, fused polycycles are assembled which are difficult to produce by conventional synthetic routes.

  2. Epoxy Coenzyme A Thioester pathways for degradation of aromatic compounds.

    Science.gov (United States)

    Ismail, Wael; Gescher, Johannes

    2012-08-01

    Aromatic compounds (biogenic and anthropogenic) are abundant in the biosphere. Some of them are well-known environmental pollutants. Although the aromatic nucleus is relatively recalcitrant, microorganisms have developed various catabolic routes that enable complete biodegradation of aromatic compounds. The adopted degradation pathways depend on the availability of oxygen. Under oxic conditions, microorganisms utilize oxygen as a cosubstrate to activate and cleave the aromatic ring. In contrast, under anoxic conditions, the aromatic compounds are transformed to coenzyme A (CoA) thioesters followed by energy-consuming reduction of the ring. Eventually, the dearomatized ring is opened via a hydrolytic mechanism. Recently, novel catabolic pathways for the aerobic degradation of aromatic compounds were elucidated that differ significantly from the established catabolic routes. The new pathways were investigated in detail for the aerobic bacterial degradation of benzoate and phenylacetate. In both cases, the pathway is initiated by transforming the substrate to a CoA thioester and all the intermediates are bound by CoA. The subsequent reactions involve epoxidation of the aromatic ring followed by hydrolytic ring cleavage. Here we discuss the novel pathways, with a particular focus on their unique features and occurrence as well as ecological significance.

  3. Synthesis of hyperbranched copolymers by combining enzymatic ring-opening polymerization and A TRP from a novel bifunctional initiator

    Institute of Scientific and Technical Information of China (English)

    Al Peng; CHEN Liang; HU Dehua; CHEN Yanhua; LI Dongshuang; ZHANG Bao; SHA Ke; WANG Jingyuan

    2006-01-01

    The hyperbranched aliphatic polyester P(ε-CL) was synthesized by means of Novozyme435-catalyzed ring-opening polymerization (ROP) of BHB (2, 2-bis(hydroxymethyl) butyric acid). The chains ended with hydroxyl of P(ε-CL) were modified by the esterification of α-bromopropionyl bromide to obtain hyperbranched difunctional macroinitiator, which was used in the ATRP of St. CuCI/HMTETA was used as the catalyst system in the reaction of ATRP to acquire the hyperbranched copolymers polystyrene-blockpoly(2,2-bis(hydroxymethyl) butyric acid). The copolymer was confirmed by NMR and GPC.

  4. Synthesis and Characterization of trans-1,4-Cyclohexylene Ring Containing Poly(arylene ether sulfone)s

    OpenAIRE

    ZHANG Bin

    2012-01-01

    Poly(arylene ether sulfone)s (PAES) are important commercial polymers and have been extensively studied due to their excellent thermal and mechanical properties. However, some applications are still limited when good solvent resistance and low thermal expansion coefficient are required. There has been a continuous interest in developing new PAES based on new monomers or polymer modifications to obtain new properties or to enhance existing properties. In this dissertation, the synthesis, chara...

  5. Silicone elastomers with aromatic voltage stabilizers

    DEFF Research Database (Denmark)

    A Razak, Aliff Hisyam; Skov, Anne Ladegaard

    with enhanced electrical breakdown strength due to delocalized pi-electrons of aromatic rings attached to the silicone backbone. The dielectric relative permittivity of PDMS-PPMS copolymers remained between 2 to3 with low conductivity and low dielectric loss as well as high storage moduli with low viscousloss...

  6. Design, Synthesis, EPR-Studies and Conformational Bias of Novel Spin-Labeled DCC-Analogues for the Highly Regioselective Labeling of Aliphatic and Aromatic Carboxylic Acids.

    Science.gov (United States)

    Gölz, Jan Philipp; NejatyJahromy, Yaser; Bauer, Mirko; Muhammad, Ashraf; Schnakenburg, Gregor; Grimme, Stefan; Schiemann, Olav; Menche, Dirk

    2016-07-01

    Novel types of spin-labeled N,N'-dicyclohexylcarbodiimides (DCC) are reported that bear a 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO) residue on one side and different aromatic and aliphatic cyclohexyl analogues on the other side of the diimide core. These readily available novel reagents add efficiently to aliphatic and aromatic carboxylic acids, forming two possible spin-labeled amide derivatives with different radical distances of the resulting amide. The addition of aromatic DCC analogues proceeds with excellent selectivity, giving amides where the carboxylic acid is exclusively connected to the aromatic residue, while little or no selectivity was observed for the aliphatic congeners. The usefulness of these adducts in structural studies was demonstrated by EPR (electron paramagnetic resonance) measurements of biradical adducts of biphenyl-4,4'-dicarboxylic acids. These analyses also reveal high degrees of conformational bias for aromatic DCC derivatives, which further underlines the powerfulness of these novel reagents. This observation was further corroborated by quantum chemical calculations, giving a detailed understanding of the structural dynamics, while detailed information on the solid state structure of all novel reagents was obtained by X-ray structure analyses. PMID:27272435

  7. Novel Approach for Evaluating Secondary Organic Aerosol from Aromatic Hydrocarbons: SOA Yield and Chemical Composition

    Science.gov (United States)

    Li, Lijie; Tang, Ping; Nakao, Shunsuke; Qi, Li; Kacarab, Mary; Cocker, David

    2016-04-01

    Aromatic hydrocarbons account for 20%-30% of urban atmospheric VOCs and are major contributors to anthropogenic secondary organic aerosol (SOA). However, prediction of SOA from aromatic hydrocarbons as a function of structure, NOx concentration, and OH radical levels remains elusive. Innovative SOA yield and chemical composition evaluation approaches are developed here to investigate SOA formation from aromatic hydrocarbons. SOA yield is redefined in this work by adjusting the molecular weight of all aromatic precursors to the molecular weight of benzene (Yield'= Yieldi×(MWi/MWBenzene); i: aromatic hydrocarbon precursor). Further, SOA elemental ratio is calculated on an aromatic ring basis rather than the classic mole basis. Unified and unique characteristics in SOA formed from aromatic hydrocarbons with different alkyl groups (varying in carbon number and location on aromatic ring) are explored by revisiting fifteen years of UC Riverside/CE-CERT environmental chamber data on 129 experiments from 17 aromatic precursors at urban region relevant low NOx conditions (HC:NO 11.1-171 ppbC:ppb). Traditionally, SOA mass yield of benzene is much greater than that of other aromatic species. However, when adjusting for molecular weight, a similar yield is found across the 17 different aromatic precursors. More importantly, four oxygens per aromatic ring are observed in the resulting SOA regardless of the alkyl substitutes attached to the ring, which majorly affect H/C ratio in SOA. Therefore, resulting SOA bulk composition from aromatic hydrocarbons can be predicted as C6+nH6+2nO4 (n: alkyl substitute carbon number). Further, the dominating role of the aromatic ring carbons is confirmed by studying the chemical composition of SOA formed from the photooxidation of an aromatic hydrocarbon with a 13C isotopically labeled alkyl carbon. Overall, this study unveils the similarity in SOA formation from aromatic hydrocarbons enhancing the understanding of SOA formation from

  8. Inhibitory effects of polycyclic aromatic hydrocarbons (PAHs) on photosynthetic performance are not related to their aromaticity.

    Science.gov (United States)

    Jajoo, Anjana; Mekala, Nageswara Rao; Tomar, Rupal Singh; Grieco, Michele; Tikkanen, Mikko; Aro, Eva-Mari

    2014-08-01

    Polycyclic aromatic hydrocarbons (PAHs) are very toxic and highly persistent environmental pollutants which accumulate in soil and affect growth of the plants adversely. This study aims to investigate inhibitory effects of 3 major PAH particularly on photosynthetic processes in Arabidopsis thaliana grown in soil treated with PAH. The 3 PAH chosen differ from each other in aromaticity (number of rings) comprising their structure (2 rings: naphthalene, 3 rings: anthracene and 4 rings: pyrene). Several growth parameters and Chlorophyll a fluorescence was monitored in PAH treated plants. BN-PAGe analysis was done in order to get information about change in the protein conformation. PAH treatment led to increased value of Fo which collaborated with increase in the amount of free LHC as seen through BN-Page analysis. Thus PAH were found to inhibit PS II photochemistry and caused distinct change in pigment composition. However the results led us to infer that 3-ring anthracence is more inhibitory as compared to 2-ring naphthalene and 4-ring pyrene. This indicates that aromaticity of PAH is unrelated to their response on photosynthetic processes.

  9. Synthesis and biological evaluation with plant cells of new fosmidomycin analogues containing a benzoxazolone or oxazolopyridinone ring.

    Science.gov (United States)

    Courtois, Martine; Mincheva, Zoia; Andreu, Françoise; Rideau, Marc; Viaud-Massuard, Marie-Claude

    2004-12-01

    Fosmidomycin, 3-(N-formyl-N-hydroxyamido) propylphosphonic acid sodium salt, is an efficient inhibitor of 1-deoxy-D-xylulose-5-phosphate (DOXP) reductoisomerase, the second enzyme of the 2C-methyl-D-erythritol-4-phosphate (MEP) pathway notably present in Plasmodium species. We have synthesized a new series of analogues of fosmidomycin, containing a benzoxazolone, benzoxazolethione or oxazolopyridinone ring. As the MEP pathway is involved in the biosynthesis of all isoprenoids, accumulation of ajmalicine in Catharanthus roseus cells was chosen as a marker of monoterpenoid indole alkaloid (MIA) production. None of the twelve studied phosphonic esters 3 and phosphonic acids 4 affected periwinkle cell growth, but some of them (3c, 3e, 3g and 3h) showed a significant inhibition of ajmalicine accumulation: 45-85% at 125 microM. Surprisingly, this effect disappeared by conversion of 3c and 3g into the corresponding acids 4c and 4g, respectively.

  10. Synthesis and Biological Activities of Novel Thiophosphoryl Oximates Containing Thiazole and 1,2,3-Triazole Rings

    Institute of Scientific and Technical Information of China (English)

    ZHU,Xiaofei; SHI,Deqing

    2009-01-01

    In order to find novel high activity and low toxicity agrochemicals,a series of novel thiophosphoryl oximates containing thiazole and 1,2,3-triazole rings 4 were synthesized by the reactions of 1-{1-[(2-chlorothiazol-5-y1)methyl]-5-methyl-1H-1,2,3-triazol-4-yl}ethanone oxime with various asymmetric thiophosphoryl chlorides.Their structures were confn'med by IR,1H NMR,31P NMR,EI-MS and elemental analyses.The target compounds existed as E-configuration,which was deduced by NMR analysis and by comparison with their pyfidyl analog de-termined by X-ray diffraction.The results of preliminary bioassay indicate that some of title compounds possess moderate insecticidal and fungicidal activities.

  11. Synthesis and biological evaluation of colchicine C-ring analogues tethered with aliphatic linkers suitable for prodrug derivatisation.

    Science.gov (United States)

    Fournier-Dit-Chabert, Jérémie; Vinader, Victoria; Santos, Ana Rita; Redondo-Horcajo, Mariano; Dreneau, Aurore; Basak, Ramkrishna; Cosentino, Laura; Marston, Gemma; Abdel-Rahman, Hamdy; Loadman, Paul M; Shnyder, Steven D; Díaz, José Fernando; Barasoain, Isabel; Falconer, Robert A; Pors, Klaus

    2012-12-15

    Colchicine was modified at the 10-OCH(3) position of the C-ring by reaction with heterocyclic amines or commercially available amines to afford a library of target colchicinoids in high yields (62-99%). Molecular modeling revealed that the incorporation of the linker groups led to a reduction in entropy and therefore binding affinity when compared with colchicine. Some colchicinoids were shown to be equicytotoxic with colchicine when evaluated in the DLD-1 colon cancer cells and retained activity in resistant A2780AD or HeLa cells with mutant Class III β-tubulin. Importantly, unlike colchicine, the analogues in this study are amenable for prodrug derivatisation and with potential for tumor-selective delivery. PMID:23103097

  12. Synthesis and biological activity of new (E)-alpha-(Methoxyimino)benzeneacetate derivatives containing a substituted pyrazole ring.

    Science.gov (United States)

    Li, Miao; Liu, Chang-Ling; Yang, Ji-Chun; Zhang, Jin-Bo; Li, Zhi-Nian; Zhang, Hong; Li, Zheng-Ming

    2010-03-10

    Strobilurins are one of the most important classes of agricultural fungicides. To discover new strobilurin analogues with high activity, a series of new strobilurin derivatives containing a substituted pyrazole in the side chain were synthesized and their biological activities were tested. The compounds were identified by (1)H nuclear magnetic resonance, infrared, and elemental analysis. The test results indicated that the compounds exhibited strong fungicidal activities against Pyricularia oryzae , Phytophthora infestans , Pseudoperonospora cubensis , and Erysiphe graminis . The relationship between structure and biological activity is discussed in terms of the effects of the substituents on the pyrazole ring. The present work demonstrates that strobilurin analogues with a 3-(substituted phenyl)-1H-pyrazol-5-oxy side chain can be used as possible lead compounds for the development of potential agrochemicals. PMID:19961182

  13. cis-Nitenpyram Analogues Bearing Acyloxy Segments Anchored on the Tetrahydropyrimidine Ring: Synthesis,Insecticidal Activities and Molecular Docking Studies

    Institute of Scientific and Technical Information of China (English)

    SUN Chuan-wen; WU Ying; CHEN Yan-xia; NAN Shi-bin; ZHANG Wang-geng

    2013-01-01

    A series of novel cis-nitenpyram analogues bearing acyloxy segments anchored on the tetrahydropyrimidine ring was designed and synthesized.Preliminary bioassays indicate that all the nitenpyram analogues 3a—3n exhibit good insecticidal activities against Nilaparvata lugens and Aphis medicaginis at 100 mg/L,while analogue 3k affords the best activity in vitro and the lethal concentration 50(LC50) values(0.187,0.214 mg/L) are close to that of nitenpyram.The structure activity relationships(SARs) suggest that their insecticidal potency is influenced by the species of acyloxy segments.The docking results reveal that analogue 3k forms stronger hydrogen-bonding with the nAChR,which explain the structure activity relationships(SARs) observed in vitro and imply that the strategies of our designed nitenpyram analogues are feasible.

  14. Ring theory

    CERN Document Server

    Rowen, Louis H

    1991-01-01

    This is an abridged edition of the author's previous two-volume work, Ring Theory, which concentrates on essential material for a general ring theory course while ommitting much of the material intended for ring theory specialists. It has been praised by reviewers:**""As a textbook for graduate students, Ring Theory joins the best....The experts will find several attractive and pleasant features in Ring Theory. The most noteworthy is the inclusion, usually in supplements and appendices, of many useful constructions which are hard to locate outside of the original sources....The audience of non

  15. Fusing porphyrins with polycyclic aromatic hydrocarbons and heterocycles for optoelectronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Mark E.; Diev, Viacheslav; Hanson, Kenneth; Forrest, Stephen R.

    2015-08-18

    A compound that can be used as a donor material in organic photovoltaic devices comprising a non-activated porphyrin fused with one or more non-activated polycyclic aromatic rings or one or more non-activated heterocyclic rings can be obtained by a thermal fusion process. The compounds can include structures of Formula I: ##STR00001## By heating the reaction mixture of non-activated porphyrins with non-activated polycyclic aromatic rings or heterocyclic rings to a fusion temperature and holding for a predetermined time, fusion of one or more polycyclic rings or heterocyclic rings to the non-activated porphyrin core in meso,.beta. fashion is achieved resulting in hybrid structures containing a distorted porphyrin ring with annulated aromatic rings. The porphyrin core can be olygoporphyrins.

  16. (Hetero)aromatics from dienynes, enediynes and enyne-allenes.

    Science.gov (United States)

    Raviola, Carlotta; Protti, Stefano; Ravelli, Davide; Fagnoni, Maurizio

    2016-08-01

    The construction of aromatic rings has become a key objective for organic chemists. While several strategies have been developed for the functionalization of pre-formed aromatic rings, the direct construction of an aromatic core starting from polyunsaturated systems is yet a less explored field. The potential of such reactions in the formation of aromatics increased at a regular pace in the last few years. Nowadays, there are reliable and well-established procedures to prepare polyenic derivatives, such as dienynes, enediynes, enyne-allenes and hetero-analogues. This has stimulated their use in the development of innovative cycloaromatizations. Different examples have recently emerged, suggesting large potential of this strategy in the preparation of (hetero)aromatics. Accordingly, this review highlights the recent advancements in this field and describes the different conditions exploited to trigger the process, including thermal and photochemical activation, as well as the use of transition metal catalysis and the addition of electrophiles/nucleophiles or radical species.

  17. Synthesis of Aromatic Hyperbranched Polyesters and Modification of Their End-groups%全芳型超支化聚酯的合成及端基改性

    Institute of Scientific and Technical Information of China (English)

    唐黎明

    2001-01-01

    Soluble aromatic hyperbranched polyesters with controlled viscosities have been preparedby melt polycondensation of sililated 5-acetoxyisophathalic acid with sililated p-tert-butyl benzoic acidin various molar ratios. By further reaction with thionyl chloride and propargyl alcohol successively,the endgroups of the crude polyester were transferred into ethynylic groups in 78. 2% yield as calculat-ed by 1H NMR spectra.

  18. Visible-light photoredox catalyzed synthesis of pyrroloisoquinolines via organocatalytic oxidation/[3 + 2] cycloaddition/oxidative aromatization reaction cascade with Rose Bengal

    Directory of Open Access Journals (Sweden)

    Carlos Vila

    2014-05-01

    Full Text Available Pyrrolo[2,1-a]isoquinoline alkaloids have been prepared via a visible light photoredox catalyzed oxidation/[3 + 2] cycloaddition/oxidative aromatization cascade using Rose Bengal as an organo-photocatalyst. A variety of pyrroloisoquinolines have been obtained in good yields under mild and metal-free reaction conditions.

  19. Tri- and tetra-dentate imine vanadyl complexes: synthesis, structure and ethylene polymerization/ring opening polymerization capability.

    Science.gov (United States)

    Ma, Jing; Zhao, Ke-Qing; Walton, Mark; Wright, Joseph A; Hughes, David L; Elsegood, Mark R J; Michiue, Kenji; Sun, Xinsen; Redshaw, Carl

    2014-11-28

    Reaction of the ligand 2,4-tert-butyl-6-[(2-methylquinolin-8-ylimino)methyl]phenol (L(1)H) with [VOCl3] in the presence of triethylamine afforded the complex [VOCl2L(1)] (1), whereas use of [VO(OnPr)3] led to the isolation of [VO2L(1)] (2) or [VO2L(1)]·2/3MeCN (2·2/3MeCN). Reaction of 2-((2-(1H-benzo[d]imidazol-2-yl)quinolin-8-ylimino)methyl)-4,6-R(1),R(2)-phenols (R(1) = R(2) = (t)Bu; L(2)H), (R(1) = R(2) = Me; L(3)H) or (R(1) = Me, R(2) = Ad; L(4)H) with [VO(OnPr)3] afforded complexes of the type [L(2-4)VO] (where L(2) = 3, L(3) = 4, L(4) = 5). The molecular structures of 1 to 3 are reported; the metal centre adopts a distorted octahedral, trigonal bipyramidal or square-based pyramidal geometry respectively. In Schlenk line tests, all complexes have been screened as pre-catalysts for the polymerization of ethylene using diethylaluminium chloride (DEAC) as co-catalyst in the presence of ethyltrichloroacetate (ETA), and for the ring opening polymerization (ROP) of ε-caprolactone in the presence of benzyl alcohol. All pre-catalyst/DEAC/ETA systems are highly active ethylene polymerization catalysts affording linear polyethylene with activities in the range 3000-10,700 g (mol h bar)(-1); the use of methylaluminoxane (MAO) or modified MAO as co-catalyst led to poor or no activity. In a parallel pressure reactor, 3-5 have been screened as pre-catalysts for ethylene polymerization in the presence of either DEAC or DMAC (dimethylaluminium chloride) and ETA at various temperatures and for the co-polymerization of ethylene with propylene. The use of DMAC proved more promising with 3 achieving an activity of 63,000 g (mol h bar)(-1) at 50 °C and affording UHMWPE (M(w) ~ 2,000,000). In the case of the co-polymerization, the incorporation of propylene was 6.9-8.8 mol%, with 3 exhibiting the highest incorporation when using either DEAC or DMAC. In the case of the ring opening polymerization (ROP) of ε-caprolactone, systems employing complexes 1-5 were virtually inactive

  20. Dimethandrolone (7α,11β-dimethyl-19-nortestosterone) and 11β-methyl-19-nortestosterone are not converted to aromatic A-ring products in the presence of recombinant human aromatase☆

    OpenAIRE

    Attardi, Barbara J.; Pham, Trung C.; Radler, Lisa M.; Burgenson, Janet; Hild, Sheri A.; Reel, Jerry R.

    2008-01-01

    Dimethandrolone undecanoate (DMAU: 7α,11β-dimethyl-19-nortestosterone 17β-undecanoate) is a potent orally active androgen in development for hormonal therapy in men. Cleavage of the 17β-ester bond by esterases in vivo leads to liberation of the biologically active androgen, dimethandrolone (DMA), a 19-norandrogen. For hormone replacement in men, administration of C19 androgens such as testosterone (T) may lead to elevations in circulating levels of estrogens due to aromatization. As several r...

  1. Contorted polycyclic aromatics.

    Science.gov (United States)

    Ball, Melissa; Zhong, Yu; Wu, Ying; Schenck, Christine; Ng, Fay; Steigerwald, Michael; Xiao, Shengxiong; Nuckolls, Colin

    2015-02-17

    CONSPECTUS: This Account describes a body of research in the design, synthesis, and assembly of molecular materials made from strained polycyclic aromatic molecules. The strain in the molecular subunits severely distorts the aromatic molecules away from planarity. We coined the term "contorted aromatics" to describe this class of molecules. Using these molecules, we demonstrate that the curved pi-surfaces are useful as subunits to make self-assembled electronic materials. We have created and continue to study two broad classes of these "contorted aromatics": discs and ribbons. The figure that accompanies this conspectus displays the three-dimensional surfaces of a selection of these "contorted aromatics". The disc-shaped contorted molecules have well-defined conformations that create concave pi-surfaces. When these disc-shaped molecules are substituted with hydrocarbon side chains, they self-assemble into columnar superstructures. Depending on the hydrocarbon substitution, they form either liquid crystalline films or macroscopic cables. In both cases, the columnar structures are photoconductive and form p-type, hole- transporting materials in field effect transistor devices. This columnar motif is robust, allowing us to form monolayers of these columns attached to the surface of dielectrics such as silicon oxide. We use ultrathin point contacts made from individual single-walled carbon nanotubes that are separated by a few nanometers to probe the electronic properties of short stacks of a few contorted discs. We find that these materials have high mobility and can sense electron-deficient aromatic molecules. The concave surfaces of these disc-shaped contorted molecules form ideal receptors for the molecular recognition and assembly with spherical molecules such as fullerenes. These interfaces resemble ball-and-socket joints, where the fullerene nests itself in the concave surface of the contorted disc. The tightness of the binding between the two partners can be

  2. Zinc complexes supported by multidentate aminophenolate ligands: synthesis, structure and catalysis in ring-opening polymerization of rac-lactide.

    Science.gov (United States)

    Wang, Liying; Ma, Haiyan

    2010-09-14

    Monomeric zinc silylamido and ethyl complexes bearing tetradentate aminophenolato ligands [(DNNO)ZnR] (D = NMe(2), OMe; R = N(SiMe(3))(2) (1-5, 8), Et (6, 7, 9, 10)), were isolated from the reaction of Zn[N(SiMe(3))(2)](2) or ZnEt(2) and one equivalent of aminophenols {aryl-CH(2)N[(CH(2))(2)NMe(2)]CH(2)-phenol} in moderate to high yields. The monomeric nature of these complexes was further confirmed by X-ray diffraction studies of silylamido complexes 1, 3 and ethyl complexes 7, 9, 10. The methoxy or N,N-dimethylamino group of the aryl unit does not coordinate with the metal center in the solid state, only the remaining three donors of the ligand and silylamido or ethyl group interact with zinc center constructing a distorted tetrahedral coordination geometry at the metal center. All these zinc complexes efficiently initiated the ring-opening polymerization of rac-lactide, and the polymerization runs were better controlled in the presence of isopropanol, giving atactic PLAs end-capped with isopropyl ester and hydroxyl groups. The structure of the ancillary ligands showed some influence on the catalytic activity and selectivity of the corresponding zinc complexes. The introduction of bulky ortho-substituents on the phenoxy unit resulted in a decrease of the polymerization rate, whereas the isotactic dyad selectivity in the ROP of rac-lactide was enhanced. PMID:20657936

  3. Synthesis of biodegradable amphiphilic Y-shaped block co-polymers via ring-opening polymerization for drug delivery.

    Science.gov (United States)

    Jia, Lin; Yan, Lifeng; Li, Yang

    2011-01-01

    A series of novel Y-shaped biodegradable block co-polymers of poly(ε-caprolactone) (PCL) and poly(ethyl ethylene phosphate) (PEEP) (PCL-(PEEP)2) were synthesized via ring-opening polymerization (ROP) of EEP with bis-hydroxy-functional ROP initiator (init-PCL-(OH)2). The init-PCL-(OH)2 was synthesized by ROP of CL using 4-hydroxybutyl acrylate (HBA) as initiator and L-tartaric acid as catalyst in bulk, and subsequently the resulting vinyl-terminated PCL was end-capped by acetyl chloride, followed by Michael addition using excess diethanolamine. The Y-shaped co-polymers and their intermediates were characterized by (1)H-, (13)C-, (31)P-NMR, FT-IR and gel-permeation chromatography. The results indicated that the molecular weight of the Y-shaped co-polymers increased with the increasing of the molar ratios of EEP to init-PCL-(OH)2 in the feed, while the PCL chain length was kept constant. The amphiphilic block co-polymers could self-assemble into micelles in aqueous solution, which was demonstrated by dynamic light scattering, (1)H-NMR and atomic force microscopy. A study of controlled release of indomethacin indicated that the amphiphilic block co-polymers could potentially provide novel vehicles for drug delivery.

  4. Synthesis of High Performance Cyclic Olefin Polymers (COPs with Ester Group via Ring-Opening Metathesis Polymerization

    Directory of Open Access Journals (Sweden)

    Jing Cui

    2015-08-01

    Full Text Available Novel ester group functionalized cyclic olefin polymers (COPs with high glass transition temperature, high transparency, good mechanical performance and excellent film forming ability have been achieved in this work via efficient ring-opening metathesis copolymerization of exo-1,4,4a,9,9a,10-hexahydro-9,10(1′,2′-benzeno-l,4-methanoanthracene (HBM and comonomers (5-norbornene-2-yl methylacetate (NMA, 5-norbornene-2-yl methyl 2-ethylhexanoate (NME or 5-norbornene-2-yl methyldodecanoate (NMD utilizing the Grubbs first generation catalyst, Ru(CHPh(Cl2(PCy32 (Cy = cyclohexyl, G1, followed by hydrogenation of double bonds in the main chain. The fully hydrogenated copolymers were characterized by nuclear magnetic resonance, FT-IR spectroscopy analysis, gel permeation chromatography, and thermo gravimetric analysis. Differential scanning calorimetry curves showed that the glass transition temperatures (Tg linearly decreased with the increasing of comonomers content, which was easily controlled by changing feed ratios of HBM and comonomers. Static water contact angles tests indicate that hydrophilicity of copolymers can also be modulated by changing the comonomers incorporation. Additionally, the mechanical performances of copolymers were also investigated.

  5. Synthesis, fungicidal activity, and structure-activity relationship of spiro-compounds containing macrolactam (macrolactone) and thiadiazoline rings.

    Science.gov (United States)

    Li, Jian-Jun; Liang, Xiao-Mei; Jin, Shu-Hui; Zhang, Jian-Jun; Yuan, Hui-Zhu; Qi, Shu-Hua; Chen, Fu-Heng; Wang, Dao-Quan

    2010-03-10

    Two series of novel spiro-compounds containing macrolactam or macrolactone and thiadiazoline rings, 1-thia-2-alkylimino-3,4,9-triaza-10-oxospiro[4.15]eicosyl-3-ene (4F) and 1-thia-2-alkylimino-3,4-diaza-9-oxa-10-oxospiro[4.15]eicosyl-3-ene (4G), were synthesized from 12-oxo-1,15-pentadecanlactam and 12-oxo-1,15-pentadecanlactone, respectively. Their structures were confirmed by elemental analysis, (1)H NMR, and (13)C NMR. The conformation of compounds 4F was determined via the crystal structure of a representative compound (4F(6)). The bioassay showed that compounds 4F have much better fungicidal activity against five fungi ( Botrytis cinerea Pers., Sclerotinia sclerotiorum , Rhizoctonia solani Kuhn., Phomopsis asparagi Sacc., and Pyricularia oryzae Cav.) than compounds 4G. The fact above showed that the presence of a hydrogen-bonding donor for the fungicidal activity of macrocyclic compounds is very important. 4F(6) showed excellent fungicidal activity against P. oryzae, which is much better than the commercial fungicide isoprothiolane, and 4F(13) showed excellent fungicidal activity against P. oryzae and good fungicidal activity against P. asparagi. PMID:20041703

  6. Planetary Rings

    CERN Document Server

    Tiscareno, Matthew S

    2011-01-01

    Planetary rings are the only nearby astrophysical disks, and the only disks that have been investigated by spacecraft. Although there are significant differences between rings and other disks, chiefly the large planet/ring mass ratio that greatly enhances the flatness of rings (aspect ratios as small as 1e-7), understanding of disks in general can be enhanced by understanding the dynamical processes observed at close-range and in real-time in planetary rings. We review the known ring systems of the four giant planets, as well as the prospects for ring systems yet to be discovered. We then review planetary rings by type. The main rings of Saturn comprise our system's only dense broad disk and host many phenomena of general application to disks including spiral waves, gap formation, self-gravity wakes, viscous overstability and normal modes, impact clouds, and orbital evolution of embedded moons. Dense narrow rings are the primary natural laboratory for understanding shepherding and self-stability. Narrow dusty...

  7. Planetary Rings

    Science.gov (United States)

    Gordon, M. K.; Araki, S.; Black, G. J.; Bosh, A. S.; Brahic, A.; Brooks, S. M.; Charnoz, S.; Colwell, J. E.; Cuzzi, J. N.; Dones, L.; Durisen, R. H.; Esposito, L. W.; Ferrari, C.; Festou, M.; French, R. G.; Giuliatti-Winter, S. M.; Graps, A. L.; Hamilton, D. P.; Horanyi, M.; Karjalainen, R. M.; Krivov, A. V.; Krueger, H.; Larson, S. M.; Levison, H. F.; Lewis, M. C.; Lissauer, J. J.; Murray, C. D.; Namouni, F.; Nicholson, P. D.; Olkin, C. B.; Poulet, F.; Rappaport, N. J.; Salo, H. J.; Schmidt, J.; Showalter, M. R.; Spahn, F.; Spilker, L. J.; Srama, R.; Stewart, G. R.; Yanamandra-Fisher, P.

    2002-08-01

    The past two decades have witnessed dramatic changes in our view and understanding of planetary rings. We now know that each of the giant planets in the Solar System possesses a complex and unique ring system. Recent studies have identified complex gravitational interactions between the rings and their retinues of attendant satellites. Among the four known ring systems, we see elegant examples of Lindblad and corotation resonances (first invoked in the context of galactic disks), electromagnetic resonances, spiral density waves and bending waves, narrow ringlets which exhibit internal modes due to collective instabilities, sharp-edged gaps maintained via tidal torques from embedded moonlets, and tenuous dust belts created by meteoroid impact onto, or collisions between, parent bodies. Yet, as far as we have come, our understanding is far from complete. The fundamental questions confronting ring scientists at the beginning of the twenty-first century are those regarding the origin, age and evolution of the various ring systems, in the broadest context. Understanding the origin and age requires us to know the current ring properties, and to understand the dominant evolutionary processes and how they influence ring properties. Here we discuss a prioritized list of the key questions, the answers to which would provide the greatest improvement in our understanding of planetary rings. We then outline the initiatives, missions, and other supporting activities needed to address those questions, and recommend priorities for the coming decade in planetary ring science.

  8. Green Synthesis of Silver Nanoparticles using Achillea biebersteinii Flower Extract and Its Anti-Angiogenic Properties in the Rat Aortic Ring Model

    Directory of Open Access Journals (Sweden)

    Javad Baharara

    2014-04-01

    Full Text Available Silver nanoparticles display unique physical and biological properties which have attracted intensive research interest because of their important medical applications. In this study silver nanoparticles (Ab.Ag-NPs were synthesized for biomedical applications using a completely green biosynthetic method using Achillea biebersteinii flowers extract. The structure and properties of Ab.Ag-NPs were investigated using UV-visible spectroscopic techniques, transmission electron microscopy (TEM, zeta potential and energy dispersive X-ray spectrometers (EDS. The UV-visible spectroscopic analysis showed the absorbance peak at 460 nm, which indicates the synthesis of silver nanoparticles. The average particle diameter as determined by TEM was found to be 12 ± 2 nm. The zeta potential analysis indicated that Ab.Ag-NPs have good stability EDX analysis also exhibits presentation of silver element. As angiogenesis is an important phenomenon and as growth factors imbalance in this process causes the acceleration of several diseases including cancer, the anti-angiogenic properties of Ab.Ag-NPs were evaluated using the rat aortic ring model. The results showed that Ab.Ag-NPs (200 μg/mL lead to a 50% reduction in the length and number of vessel-like structures. The synthesized silver nanoparticles from the Achillea biebersteinii flowers extract, which do not involve any harmful chemicals were well-dispersed and stabilized through this green method and showed potential therapeutic benefits against angiogenesis.

  9. Bis-perfluoroalkylation of aromatic compounds with sodium perfluoroalkanesulfinates

    Institute of Scientific and Technical Information of China (English)

    LIU, Jin-Tao(刘金涛); LU, He-Jun(吕贺军)

    2000-01-01

    Bis-perfluoroalkylation of aromatic compounds such as dimethoxybenzenes (2,4,6), anisole (8), pyridine (10) and quinoline (13) was accomplished by reaction with excess sodium perfluoroalkanesulfinates, RFSO2Na (1), in the presence of Mn(OAc)3·2H2O under mild conditions. The reaction provides a facile method for the synthesis of bis-perfluoroalkylated aromatic compounds.

  10. Study on Synthesis and Application of a New Substituted Aromatic Tannage%一种新的置换型合成鞣剂的制备与应用

    Institute of Scientific and Technical Information of China (English)

    吕生华; 强西怀; 颜天焰

    2001-01-01

    A new substiuted synthetic tanning agent was produced by sulfonation reaction andcondensation polymerization with aromatic compounds. Furthermore, the properties as tarning,pretanning and retanning agents was measured. Its principle of synthesis and structuralcharacteristics was also shown.%本文对以芳香族单体为主要原料制备的新的置换型合成鞣剂的应用性能进行了研究,表征了共作为鞣剂、预鞣剂及复鞣剂的性能特征,同时对其制备原理及结构特点也作了必要的说明。

  11. Oligomeric ferrocene rings

    Science.gov (United States)

    Inkpen, Michael S.; Scheerer, Stefan; Linseis, Michael; White, Andrew J. P.; Winter, Rainer F.; Albrecht, Tim; Long, Nicholas J.

    2016-09-01

    Cyclic oligomers comprising strongly interacting redox-active monomer units represent an unknown, yet highly desirable class of nanoscale materials. Here we describe the synthesis and properties of the first family of molecules belonging to this compound category—differently sized rings comprising only 1,1‧-disubstituted ferrocene units (cyclo[n], n = 5–7, 9). Due to the close proximity and connectivity of centres (covalent Cp–Cp linkages; Cp = cyclopentadienyl) solution voltammograms exhibit well-resolved, separated 1e– waves. Theoretical interrogations into correlations based on ring size and charge state are facilitated using values of the equilibrium potentials of these transitions, as well as their relative spacing. As the interaction free energies between the redox centres scale linearly with overall ring charge and in conjunction with fast intramolecular electron transfer (∼107 s‑1), these molecules can be considered as uniformly charged nanorings (diameter ∼1–2 nm).

  12. Synthesis, Spectral, and Biological Properties of Copper(II) Complexes of Thiosemicarbazones of Schiff Bases Derived from 4-Aminoantipyrine and Aromatic Aldehydes

    OpenAIRE

    2006-01-01

    We have synthesized a novel series of Schiff bases by condensation of 4-aminoantipyrine and various aromatic aldehydes followed by reaction with thiosemicarbazide. These thiosemicarbazones are potential ligands toward transition metal ions. The reaction of copper(II) salts with 4[N-(benzalidene)amino]antipyrinethiosemicarbazone (BAAPTS), 4[N-(4′-methoxybenzalidene) amino] antipyrinethiosemicarbozone (MBAAPTS), 4[N-(4′-dimethylamino benzalidene) amino] antipyrinethiosemicarbazone (DA...

  13. One-pot synthesis of fully substituted 1,3,4-oxadiazole derivatives from aromatic carboxylic acids, cyclobutanone and N-isocyaniminotriphenylphosphorane

    OpenAIRE

    HOLAGH, Mohsen VALIZADEH; MAHARRAMOV, Abel Mohammadali oglu

    2012-01-01

    Reactions of N-isocyaniminotriphenylphosphorane with cyclobutanone in the presence of aromatic (or heteroaromatic) carboxylic acids proceeded smoothly at room temperature and in neutral conditions to afford sterically congested 1-(5-aryl-1,3,4-oxadiazol-2-yl)- 1-cyclobutanol derivatives in high yields. The reaction proceeded smoothly and cleanly under mild conditions and no side reactions were observed. The structures of the products were deduced from their IR, 1HNMR, and 13CNMR spec...

  14. Electron beam irradiation effects on aromatic polymers

    International Nuclear Information System (INIS)

    Electron irradiation effects on aromatic polymers having various molecular structures were studied to elucidate the following subjects; (1) relation between radiation stability and molecular structure of repeating units, (2) mechanism of deterioration and (3) adaptability to matrix resin for radiation resistant FRP. Results are summarized as follows: (1) An order of radiation stability of units is; imide ring > diphenyl ether, diphenyl ketone > aromatic amide >> bis-phenol A > diphenyl sulphone. (2) Poly (ether-ether-ketone) and most polyimide are crosslinkable but polysulphones and polyarylate are chain degradation type polymers. (3) Newly developed thermoplastic polyimides have possibilities for use as matrix materials in radiation resistant FRP. (author)

  15. Translation of an aromatic field image

    Science.gov (United States)

    Yastrebov, Anatoliy S.; Makarov, Leonid M.; Protasenya, Sergey V.; Vereshak, Evgeniy V.

    2005-04-01

    As is known, for a person there are possibilities of perception of audio, video, and aromatic information messages by means of touch systems available to him. Such packages of the messages are accepted remotely without direct contact to a message source. Now the direction bound with creation of devices capable to playback aromatic information images is actively developed. Such systems switched on in special transmission channels of information provide adequate perception of information highways describing actual event which happen in the enclosing world. One can present the aromatic-field image through a series of control codes for an aromatic field synthesizer, thereupon it is possible to transmit the image on telecommunication networks. For odor oscillators installation problems in compartments of automobiles, buses as well as of airplanes are widely discussed. In this work we deal with a device for synthesis of an image of an aromatic field which works under the control of a personal computer with an express program. In the given operation, the possibility of remote handle of an image of an aromatic field and, as a corollary, organization of a new tansmission channel for the information on the aromatic-field image through an existing synthesizer is considered.

  16. THE POLYMERIZATION OF AROMATIC AND HETEROCYCLIC DINITRILES

    Institute of Scientific and Technical Information of China (English)

    HUANG Zhitang

    1988-01-01

    This review is a concise survey about the works in our laboratory on the polymerization of aromatic and heterocyclic dinitriles, including the polymerization kinetics and mechanism, synthesis of heterocyclic dinitriles, the structure of polymers, and the correlation between the structures of dinitriles and polymerization rates and thermal performances of polymers.

  17. Tandem Ring-Opening-Ring-Closing Metathesis for Functional Metathesis Catalysts.

    Science.gov (United States)

    Nagarkar, Amit A; Yasir, Mohammad; Crochet, Aurelien; Fromm, Katharina M; Kilbinger, Andreas F M

    2016-09-26

    Use of a tandem ring-opening-ring-closing metathesis (RORCM) strategy for the synthesis of functional metathesis catalysts is reported. Ring opening of 7-substituted norbornenes and subsequent ring-closing metathesis forming a thermodynamically stable 6-membered ring lead to a very efficient synthesis of new catalysts from commercially available Grubbs' catalysts. Hydroxy functionalized Grubbs' first- as well as third-generation catalysts have been synthesized. Mechanistic studies have been performed to elucidate the order of attack of the olefinic bonds. This strategy was also used to synthesize the ruthenium methylidene complex. PMID:27592840

  18. Tandem Ring-Opening-Ring-Closing Metathesis for Functional Metathesis Catalysts.

    Science.gov (United States)

    Nagarkar, Amit A; Yasir, Mohammad; Crochet, Aurelien; Fromm, Katharina M; Kilbinger, Andreas F M

    2016-09-26

    Use of a tandem ring-opening-ring-closing metathesis (RORCM) strategy for the synthesis of functional metathesis catalysts is reported. Ring opening of 7-substituted norbornenes and subsequent ring-closing metathesis forming a thermodynamically stable 6-membered ring lead to a very efficient synthesis of new catalysts from commercially available Grubbs' catalysts. Hydroxy functionalized Grubbs' first- as well as third-generation catalysts have been synthesized. Mechanistic studies have been performed to elucidate the order of attack of the olefinic bonds. This strategy was also used to synthesize the ruthenium methylidene complex.

  19. Synthesis and preliminary evaluation of N-acylhydrazone compounds as antibacterial and antifungal agents

    International Nuclear Information System (INIS)

    We describe the synthesis and evaluation of N-acylhydrazone compounds bearing different electron-donating groups in one of its aromatic rings, obtained using a four-step synthetic route. IC50 values against pathogenic fungi and bacteria were determined by serial microdilution. Compounds showed low activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. By contrast, a derivative with a meta-oriented electron-donating group showed significant activity (IC50) against Candida albicans (17 μM), C. krusei (34 μM) and C. tropicalis (17 μM). Results suggest this is a promising lead-compound for synthesis of potent antifungal agents. (author)

  20. One-pot synthesis of 4′-alkyl-4-cyanobiaryls on the basis of the terephthalonitrile dianion and neutral aromatic nitrile cross-coupling

    Science.gov (United States)

    Peshkov, Roman Yu; Chunyan, Wang; Tretyakov, Evgeny V; Shteingarts, Vitalij D

    2016-01-01

    Summary A convenient one-pot approach to alkylcyanobiaryls is described. The method is based on biaryl cross-coupling between the sodium salt of the terephthalonitrile dianion and a neutral aromatic nitrile in liquid ammonia, and successive alkylation of the long-lived anionic intermediate with alkyl bromides. The reaction is compatible with benzonitriles that contain methyl, methoxy and phenyl groups, fluorine atoms, and a 1-cyanonaphthalene residue. The variety of ω-substituted alkyl bromides, including an extra bromine atom, a double bond, cyano and ester groups, as well as a 1,3-dioxane fragment are suitable as alkylation reagents. PMID:27559409

  1. Synthesis and characterization of new polyesters based on 2,5-bis[(4-chloro carboxyanilino)carbonyl]pyridine and aromatic diols

    Institute of Scientific and Technical Information of China (English)

    Khalil; Faghihi

    2010-01-01

    Six new polyesters 7a-f were synthesized through the solution polycondensation reaction of diacid chloride 5 with six aromatic diols 6a-f in N,N-dimethyl acetamide(DMAc) as solvent in the presence of pyridine as base.The polycondensation reaction produced a series of novel polyester containing pyridyl moiety in the main chain in high yields with inherent viscosities between 0.35 and 0.54 dL/g.The resulted polymers were fully characterized by means of FT-IR spectroscopy,elemental analyses,inherent viscosi...

  2. SUPRAMITRAL RING

    Directory of Open Access Journals (Sweden)

    Rajesh G

    2011-11-01

    Full Text Available Supra mitral ring is a rare cause for congenital mitral valve obstr uction. The reported incidence of supramitral ring is 0.2-0.4% in general population and 8% in patients with congenital mitral valve disease. The condition is characterized by an abnormal ridge of connective tissue often circumferential in shape ,on the atrial side of the mitral valve encroaching on the orifice of the mitral valve. It may adhere to the leaflets of the valve and restrict their movements. Although a supramitral ring may be rarely nonobstructive, it often results in mitral valve inflow obstruction.

  3. Synthesis and characterization of heat-resistant and soluble poly(amide-imide)s from unsymmetrical dicarboxylic acid containing 2-(triphenyl phosphoranylidene) moiety and various aromatic diamines

    Indian Academy of Sciences (India)

    Seema Agrawal; Anudeep Kumar Narula

    2015-04-01

    An unsymmetrical and non-coplaner heterocyclic phosphorus containing dicarboxylic acid monomer, (DCA-3) is successfully synthesized with high purity. A series of novel aromatic poly(amide-imide)s having ether or/sulphur or/fluorine or/phosphorus containing phenyl moieties in their backbone are then prepared via a direct phosphorylation polycondensation of synthesized dicarboxylic acid with various aromatic diamines. Chemical structures of DCA-3 as well as resulting polymers are confirmed by FT-IR, NMR spectroscopic techniques and elemental analysis. These polymers are readily soluble in a variety of aprotic polar solvents such as NMP, DMSO, DMAc and DMF, etc. UV spectra showed that all poy(amide-imide)s films exhibit high optical transparency. In addition, the glass transition temperatures (Tg) of these polymers were determined by differential scanning calorimetry and found in the range 271–346°C. Furthermore, thermogravimetric analysis of these polymers showed good thermal stability, 10% weight loss at temperature in excess of 538°C and char yield at 700°C in nitrogen ranging from 68 to 79%. From wide-angle X-ray diffraction experiments, all polymers showed amorphous behaviour.

  4. 1-氨基乙内酰脲芳香醛类席夫碱的有效合成%Synthesis of 1-aminohydantoin aromatic aldehyde Schiff bases

    Institute of Scientific and Technical Information of China (English)

    张逢源; 周惠良; 胡奇林

    2014-01-01

    以1-氨基乙内酰脲与芳香醛为原料,合成了6种1-氨基乙内酰脲芳香醛类席夫碱,收率为72.6%-89.2%,并对其反应条件进行了优化,得出在回流温度下,1-氨基乙内酰脲与芳香醛的投料摩尔比为1∶1(对苯二甲醛为2∶1)时反应1.5~2h产率最高。通过IR、1 HNMR和元素分析表征了目标化合物的结构。%Six aromatic aldehyde Schiff bases were synthesized from 1-aminohydantoin and aromatic aldehyde. Its yield from 72. 6%-89. 2%and the reactive condition were optimized. The target compounds were identified by IR,1 HNMR and elemental analysis.

  5. Preferential Utilization of Aromatic Compounds over Glucose by Pseudomonas putida CSV86

    OpenAIRE

    Basu, Aditya; Apte, Shree K.; Phale, Prashant S.

    2006-01-01

    Pseudomonas putida CSV86, a naphthalene-degrading organism, exhibited diauxic growth on aromatic compounds plus glucose, with utilization of aromatics in the first log phase and of glucose in the second log phase. Glucose supplementation did not suppress the activity of degrading enzymes, which were induced upon addition of aromatic compounds. The induction was inhibited by chloramphenicol, suggesting that de novo protein synthesis was essential. Cells showed cometabolism of aromatic compound...

  6. Synthesis of novel β-aminocyclobutanecarboxylic acid derivatives by a solvent-free aza-Michael addition and subsequent ring closure

    OpenAIRE

    Meiresonne, Tamara; Mangelinckx, Sven; De Kimpe, Norbert

    2011-01-01

    Novel beta-aminocyclobutanecarboxylic acid derivatives were prepared via a sequential solvent-free aza-Michael addition of benzophenone imine across 3-halopropylidenemalonates and base-induced ring closure. These highly substituted cyclobutanedicarboxylic acid derivatives were subjected to a reactivity study which demonstrated the tendency of these donor-acceptor substituted four-membered rings to be converted into their corresponding ring-opened products.

  7. Advances in Synthesis and Aromatization of Hantzsch 1,4-Dihydropyridine Derivatives%Hantzsch 1,4-二氢吡啶衍生物的合成及其芳香化研究进展

    Institute of Scientific and Technical Information of China (English)

    尹显洪

    2003-01-01

      综述了Hantzsch 1,4-二氢吡啶衍生物的合成及其芳香化研究进展.Hantzsch 1,4-二氢吡啶衍生物的合成方法有:(1)乙酰乙酸乙酯、芳香醛和氨或伯胺反应;(2)1,3-二酮化合物、芳香醛和氨或伯胺反应;(3)烯胺化合物和芳香醛反应;(4)1,5-二酮与氨反应;(5) a,b-不饱和酮与烯胺或酮和氨反应等.在合成技术上有固相合成和微波辅助合成等.Hantzsch 1,4-二氢吡啶芳香化方法有:光化学反应、电化学反应、脱氢反应、氢转移反应等,本文主要对脱氢反应研究进展进行综述.%  The main methods of synthesis and aromatization of Hantzsch 1,4-dihydropyridine derivatives was reviewed in this paper. The former included the reactions of ethyl acetoacetate and aromaticaldehyde with ammonia or primary amine, the reactions of 1,3-diketone compounds and aromaticaldehyde with ammonia or primary amine, the reactions of enamine compounds with aromaticaldehyde, the reactions of 1,5-diketone with amine, the reactions of a,b-unsaturated ketone with enamine or ketone and amine. The synthetic technologies included solid-phase synthesis and microwave-assistant synthesis. The latter included photochemical reactions, electrochemical reactions, dehydrogenation reactions, hydrogen transfer reactions.

  8. Determinantal rings

    CERN Document Server

    Bruns, Winfried

    1988-01-01

    Determinantal rings and varieties have been a central topic of commutative algebra and algebraic geometry. Their study has attracted many prominent researchers and has motivated the creation of theories which may now be considered part of general commutative ring theory. The book gives a first coherent treatment of the structure of determinantal rings. The main approach is via the theory of algebras with straightening law. This approach suggest (and is simplified by) the simultaneous treatment of the Schubert subvarieties of Grassmannian. Other methods have not been neglected, however. Principal radical systems are discussed in detail, and one section is devoted to each of invariant and representation theory. While the book is primarily a research monograph, it serves also as a reference source and the reader requires only the basics of commutative algebra together with some supplementary material found in the appendix. The text may be useful for seminars following a course in commutative ring theory since a ...

  9. Spectroscopic Characterisation of Novel Polycyclic Aromatic Polymers

    OpenAIRE

    O'Neill, Luke; Lynch, Patrick; McNamara, Mary; Byrne, Hugh

    2007-01-01

    A series of novel polyphenylenevinylene (PPV) derivative polymers were studied by absorption and photoluminescence spectroscopies. The effect of the sequential introduction of polycyclic aromatic ring substituents into the delocalized backbone was examined with relation to hypsochromatic and bathochromatic shifting. While the replacement of the phenyl units by naphthyl units results in a substantial hypsochromic shift of both the absorption and emission spectra, their subsequent substitution ...

  10. Self-Assembled Templates of Aromatic Pentapeptides for Synthesis of CdS Quantum-Dots to Detect the Trace Amounts of Hg(2+) in Aqueous Solutions.

    Science.gov (United States)

    Meng, Min; Dou, Yingying; Xu, Wenlong; Hao, Jingcheng

    2016-05-01

    Molecular self-assembly has become a popular tool to prepare nanomaterials with potential applications, such as ion-responsive detection of Hg(2+) in aqueous solutions. In this study, FFACD aromatic pentapeptides, whose N-terminuses were protected by carboxyl (Ac-FFACD) or a 9-fluorenylmethoxycarbonyl group (Fmoc-FFACD), were chosen as building blocks to produce nanostructures in solutions. Based on the preliminary determination of the critical aggregation concentration (CAC) of Ac-FFACD and Fmoc-FFACD aromatic pentapeptides in water, the order of magnitude of which is 10(-5) mol·L(-1), self-assembled spiral and networked nanowires can be easily obtained over a range of concentrations. These nanowires were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The self-assembled spiral and networked nanowires were designed to be used as templates for preparing CdS quantum dots (QDs) in-situ at room temperature. The peptide-functionalized, nanowire-encapsulated CdS QDs can be used for rapid, sensitive, and selective detection of trace amounts of mercuric ions (Hg(2+)) in aqueous solutions. This method enables rapid, linear detection (the linear correlation coefficients are 0.9972 of ΔF = 257.09 + 3.58 cHg(2+) for Ac-FFACD and 0.9994 of ΔF = 48.13 + 32.96 cHg(2+) for Fmoc-FFACD) with the Hg(2+) limit of detection at 300.85 ng·L(-1) and 32.09 ng·L(-1) for Ac-FFACD and Fmoc-FFACD, respectively. The supramolecular, self-assembled nanowires, fabricated from the two aromatic pentapeptides and having encapsulated QDs, exhibit superior properties attributable to the large loading capacity and the coordination sites of these peptides with Hg(2+). These structures can serve as novel Hg(2+) sensors and have possible applications for detection of various targets in scientific and engineering systems. PMID:27086999

  11. Synthesis of a new cyclosporine-based stationary phase and separation behaviors toward aromatic positional isomers by high-performance liquid chromatography.

    Science.gov (United States)

    Liu, Wen-na; Fan, Jun; Lin, Chun; Zheng, Sheng-run; Zhang, Wei-guang

    2015-04-01

    A new cyclosporine-bonded stationary phase has been synthesized through the Staudinger reaction between azido cyclosporine A (CsA) and aminopropyl silica gel and applied in separations of six disubstituted aromatic analytes by high-performance liquid chromatography. For dimethyl phthalate, nitroaniline and chloronitrobenzene, their positional isomers were well-separated on this CsA stationary phase, in which the separation factor for m-/o-dimethyl phthalates was the biggest. For nitrotoluene, dichlorobenzene and benzenediol, the m-/o-isomers were co-eluted. Then, effects of chromatographic conditions (such as types and content of alcoholic modifiers) on separation of nitroaniline positional isomers have been investigated. Retention behaviors of nitroaniline isomers on the column exhibited the strengthening trend along with increasing carbon number of alcohols, from ethanol to 1-propanol, and to 1-butanol. A similar phenomenon was observed by lowering the content of alcohol.

  12. Batch and flow photochemical benzannulations based on the reaction of ynamides and diazo ketones. Application to the synthesis of polycyclic aromatic and heteroaromatic compounds.

    Science.gov (United States)

    Willumstad, Thomas P; Haze, Olesya; Mak, Xiao Yin; Lam, Tin Yiu; Wang, Yu-Pu; Danheiser, Rick L

    2013-11-15

    Highly substituted polycyclic aromatic and heteroaromatic compounds are produced via a two-stage tandem benzannulation/cyclization strategy. The initial benzannulation step proceeds via a pericyclic cascade mechanism triggered by thermal or photochemical Wolff rearrangement of a diazo ketone. The photochemical process can be performed using a continuous flow reactor which facilitates carrying out reactions on a large scale and minimizes the time required for photolysis. Carbomethoxy ynamides as well as more ketenophilic bis-silyl ynamines and N-sulfonyl and N-phosphoryl ynamides serve as the reaction partner in the benzannulation step. In the second stage of the strategy, RCM generates benzofused nitrogen heterocycles, and various heterocyclization processes furnish highly substituted and polycyclic indoles of types that were not available by using the previous cyclobutenone-based version of the tandem strategy.

  13. Synthesis and Structural Study of Some Pyrimidinium Hexafluoridosilicates.

    Science.gov (United States)

    Pevec, Andrej

    2015-01-01

    The synthesis and spectroscopic characterization of some pyrimidinium hexafluoridosilicate salts with the formula (RH)2[SiF]6 (where R = 2-aminopyrimidine (1), cytosine (2) and 5-cyanocytosine (3)) is obtained in the reaction of SiO2 with hydrofluoric acid solution and subsequent addition of 2-aminopyrimidine, cytosine or 4-amino-2-chloropyrimidine-5-carbonitrile. The crystal structures of 1 and 3 have been determined by single-crystal X‒ray diffraction analysis. The combination of N‒H···F hydrogen bonds along with π‒π interactions between aromatic rings resulted in supramolecular architecture of cations and anions in the solid state. PMID:26085410

  14. Synthesis of 1,7-Bis(4-hydroxyphenyl)hepta-4E,6E-dien-3-one

    Institute of Scientific and Technical Information of China (English)

    XU,Guang-Bing; LI,Shao-Bai

    2004-01-01

    @@ Diarylheptanoids, most of which appearing in the areas of anti-inflammatory, anti-oxidative, super-oxide scavenging and anti-hepatotoxic effects, constitute a distinct group of metabolites of natural plants characterized by two aromatic rings linked by a linear seven aliphatic chain. We have investigated this kind of compounds and made some progress.[1]1,7-Bis(4-hydroxy-phenyl)hepta-4E,6E-dien-3-one (1) was firstly isolated from the seeds of Alpinia blepharocalyx.[2] So far the synthesis of the compound has not been reported yet. Herein, we report the synthesis of compound 1. The synthetic route is outlined in Scheme 1.

  15. Regioselective Preparation of Diethyl 3,4-Disubstituted 1,5-Dihydro-5-oxo-2H-pyrrol-2-ylphosphonates and Their Coupling with Aldehydes. Application to the Synthesis of C/D-Rings Component of Phycocyanobilin

    OpenAIRE

    Ngwe, Hla; Kinoshita, Hideki; Inomata, Katsuhiko

    1994-01-01

    Diethyl 3,4-disubstituted 1,5-dihydro-5-oxo-2H-pyrrol-2-ylphosphonates were regioselectively prepared by acidic hydrolysis of diethyl 3,4-disubstituted 5-bromo-2-pyrrolylphosphonates. The resulting 1,5-dihydro-2H-pyrrol-2-ones readily underwent the coupling reaction with various aldehydes to afford the corresponding 1,5-dihydro-5-methylene-2H-pyrrol-2-ones including pyrromethenone derivatives in good yields. A series of these reactions was successfully applied to the synthesis of C/D-rings co...

  16. Topological rings

    CERN Document Server

    Warner, S

    1993-01-01

    This text brings the reader to the frontiers of current research in topological rings. The exercises illustrate many results and theorems while a comprehensive bibliography is also included. The book is aimed at those readers acquainted with some very basic point-set topology and algebra, as normally presented in semester courses at the beginning graduate level or even at the advanced undergraduate level. Familiarity with Hausdorff, metric, compact and locally compact spaces and basic properties of continuous functions, also with groups, rings, fields, vector spaces and modules, and with Zorn''s Lemma, is also expected.

  17. Occurrence and transformation of tricyclic aromatic hydrocarbons in low rank coals

    Energy Technology Data Exchange (ETDEWEB)

    Hazai, I.; Alexander, G. (Hungarian Academy of Sciences, Budapest (Hungary). Research Laboratory for Inorganic Chemistry)

    1991-08-01

    Aromatic components of extracts obtained from four low rank coal samples were investigated by gas chromatography-mass spectrometry. A number of compounds were observed for the first time. The tricyclic aromatic hydrocarbons were investigated in detail. They show close similarities in structure to those reported to be formed in laboratory dehydrogenation experiments. The co-occurrence of molecules in the same samples containing additional unsaturation as well as the aromatic ring(s), offers strong support for the hypothesis of progressive aromatization of diterpenoids. A hypothetical diagenetic pathway is proposed to explain the generation of many of the compounds present. In the pathway the following reactions were considered: aromatization (i.e. dehydrogenation), elimination of substituents, methyl shift, isomerization and side chain shortening of fully aromatized species. 40 refs., 5 figs., 2 tabs.

  18. In situ solvothermal synthesis of metal-organic framework coated fiber for highly sensitive solid-phase microextraction of polycyclic aromatic hydrocarbons.

    Science.gov (United States)

    Gao, Jia; Huang, Chuanhui; Lin, Yifen; Tong, Ping; Zhang, Lan

    2016-03-01

    The present work reported a facile and simple in situ solvothermal growth method for immobilization of metal-organic framework UiO-66 via covalent bonding on amino functional silica fiber for highly sensitive solid-phase microextraction (SPME) of ten polycyclic aromatic hydrocarbons (PAHs) by coupling with gas chromatography-mass spectrometry (GC-MS) analysis. The developed SPME coated fiber has been characterized through SEM, TGA and XRD, confirmed the coating thickness of ∼25μm with high thermal and chemical stability. Under optimized conditions, the obtained method exhibited satisfactory linearity in range of 1.0-5000.0ngL(-1) for all the PAHs. The low detection limits were from 0.28ngL(-1) to 0.60ngL(-1) (S/N=3). The UiO-66 coated fibers showed good repeatability (RSDs less than 8.2%, n=5) and satisfying reproducibility between fiber to fiber (RSDs less than 8.9%, n=5). This method was successfully used for simultaneous determination of ten PAHs from Minjiang water and soil samples with satisfactory recoveries of 87.0-113.6% and 83.8-116.7%, respectively. Experimental results shows that the chemical bonding approach has dramatically improve the stability and lifetime of pure MOFs coating for SPME in sample pretreatment.

  19. First Synthesis and Isolation of the E- and Z-Isomers of Some New Schiff Bases. Reactions of 6-Azido-5-Formyl-2-Pyridone with Aromatic Amines

    Directory of Open Access Journals (Sweden)

    Kamal U. Sadek

    2008-01-01

    Full Text Available Some novel Schiff bases have been prepared by reacting 6-azido-5-formyl-2-pyridone 1 with a series of aromatic amines 2a-f. 5-Arylaminomethylene-6-(E-aryliminopyridones3a-e were obtained by reaction of 1 with 2a-e at room temperature,whereas with 2f, the 6-azido-5-naphthalen-2-yl-iminomethylpyridone derivative 4 wasformed. On the other hand, heating 1 with 2a-d at 140-150°C yielded two sets of isomericproducts, (E-3a-d and (Z-5a-d. Refluxing compounds (Z-3a,c with hydroxyl-amine inmethanol gave the corresponding hydroxyliminopyridones 8a,c. Heating of (E-3a-d withexcess POCl3 at reflux did not give the expected tricyclic compound 9, but rather theisomeric products (Z-5a-d were obtained. The structures of all these products have beencharacterized using IR and 1H- and 13C-NMR spectroscopy.

  20. Aromatic fumaronitrile core-based donor-linker-acceptor-linker-donor (D-pi-A-pi-D) compounds: synthesis and photophysical properties.

    Science.gov (United States)

    Panthi, Krishna; Adhikari, Ravi M; Kinstle, Thomas H

    2010-04-01

    A new class of aromatic fumaronitrile core-based compounds with different donors and linkers has been synthesized and well characterized. Compounds 1 and 2 have indole and 2-phenylindole groups as electron donors, respectively. Compounds 3 and 4 have a diphenylamino group as the electron donor, and compound 5 has a 3,6-di-tert-butylcarbazole group as an electron donor. These compounds absorb in the blue-to-green region and emit in the blue-to-red region depending on the electron donor, linker, and solvents. The quantum yields of fluorescence of these compounds in solution are measured and found to be moderate, but in solid states, they are high. These compounds display strong emission solvatochromism that is reflected by a large shift in their fluorescence emission maxima on changing the solvents. This change is accompanied by a successive decrease in fluorescence intensity. The fluorescence lifetimes of these compounds are measured in different solvent and found to vary from compounds with solvents, concentration, and excitation energy have been studied. The correlation between the functional group and optical properties has been established to some extent. The ability of these compounds to function as colorimetric and luminescence pH sensors is demonstrated with color changes and luminescence switching upon the addition of trifluoroacetic acid. The potentiality of these compounds for application in optoelectronics has been optically assessed.

  1. Hydroxylation activity of P450 BM-3 mutant F87V towards aromatic compounds and its application to the synthesis of hydroquinone derivatives from phenolic compounds.

    Science.gov (United States)

    Sulistyaningdyah, Woro Triarsi; Ogawa, Jun; Li, Qing-Shan; Maeda, Chiharu; Yano, Yuki; Schmid, Rolf D; Shimizu, Sakayu

    2005-06-01

    Cytochrome P450 BM-3 from Bacillus megaterium is a fatty acid hydroxylase exhibiting selectivity for long-chain substrates (12-20 carbons). Replacement of Phe87 in P450 BM-3 by Val (F87V) greatly increased its activity towards a variety of aromatic and phenolic compounds. The apparent initial reaction rates of F87V as to benzothiophene, indan, 2,6-dichlorophenol, and 2-(benzyloxy)phenol were 227, 204, 129, and 385 nmol min(-1) nmol(-1) P450, which are 220-, 66-, 99-, and 963-fold those of the wild type, respectively. These results indicate that Phe87 plays a critical role in the control of the substrate specificity of P450 BM-3. Furthermore, F87V catalyzed regioselective hydroxylation at the para position of various phenolic compounds. In particular, F87V showed high activity as to the hydroxylation of 2-(benzyloxy)phenol to 2-(benzyloxy)hydroquinone. With F87V as the catalyst, 0.71 mg ml(-1) 2-(benzyloxy)hydroquinone was produced from 1.0 mg ml(-1) 2-(benzyloxy)phenol in 4 h, with a molar yield of 66%.

  2. Biomimetic synthesis of silver nanoparticles using the fish scales of Labeo rohita and their application as catalysts for the reduction of aromatic nitro compounds.

    Science.gov (United States)

    Sinha, Tanur; Ahmaruzzaman, M; Sil, A K; Bhattacharjee, Archita

    2014-10-15

    In this article, a cleaner, greener, cheaper and environment friendly method for the generation of self assembled silver nanoparticles (Ag NPs) applying a simple irradiation technique using the aqueous extract of the fish scales (which is considered as a waste material) of Labeo rohita is described. Gelatin is considered as the major ingredient responsible for the reduction as well as stabilisation of the self assembled Ag NPs. The size and morphology of the individual Ag NPs can be tuned by controlling the various reaction parameters, such as temperature, concentration, and pH. Studies showed that on increasing concentration and pH Ag NPs size decreases, while on increasing temperature, Ag NPs size increases. The present process does not need any external reducing agent, like sodium borohydride or hydrazine or others and gelatin itself can play a dual role: a 'reducing agent' and 'stabilisation agent' for the formation of gelatin-Ag NPs colloidal dispersion. The synthesized Ag NPs were characterised by Ultraviolet-Visible spectroscopy (UV-Vis), Transmission electron microscopy (TEM) and Selected area electron diffraction (SAED) analyses. The synthesized Ag NPs was used to study the catalytic reduction of various aromatic nitro compounds in aqueous and three different micellar media. The hydrophobic and electrostatic interaction between the micelle and the substrate is responsible for the catalytic activity of the nanoparticles in micelle.

  3. Facile synthesis of magnetic carbon nitride nanosheets and its application in magnetic solid phase extraction for polycyclic aromatic hydrocarbons in edible oil samples.

    Science.gov (United States)

    Zheng, Hao-Bo; Ding, Jun; Zheng, Shu-Jian; Zhu, Gang-Tian; Yuan, Bi-Feng; Feng, Yu-Qi

    2016-01-01

    In this study, we proposed a method to fabricate magnetic carbon nitride (CN) nanosheets by simple physical blending. Low-cost CN nanosheets prepared by urea possessed a highly π-conjugated structure; therefore the obtained composites were employed as magnetic solid-phase extraction (MSPE) sorbent for extraction of polycyclic aromatic hydrocarbons (PAHs) in edible oil samples. Moreover, sample pre-treatment time could be carried out within 10 min. Thus, a simple and cheap method for the analysis of PAHs in edible oil samples was established by coupling magnetic CN nanosheets-based MSPE with gas chromatography-mass spectrometry (GC/MS) analysis. Limits of quantitation (LOQs) for eight PAHs ranged from 0.4 to 0.9 ng/g. The intra- and inter-day relative standard deviations (RSDs) were less than 15.0%. The recoveries of PAHs for spiked soybean oil samples ranged from 91.0% to 124.1%, with RSDs of less than 10.2%. Taken together, the proposed method offers a simple and cost-effective option for the convenient analysis of PAHs in oil samples.

  4. Birds and polycyclic aromatic hydrocarbons

    Science.gov (United States)

    Albers, P.H.

    2006-01-01

    Polycyclic aromatic hydrocarbons (PAH) are present throughout the global environment and are produced naturally and by activities of humans. Effects of PAH on birds have been determined by studies employing egg injection, egg immersion, egg shell application, single and multiple oral doses, subcutaneous injection, and chemical analysis of field-collected eggs and tissue. The four-to six-ring aromatic compounds are the most toxic to embryos, young birds, and adult birds. For embryos, effects include death, developmental abnormalities, and a variety of cellular and biochemical responses. For adult and young birds, effects include reduced egg production and hatching, increased clutch or brood abandonment, reduced growth, increased organweights, and a variety of biochemical responses. Trophic level accumulation is unlikely. Environmental exposure to PAH in areas of high human population or habitats affected by recent petroleum spills might be sufficient to adversely affect reproduction. Evidence of long-term effects of elevated concentrations of environmental PAH on bird populations is very limited and the mechanisms of effect are unclear.

  5. Ring interferometry

    CERN Document Server

    Malykin, Grigorii B; Zhurov, Alexei

    2013-01-01

    This monograph is devoted to the creation of a comprehensive formalism for quantitative description of polarized modes' linear interaction in modern single-mode optic fibers. The theory of random connections between polarized modes, developed in the monograph, allows calculations of the zero shift deviations for a fiber ring interferometer. The monograph addresses also the

  6. An Expeditious and Safe Synthesis of Some Exocyclic α,β-Unsaturated Ketones by Microwave-Assisted Condensation of Cyclic Ketones with Aromatic Aldehydes over Anhydrous Potassium Carbonate

    OpenAIRE

    Rina Mondal; Tapas K. Mandal; Mallik, Asok K.

    2012-01-01

    A rapid, efficient, and solvent-free methodology for synthesis of exocyclic α,β-unsaturated ketones of the categories E-3-arylidene-4-chromanones, E-2-arylidene-1-tetralones, E-2-arylidene-1-indanones, E-3-cinnamylidene-4-chromanones, E-2-cinnamylidene-1-tetralones, E-2-cinnamylidene-1-indanones, α,α′-(E,E)-bis(arylidene)-cycloalkanones, and α,α′-(E,E)-bis(cinnamylidene)-cycloalkanones has been developed through cross-aldol condensation of the constituent cyclic ketones and aldehydes by micro...

  7. Aromater i drikkevand

    DEFF Research Database (Denmark)

    Nyeland, B. A.; Hansen, A. B.

    DMU har den 10. Juni 1997 afholdt en præstationsprøvning: Aromater i drikkevand. Der deltog 21 laboratorier i præstationsprøvningen. Prøvningen omfattede 6 vandige prøver og 6 ampuller indeholdende 6 aromater. Laboratorierne spikede de tilsendte vandprøver med indholdet fra ampullerne...

  8. The Synthesis and Characterization of Aromatic Hybrid Anderson-Evans POMs and their Serum Albumin Interactions: The Shift from Polar to Hydrophobic Interactions.

    Science.gov (United States)

    Al-Sayed, Emir; Blazevic, Amir; Roller, Alexander; Rompel, Annette

    2015-12-01

    Four aromatic hybrid Anderson polyoxomolybdates with Fe(3+) or Mn(3+) as the central heteroatom have been synthesized by using a pre-functionalization protocol and characterized by using single-crystal X-ray diffraction, FTIR, ESI-MS, (1) H NMR spectroscopy, and elemental analysis. Structural analysis revealed the formation of (TBA)3 [FeMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ]⋅3.5 ACN (TBA-FeMo6 -bzn; TBA=tetrabutylammonium, ACN=acetonitrile, bzn=TRIS-benzoic acid alkanolamide, TRISR=(HOCH2 )3 CR)), (TBA)3 [FeMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ]⋅2.5 ACN (TBA-FeMo6 -cin; cin=TRIS-cinnamic acid alkanolamide), (TBA)3 [MnMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ]⋅3.5 ACN (TBA-MnMo6 -bzn), and (TBA)3 [MnMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ]⋅2.5 ACN (TBA-MnMo6 -cin). To make these four compounds applicable in biological systems, an ion exchange was performed that gave the water-soluble (up to 80 mM) sodium salts Na3 [FeMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ] (Na-FeMo6 -bzn), Na3 [FeMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ] (Na-FeMo6 -cin), Na3 [MnMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ] (Na-MnMo6 -bzn), and Na3 [MnMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ] (Na-MnMo6 -cin). The hydrolytic stability of the sodium salts was examined by applying ESI-MS in the pH range of 4 to 9. Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that human and bovine serum albumin (HSA and BSA) remain intact in solutions that contain up to 100 equivalents of the sodium salts over more than 4 d at 20 °C. Tryptophan (Trp) fluorescence quenching was applied to study the interactions between the sodium salts and HSA and BSA at pH 5.5 and 7.4. The quenching constants were extracted by using Stern-Volmer analysis, which suggested the formation of a 1:1 POM-protein complex in all samples. It is suggested that the aromatic hybrid POM approaches subdomain IIA of HSA and exhibits hydrophobic interactions with its hydrophobic tails, whereas the Anderson core is stabilized through electrostatic

  9. Synthesis of Isoiminosugars

    DEFF Research Database (Denmark)

    Hyldtoft, Lene; Godskesen, Michael Anders; Lundt, Inge

    1998-01-01

    A short synthesis of isoiminosugars have been developed. Bromolactones are diastereoselectively alkylated at C-2 followed by ring closure to the corresponding lactams. Reduction of these then gives isoiminosugars......A short synthesis of isoiminosugars have been developed. Bromolactones are diastereoselectively alkylated at C-2 followed by ring closure to the corresponding lactams. Reduction of these then gives isoiminosugars...

  10. Synthesis and preliminary evaluation of N-acylhydrazone compounds as antibacterial and antifungal agents; Sintese e avaliacao preliminar da atividade antibacteriana e antifungica de derivados N-acilidrazonicos

    Energy Technology Data Exchange (ETDEWEB)

    Cachiba, Thomas Haruo; Carvalho, Bruno Demartini; Carvalho, Diogo Teixeira [Universidade Federal de Alfenas, MG (Brazil). Fac. de Ciencias Farmaceuticas. Dept. de Alimentos e Medicamentos; Cusinato, Marina; Prado, Clara Gaviao; Dias, Amanda Latercia Tranches, E-mail: diogo.carvalho@unifal-mg.edu.br [Universidade Federal de Alfenas, MG (Brazil). Inst. de Ciencias Biomedicas

    2012-07-01

    We describe the synthesis and evaluation of N-acylhydrazone compounds bearing different electron-donating groups in one of its aromatic rings, obtained using a four-step synthetic route. IC{sub 50} values against pathogenic fungi and bacteria were determined by serial microdilution. Compounds showed low activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. By contrast, a derivative with a meta-oriented electron-donating group showed significant activity (IC50) against Candida albicans (17 {mu}M), C. krusei (34 {mu}M) and C. tropicalis (17 {mu}M). Results suggest this is a promising lead-compound for synthesis of potent antifungal agents. (author)

  11. Hexagonal graphene onion rings.

    Science.gov (United States)

    Yan, Zheng; Liu, Yuanyue; Lin, Jian; Peng, Zhiwei; Wang, Gunuk; Pembroke, Elvira; Zhou, Haiqing; Xiang, Changsheng; Raji, Abdul-Rahman O; Samuel, Errol L G; Yu, Ting; Yakobson, Boris I; Tour, James M

    2013-07-24

    Precise spatial control of materials is the key capability of engineering their optical, electronic, and mechanical properties. However, growth of graphene on Cu was revealed to be seed-induced two-dimensional (2D) growth, limiting the synthesis of complex graphene spatial structures. In this research, we report the growth of onion ring like three-dimensional (3D) graphene structures, which are comprised of concentric one-dimensional hexagonal graphene ribbon rings grown under 2D single-crystal monolayer graphene domains. The ring formation arises from the hydrogenation-induced edge nucleation and 3D growth of a new graphene layer on the edge and under the previous one, as supported by first principles calculations. This work reveals a new graphene-nucleation mechanism and could also offer impetus for the design of new 3D spatial structures of graphene or other 2D layered materials. Additionally, in this research, two special features of this new 3D graphene structure were demonstrated, including nanoribbon fabrication and potential use in lithium storage upon scaling. PMID:23815279

  12. Calculations of proton chemical shifts in olefins and aromatics

    CERN Document Server

    Escrihuela, M C

    2000-01-01

    induced reagents on alpha,beta unsaturated ketones has also been investigated in order to deduce molecular structures and to obtain the assignment of the spectra of these molecules. A semi-empirical calculation of the partial atomic charges in organic compounds based on molecular dipole moments (CHARGE3) was developed into a model capable of predicting proton chemical shifts in a wide variety of organic compounds to a reasonable degree of accuracy. The model has been modified to include condensed aromatic hydrocarbons and substituted benzenes, alkenes, halo-monosubstituted benzenes and halo-alkenes. Within the aromatic compounds the influence of the pi electron densities and the ring current have been investigated, along with the alpha, beta and gamma effects. The model gives the first accurate calculation of the proton chemical shifts of condensed aromatic compounds and the proton substituent chemical shifts (SCS) in the benzene ring. For the data set of 55 proton chemical shifts spanning 3 ppm the rms error...

  13. Fused aromatic thienopyrazines: structure, properties and function

    KAUST Repository

    Mondal, Rajib

    2010-01-01

    Recent development of a fused aromatic thieno[3.4-b]pyrazine system and their application in optoelectronic devices are reviewed. Introduction of a fused aromatic unit followed by side chain engineering, dramatically enhanced the charge carrier mobility in thin film transistor devices and mobilities up to 0.2 cm2/Vs were achieved. The optoelectronic properties of these fused aromatic thienopyrazine polymers (Eg = 1.3 to 1.6 eV, HOMO = -4.9 to -5.2 V) were tuned by introduction of various fused aromatic rings within thienopyrazine. By balancing the fundamental properties of these polymers, both high charge carrier mobilities and moderate PCEs in solar cells were achieved. Further, effects of copolymerizing units are discussed. Low band gap semiconducting polymer (Eg ∼ 1 eV) with high field effect mobility (0.044 cm2/Vs) was obtained using cyclopentadithiophene as copolymerizing unit. Finally, a molecular design approach to enhance the absorption coefficients is discussed, which resulted in improved power conversion efficiency in bulk heterojunction solar cells. © 2010 The Royal Society of Chemistry.

  14. Construction of carbocyclic ring of indoles using ruthenium-catalyzed ring-closing olefin metathesis.

    Science.gov (United States)

    Yoshida, Kazuhiro; Hayashi, Kazushi; Yanagisawa, Akira

    2011-09-16

    The selective synthesis of substituted indoles was achieved by the ring-closing olefin metathesis (RCM)/elimination sequence or the RCM/tautomerization sequence of functionalized pyrrole precursors. The RCM/elimination sequence was also applied to double ring closure to yield a substituted carbazole.

  15. From Fragmentation to Construction--from Void to Massive: Fascination with Organic Mass Spectrometry and the Synthesis of Novel Three-Dimensional Polycyclic Aromatic Hydrocarbons.

    Science.gov (United States)

    Kuck, Dietmar

    2015-12-01

    Detailed insights gained from our research into the gas-phase chemistry of ionized and protonated diphenylalkanes and their congeners, obtained by extended synthesis of isotopically labeled model compounds and mass spectrometry, are presented and merged with those acquired during our development of a new family of polycyclic hydrocarbons, the centropolyindanes. Aside from a Personal Account that describes "two scientific lives in one", it is demonstrated, on the one hand, how our understanding of organic chemistry can help to shed light on the details of mass spectrometric fragmentation and to unravel, in a more fundamental way, the unimolecular reactivity of gaseous ions. On the other hand, it is shown how unexpected reactivity of related ions in solution, being subject to the very same fundamentals of organic chemistry, can lead to the construction of novel and, in part, unique three-dimensional polycyclic structures that may contribute to future research in material science. Two such apparently independent fields of organic chemistry may be seen as joint contributions of the art of science. PMID:26202384

  16. Radiation chemistry of aromatic dimer radical cations

    International Nuclear Information System (INIS)

    π-π Interactions of aromatic molecules are paid attention much in many fields, especially biology, chemistry, and applied physics, represented as protein, DNA, electron donor-accepter complexes, charge transfers, and self assembly molecules. Aromatic molecules including benzene rings are the simplest case to study the π-π interactions. To interpret the charge resonance (CR) structure in the dimer radical cations, spectroscopic and ESR methods have been carried out. The spectroscopic study on the dimer radical ion of molecules with two chromophores would be profitable to identify the electronic and configurational properties. In this article, dynamics of the dimer radical cation of benzenes, polystyrenes, and resist polymers is described on the basis of direct observation of CR band by the nanosecond pulse radiolysis and low temperature γ-radiolysis methods. (author)

  17. [Inhibition of aromatics on ammonia-oxidizing activity of sediment].

    Science.gov (United States)

    Dong, Chun-hong; Hu, Hong-ying; Wei, Dong-bin; Huang, Xia; Qian, Yi

    2004-03-01

    The inhibition of 24 aromatics on ammonia-oxidizing activity of nitrifying bacteria in sediment was measured. The effects of the kind, number and position of substituted groups on ammonia-oxidizing activity of nitrifying bacteria were discussed. The inhibition of mono-substituted benzenes on ammonia-oxidizing activity of nitrifying bacteria were in order of -OH > -NO2 > -NH2 > -Cl > -CH3 > -H. The position of substituted groups of di-substituted benzenes also affected the inhibition, and the inhibitions of dimethylbenzenes(xylene) were in order of meta-> ortho-> para-. The increase in number of substituted group on benzene-ring enhanced the inhibition of aromatics studied in this study on nitrifying bacteria. There was a linear relationship between inhibition (IC50, mumol.L-1) of aromatics on ammonia-oxidizing activity and total electronegativity (sigma E) of aromatics: lgIC50 = 14.72 - 0.91 sigma E.

  18. A new type of self-supported, polymeric Ru-carbene complex for homogeneous catalysis and heterogeneous recovery: synthesis and catalytic activities for ring-closing metathesis.

    Science.gov (United States)

    Chen, Shu-Wei; Kim, Ju Hyun; Shin, Hyunik; Lee, Sang-Gi

    2008-08-01

    A novel 2nd generation Grubbs-type catalyst tethering an isopropoxystyrene has been synthesized and automatically polymerized in solution to form a self-supported polymeric Ru-carbene complex, which catalyzed ring-closing metathesis homogeneously, but was recovered heterogeneously.

  19. Green chemistry approaches to the regioselective synthesis of spiro heterobicyclic rings using iodine as a new and efficient catalyst under solvent-free conditions.

    Science.gov (United States)

    Prajapati, Dipak; Bhuyan, Debajyoti; Gohain, Mukut; Hu, Wenhao

    2011-02-01

    Iodine catalyzes the pseudo four-component reaction of an aldehyde, a urea or thiourea, and cyclic 1,3-dicarbonyl compounds under microwave irradiation in a solvent-free condition to yield various σ symmetric spiro heterobicyclic rings in excellent yields. PMID:20364370

  20. Nobel Chemistry in the Laboratory: Synthesis of a Ruthenium Catalyst for Ring-Closing Olefin Metathesis--An Experiment for the Advanced Inorganic or Organic Laboratory

    Science.gov (United States)

    Greco, George E.

    2007-01-01

    An experiment for the upper-level undergraduate laboratory is described in which students synthesize a ruthenium olefin metathesis catalyst, then use the catalyst to carry out the ring-closing metathesis of diethyl diallylmalonate. The olefin metathesis reaction was the subject of the 2005 Nobel Prize in chemistry. The catalyst chosen for this…

  1. Green chemistry approaches to the regioselective synthesis of spiro heterobicyclic rings using iodine as a new and efficient catalyst under solvent-free conditions.

    Science.gov (United States)

    Prajapati, Dipak; Bhuyan, Debajyoti; Gohain, Mukut; Hu, Wenhao

    2011-02-01

    Iodine catalyzes the pseudo four-component reaction of an aldehyde, a urea or thiourea, and cyclic 1,3-dicarbonyl compounds under microwave irradiation in a solvent-free condition to yield various σ symmetric spiro heterobicyclic rings in excellent yields.

  2. Synthetic fuel aromaticity and staged combustion

    Energy Technology Data Exchange (ETDEWEB)

    Longanbach, J. R.; Chan, L. K.; Levy, A.

    1982-11-15

    Samples of middle and heavy SRC-II distillates were distilled into 50 C boiling point range fractions. These were characterized by measurements of their molecular weight, elemental analysis and basic nitrogen content and calculation of average molecular structures. The structures typically consisted of 1 to 3 aromatic rings fused to alicyclic rings with short, 1 to 3 carbon aliphatic side chains. The lower boiling fractions contained significant amounts (1 atom/molecule) of oxygen while the heavier fractions contained so few heteroatoms that they were essentially hydrocarbons. Laboratory scale oxidative-pyrolysis experiments were carried out at pyrolysis temperatures of 500 to 1100 C and oxygen concentrations from 0 to 100 percent of stoichiometry. Analysis of liquid products, collected in condensers cooled with liquid nitrogen showed that aromatization is a major reaction in the absence of oxygen. The oxygen-containing materials (phenolics) seem to be more resistant to thermal pyrolysis than unsubstituted aromatics. Nitrogen converts from basic to nonbasic forms at about 500 C. The nonbasic nitrogen is more stable and survives up to 700 C after which it is slowly removed. A recently constructed 50,000 Btu/hr staged combustor was used to study the chemistry of the nitrogen and aromatics. SRC II combustion was studied under fuel-rich, first-stage conditions at air/fuel ratios from 0.6 to 1.0 times stoichiometric. The chemistry of the fuel during combustion calls for further investigation in order to examine the mechanism by which HCN is evolved as a common intermediate for the formation of the nitrogen-containing gaseous combustion products. 25 references, 45 figures, 25 tables.

  3. Synthesis of reported and revised structures of amathamide D and synthesis of convolutamine F, H and lutamide A, C.

    Science.gov (United States)

    Khan, Faiz Ahmed; Ahmad, Saeed

    2012-03-01

    Total synthesis of the published structure of amathamide D is described. Methyl 2,3,4-tribromo-5-hydroxybenzoate was selected as starting compound because it is readily accessible via acid-mediated Grob fragmentation-aromatization reaction of 1,4,5,6-tetrabromo-7,7-dimethoxybicyclo[2.2.1]hept-5-en-2-one. The aforementioned ester was transformed into the reported structure of amathamide D through methylation of a hydroxyl group and conversion of the ester moiety to a β-aminoethyl side chain. The NMR data of the synthetic compound did not conform to the reported natural product structure possessing contiguously positioned β-aminoethyl side chain, a set of three adjacent bromines, and a methyl ether linkage on the phenyl ring. This prompted us to redefine the natural product structure by synthesizing a product whose spectral data exactly matched with the reported data of amathamide D. The convolutamine H, with completely substituted phenyl ring adorned with an extra methyl ether functional group, has also been synthesized by application of Grob fragmentation-aromatization strategy to 3-(benzyloxy)-1,4,5,6-tetrabromo-7,7-dimethoxybicyclo[2.2.1]hept-5-en-2-one. This approach furnished directly methyl 2,3,4-tribromo-5,6-dimethoxybenzoate, which was converted straightforwardly into convolutamine H. Further, synthesis of convolutamine F and lutamide A and C is also described.

  4. Metabolism of aromatic compounds by Caulobacter crescentus

    Energy Technology Data Exchange (ETDEWEB)

    Chatterjee, D.K.; Bourquin, A.W.

    1987-05-01

    Cultures of Caulobacter crescentus were found to grow on a variety of aromatic compounds. Degradation of benzoate, p-hydroxybenzoate, and phenol was found to occur via ..beta..-ketoadipate. The induction of degradative enzymes such as benzoate 1,2-dioxygenase, the ring cleavage enzyme catechol 1,2-dioxygenase, and cis,cis-muconate lactonizing enzyme appeared similar to the control mechanism present in Pseudomonas spp. Both benzoate 1,2-dioxygenase and catechol 1,2-dioxygenase had stringent specificities, as revealed by their action toward substituted benzoates and substituted catechols, respectively.

  5. MORPHOLOGY OF A THERMOTROPIC AROMATIC POLYESTER

    Institute of Scientific and Technical Information of China (English)

    CHEN Shouxi; JIN Yongze; XU Mao

    1992-01-01

    The crystalline morphology of a thermotropic aromatic polyester has been studied by microscopy techniques. Spherulites with ringed structure under polarizing microscope were observed for solution cast specimens, They were composed of radially growing crystalline lamellae of thickness around 100A. It was found that the molecules were packed in the thickness direction. Banded texture was observed in randomly packed domains for melt cast specimens. The bands have the same width and internal structure as those usually observed in oriented specimens of these polymers obtained by shearing their mesomorphic melt.

  6. Palladium- and copper-mediated N-aryl bond formation reactions for the synthesis of biological active compounds

    Directory of Open Access Journals (Sweden)

    Burkhard Koenig

    2011-01-01

    Full Text Available N-Arylated aliphatic and aromatic amines are important substituents in many biologically active compounds. In the last few years, transition-metal-mediated N-aryl bond formation has become a standard procedure for the introduction of amines into aromatic systems. While N-arylation of simple aromatic halides by simple amines works with many of the described methods in high yield, the reactions may require detailed optimization if applied to the synthesis of complex molecules with additional functional groups, such as natural products or drugs. We discuss and compare in this review the three main N-arylation methods in their application to the synthesis of biologically active compounds: Palladium-catalysed Buchwald–Hartwig-type reactions, copper-mediated Ullmann-type and Chan–Lam-type N-arylation reactions. The discussed examples show that palladium-catalysed reactions are favoured for large-scale applications and tolerate sterically demanding substituents on the coupling partners better than Chan–Lam reactions. Chan–Lam N-arylations are particularly mild and do not require additional ligands, which facilitates the work-up. However, reaction times can be very long. Ullmann- and Buchwald–Hartwig-type methods have been used in intramolecular reactions, giving access to complex ring structures. All three N-arylation methods have specific advantages and disadvantages that should be considered when selecting the reaction conditions for a desired C–N bond formation in the course of a total synthesis or drug synthesis.

  7. Development of Enantiospecific Coupling of Secondary and Tertiary Boronic Esters with Aromatic Compounds.

    Science.gov (United States)

    Odachowski, Marcin; Bonet, Amadeu; Essafi, Stephanie; Conti-Ramsden, Philip; Harvey, Jeremy N; Leonori, Daniele; Aggarwal, Varinder K

    2016-08-01

    The stereospecific cross-coupling of secondary boronic esters with sp(2) electrophiles (Suzuki-Miyaura reaction) is a long-standing problem in synthesis, but progress has been achieved in specific cases using palladium catalysis. However, related couplings with tertiary boronic esters are not currently achievable. To address this general problem, we have focused on an alternative method exploiting the reactivity of a boronate complex formed between an aryl lithium and a boronic ester. We reasoned that subsequent addition of an oxidant or an electrophile would remove an electron from the aromatic ring or react in a Friedel-Crafts-type manner, respectively, generating a cationic species, which would trigger 1,2-migration of the boron substituent, creating the new C-C bond. Elimination (preceded by further oxidation in the former case) would result in rearomatization giving the coupled product stereospecifically. Initial work was examined with 2-furyllithium. Although the oxidants tested were unsuccessful, electrophiles, particularly NBS, enabled the coupling reaction to occur in good yield with a broad range of secondary and tertiary boronic esters, bearing different steric demands and functional groups (esters, azides, nitriles, alcohols, and ethers). The reaction also worked well with other electron-rich heteroaromatics and 6-membered ring aromatics provided they had donor groups in the meta position. Conditions were also found under which the B(pin)- moiety could be retained in the product, ortho to the boron substituent. This protocol, which created a new C(sp(2))-C(sp(3)) and an adjacent C-B bond, was again applicable to a range of secondary and tertiary boronic esters. In all cases, the coupling reaction occurred with complete stereospecificity. Computational studies verified the competing processes involved and were in close agreement with the experimental observations. PMID:27384259

  8. Development of Enantiospecific Coupling of Secondary and Tertiary Boronic Esters with Aromatic Compounds

    Science.gov (United States)

    2016-01-01

    The stereospecific cross-coupling of secondary boronic esters with sp2 electrophiles (Suzuki–Miyaura reaction) is a long-standing problem in synthesis, but progress has been achieved in specific cases using palladium catalysis. However, related couplings with tertiary boronic esters are not currently achievable. To address this general problem, we have focused on an alternative method exploiting the reactivity of a boronate complex formed between an aryl lithium and a boronic ester. We reasoned that subsequent addition of an oxidant or an electrophile would remove an electron from the aromatic ring or react in a Friedel–Crafts-type manner, respectively, generating a cationic species, which would trigger 1,2-migration of the boron substituent, creating the new C–C bond. Elimination (preceded by further oxidation in the former case) would result in rearomatization giving the coupled product stereospecifically. Initial work was examined with 2-furyllithium. Although the oxidants tested were unsuccessful, electrophiles, particularly NBS, enabled the coupling reaction to occur in good yield with a broad range of secondary and tertiary boronic esters, bearing different steric demands and functional groups (esters, azides, nitriles, alcohols, and ethers). The reaction also worked well with other electron-rich heteroaromatics and 6-membered ring aromatics provided they had donor groups in the meta position. Conditions were also found under which the B(pin)- moiety could be retained in the product, ortho to the boron substituent. This protocol, which created a new C(sp2)–C(sp3) and an adjacent C–B bond, was again applicable to a range of secondary and tertiary boronic esters. In all cases, the coupling reaction occurred with complete stereospecificity. Computational studies verified the competing processes involved and were in close agreement with the experimental observations. PMID:27384259

  9. 丙交酯开环聚合法合成高分子量聚乳酸%Synthesis of High Molecular Weight Poly Lactic Acid by Lactide Ring-opening Polymerization

    Institute of Scientific and Technical Information of China (English)

    刘辉; 王肖杰; 张留学

    2015-01-01

    以80%的L-乳酸为原料,辛酸亚锡为催化剂,丙交酯开环聚合得到了粘均分子量为5.1×105的聚乳酸。考察了脱水时间、反应温度、催化剂用量对丙交酯合成的影响,得到了合成丙交酯的最佳工艺条件,其收率最高达到76.7%;研究了合成高分子量聚乳酸的最佳工艺条件。红外光谱表征并对比分析了合成的丙交酯和聚乳酸。用DSC-TG分析了不同提纯次数的丙交酯的纯度,表明提纯三次后的丙交酯纯度较高,同时也分析了在不同温度下合成的聚乳酸,表明在130℃下合成的聚乳酸热稳定性好。%Using 80% L-lactic acid as raw materials , stannous caprylate as the catalyst , sticky molecular weight 5.1×105 of poly lactic acid (PLA) was synthesized by the lactide ring-opening polymerization.The influence factors of lactide synthesis such as reaction time , temperature and catalyst dosage were studied , obtained the optimum technological conditions for synthesis of lactide , its yield was up to 76.7%.Aynthetic optimum process conditions for the synthesis of high molecular weight poly lactic acid , fourier transforms infrared spectrum characterization and analysis of the synthesis of lactide and poly lactic acid were researched.Analyzed by DSC and TG in different times for the purification of the purity of lactide , the results showed that the purity was higher after the three times for the purification of lactide.Synthesis of poly lactic acid under the different synthesis temperature was analyzed too.It was suggested that heat stability of synthetic poly lactic acid was good in 130 ℃.

  10. Exploration of an epoxidation–ring-opening strategy for the synthesis of lyconadin A and discovery of an unexpected Payne rearrangement

    Directory of Open Access Journals (Sweden)

    Brad M. Loertscher

    2013-06-01

    Full Text Available In the context of synthetic efforts targeting the alkaloid lyconadin A, scalemic epoxide 25 was prepared by a highly stereoselective sequence involving a Myers alkylation and a Shi epoxidation. Ring-opening of this epoxide with a vinylcopper complex afforded alcohol 26 instead of the expected product 27. An unusual Lewis acid promoted Payne rearrangement of an α-trityloxy epoxide is proposed to account for this outcome.

  11. Exploration of an epoxidation–ring-opening strategy for the synthesis of lyconadin A and discovery of an unexpected Payne rearrangement

    OpenAIRE

    Brad M. Loertscher; Yu Zhang; Castle, Steven L.

    2013-01-01

    In the context of synthetic efforts targeting the alkaloid lyconadin A, scalemic epoxide 25 was prepared by a highly stereoselective sequence involving a Myers alkylation and a Shi epoxidation. Ring-opening of this epoxide with a vinylcopper complex afforded alcohol 26 instead of the expected product 27. An unusual Lewis acid promoted Payne rearrangement of an α-trityloxy epoxide is proposed to account for this outcome.

  12. A Convenient Approach to Heterocyclic Building Blocks: Synthesis of Novel Ring Systems Containing a [5,6]Pyrano[2,3-c]pyrazol-4(1H-one Moiety

    Directory of Open Access Journals (Sweden)

    Wolfgang Holzer

    2007-01-01

    Full Text Available Starting from commercially available educts, a straightforward synthetic route to new heterocyclic building blocks is exemplified with the one- or two-step synthesis of tri-, tetra-, or pentacyclic ring systems. Representatives of the following novel ring systems are prepared from 3-methyl-1-phenyl-2-pyrazolin-5-one and the corresponding o-halo-arenecarbonyl chloride using calcium hydroxide in refluxing 1,4-dioxane: pyrimidino[4',5':5,6]pyrano[2,3-c]pyrazol-4(1H-one, thieno[3',2':5,6]pyrano[2,3c]pyrazol- 4-(1H-one, thieno[3',4':5,6]pyrano[2,3-c]pyrazol-4(1H-one, thieno[3'',2'':4',5']thieno[2',3':5,6]-pyrano[2,3-c]pyrazol-4(1H-one, [1,3]dioxolo[5',6'][1]benzothieno[2',3':5,6]pyrano-[2,3-c]- pyrazol-4(1H-one, pyridazino[4',3':5,6]pyrano[2,3-c]pyrazol-4(1H-one and pyrazolo-[4'',3'':5',6']pyrido[3',4':5,6]pyrano[2,3-c]pyrazol-4(1H-one. While the latter two ring systems are directly obtained due to a spontaneous intramolecular substitution reaction, in the other reactions uncyclised 4-aroylpyrazol-5-ols are produced, which are cyclised into the target heterocycles in a subsequent synthetic step (i.e. treatment with NaH in DMF. Detailed NMR spectroscopic investigations (1H-, 13C-, 15N- with the obtained compounds were undertaken to unambiguously prove the new structures.

  13. (Hetero)aromatics from dienynes, enediynes and enyne-allenes.

    Science.gov (United States)

    Raviola, Carlotta; Protti, Stefano; Ravelli, Davide; Fagnoni, Maurizio

    2016-08-01

    The construction of aromatic rings has become a key objective for organic chemists. While several strategies have been developed for the functionalization of pre-formed aromatic rings, the direct construction of an aromatic core starting from polyunsaturated systems is yet a less explored field. The potential of such reactions in the formation of aromatics increased at a regular pace in the last few years. Nowadays, there are reliable and well-established procedures to prepare polyenic derivatives, such as dienynes, enediynes, enyne-allenes and hetero-analogues. This has stimulated their use in the development of innovative cycloaromatizations. Different examples have recently emerged, suggesting large potential of this strategy in the preparation of (hetero)aromatics. Accordingly, this review highlights the recent advancements in this field and describes the different conditions exploited to trigger the process, including thermal and photochemical activation, as well as the use of transition metal catalysis and the addition of electrophiles/nucleophiles or radical species. PMID:27263976

  14. A photochemical approach to aromatic extension of the corannulene nucleus.

    Science.gov (United States)

    Rajeshkumar, Venkatachalam; Stuparu, Mihaiela C

    2016-08-01

    A high yielding, general, and mild synthetic strategy is established for aromatic annulation of the corannulene scaffold. In this approach, a corannulene-based aldehyde, ylide, or ketone compound is conjugated with an aromatic unit of choice through a Wittig reaction. The resulting stilbene-like precursor can be subjected to a photochemically induced oxidative-cyclization process to yield a corannulene structure with an extended π-framework. The generality of synthesis allows for preparation of a wide range of polycyclic aromatic arene as well as heteroarene structures. Meanwhile, the mild nature of the developed protocol permits for incorporation of reactive and functional substituents onto the fused aromatic scaffold. Furthermore, efficient and simple synthesis ensures access to significant amounts of the material in a facile manner. In essence, this work demonstrates, for the first time, that photochemical synthesis is a highly practical alternative to the known flash vacuum pyrolysis and metal catalyzed processes for the aromatic extension of the bucky-bowl structure. PMID:27440449

  15. Disordered organic electronic materials based on non-benzenoid 1,6-methano[10]annulene rings

    Energy Technology Data Exchange (ETDEWEB)

    Tovar, John D; Streifel, Benjamin C; Peart, Patricia A

    2014-10-07

    Conjugated polymers and small molecules including the nonplanar aromatic 1,6-methano[10]annulene ring structure along with aromatic subunits, such as diketopyrrolopyrrole, and 2,1,3-benzothiadiazole, substituted with alkyl chains in a "Tail In," "Tail Out," or "No Tail" regiochemistry are disclosed.

  16. Mercaptolysis of the E/F Rings of Steroidal Sapogenins: A Concise Synthesis of Δ20(22)-Furostene-26-thioethers

    Institute of Scientific and Technical Information of China (English)

    田伟生; 关慧平; 潘鑫复

    2003-01-01

    Lewis acid catalyzed mercaptolysls of steroidal sapogenins was reinvestigated. Besides obtaining the reported 26-thioacetals 5 under milder conditions, a new type of compounds Δ20(22)-furostene-26-thioethers 6 were also synthesized through the mercaptolysis of steroidal sapogenlns, which can be used to the synthesis of the steroidal molecule with side chains.

  17. Synthesis of nisin AB dicarba analogs using ring-closing metathesis: influence of sp(3) versus sp(2) hybridization of the α-carbon atom of residues dehydrobutyrine-2 and dehydroalanine-5 on the lipid II binding affinity.

    Science.gov (United States)

    Slootweg, Jack C; van Herwerden, Eric F; van Doremalen, Mark F M; Breukink, Eefjan; Liskamp, Rob M J; Rijkers, Dirk T S

    2015-06-01

    Herein the synthesis of two nisin AB dicarba analogs is described, focusing on amino acid modifications at positions 2 and 5. The nisin mimics were synthesized by a combination of solid phase synthesis of the linear peptides, followed by macrocyclization via ring-closing metathesis and fragment assembly by means of solution phase chemistry. The two N-terminal nisin AB-fragment mimics contain either the native dehydrobutyrine (Dhb)/dehydroalanine (Dha) amino acid residues or alanine at position 2 and 5, respectively. The native dehydrobutyrine at position 2 and dehydroalanine at position 5 were introduced as their precursors, namely threonine and serine, respectively, and subsequent dehydration was carried out by EDCI/CuCl as the condensing agent. Both AB-fragment mimics were analyzed in a lipid II binding assay and it was found that the Ala2/Ala5 AB-mimic (2) showed a reduced activity, while the Dhb2/Dha5 AB-mimic (3) was as active as the native AB-fragment (1).

  18. Draft Genome Sequence of Pseudomonas sp. Strain 10-1B, a Polycyclic Aromatic Hydrocarbon Degrader in Contaminated Soil

    OpenAIRE

    Bello-Akinosho, Maryam; Adeleke, Rasheed; Swanevelder, Dirk; Thantsha, Mapitsi

    2015-01-01

    Pseudomonas sp. strain 10-1B was isolated from artificially polluted soil after selective enrichment. Its draft genome consists of several predicted genes that are involved in the hydroxylation of the aromatic ring, which is the rate-limiting step in the biodegradation of polycyclic aromatic hydrocarbons.

  19. Synthesis of Fused-Ring Sydnones with a Spirocyclohexane Moiety%含有螺环己烷结构的稠环斯德酮的合成

    Institute of Scientific and Technical Information of China (English)

    张站斌; 张红海

    2012-01-01

    3-(3-芳基-3-羟基丙基)斯德酮在三氟化硼乙醚的催化作用下可以与环己酮发生类似于Oxa-Pictet-Spengler反应的成环反应,生成带有螺环己烷结构的稠环斯德酮.%Fused-ring sydnones with a spire cyclohexane moiety were prepared via oxa-Pictet-Spengler reaction of 3-(3-aryl-3-hydroxypropyl)sydnones with cyclohexanone in the presence of boron trifluoride ether complex.

  20. Synthesis of Azanucleosides through Regioselective Ring-Opening of Epoxides Catalyzed by Sulphated Zirconia under Microwave and Solvent-Free Conditions

    Directory of Open Access Journals (Sweden)

    Guillermo E. Negrón-Silva

    2012-03-01

    Full Text Available New azanucleosides were obtained using sulphated zirconia (ZS as catalyst in the nucleophilic oxirane ring opening reaction of 1-allyl-3-(oxiran-2-ylmethyl pyrimidine-2,4(1H,3H-dione and 1-allyl-5-methyl-3-(oxiran-2-ylmethyl-pyrimidine-2,4(1H,3H-dione, with (S-prolinol. The new templates were obtained with good yields following a route which exploits the reactivity of epoxides in the presence of sulphated zirconia as catalyst. The key step was carried out using microwave and solvent-free conditions and proceeds with high selectivity.

  1. Aromatic products from reaction of lignin model compounds with UV-alkaline peroxide

    International Nuclear Information System (INIS)

    A series of guaiacyl and syringyl lignin model compounds and their methylated analogues were reacted with alkaline hydrogen peroxide while irradiating with UV light at 254 nm. The aromatic products obtained were investigated by gas chromatography-mass spectrometry (GC-MS). Guaiacol, syringol and veratrol gave no detectable aromatic products. However, syringol methyl ether gave small amounts of aromatic products, resulting from ring substitution and methoxyl displacement by hydroxyl radicals. Reaction of vanillin and syringaldehyde gave the Dakin reaction products, methoxy-1,4-hydroquinones, while reaction of their methyl ethers yielded benzoic acids. Acetoguaiacone, acetosyringone and their methyl ethers afforded several hydroxylated aromatic products, but no aromatic products were identified in the reaction mixtures from guaiacylpropane and syringylpropane. In contrast, veratrylpropane gave a mixture from which 17 aromatic hydroxylated compounds were identified. It is concluded that for phenolic lignin model compounds, particularly those possessing electrondonating aromatic ring substituents, ring-cleavage reactions involving superoxide radical anions are dominant, whereas for non-phenolic lignin models, hydroxylation reactions through attack of hydroxyl radicals prevail

  2. Synthesis and Performance of Aromatic Polyurethane Elastomer with m-Phenylenediamine Chain Extender%间苯二胺扩链的芳香族聚氨酯弹性体的合成与性能

    Institute of Scientific and Technical Information of China (English)

    王子龙; 范伟博; 车彦慧; 冯利邦

    2013-01-01

    以甲苯二异氰酸酯和聚氧化丙烯二元醇合成聚氨酯预聚体,通过间苯二胺扩链,得到一种芳香族聚氨酯弹性体.探讨了异氰酸根指数(R值)对聚氨酯预聚体和弹性体合成及固化行为的影响;并利用FT-IR、DSC和拉伸实验等对合成聚氨酯的结构、组成、热性能和力学性能等进行了表征.结果表明,随着R值的增加,聚氨酯弹性体的凝胶时间和表干时间逐渐缩短,拉伸强度增大,断裂伸长率降低,硬段的玻璃化转变温度和热分解温度升高;R值为2.0、2.5和3.0时,合成了固化参数适宜、拉伸性能优异、可用于混凝土防护的聚氨酯弹性体材料.%Polyurethane prepolymer was synthesized with toluene diisocyanate and polypropylene glycol,and then a high performance aromatic polyurethane elastomer was prepared by extending the chains of polyurethane prepolymer with m-phenylenediamine.The effect of R value (isocyanate index) on synthesis and curing behavior of polyurethane prepolymer and elastomer was investigated.Additionally,the structure,composition,thermal property and the tensile property of the polyurethane were characterized by FT-IR,DSC and tensile test.Results showed that the gel time and tack-free time of the polyurethane elastomer gradually were shorten and the elongation at break decreased,while the tensile strength,glass transition temperature and thermal decomposition temperature increased with R value increasing.Consequently,polyurethane elastomer with the good curing behavior and tensile property was prepared when R was 2.0,2.5 and 3.0,which could be used to protect the concrete.

  3. Prime rings with PI rings of constants

    CERN Document Server

    Kharchenko, V K; Rodríguez-Romo, S

    1996-01-01

    It is shown that if the ring of constants of a restricted differential Lie algebra with a quasi-Frobenius inner part satisfies a polynomial identity (PI) then the original prime ring has a generalized polynomial identitiy (GPI). If additionally the ring of constants is semiprime then the original ring is PI. The case of a non-quasi-Frobenius inner part is also considered.

  4. Studies on polynuclear furoquinones. Part 1: Synthesis of tri- and tetra-cyclic furoquinones simulating BCD/ABCD ring system of furoquinone diterpenoids

    Directory of Open Access Journals (Sweden)

    Faruk H. Shaik

    2009-09-01

    Full Text Available Synthesis of phenanthro[1,2-b]furan-10,11-dione, the core nucleus present in Tanshinone-I is described in 8–10 steps starting from 2-bromo-3,4-dihydro-1-naphthaldehyde. The bromoaldehyde was converted to methyl 2-(2-bromo-1-naphthylacetate or 2-(2-bromo-1-naphthylacetonitrile following the protocol of functional group transformations. Subsequent Suzuki coupling of this ester/nitrile derivative with furan-2-boronic acid produced [2-(2-furyl-1-naphthyl]acetic ester/nitrile which on hydrolysis furnished the corresponding acid derivative. Cyclization of the acid followed by oxidation of the phenol, with Fremy’s salt, produced the tetra-cyclic furoquinone, phenanthro[1,2-b]furan-10,11-dione. This method has also been extended for the synthesis of the tricyclic furoquinone, naphtho[1,2-b]furan-4,5-dione.

  5. The Effect of n vs. iso Isomerization on the Thermophysical Properties of Aromatic and Non-aromatic Ionic Liquids

    Science.gov (United States)

    Rodrigues, Ana S.M.C.; Almeida, Hugo F. D.; Freire, Mara G.; Lopes-da-Silva, José A.; Coutinho, João A. P.; Santos, Luís M. N. B. F.

    2016-01-01

    This work explores the n vs. iso isomerization effects on the physicochemical properties of different families of ionic liquids (ILs) with variable aromaticity and ring size. This study comprises the experimental measurements, in a wide temperature range, of the ILs’ thermal behavior, heat capacities, densities, refractive indices, surface tensions, and viscosities. The results here reported show that the presence of the iso-alkyl group leads to an increase of the temperature of the glass transition, Tg. The iso-pyrrolidinium (5 atoms ring cation core) and iso-piperidinium (6 atoms ring cation core) ILs present a strong differentiation in the enthalpy and entropy of melting. Non-aromatic ILs have higher molar heat capacities due to the increase of the atomic contribution, whereas it was not found any significant differentiation between the n and iso-alkyl isomers. A small increase of the surface tension was observed for the non-aromatic ILs, which could be related to their higher cohesive energy of the bulk, while the lower surface entropy observed for the iso isomers indicates a structural resemblance between the IL bulk and surface. The significant differentiation between ILs with a 5 and 6 atoms ring cation in the n-alkyl series (where 5 atoms ring cations have higher surface entropy) is an indication of a more efficient arrangement of the non-polar region at the surface in ILs with smaller cation cores. The ILs constituted by non-aromatic piperidinium cation, and iso-alkyl isomers were found to be the most viscous among the studied ILs due to their higher energy barriers for shear stress. PMID:27682333

  6. Weakly Dual Rings

    Institute of Scientific and Technical Information of China (English)

    魏俊潮; 孙建华

    2004-01-01

    In This paper, the concept of weakly dual ring is introduced, which is a proper generalization of the dual ring. If R is a right weakly dual ring, then (1)Z(RR) = J(R); (2) If R is also a zero-division power ring, then R is a right AP-injective ring. In addition, some properties of weakly dual rings are given.

  7. Aromatization of n-octane over Pd/C catalysts

    KAUST Repository

    Yin, Mengchen

    2013-01-01

    Gas-phase aromatization of n-octane was investigated using Pd/C catalyst. The objectives were to: (1) determine the effects of temperature (400-600 °C), weight hourly space velocity (WHSV) (0.8-∞), and hydrogen to hydrocarbon molar ratio (MR) (0-6) on conversion, selectivity, and yield (2) compare the activity of Pd/C with Pt/C and Pt/KL catalysts and (3) test the suitability of Pd/C for aromatization of different alkanes including n-hexane, n-heptane, and n-octane. Pd/C exhibited the best aromatization performance, including 54.4% conversion and 31.5% aromatics yield at 500 °C, WHSV = 2 h-1, and a MR of 2. The Pd/C catalyst had higher selectivity towards the preferred aromatics including ethylbenzene and xylenes, whereas Pt/KL had higher selectivity towards benzene and toluene. The results were somewhat consistent with adsorbed n-octane cyclization proceeding mainly through the six-membered ring closure mechanism. In addition, Pd/C was also capable of catalyzing aromatization of n-hexane and n-heptane. © 2012 Elsevier Ltd. All rights reserved.

  8. Radical theory of rings

    CERN Document Server

    Gardner, JW

    2003-01-01

    Radical Theory of Rings distills the most noteworthy present-day theoretical topics, gives a unified account of the classical structure theorems for rings, and deepens understanding of key aspects of ring theory via ring and radical constructions. Assimilating radical theory's evolution in the decades since the last major work on rings and radicals was published, the authors deal with some distinctive features of the radical theory of nonassociative rings, associative rings with involution, and near-rings. Written in clear algebraic terms by globally acknowledged authorities, the presentation

  9. Redox Switching of Orthoquinone-Containing Aromatic Compounds with Hydrogen and Oxygen Gas.

    Science.gov (United States)

    Urakawa, Kazuki; Sumimoto, Michinori; Arisawa, Mitsuhiro; Matsuda, Masaki; Ishikawa, Hayato

    2016-06-20

    Unique redox switching of orthoquinone-containing pentacyclic aromatic compounds with molecular hydrogen and oxygen in the presence of a palladium nanoparticle catalyst (SAPd) is disclosed. These molecules were predicted by in silico screening before synthesis. Efficient protocols for the synthesis of orthoquinone-containing aromatic compounds by palladium-mediated homocoupling and the benzoin condensation reaction were developed. Clear switching between orthoquinone and aromatic hydroquinone compounds was observed on the basis of their photoluminescence properties. Furthermore, the twist strain of the orthoquinone moiety could induce dramatic changes in color and emission.

  10. Glucopyranosylidene-spiro-iminothiazolidinone, a new bicyclic ring system: synthesis, derivatization, and evaluation for inhibition of glycogen phosphorylase by enzyme kinetic and crystallographic methods.

    Science.gov (United States)

    Czifrák, Katalin; Páhi, András; Deák, Szabina; Kiss-Szikszai, Attila; Kövér, Katalin E; Docsa, Tibor; Gergely, Pál; Alexacou, Kyra-Melinda; Papakonstantinou, Maria; Leonidas, Demetres D; Zographos, Spyros E; Chrysina, Evangelia D; Somsák, László

    2014-08-01

    The reaction of thiourea with O-perbenzoylated C-(1-bromo-1-deoxy-β-D-glucopyranosyl)formamide gave the new anomeric spirocycle 1R-1,5-anhydro-D-glucitol-spiro-[1,5]-2-imino-1,3-thiazolidin-4-one. Acylation and sulfonylation with the corresponding acyl chlorides (RCOCl or RSO₂Cl where R=tBu, Ph, 4-Me-C₆H₄, 1- and 2-naphthyl) produced the corresponding 2-acylimino- and 2-sulfonylimino-thiazolidinones, respectively. Alkylation by MeI, allyl-bromide and BnBr produced mixtures of the respective N-alkylimino- and N,N'-dialkyl-imino-thiazolidinones, while reactions with 1,2-dibromoethane and 1,3-dibromopropane furnished spirocyclic 5,6-dihydro-imidazo[2,1-b]thiazolidin-3-one and 6,7-dihydro-5H-thiazolidino[3,2-a]pyrimidin-3-one, respectively. Removal of the O-benzoyl protecting groups by the Zemplén protocol led to test compounds most of which proved micromolar inhibitors of rabbit muscle glycogen phosphorylase b (RMGPb). Best inhibitors were the 2-benzoylimino- (Ki=9μM) and the 2-naphthoylimino-thiazolidinones (Ki=10 μM). Crystallographic studies of the unsubstituted spiro-thiazolidinone and the above most efficient inhibitors in complex with RMGPb confirmed the preference and inhibitory effect that aromatic (and especially 2-naphthyl) derivatives show for the catalytic site promoting the inactive conformation of the enzyme. PMID:25009003

  11. Synthesis and characterization of optically active and organosoluble poly(amide-imide)s containing imidazole rings as pendent groups by direct polycondensation

    Institute of Scientific and Technical Information of China (English)

    KHALIL; Faghihi; MEISAM; Shabanian

    2010-01-01

    Six new optically active poly(amide-imide)s(PAIs) 6a-f were prepared by direct polycondensation reaction of N-trimelli-tylimido-L-histidine 4 as a chiral diacid with various aromatic diamines 5a-f.Triphenyl phosphite(TPP)/pyridine(Py) in the presence of calcium chloride(CaCl2) and N-methyl-2-pyrrolidone(NMP) were successfully applied to direct polycondensation reaction.The resulting new polymers were in good yields,and had inherent viscosities ranging between 0.29 and 0.41 dL g-1 and were detected with elemental analysis,FTIR,1H-NMR spectroscopy,specific rotation and differential scanning calorimeter(DSC),thermogravimetric analysis(TGA),and derivative of thermaogravimetry(DTG).Imidazole pendent groups of the polymer chains disturb interchain and intrachain interactions and make these PAIs readily soluble in polar aprotic solvents such as N,N-dimethylacetamide(DMAc),N,N-dimethylformamide(DMF),dimethylsulfoxide(DMSO),NMP and solvents such as sulfuric acid.Thermogravimetric analysis indicated that the residual weight percents of polymers at 600 °C were between 56.47% and 68.76%,which show their thermal stability.

  12. Synthesis of chiral five-membered carbocyclic ring amino acids with an acetal moiety and helical conformations of its homo-chiral homopeptides.

    Science.gov (United States)

    Koba, Yurie; Hirata, Yoko; Ueda, Atsushi; Oba, Makoto; Doi, Mitsunobu; Demizu, Yosuke; Kurihara, Masaaki; Tanaka, Masakazu

    2016-11-01

    Chiral five-membered carbocyclic ring amino acids bearing various diol acetal moieties were synthesized starting from l-malic acid, and homo-chiral homopeptides composed of cyclic amino acid (S)-Ac5 c(3EG) bearing an ethylene glycol acetal, up to an octapeptide, were prepared. A conformational analysis revealed that (S)-Ac5 c(3EG) homopeptides formed helical structures. (S)-Ac5 c(3EG) homopeptides, up to hexapeptides, formed helical structures without controlling the helical screw direction, while (S)-Ac5 c(3EG) hepta- and octapeptides formed helical structures with a preference for the left-handed (M) helical-screw direction. © 2015 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 555-562, 2016. PMID:26566886

  13. 含有三苯胺环类席夫碱的合成%Synthesis of Schiff Bases Containing Triphenylamine Ring

    Institute of Scientific and Technical Information of China (English)

    刘朝兴; 曹建花; 马素芳; 梁辉辉; 延靖; 张昭

    2013-01-01

    以4,4'-二甲酰基三苯胺为原料,通过Wittig和胺醛缩合反应合成了两个含有三苯胺环席夫碱类化合物——4-(对甲基苯乙烯基)-4'-亚(α-萘胺)甲基三苯胺和4-(对甲基苯乙烯基)-4'-亚(2-氨基芴)甲基三苯胺,其结构经1H NMR,13CNMR和IR确证.%Two schiff bases compounds containing triphenylamine ring,4-(p-methylstyryl)-4'-(α-naphthylamine) methylenetriphenylamine and 4-(p-methylstyryl)-4'-(2-aminofluorene) methylenetri-phenylamine,were synthesized by Wittig reaction and aldimine condensation reaction from 4,4'-di-formyltriphenylamine.The structures were confirmed by 1 H NMR,13C NMR and IR.

  14. TARTARIC ACID TEMPLATED SYNTHESIS OF MESOPOROUS Ti-INCORPORATED SILICA AND ITS CATALYTIC ACTIVITY FOR THE RING-OPENING POLYMERIZATION OF ε-CAPROLACTONE

    Institute of Scientific and Technical Information of China (English)

    Jie-bin Pang; Chang-ming Dong; Kun-yuan Qiu; Yen Wei

    2002-01-01

    Ti-incorporated mesoporous silica materials with pore diameters of 3-4 nm have been prepared via the co-hydrolysis and co-condensation reactions, that is the sol-gel reactions, of titanium (Ⅳ) tetrabutoxide and tetraethylorthosilicate in the presence of tartaric acid as template, followed by extraction with ethanol to remove the templatemolecules. The materials were characterized in detail by Fourier transform infrared spectroscopy, nitrogen adsorption-desorption test, powder X-ray diffraction, transmission electron microscopy and X-ray energy dispersive spectroscopy. Theresults indicate that the Ti-containing silica materials have large specific surface areas (ca. 1200 m2 g-1) and pore volumes(ca. 0.900 cm3 g-1). The mesoporosity arises from disordered interconnecting channels or pores. The Ti-incorporated silicasexhibit catalytic activity for the ring-opening polymerization of ε-caprolactone, otherwise, the pure mesoporous silicamaterial shows no catalytic activity under the identical conditions.

  15. Quadrupolar, emission-tunable pi-expanded 1,4-dihydropyrrolo 3,2-b pyrroles - synthesis and optical properties

    DEFF Research Database (Denmark)

    Janiga, A.; Bednarska, D.; Thorsted, B.;

    2014-01-01

    . It was demonstrated that the increase in the molecular length of the chromophore effectively extends pi-conjugation. The effect of structural variations on photophysical properties was studied in detail for these compounds and the relationship between the structure and photophysical properties was thoroughly......The synthesis and optical characterization of six novel heteroaromatic-based chromophores is described. The new dyes present mostly an A-D-A general framework, where A is an electron-deficient aromatic ring and D is an electron-rich pyrrolo[3,2-b] pyrrole moiety, linked via triple bonds...

  16. New Palladium-Catalyzed Domino Reaction with Intramolecular Ring Closure of an N-(2-Chloro-3-heteroaryl) arylamide: First Synthesis of Oxazolo[4,5-b] pyrazines

    DEFF Research Database (Denmark)

    Demmer, Charles S.; Hansen, Jacob C.; Kehler, Jan;

    2014-01-01

    lipophilicity and target interaction points are often desired. In this respect, the oxazolo[4,5-b]pyrazine is an attractive heterocyclic scaffold as it possesses increased water solubility as well as two additional hydrogen bonding acceptors. We here report a new Pd(II)-catalyzed domino reaction comprising...... is required for the domino reaction to proceed. The robustness of the methodology is confirmed by the synthesis of 23 2-substituted oxazolo[4,5-b]pyrazine analogues in good-to-high yields and containing both electron-withdrawing as well as electron-donating substituents on the reacting arylamide....

  17. Aromatic Structure in Simulates Titan Aerosol

    Science.gov (United States)

    Trainer, Melissa G.; Loeffler, M. J.; Anderson, C. M.; Hudson, R. L.; Samuelson, R. E.; Moore, M. A.

    2011-01-01

    Observations of Titan by the Cassini Composite Infrared Spectrometer (CIRS) between 560 and 20 per centimeter (approximately 18 to 500 micrometers) have been used to infer the vertical variations of Titan's ice abundances, as well as those of the aerosol from the surface to an altitude of 300 km [1]. The aerosol has a broad emission feature centered approximately at 140 per centimeter (71 micrometers). As seen in Figure 1, this feature cannot be reproduced using currently available optical constants from laboratory-generated Titan aerosol analogs [2]. The far-IR is uniquely qualified for investigating low-energy vibrational motions within the lattice structures of COITIDlex aerosol. The feature observed by CIRS is broad, and does not likely arise from individual molecules, but rather is representative of the skeletal movements of macromolecules. Since Cassini's arrival at Titan, benzene (C6H6) has been detected in the atmosphere at ppm levels as well as ions that may be polycyclic aromatic hydrocarbons (PAHs) [3]. We speculate that the feature may be a blended composite that can be identified with low-energy vibrations of two-dimensional lattice structures of large molecules, such as PAHs or nitrogenated aromatics. Such structures do not dominate the composition of analog materials generated from CH4 and N2 irradiation. We are performing studies forming aerosol analog via UV irradiation of aromatic precursors - specifically C6H6 - to understand how the unique chemical architecture of the products will influence the observable aerosol characteristics. The optical and chemical properties of the aromatic analog will be compared to those formed from CH4/N2 mixtures, with a focus on the as-yet unidentified far-IR absorbance feature. Preliminary results indicate that the photochemically-formed aromatic aerosol has distinct chemical composition, and may incorporate nitrogen either into the ring structure or adjoined chemical groups. These compositional differences are

  18. 新型锗中心多孔芳香材料的设计合成和表征%Designed Synthesis and Characterization of Novel Germanium Centered Porous Aromatic Frameworks (Ge-PAFs)

    Institute of Scientific and Technical Information of China (English)

    元野; 闫卓君; 任浩; 刘青英; 朱广山; 孙福兴

    2012-01-01

    采用四(4-溴苯基)锗烷作为基块,以1,4-苯二硼酸和4,4'-联苯基二硼酸作为桥联,合成了两种锗中心的多孔芳香材料(Ge-PAFs).通过FTIR,MAS NMR,TGA,PXRD,SEM,TEM及N2吸附对该化合物的结构及性质进行表征.Ge-PAF-1和Ge-PAF-2具有优良的热稳定性(420℃失重5%)及化学稳定性.另外,该材料成功地在聚合物中引入锗元素为其在半导体等方面的应用提供了可能[1].%A novel series of germanium centered porous aromatic frameworks (Ge-PAFs) based on tetrakis(4-bromophenyl)germane as building units and 1,4-benzenediboronic acid or 4,4'-biphenyldiboronic acid as linkers were synthesized. These materials were characterized by Fourier transform infrared spectroscopy (FT-IR), 13C solid-state NMR, thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (TEM), and N2 gas sorption. FTIR spectroscopy is useful in probing the structure of Ge-PAFs networks. From the disappearance of the intense B--OH bands (at 3370 cm^-1) and the C--Br bands (at 482 cm^-1) in the FT-IR spectra, the formation of the product can be preliminarily confirmed. The solid-state 13C CP/MAS NMR spectra of Ge-PAFs indicate that a group of signals with a chemical shift in the range of J 120--145 could be observed. They are related to aromatic carbon atoms in the framework-building phenylene groups. Both the FTIR and 13C CP/MAS NMR analyses show no obvious signals assigned to the halogen or boronic acid end groups, testifying that an almost com- plete coupling reaction has taken place. PXRD was carried out to investigate the crystallinity of Ge-PAFs, which indicate the amorphous texture. No long-range frameworks could be due to distortion and interpenetration of the phenyl rings. SEM im- ages showed that Ge-PAF-1 and Ge-PAF-2 afforded a spherical morphology. Simultaneously, TEM revealed that

  19. Bacterial degradation of aromatic pollutants: a paradigm of metabolic versatility

    OpenAIRE

    Díaz Fernández, Eduardo

    2004-01-01

    Although most organisms have detoxification abilities (i.e mineralization, transformation and/or immobilization of pollutants), microorganisms, particularly bacteria, play a crucial role in biogeochemical cycles and in sustainable development of the biosphere. Next to glucosyl residues, the benzene ring is the most widely distributed unit of chemical structure in nature, and many of the aromatic compounds are major environmental pollutants. Bacteria have developed strategies fo...

  20. Efficient Route to Deuterated Aromatics by the Deamination of Anilines.

    Science.gov (United States)

    Burglova, Kristyna; Okorochenkov, Sergei; Hlavac, Jan

    2016-07-15

    One-step replacement of NH2 groups in ring-substituted anilines by deuterium is reported. Approaches comprising both solid-phase and solution-phase syntheses can be used on a large variety of substrates. The method uses diazotization in a mixture of water and either dichloromethane or chloroform, which serve as a source of hydrogen. This protocol can be used as a general method for fast and easy incorporation of deuterium into an aromatic system using deuterated chloroform.

  1. Alternative loop rings

    CERN Document Server

    Goodaire, EG; Polcino Milies, C

    1996-01-01

    For the past ten years, alternative loop rings have intrigued mathematicians from a wide cross-section of modern algebra. As a consequence, the theory of alternative loop rings has grown tremendously. One of the main developments is the complete characterization of loops which have an alternative but not associative, loop ring. Furthermore, there is a very close relationship between the algebraic structures of loop rings and of group rings over 2-groups. Another major topic of research is the study of the unit loop of the integral loop ring. Here the interaction between loop rings and group ri

  2. The formation of polycyclic aromatic hydrocarbons in evolved circumstellar environments

    CERN Document Server

    Cherchneff, Isabelle

    2010-01-01

    The formation of Polycyclic Aromatic Hydrocarbons in the circumstellar outflows of evolved stars is reviewed, with an emphasis on carbon stars on the Asymptotic Giant Branch. Evidence for PAHs present in their winds is provided by meteoritic studies and recent observations of the Unidentified Infrared bands. We detail the chemical processes leading to the closure of the first aromatic ring as well as the growth mechanisms leading to amorphous carbon grains. Existing studies on PAH formation in evolved stellar envelopes are reviewed and new results for the modelling of the inner wind of the archetype carbon star IRC+10216 are presented. Benzene, C6H6, forms close to the star, as well as water, H2O, as a result of non-equilibrium chemistry induced by the periodic passage of shocks. The growth process of aromatic rings may thus resemble that active in sooting flames due to the presence of radicals like hydroxyl, OH. Finally, we discuss possible formation processes for PAHs and aromatic compounds in the hydrogen-...

  3. One-pot synthesis of linear- and three-arm star-tetrablock quarterpolymers via sequential metal-free ring-opening polymerization using a "catalyst switch" strategy

    KAUST Repository

    Zhao, Junpeng

    2014-08-06

    A "catalyst switch" strategy has been used to sequentially polymerize four different heterocyclic monomers. In the first step, epoxides (1,2-butylene oxide and ethylene oxide) were successively polymerized from a monohydroxy or trihydroxy initiator in the presence of a strong phosphazene base promoter (t-BuP4). Then, an excess of diphenyl phosphate (DPP) was introduced, followed by addition and polymerization of a cyclic carbonate (trimethylene carbonate) and a cyclic ester (δ-valerolactone or ε-caprolactone). DPP acted as both neutralizer of the phosphazenium alkoxide (polyether chain end) and activator of the cyclic carbonate/ester. Using this method, linear- and star-tetrablock quarterpolymers were prepared in one pot. This work is emphasizing the strength of the previously developed catalyst switch strategy for the facile metal-free synthesis of complex macromolecular architectures. © 2014 Wiley Periodicals, Inc.

  4. Irradiation of ethylene/styrene copolymers: evidence of sensitization of the aromatic moiety as counterpart of the radiation protection effect.

    Science.gov (United States)

    Ferry, M; Bessy, E; Harris, H; Lutz, P J; Ramillon, J-M; Ngono-Ravache, Y; Balanzat, E

    2012-02-16

    Molecules containing aromatics systems are more stable in the presence of ionizing radiations than alkanes. In the same way, introducing aromatic rings into aliphatic compounds increases their stability. The protective effect is nonlocal and likely results from the transfer of energy and species from the aliphatic moiety to the aromatic one. For years, it was commonly assumed that the aromatic moiety, which is very radiation resistant, accommodates the extra energy remaining unaffected. The use of Fourier transform infrared spectroscopy, online with high energy ion beam irradiation of ethylene/styrene random copolymers, allows us to bring experimental evidence that the benzene rings are sensitized by transfer reactions and consequently that this effect is more important in polymers with low benzene ring molar content. PMID:22236059

  5. Synthesis and Structural Characterization of Lithium and Titanium Complexes Bearing a Bulky Aryloxide Ligand Based on a Rigid Fused-Ring s-Hydrindacene Skeleton.

    Science.gov (United States)

    Kanazawa, Shoya; Ohira, Taishi; Goda, Shun; Hayakawa, Naoki; Tanikawa, Tomoharu; Hashizume, Daisuke; Ishida, Yutaka; Kawaguchi, Hiroyuki; Matsuo, Tsukasa

    2016-07-01

    The bulky aryl alcohols, (Rind)OH (1) [Rind = EMind (a) and Eind (b)], based on the rigid fused-ring 1,1,3,3,5,5,7,7-octa-R-substituted s-hydrindacene skeleton were prepared by the reaction of (Rind)Li with nitrobenzene followed by protonation. The treatment of 1 with (n)BuLi affords the lithium aryloxide dimers [(Rind)OLi(THF)]2 (2) or trimers [(Rind)OLi]3 (3), depending on the employed solvents (THF = tetrahydrofuran). The salt metathesis reaction of [(EMind)OLi(THF)]2 (2a) with TiCl4(THF)2 leads to the formation of the mononuclear diamagnetic mono- and bis(aryloxide) Ti(IV) complexes, [(EMind)O]TiCl3(THF) (4a) and [(EMind)O]2TiCl2 (5a). We also isolated a trace amount of the tris(aryloxide) Ti(IV) complex, [(EMind)O]3TiCl (6a). The reaction between 2a and TiCl3(THF)3 resulted in the isolation of the mononuclear paramagnetic mono- and bis(aryloxide) Ti(III) complexes, [(EMind)O]TiCl2(THF)2 (7a) and [(EMind)O]2TiCl(THF)2 (8a). The discrete monomeric structures of the titanium complexes 4a, 5a, 6a, 7a, and 8a were determined by X-ray crystallography. PMID:27284975

  6. Amphiphilic block copolymers bearing six-membered ortho ester ring in side chains as potential drug carriers: synthesis, characterization, and in vivo toxicity evaluation.

    Science.gov (United States)

    Luo, Shi; Tao, Yangyang; Tang, Rupei; Wang, Rui; Ji, Weihang; Wang, Chun; Zhao, Youliang

    2014-07-01

    A new type of amphiphilic block copolymers, poly(ethylene glycol)-block-poly(2-methyl-acrylicacid 2-methoxy-5-methyl-[1,3]dioxin-5-ylmethyl ester) (PEG-b-PMME), bearing acid-labile six-membered ortho ester rings in side chains was synthesized by reversible addition-fragmentation chain-transfer polymerization, and the influence of chain length of the hydrophobic PMME block on micelle properties was investigated. The PEG-b-PMME micelles were stable in aqueous buffer at physiological pH with a low critical micelle concentration. Nile Red as a model drug was encapsulated into the micelles to explore the release profiles. The Nile Red-loaded polymeric micelles showed rapid release of Nile Red in weakly acidic environments (pH 5) but slow release under physiological condition (pH 7.4), due to different hydrolysis rate of ortho ester side chains of PEG-b-PMME. The Paclitaxel (PTX)-loaded micelles retained potency in killing lung cancer cells (A549), compared with the free PTX. No obvious toxicity was found in vitro and in vivo after intraperitoneal injection of the micelles, which confirms that the PEG-b-PMME micelles with unique acid-labile characteristic have great potential as nano-scaled carriers for drug delivery.

  7. Synthesis and quantitative structure-activity relationship (QSAR) study of novel 4-acyloxypodophyllotoxin derivatives modified in the A and C rings as insecticidal agents.

    Science.gov (United States)

    He, Shuzhen; Shao, Yonghua; Fan, Lingling; Che, Zhiping; Xu, Hui; Zhi, Xiaoyan; Wang, Juanjuan; Yao, Xiaojun; Qu, Huan

    2013-01-23

    In continuation of our program aimed at the discovery and development of natural-product-based insecticidal agents, we have synthesized three series of novel 4-acyloxy compounds derived from podophyllotoxin modified in the A and C rings, which is isolated as the main secondary metabolite from the roots and rhizomes of Podophyllum hexandrum . Their insecticidal activity was preliminarily evaluated against the pre-third-instar larvae of Mythimna separata in vivo. Compound 9g displayed the best promising insecticidal activity. It revealed that cleavage of the 6,7-methylenedioxy group of podophyllotoxin will lead to a less active compound and that the C-4 position of podophyllotoxin was the important modification location. A quantitative structure-activity relationship (QSAR) model was developed by genetic algorithm combined with multiple linear regression (GA-MLR). For this model, the squared correlation coefficient (R(2)) is 0.914, the leave-one-out cross-validation correlation coefficient (Q(2)(LOO)) is 0.881, and the root-mean-square error (RMSE) is 0.024. Five descriptors, BEHm2, Mor14v, Wap, G1v, and RDF020e, are likely to influence the biological activity of these compounds. Among them, two important ones are BEHm2 and Mor14v. This study will pave the way for further design, structural modification, and development of podophyllotoxin derivatives as insecticidal agents. PMID:23278333

  8. Enolate chelating N-heterocyclic carbene complexes of Fe(Ⅱ): Synthesis, structure and their catalytic activity for ring-opening polymerization of ε-caprolactone

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The reaction of anhydrous FeBr2 with two equivalents of anionic N-heterocyclic carbene (NaL1 and NaL2), which are generated in situ by the reaction of the corresponding salt [4-R-C6H4COCH2{CH- (NCHCHNiPr)}Br] (R = OCH3, H2L1Br, 1; R = F, H2L2Br, 2) with two equivalents of NaN(SiMe3)2, affords bis-ligand Fe(Ⅱ) complexes of L21Fe (3) and L22Fe (4) in high yield, respectively. Attempt to synthesize mono-ligand Fe(Ⅱ) bromide by the 1:1 molar ratio of NaL to FeBr2 is unsuccessful, and the same complexes of 3 and 4 were obtained. Both 3 and 4 have been depicted by elemental analysis and X-ray structure determination. Preliminary studies show that both 3 and 4 can be used as single-component catalyst for the ring-opening polymerization of ε-caprolactone, and the catalytic activity of 3 is higher than that of 4.

  9. Synthesis, Structure of Zinc Complexes Containing Sulfon- ylated Binaphtholate Ligands and Their Catalytic Activities towards Ring-Opening Polymerization of Lactide and ε-Caprolactone

    Institute of Scientific and Technical Information of China (English)

    周双六; 姜永要; 谢陶; 吴章栓; 周凌敏; 许文静; 张丽军; 王绍武

    2012-01-01

    Reaction of sulfonylated binaphthol [2-hydroxy-2'-tosyloxy-l,l-binaphthyl (la, Ts-Binol) or 2-hydroxy-2'- (phenylsulfonyloxy)-l,l-binaphthyl (lb, Ps-Binol)] with 1 equiv, of ZnEt2 afforded zinc complexes [(Ys-Binol)ZnEt]2 (2a) and [(Ps-Binol)ZnEt]2 (2b). Further reaction of zinc complexes 2a and 2b with benzyl alco- hol (BnOH) gave the zinc benzyloxide [(Ts-Binol)2Zn2(OBn)2]2 (3a) and [(Ps-Binol)2Znz(OBn)2]2 (3b). Alterna- tively, the zinc benzyloxides 3a and 3b could also be obtained by reaction of compound la or lb with Zn(OBn)2 (in situ reaction of ZnEt2 and BnOH). The complexes were fully characterized by elemental analyses and spectroscopic analyses, and complexes 2a, 2b and 3a were further characterized by single-crystal X-ray analyses. The catalytic activities of these zinc complexes towards ring-opening polymerization of ε-caprolactone and D,L-lactide were studied.

  10. The reduction ring-opening reaction of imidazoline

    Institute of Scientific and Technical Information of China (English)

    史真; 李诤; 白银娟

    2000-01-01

    A new reduction ring-opening reaction of 2-imidazoline with sodium borohydride is reported, and the effect of reaction condition on the yield, reaction mechanism and the use of the new reaction in synthesis of ethylenediamine derivatives are discussed. A new method for the preparation of unsymmetrical substituted ethylenediamine via the reduction ring-opening reaction of imidazoline is provided.

  11. A New Pathway to Synthesize Cyclomercurated Ferrocenylimines Containing Heterocyclic Ring

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The cyclomercurated ferrocenylimines containing heterocyclic ring were prepared by the condensation of cyclomercuration of acylferrocene with the appropriate heterocyclic amine. This procedure provides an efficient method for the synthesis of cyclomerucurated ferroceny- limines containing heterocyclic ring which are difficultly synthesized by the conventional method. The reaction mechanism is proposed.

  12. Synthetic applications of gold-catalyzed ring expansions

    Directory of Open Access Journals (Sweden)

    Cristina Nevado

    2011-06-01

    Full Text Available The development of new methodologies catalyzed by late transition metals involving cycloisomerizations of strained rings can open new venues for the synthesis of structurally complex molecules with interesting biological activities. Herein we summarize, from both a synthetic as well as a mechanistic point of view, the most recent developments in gold-catalyzed ring expansions.

  13. Synthesis and biological activity of sulfur compounds showing structural analogy with combretastatin A-4

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Edson dos A. dos; Prado, Paulo C.; Carvalho, Wanderley R. de; Lima, Ricardo V. de; Beatriz, Adilson; Lima, Denis P. de, E-mail: denis.lima@ufms.br [Universidade Federal de Mato Grosso do Sul (UFMS), Campo Grande, MS (Brazil). Departamento de Quimica; Hamel, Ernest [Screening Technologies Branch, Developmental Therapeutics Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD (United States); Dyba, Marzena A. [Basic Science Program , SAIC-Frederick, Inc., Structural Biophysics Laboratory National Cancer Institute, Frederick, MD (United States); Albuquerque, Sergio [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Ciencias Farmaceuticas

    2013-09-01

    We extended our previous exploration of sulfur bridges as bioisosteric replacements for atoms forming the bridge between the aromatic rings of combretastatin A-4. Employing coupling reactions between 5-iodo-1,2,3-trimethoxybenzene and substituted thiols, followed by oxidation to sulfones with m-CPBA, different locations for attaching the sulfur atom to ring A through the synthesis of nine compounds were examined. Antitubulin activity was performed with electrophoretically homogenous bovine brain tubulin, and activity occurred with the 1,2,3-trimethoxy-4-[(4-methoxyphenyl)thio]benzene (12), while the other compounds were inactive. The compounds were also tested for leishmanicidal activity using promastigote forms of Leishmania braziliensis (MHOM/BR175/M2904),and the greatest activity was observed with 1,2,3-trimethoxy-4-(phenylthio)benzene (10) and 1,2,3-trimethoxy-4-[(4-methoxyphenyl) sulfinyl]benzene (15). (author)

  14. Synthesis of novel 5-alkyl/aryl/heteroaryl substituted diethyl 3,4-dihydro-2H-pyrrole-4,4-dicarboxylates by aziridine ring expansion of 2-[(aziridin-1-yl-1-alkyl/aryl/heteroaryl-methylene]malonic acid diethyl esters

    Directory of Open Access Journals (Sweden)

    U. K. Syam Kumar

    2011-06-01

    Full Text Available A novel synthetic methodology has been developed for the synthesis of diethyl 5-alkyl/aryl/heteroaryl substituted 3,4-dihydro-2H-pyrrole-4,4-dicarboxylates (also called 2-substituted pyrroline-4,5-dihydro-3,3-dicarboxylic acid diethyl esters by iodide ion induced ring expansion of 2-[(aziridin-1-yl-1-alkyl/aryl/heteroaryl-methylene]malonic acid diethyl esters in very good to excellent yields under mild reaction conditions. The electronic and steric impact of the substituents on the kinetics of ring expansion of N-vinyl aziridines to pyrrolines has been studied. Various diversely substituted novel pyrroline derivatives have been synthesized by this methodology and the products can be used as key intermediates in the synthesis of substituted pyrrolines, pyrroles and pyrrolidines.

  15. π-Electron rotations in chiral aromatic molecules induced by ultashort laser pulses

    International Nuclear Information System (INIS)

    π Electron play an important role in formation of the molecular structures and reactivity of aromatic molecules. In recent years, research fields of electron dynamics in atoms and molecules have attracted considerable attention with rapid progress in laser science and technology in femtosecond to attosecond time regimes [1]. This is a new branch of femtosecond chemistry. In this talk, we present the results of our recent works on control of π-electron rotation in photo-induced chiral aromatic molecules [2-4]. Control of π-electron rotation has potential utility to next-generation ultrafast switching devices. After a short introduction, the principle of generation of unidirectional π-electron rotation in aromatic molecules induced by a linearly polarized UV laser pulse is described. Next, the results of control simulations of π-electron rotations and those of the π- electron ring currents are presented for two representative chiral aromatic molecules; one is 2,5-dichlor[n] (3,6) pyrazinophane with one aromatic pyrzine ring [2], and the other is (P)-2,2’-biphenol with two aromatic rings [3,4]. Finally, the summary of the π-electron rotations and perspectives of ultrashort quantum switching investigations are described. (author)

  16. Novel Ring Cleavage Products in the Biotransformation of Biphenyl by the Yeast Trichosporon mucoides

    OpenAIRE

    Sietmann, Rabea; Hammer, Elke; Specht, Michael; Carl E Cerniglia; Schauer, Frieder

    2001-01-01

    The yeast Trichosporon mucoides, grown on either glucose or phenol, was able to transform biphenyl into a variety of mono-, di-, and trihydroxylated derivatives hydroxylated on one or both aromatic rings. While some of these products accumulated in the supernatant as dead end products, the ortho-substituted dihydroxylated biphenyls were substrates for further oxidation and ring fission. These ring fission products were identified by high-performance liquid chromatography, gas chromatography-m...

  17. On JB-Rings

    Institute of Scientific and Technical Information of China (English)

    Huanyin CHEN

    2007-01-01

    A ring R is a QB-ring provided that aR + bR = R with a, b ∈ R implies that there exists a y ∈ R such that a+by ∈ R-1q. It is said that a ring R is a JB-ring provided that R/J(R) is a QB-ring, where J(R) is the Jacobson radical of R. In this paper, various necessary and sufficient conditions, under which a ring is a JB-ring, are established. It is proved that JB-rings can be characterized by pseudo-similarity. Furthermore, the author proves that R is a J B-ring iff so is R/J(R)2.

  18. Studies on the structure of peat humic acid (II). Study on the determination of the aromatic skeletons in peat humic acid by zinc-dust distillation

    Energy Technology Data Exchange (ETDEWEB)

    Oka, H.; Sasaki, M.

    1979-01-01

    In order to determine aromatic skeletons in the chemical structure of peat humic acid, zinc-dust distillation was carried out at 500 C for 2 hours in a stream of hydrogen, and the results compared to those from other substances such as phtholic acid, cumarin, naphthoquinone and ..cap alpha..-lactone. Subsequently, methods for the identification and semi-quantitative determination of polycyclic aromatic hydrocarbons were applied. The total yield of polycyclic hydrocarbon having anthracene, pyrene and perylene rings was 1.9% of the original peat humic acid. However, the yield of aromatic hydrocarbons containing 3 to 5 rings from peat humic acid was approximately equal to those from the other substances. From the results, it is assumed that peat humic acid has no polycyclic ring systems as the aromatic structure, and that the polycyclic aromatic hydrocarbons produced by zinc-dust distillation were formed by a rearrangement and condensation of oxygen containing structures during the reaction.

  19. Aromatic Character Studies on Divalent 3, 5 and 7-membered Rings C2H2M,C4H4M and C6H6M(M=C,Si,Ge,Sn and Pb)via Nucleus-independent Chemical Shifts (NICS) Calculation%通过核独立化学位移(NICS)计算研究二价三、五、七元环C2H2M,C4H4M and C6H6M(M=C,Si,Ge,Sn and Pb)的芳香族特性

    Institute of Scientific and Technical Information of China (English)

    Vessally E; Nikoorazm M; Ramazani A

    2008-01-01

    The aromatic character of divalent three, five and seven-membered rings C2H2M,C4H4 and C6H6M(M=C,Si, Ge, Sn and Pb) is investigated through magnetic and geometric criteria by Density Functional Theory (DFT) method using 6-311++G (3df,2p) basis set of the GAUSSIAN 98 program. The result of Nucleus-independent Chemical Shifts (NICS) (0.5) calculations show an aromatic character for singlet state of C2H2M,(M=C, Si, Ge, Sn and Sn) and nonaromatic character for triplet states of C2H2M (except M =Ge and Pb). NICS (0.5) calculations show nonaromatic character for the singlet state of C4H4C and antiaromatic character for C4H4M (M=Si, Ge, Sn and Pb). In contrast, NICS (0.5) calculations indicate antiaromatic character for the triplet state of C4H4C and nonaromatic character to C4H4M (M=Si, Ge, Sn and Pb). NICS (0.5) calculations show a slightly homoaromatic character for the singlet state of C6H6M and anti-aromatic character for triplet state of C6H6M.

  20. Exploring aromatic chemical space with NEAT: novel and electronically equivalent aromatic template.

    Science.gov (United States)

    Tu, Meihua; Rai, Brajesh K; Mathiowetz, Alan M; Didiuk, Mary; Pfefferkorn, Jeffrey A; Guzman-Perez, Angel; Benbow, John; Guimarães, Cristiano R W; Mente, Scot; Hayward, Matthew M; Liras, Spiros

    2012-05-25

    In this paper, we describe a lead transformation tool, NEAT (Novel and Electronically equivalent Aromatic Template), which can help identify novel aromatic rings that are estimated to have similar electrostatic potentials, dipoles, and hydrogen bonding capabilities to a query template; hence, they may offer similar bioactivity profiles. In this work, we built a comprehensive heteroaryl database, and precalculated high-level quantum mechanical (QM) properties, including electrostatic potential charges, hydrogen bonding ability, dipole moments, chemical reactivity, and othe properties. NEAT bioisosteric similarities are based on the electrostatic potential surface calculated by Brood, using the precalculated QM ESP charges and other QM properties. Compared with existing commercial lead transformation software, (1) NEAT is the only one that covers the comprehensive heteroaryl chemical space, and (2) NEAT offers a better characterization of novel aryl cores by using high-evel QM properties that are relevant to molecular interactions. NEAT provides unique value to medicinal chemists quickly exploring the largely uncharted aromatic chemical space, and one successful example of its application is discussed herein.

  1. Palladium-catalyzed regioselective intramolecular coupling of o-carborane with aromatics via direct cage B-H activation.

    Science.gov (United States)

    Quan, Yangjian; Xie, Zuowei

    2015-03-18

    Palladium-catalyzed intramolecular coupling of o-carborane with aromatics via direct cage B-H bond activation has been achieved, leading to the synthesis of a series of o-carborane-functionalized aromatics in high yields with excellent regioselectivity. In addition, the site selectivity can also be tuned by the substituents on cage carbon atom. PMID:25747772

  2. Palladium-catalyzed regioselective intramolecular coupling of o-carborane with aromatics via direct cage B-H activation.

    Science.gov (United States)

    Quan, Yangjian; Xie, Zuowei

    2015-03-18

    Palladium-catalyzed intramolecular coupling of o-carborane with aromatics via direct cage B-H bond activation has been achieved, leading to the synthesis of a series of o-carborane-functionalized aromatics in high yields with excellent regioselectivity. In addition, the site selectivity can also be tuned by the substituents on cage carbon atom.

  3. Petrochemistry - Aromatics; Petrochimie - Aromatiques

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2005-09-01

    The assignment of Unipetrol chemical activities to the Czech group Agrofert by the Polish PKN Orlen is suspended and would be renegotiated. Oman Oil Company (OOC) is joining in the Korean LG International and in its subsidiary company Oman Refinery Company (ORC) for the construction of its new aromatics complex on its site of Sohar (Oman). This plan represents an investment of one milliard of dollars; it will produce 800000 t/year of para-xylene and 210000 t/year of benzene. The unit would be operational at the third trimester 2008. (O.M.)

  4. The biodegradation vs. biotransformation of fluorosubstituted aromatics.

    Science.gov (United States)

    Kiel, Martina; Engesser, Karl-Heinrich

    2015-09-01

    Fluoroaromatics are widely and--in recent years--increasingly used as agrochemicals, starting materials for chemical syntheses and especially pharmaceuticals. This originates from the special properties the carbon-fluorine bond is imposing on organic molecules. Hence, fluoro-substituted compounds more and more are considered to be important potential environmental contaminants. On the other hand, the microbial potentials for their transformation and mineralization have received less attention in comparison to other haloaromatics. Due to the high electronegativity of the fluorine atom, its small size, and the extraordinary strength of the C-F bond, enzymes and mechanisms known to facilitate the degradation of chloro- or bromoarenes are not necessarily equally active with fluoroaromatics. Here, we review the literature on the microbial degradation of ring and side-chain fluorinated aromatic compounds under aerobic and anaerobic conditions, with particular emphasis being placed on the mechanisms of defluorination reactions.

  5. Sulfide Catalysts Supported on Porous Aromatic Frameworks for Naphthalene Hydroprocessing

    Directory of Open Access Journals (Sweden)

    Eduard Karakhanov

    2016-08-01

    Full Text Available This paper describes the first example of using porous aromatic frameworks as supports for sulfide catalysts for the hydrogenation of aromatic hydrocarbons. The synthesis of bimetallic Ni-W and Ni-Mo sulfides was performed by in situ decomposition of [(n-Bu4N]2[Ni(MeS42] (Me = W, Mo complexes, supported on mesoporous aromatic framework with a diamond-like structure. It is shown that the highest naphthalene conversions were achieved in the case of additional sulfidation with sulfur. After the reaction, catalysts were characterized by X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy. The activity of synthesized catalysts has been studied using naphthalene as a model substrate. The materials used in this study were substantially active in hydrogenation and slightly in hydrocracking of naphthalene.

  6. Theoretical Estimate of Hydride Affinities of Aromatic Carbonyl Compounds

    Institute of Scientific and Technical Information of China (English)

    AI Teng; ZHU Xiao-Qing; CHENG Jin-Pei

    2003-01-01

    @@ Aromatic carbonyl compounds are one type of the most important organic compounds, and the reductions ofthem by hydride agents such as LiAlH4 or NaBH4 are widely used in organic synthesis. The reactivity of carbonyl compounds generally increases in the following order: ketone < aldehyde, and amide < acid < ester < acid halide, which could be related to their hydride affinities (HA). In the previous paper, Robert[1] calculated the absolute HAof a series of small non-aromatic carbonyl compounds. In this paper, we use DFT method at B3LYP/6-311 + + G (2d, 2p)∥B3LYP/6-31 + G* level to estimate hydride affinities of five groups of aromatic carbonyl compounds. The detailed results are listed in Table 1.

  7. Synthesis and Biological Activity of 1,3,4-Oxadiazole Mannich Bases Containing Pyrimidine Rings%含嘧啶环的1,3,4-噁二唑 Mannich 碱的合成及生物活性

    Institute of Scientific and Technical Information of China (English)

    沈生强; 孙晓红; 刘源发; 陈邦; 靳如意; 马海霞

    2014-01-01

    1,3,4-Oxadiazole derivatives were reported to possess a broad spectrum of biological activities, such as antifungal, antibacterial, antiviral and antitubercular. Mannich bases had also been reported as poten-tial biological agents, they were applicated in the fields of synthetic study and medicinal chemistry. In recent years, Mannich bases containing 1,3,4-oxadiazole ring had attracted a lot of attention and many Mannich ba-ses of 1,3,4-oxadiazole bearing heterocycle scaffold were reported to have special bioactivity. Nevertheless, literature revealed that there were no reports of a molecular scaffold that Mannich base of 1,3,4-oxadiazole bearing pyrimidine. Prompted by these observations, a series of 1,3,4-oxadiazole derivatives containing py-rimidine( E1-E15) was synthesized from 5-aryl-1,3,4-oxadiazole-2-thione ( C1-C3), formaldehyde and substituted aminopyrimidine ( D1-D5) by Mannich reaction. 5-Aryl-1,3,4-oxadiazole-2-thione derivatives (C1-C3) were prepared from aromatic acids as the starting material via esterification, hydrazinolysis and cy-clization. The structures of all title compounds were confirmed by elemental analysis, IR, 1 H NMR tech-niques. Furthermore, their biological activities to four vegetable pathogens containing Gibberll nicotiancola, Gibberlla saubinetii, Fusarium oxysporium f. sp. niveum, Pythium solani had been tested. The preliminary re-sults indicated that most of the compounds exhibit relatively good fungicidal activities, especially compounds E3 and E8 showed better biological activity than triazolone.%以芳香酸为原料,通过酯化、肼解及环化反应制得中间体5-芳基取代-1,3,4-噁二唑-2-硫酮(C1~C3),然后中间体与甲醛和取代氨基嘧啶(D1~ D5)发生 Mannich 反应得到一系列新型含有嘧啶环的1,3,4-噁二唑类衍生物(E1~ E15)。所得目标化合物的结构经元素分析、 IR 及1 H NMR 确认。初步的生物活性测定结果表明,大部分目标化合物对植物病原菌有很好

  8. Synthesis and stereochemical investigation of potential saturated heterocyclic drugs Pt. 1

    International Nuclear Information System (INIS)

    Studies of partially and fully saturated heterocyclic compounds with condensed skeleton containing two heteroatoms are presented. The synthesis, stereochemical and conformation analyses aimed at the synthesis of potential drugs. Dihydro- and tetrahydro-1,3-oxazines were prepared from alicyclic 1,3-amino-alcohols by ring closure with aldehydes or imide esters. 1,3-oxazine-4-one derivatives were prepared by reacting alicyclic cis- and trans-2-hydroxy-1-carboxamides with aliphatic or aromatic aldehides. The conformations of the compounds prepared were determined by means of NMR spectroscopy. The main results of the determination of the steric structure of some representatives of the above described families of compounds by means of X-ray diffraction analysis are also presented. (author)

  9. New dust belts of Uranus: one ring, two ring, red ring, blue ring.

    Science.gov (United States)

    de Pater, Imke; Hammel, Heidi B; Gibbard, Seran G; Showalter, Mark R

    2006-04-01

    We compared near-infrared observations of the recently discovered outer rings of Uranus with Hubble Space Telescope results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced by impacts into the embedded moon Mab, which apparently orbits at a location where nongravitational perturbations favor the survival and spreading of submicron-sized dust. R/2003 U 2 more closely resembles Saturn's G ring, which is red, a typical color for dusty rings. PMID:16601188

  10. Groups, rings, modules

    CERN Document Server

    Auslander, Maurice

    2014-01-01

    This classic monograph is geared toward advanced undergraduates and graduate students. The treatment presupposes some familiarity with sets, groups, rings, and vector spaces. The four-part approach begins with examinations of sets and maps, monoids and groups, categories, and rings. The second part explores unique factorization domains, general module theory, semisimple rings and modules, and Artinian rings. Part three's topics include localization and tensor products, principal ideal domains, and applications of fundamental theorem. The fourth and final part covers algebraic field extensions

  11. C-H and N-H bond dissociation energies of small aromatic hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Barckholtz, C.; Barckholtz, T.A.; Hadad, C.M.

    1999-01-27

    A survey of computational methods was undertaken to calculate the homolytic bond dissociation energies (BDEs) of the C-H and N-H bonds in monocyclic aromatic molecules that are representative of the functionalities present in coal. These include six-membered rings (benzene, pyridine, pyridazine, pyrimidine, pyrazine) and five-membered rings (furan, thiophene, pyrrole, oxazole). By comparison of the calculated C-H BDEs with the available experimental values for these aromatic molecules, the B3LYP/6-31G(d) level of theory was selected to calculate the BDEs of polycyclic aromatic hydrocarbons (PAHs), including carbonaceous PAHs (naphthalene, anthracene, pyrene, coronene) and heteroatomic PAHs (benzofuran, benzothiophene, indole, benzoxazole, quinoline, isoquinoline, dibenzofuran, carbazole). The cleavage of a C-H or a N-H bond generates a {sigma} radical that is, in general, localized at the site from which the hydrogen atom was removed. However, delocalization of the unpaired electron results in {approximately} 7 kcal {center{underscore}dot} mol{sup {minus}1} stabilization of the radical with respect to the formation of phenyl when the C-H bond is adjacent to a nitrogen atom in the azabenzenes. Radicals from five-membered rings are {approximately} 6 kcal {center{underscore}dot} mol{sup {minus}1} less stable than those formed from six-membered rings due to both localization of the spin density and geometric factors. The location of the heteroatoms in the aromatic ring affects the C-H bond strengths more significantly than does the size of the aromatic network. Therefore, in general, the monocyclic aromatic molecules can be used to predict the C-H BDE of the large PAHs within 1 kcal {center{underscore}dot} mol{sup {minus}1}.

  12. Muon storage ring

    CERN Multimedia

    1974-01-01

    The muon storage ring where the g-2 of the muon is being measured with extremely high accuracy. The ring is 14-m in diameter and has very precise magnetic bending and electric focussing fields so that the muons orbit the ring under well-defined conditions.

  13. Rings Around Uranus

    Science.gov (United States)

    Maran, Stephen P.

    1977-01-01

    Events leading up to the discovery of the rings of Uranus are described. The methods used and the logic behind the methods are explained. Data collected to prove the existence of the rings are outlined and theories concerning the presence of planetary rings are presented. (AJ)

  14. Remarkable Stereoelectronic Effect of the Methylenedioxy Phenyl System in the Total Synthesis of Cephalotaxine

    Institute of Scientific and Technical Information of China (English)

    Hua YANG; Yong Qiang WANG; Wei DongZ. LI

    2005-01-01

    Methylenedioxyphenyl unit displays a significant stereoelectronic effect in some key transformations in the total synthesis of cephalotaxine. The ring-strain of methylenedioxy ring may account for some important facile ring-skeleton rearrangements.

  15. Reconfigurable ring filter with controllable frequency response.

    Science.gov (United States)

    Ab Wahab, Norfishah; Mohd Salleh, Mohd Khairul; Ismail Khan, Zuhani; Abd Rashid, Nur Emileen

    2014-01-01

    Reconfigurable ring filter based on single-side-access ring topology is presented. Using capacitive tuning elements, the electrical length of the ring can be manipulated to shift the nominal center frequency to a desired position. A synthesis is developed to determine the values of the capacitive elements. To show the advantage of the synthesis, it is applied to the reconfigurable filter design using RF lumped capacitors. The concept is further explored by introducing varactor-diodes to continuously tune the center frequency of the ring filter. For demonstration, two prototypes of reconfigurable ring filters are realized using microstrip technology, simulated, and measured to validate the proposed concept. The reconfigured filter using lumped elements is successfully reconfigured from 2 GHz to 984.4 MHz and miniaturized by 71% compared to the filter directly designed at the same reconfigured frequency, while, for the filter using varactor-diodes, the frequency is chosen from 1.10 GHz to 1.38 GHz spreading over 280 MHz frequency range. Both designs are found to be compact with acceptable insertion loss and high selectivity. PMID:25121132

  16. Facile Synthesis of New Aromatic Polyamides Based on 1,2-Dihydro-2-(4-carboxylphenyl)-4-[4-(4-carboxyl- phenoxy)-3-methylphenyl]phthalazin-1-one

    Institute of Scientific and Technical Information of China (English)

    程琳; 应磊; 杨小玲; 蹇锡高

    2005-01-01

    A new monomer diacid, 1,2-dihydro-2-(4-carboxylphenyl)-4-[4-(4-carboxylphenoxy)-3-methylphenyl]phtha-lazin-1-one (3), was synthesized through the aromatic nucleophilic substitution reaction of a readily available unsymmetrical phthalazinone 1 bisphenol-like with p-chlorobenzonitrile in the presence of potassium carbonate in N,N-dimethylacetamide and alkaline hydrolysis. The diacid could be directly polymerized with various aromatic diamines 4a-4e using triphenyl phosphite and pyridine as condensing agents to give five new aromatic poly(ether amide)s 5a-5e containing the kink non-coplanar heterocyclic units with inherent viscosities of 1.30-1.54 dL/g.The polymers were readily soluble in a variety of solvents such as N,N-dimethylformamide (DMF), N,N-dimethyl-acetamide (DMA), dimethylsulfoxide (DMSO), N-methyl-2-pyrrolidinone (NMP), and even in m-cresol and pyridine (Py). The transparent, flexible and tough films could be formed by solution casting. The glass transition tem-peratures Tg were in the range of 286-317℃.

  17. Anaerobic degradation of homocyclic aromatic compounds via arylcarboxyl-coenzyme A esters: organisms, strategies and key enzymes.

    Science.gov (United States)

    Boll, Matthias; Löffler, Claudia; Morris, Brandon E L; Kung, Johannes W

    2014-03-01

    Next to carbohydrates, aromatic compounds are the second most abundant class of natural organic molecules in living organic matter but also make up a significant proportion of fossil carbon sources. Only microorganisms are capable of fully mineralizing aromatic compounds. While aerobic microbes use well-studied oxygenases for the activation and cleavage of aromatic rings, anaerobic bacteria follow completely different strategies to initiate catabolism. The key enzymes related to aromatic compound degradation in anaerobic bacteria are comprised of metal- and/or flavin-containing cofactors, of which many use unprecedented radical mechanisms for C-H bond cleavage or dearomatization. Over the past decade, the increasing number of completed genomes has helped to reveal a large variety of anaerobic degradation pathways in Proteobacteria, Gram-positive microbes and in one archaeon. This review aims to update our understanding of the occurrence of aromatic degradation capabilities in anaerobic microorganisms and serves to highlight characteristic enzymatic reactions involved in (i) the anoxic oxidation of alkyl side chains attached to aromatic rings, (ii) the carboxylation of aromatic rings and (iii) the reductive dearomatization of central arylcarboxyl-coenzyme A intermediates. Depending on the redox potential of the electron acceptors used and the metabolic efficiency of the cell, different strategies may be employed for identical overall reactions.

  18. Skew polynomial rings over abelian and idempotent reflexive rings

    OpenAIRE

    Louzari, Mohamed

    2015-01-01

    Let $R$ be a ring and $\\sigma$ an endomorphism of $R$. In this note, we study skew polynomial rings and skew power series rings over idempotent reflexive rings and abelian rings. Also, we introduce the concept of right (resp., left) $\\sigma$-idempotent reflexive rings which generalizes right (resp., left) idempotent reflexive rings and $\\sigma$-abelian rings. Certain results are obtained as corollaries from our results.

  19. Antihyperlipidemic morpholine derivatives with antioxidant activity: An investigation of the aromatic substitution.

    Science.gov (United States)

    Ladopoulou, Eleni M; Matralis, Alexios N; Nikitakis, Anastasios; Kourounakis, Angeliki P

    2015-11-01

    Drugs affecting more than one target could result in a more efficient treatment of multifactorial diseases as well as fewer safety concerns, compared to a one-drug one-target approach. Within our continued efforts towards the design of multifunctional molecules against atherosclerosis, we hereby report the synthesis of 17 new morpholine derivatives which structurally vary in terms of the aromatic substitution on the morpholine ring. These derivatives simultaneously suppress cholesterol biosynthesis through SQS inhibition (IC50 values of the most active compounds are between 0.7 and 5.5 μM) while exhibiting a significant protection of hepatic microsomal membranes against lipid peroxidation (with IC50 values for the most active compounds being between 73 and 200 μM). Further evaluation of these compounds was accomplished in vivo in an animal model of acute experimental hyperlipidemia, where it was observed that compounds reduced the examined lipidemic parameters (TC, TG and LDL) by 15-80%. In order to examine the mode of binding of these molecules in the active catalytic site of SQS, we also performed docking simulation studies. Our results indicate that some of the new compounds can be considered interesting structures in the search for new multifunctional agents of potential application in atherosclerosis.

  20. Envelopes of Commutative Rings

    Institute of Scientific and Technical Information of China (English)

    Rafael PARRA; Manuel SAOR(I)N

    2012-01-01

    Given a significative class F of commutative rings,we study the precise conditions under which a commutative ring R has an F-envelope.A full answer is obtained when.F is the class of fields,semisimple commutative rings or integral domains.When F is the class of Noetherian rings,we give a full answer when the Krull dimension of R is zero and when the envelope is required to be epimorphic.The general problem is reduced to identifying the class of non-Noetherian rings having a monomorphic Noetherian envelope,which we conjecture is the empty class.

  1. Physics of quantum rings

    CERN Document Server

    Fomin, Vladimir M

    2013-01-01

    This book deals with a new class of materials, quantum rings. Innovative recent advances in experimental and theoretical physics of quantum rings are based on the most advanced state-of-the-art fabrication and characterization techniques as well as theoretical methods. The experimental efforts allow to obtain a new class of semiconductor quantum rings formed by capping self-organized quantum dots grown by molecular beam epitaxy. Novel optical and magnetic properties of quantum rings are associated with non-trivial topologies at the nanoscale. An adequate characterization of quantum rings is po

  2. Bacterial Degradation of Aromatic Compounds

    Directory of Open Access Journals (Sweden)

    Qing X. Li

    2009-01-01

    Full Text Available Aromatic compounds are among the most prevalent and persistent pollutants in the environment. Petroleum-contaminated soil and sediment commonly contain a mixture of polycyclic aromatic hydrocarbons (PAHs and heterocyclic aromatics. Aromatics derived from industrial activities often have functional groups such as alkyls, halogens and nitro groups. Biodegradation is a major mechanism of removal of organic pollutants from a contaminated site. This review focuses on bacterial degradation pathways of selected aromatic compounds. Catabolic pathways of naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene are described in detail. Bacterial catabolism of the heterocycles dibenzofuran, carbazole, dibenzothiophene, and dibenzodioxin is discussed. Bacterial catabolism of alkylated PAHs is summarized, followed by a brief discussion of proteomics and metabolomics as powerful tools for elucidation of biodegradation mechanisms.

  3. 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.

  4. Organic chemistry: A light touch breaks a strong ring

    Science.gov (United States)

    Banwell, Martin G.

    2016-10-01

    The high stability of aromatic compounds often limits the types of reaction that can be conducted on them. Now, a series of photochemically promoted addition reactions has been used to effect the oxidative dearomatization of benzene derivatives. These reactions provide a suite of versatile new building blocks for chemical synthesis.

  5. Extended O-Doped Polycyclic Aromatic Hydrocarbons.

    Science.gov (United States)

    Stassen, Daphné; Demitri, Nicola; Bonifazi, Davide

    2016-05-10

    The synthesis of O-doped benzorylenes, in which peripheral carbon atoms have been replaced by oxygen atoms, has been achieved for the first time. This includes key high-yielding ring-closure steps which, through intramolecular C-O bond formation, allow stepwise planarization of oligonaphthalenes. Single-crystal X-ray diffraction showed that the tetraoxa derivative forms remarkable face-to-face π-π stacks in the solid state, a favorable solid-state arrangement for organic electronics. PMID:27062492

  6. New Dust Belts of Uranus: One Ring, Two Ring, Red Ring, Blue Ring

    Energy Technology Data Exchange (ETDEWEB)

    de Pater, I; Hammel, H B; Gibbard, S G; Showalter, M R

    2006-02-02

    We compare near-infrared observations of the recently discovered outer rings of Uranus with HST results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced via impacts into the embedded moon Mab, which apparently orbits at a location where non-gravitational perturbations favor the survival and spreading of sub-micron sized dust. R/2003 U 2 more closely resembles Saturn's G ring.

  7. Aerobic dehydrogenative α-diarylation of benzyl ketones with aromatics through carbon-carbon bond cleavage.

    Science.gov (United States)

    More, Nagnath Yadav; Jeganmohan, Masilamani

    2014-02-01

    Substituted benzyl ketones reacted with aromatics in the presence of K2S2O8 in CF3COOH at room temperature, yielding α-diaryl benzyl ketones through a carbon-carbon bond cleavage. In the reaction, two new carbon-carbon bonds were formed and one carbon-carbon bond was cleaved. It is very interesting that two different nucleophiles such as benzyl ketones and aromatics were coupled together without metal, which is unusual in organic synthesis.

  8. Porphyrins Fused with Unactivated Polycyclic Aromatic Hydrocarbons

    KAUST Repository

    Diev, Vyacheslav V.

    2012-01-06

    A systematic study of the preparation of porphyrins with extended conjugation by meso,β-fusion with polycyclic aromatic hydrocarbons (PAHs) is reported. The meso-positions of 5,15-unsubstituted porphyrins were readily functionalized with PAHs. Ring fusion using standard Scholl reaction conditions (FeCl 3, dichloromethane) occurs for perylene-substituted porphyrins to give a porphyrin β,meso annulated with perylene rings (0.7:1 ratio of syn and anti isomers). The naphthalene, pyrene, and coronene derivatives do not react under Scholl conditions but are fused using thermal cyclodehydrogenation at high temperatures, giving mixtures of syn and anti isomers of the meso,β-fused porphyrins. For pyrenyl-substituted porphyrins, a thermal method gives synthetically acceptable yields (>30%). Absorption spectra of the fused porphyrins undergo a progressive bathochromic shift in a series of naphthyl (λ max = 730 nm), coronenyl (λ max = 780 nm), pyrenyl (λ max = 815 nm), and perylenyl (λ max = 900 nm) annulated porphyrins. Despite being conjugated with unsubstituted fused PAHs, the β,meso-fused porphyrins are more soluble and processable than the parent nonfused precursors. Pyrenyl-fused porphyrins exhibit strong fluorescence in the near-infrared (NIR) spectral region, with a progressive improvement in luminescent efficiency (up to 13% with λ max = 829 nm) with increasing degree of fusion. Fused pyrenyl-porphyrins have been used as broadband absorption donor materials in photovoltaic cells, leading to devices that show comparatively high photovoltaic efficiencies. © 2011 American Chemical Society.

  9. Structure-activity relationship studies of the aromatic positions in cyclopentapeptide CXCR4 antagonists

    DEFF Research Database (Denmark)

    Mungalpara, Jignesh; Zachariassen, Zack G; Thiele, Stefanie;

    2013-01-01

    ) the distal aromatic ring of the 2-Nal(3) side chain is required in order to maintain high potency and (ii) replacement of D-Tyr(5) with conformationally constrained analogues results in significantly reduced activity. However, a simplified analogue that contained Gly instead of D-Tyr(5) was only 13-fold less...

  10. On Exchange QB∞-Rings

    Institute of Scientific and Technical Information of China (English)

    Huanyin Chen

    2007-01-01

    In this paper, we introduce a new class of rings, the QB∞-rings. We investigate necessary and sufficient conditions under which an exchange ring is a QB∞-ring. The modules over an exchange QB∞-ring are studied. Also, we prove that every regular square matrix over an exchange QB∞-ring admits a diagonal reduction by pseudo-invertible matrices.

  11. N-alkylphenothiazines - synthesis, structure and application as ligands in metal complexes

    Directory of Open Access Journals (Sweden)

    Krstić Milena

    2016-01-01

    Full Text Available Phenothiazines are a large group of heterocyclic, aromatic molecules with nitrogen and sulphur between two benzene rings. Their derivatives, N-alkylphenothiazines have supstitutient on heterocyclic nitrogen atom which gives them different properties. Also, a series of these molecules have substitution on carbon atom at place 2 of phenothiazine benzene ring. Alkylphenothiazines contain aminoalkyl substituent and their alkyl, acyl and sulphonil derivatives, as well as monocyclic and bicyclic heterocycles attached at thiazine nitrogen atom or directly linked to benzene ring. The N-alkylphenothiazines have been known as antipsychotic drugs, but they also possess antibacterial, antifungal, anticancer activity, and ability to react with macromolecules and to coordinate to the metals. Metal complexes with N-alkylphenothiazines are biological active compounds with different antimicrobial activities and cytotoxic effect against tumor cell lines. Their large field of application of N-alkylphenothiazines is very attractive in terms of synthesis of new related derivatives, metal complexes, studying their properties and applications. This article presents a review of the literature and a contemporary view at N-alkylphenothiazines - their synthesis and application, as well as their metal complexes which have promising biological effects. [Projekat Ministarstva nauke Republike Srbije, br. 172014

  12. Ga BaB pharmacophoric pattern based on conformational analysis of 3-hetero aromatic baclofen analogues

    International Nuclear Information System (INIS)

    Substituting a furan, a thiophen, a benzo (b) furan or a benzo (b) thiophen ring for the p-chlorophenyl moiety of baclofen has led to GABAB (GABA = γ-aminobutyric acid) ligands with different affinities according to the nature of the hetero-aromatic ring, and the nature and position of its substituent. In order to determine the structural requirements that are important for GABAB affinity, we have aligned the 3D structures of several 3-hetero-aromatic baclofen analogues with that of baclofen. As a result, we have suggested a pharmacophoric pattern for 3-hetero-aromatic baclofen analogues. The 3D structures have been studied by X-ray diffraction and by ab initio molecular orbital calculations. (authors). 29 refs., 6 figs., 5 tabs

  13. DISTRIBUTION AND CHARACTERIZATION OF POLYCYCLIC AROMATIC HYDROCARBON COMPOUNDS IN AIRBORNE PARTICULATES OF EAST ASIA

    Institute of Scientific and Technical Information of China (English)

    Yan Liu; Libin Liu; Jin-Ming Lin; Ning Tang; Kazuichi Hayakawa

    2006-01-01

    A review is presented on the distribution and characterization of polycyclic aromatic hydrocarbons (PAHs)and their derivatives, including nitro-PAHs and hydro-PAHs, on atmospheric particulates of East Asia. Generally, PAH compounds with two or three aromatic rings are released mainly into the gas phase, while those containing three or more aromatic rings are associated with particulate matter (PM) emission. Particle-associated PAHs are primarily adsorbed on fine particles, and little associated with coarse particles. Investigation into the concentration level of PAHs in different areas can serve not only to reflect the pollutant status and sources but also to lead to the formulation of control strategies.The results of the present study show that China has more severe PAH pollution than such East Asian countries as Japan and Korea.

  14. The Phylogenetic Signature Underlying ATP Synthase c-Ring Compliance.

    Science.gov (United States)

    Pandini, Alessandro; Kleinjung, Jens; Taylor, Willie R; Junge, Wolfgang; Khan, Shahid

    2015-09-01

    The proton-driven ATP synthase (FOF1) is comprised of two rotary, stepping motors (FO and F1) coupled by an elastic power transmission. The elastic compliance resides in the rotor module that includes the membrane-embedded FO c-ring. Proton transport by FO is firmly coupled to the rotation of the c-ring relative to other FO subunits (ab2). It drives ATP synthesis. We used a computational method to investigate the contribution of the c-ring to the total elastic compliance. We performed principal component analysis of conformational ensembles built using distance constraints from the bovine mitochondrial c-ring x-ray structure. Angular rotary twist, the dominant ring motion, was estimated to show that the c-ring accounted in part for the measured compliance. Ring rotation was entrained to rotation of the external helix within each hairpin-shaped c-subunit in the ring. Ensembles of monomer and dimers extracted from complete c-rings showed that the coupling between collective ring and the individual subunit motions was independent of the size of the c-ring, which varies between organisms. Molecular determinants were identified by covariance analysis of residue coevolution and structural-alphabet-based local dynamics correlations. The residue coevolution gave a readout of subunit architecture. The dynamic couplings revealed that the hinge for both ring and subunit helix rotations was constructed from the proton-binding site and the adjacent glycine motif (IB-GGGG) in the midmembrane plane. IB-GGGG motifs were linked by long-range couplings across the ring, while intrasubunit couplings connected the motif to the conserved cytoplasmic loop and adjacent segments. The correlation with principal collective motions shows that the couplings underlie both ring rotary and bending motions. Noncontact couplings between IB-GGGG motifs matched the coevolution signal as well as contact couplings. The residue coevolution reflects the physiological importance of the dynamics that may

  15. Synthesis of some aromatic aza-heterocycle chenodeoxycholate amides and their antiproliferative actirity%N-杂芳基鹅脱氧胆酰胺化合物的合成及抗肿瘤活性研究

    Institute of Scientific and Technical Information of China (English)

    韦英亮; 姚秋翠; 杨春晖; 黄燕敏; 甘春芳; 崔建国

    2015-01-01

    甾体类药物由于其特有的生理活性而被广泛应用于各种疾病的治疗。本文采用鹅脱氧胆酸为原料,通过Jones试剂氧化其3,7-位的羟基,然后进一步与不同的芳杂环氨反应,进一步还原羰基,合成了6个新的具有不同结构特征的甾体芳杂环酰胺衍生物,合成物经IR、NMR及HRMS进行结构表征。同时采用人胃癌细胞(SGC-7901)和肝癌细胞(Bel-7404)对合成物进行了体外抑制肿瘤细胞生长增殖活性测试,结果表明其中的3,7-二羟基鹅脱氧胆酸芳杂环酰胺衍生物对所测试肿瘤细胞株具有明显的抑制活性。%The steroidal drugs were widely applied in the cure of various diseases because of their special bioactivity. Using che-nodeoxycholic acid as starting material,some aromatic heterocycle chenodeoxycholate amides were synthesized by the oxidation with Jones,reacted with various aromatic amines and reduction by NaBH4. The structures of all compounds were characterized by IR, NMR and HRMS. The antiproliferative activity of the compounds was evaluated against human gastric cancer ( SGC-7901 ) and hu-man liver cancer(Bel-7404)cells. The results showed that some aromatic heterocycle chenodeoxycholate amide with 3,7-dihydroxyl groups exhibited distinct inhibitory activity to these cancer cells.

  16. Quantification of Aromaticity Based on Interaction Coordinates: A New Proposal.

    Science.gov (United States)

    Pandey, Sarvesh Kumar; Manogaran, Dhivya; Manogaran, Sadasivam; Schaefer, Henry F

    2016-05-12

    Attempts to establish degrees of aromaticity in molecules are legion. In the present study, we begin with a fictitious fragment arising from only those atoms contributing to the aromatic ring and having a force field projected from the original system. For example, in benzene, we adopt a fictitious C6 fragment with a force field projected from the full benzene force field. When one bond or angle is stretched and kept fixed, followed by a partial optimization for all other internal coordinates, structures change from their respective equilibria. These changes are the responses of all other internal coordinates for constraining the bond or angle by unit displacements and relaxing the forces on all other internal coordinates. The "interaction coordinate" derived from the redundant internal coordinate compliance constants measures how a bond (its electron density) responds for constrained optimization when another bond or angle is stretched by a specified unit (its electron density is perturbed by a finite amount). The sum of interaction coordinates (responses) of all bonded neighbors for all internal coordinates of the fictitious fragment is a measure of the strength of the σ and π electron interactions leading to aromatic stability. This sum, based on interaction coordinates, appears to be successful as an aromaticity index for a range of chemical systems. Since the concept involves analyzing a fragment rather than the whole molecule, this idea is more general and is likely to lead to new insights.

  17. Asymmetric catalysis in organic synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Reilly, S.D.; Click, D.R.; Grumbine, S.K.; Scott, B.L.; Watkins, J.G.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The goal of the project was to prepare new catalyst systems, which would perform chemical reactions in an enantioselective manner so as to produce only one of the possible optical isomers of the product molecule. The authors have investigated the use of lanthanide metals bearing both diolate and Schiff-base ligands as catalysts for the enantioselective reduction of prochiral ketones to secondary alcohols. The ligands were prepared from cheap, readily available starting materials, and their synthesis was performed in a ''modular'' manner such that tailoring of specific groups within the ligand could be carried out without repeating the entire synthetic procedure. In addition, they have developed a new ligand system for Group IV and lanthanide-based olefin polymerization catalysts. The ligand system is easily prepared from readily available starting materials and offers the opportunity to rapidly prepare a wide range of closely related ligands that differ only in their substitution patterns at an aromatic ring. When attached to a metal center, the ligand system has the potential to carry out polymerization reactions in a stereocontrolled manner.

  18. 烷氧基和酚氧基取代的茂铁盐阳离子光引发剂的合成和表征%Synthesis and Characterization of Alkoxy and Phenoxy-substituted Ferrocenium Salt Cationic Photoinitiators

    Institute of Scientific and Technical Information of China (English)

    王涛; 万平玉; 马丽君

    2006-01-01

    Alkyl-substituted ferrocenium salts have limited solubility in epoxy oligomers and produce poisonous arene by photolysis. Herein, the synthesis and photoactivity of several alkoxy-substituted ferrocenium salts as long-wavelength UV light photoinitiators have been reported. [Cyclopendadien-Fe-anisole]PF6, [Cyclopendadien-Fe-anisole]BF4, [Cyclopendadien-Fe-diphenylether]PF6, [Cyclopendadien-Fe-diphenylether]BF4. and [Cyclopendadien-Fe-diethoxybenzene] PF6 for polymerization of epoxy resin were prepared through the ligand exchange reaction between one ring of ferrocene and aromatic ether. They all display good solubility and photoinitiating activities in epoxy resins.

  19. Token Ring Project

    Directory of Open Access Journals (Sweden)

    Adela Ionescu

    2007-01-01

    Full Text Available Ring topology is a simple configuration used to connect processes that communicate among themselves. A number of network standards such as token ring, token bus, and FDDI are based on the ring connectivity. This article will develop an implementation of a ring of processes that communicate among themselves via pipe links. The processes are nodes in the ring. Each process reads from its standard input and writes in its standard output. N-1 process redirects the its standard output to a standard input of the process through a pipe. When the ring-structure is designed, the project can be extended to simulate networks or to implement algorithms for mutual exclusion

  20. Asymmetric Total Synthesis of (-)-Cladospolide B

    Institute of Scientific and Technical Information of China (English)

    WANG,Wen-Kuan; ZHANG,Ji-Yong; HE,Jin-Mei; TANG,Shi-Bing; WANG,Xiao-Lei; SHE,Xue-Gong; PAN,Xin-Fu

    2008-01-01

    An enantioselective total synthesis of (-)-cladospolide B was described.The key steps in this synthesis include (a) a Sharpless asymmetric dihydroxylation to elaborate syn diol at C-4 and C-5 positions;(b) a Mitsunobu esterification to reverse the configuration at C-11 from (S) to (R);and (c) a ring-closing metathesis to access the 12-membered macrocyclic ring.

  1. Token ring technology report

    CERN Document Server

    2013-01-01

    Please note this is a Short Discount publication. This report provides an overview of the IBM Token-Ring technology and products built by IBM and compatible vendors. It consists of two sections: 1. A summary of the design trade-offs for the IBM Token-Ring. 2. A summary of the products of the major token-ring compatible vendors broken down by adapters and components, wiring systems, testing, and new chip technology.

  2. Microwave-assisted syntheses of N-heterocycles using alkenone-, alkynone- and aryl-carbonyl O-phenyl oximes: formal synthesis of neocryptolepine.

    Science.gov (United States)

    Portela-Cubillo, Fernando; Scott, Jackie S; Walton, John C

    2008-07-18

    This research aimed to provide a new and "clean" synthetic method that would enable both known and novel N-heterocycles to be prepared efficiently. O-Phenyl oximes were found to be excellent precursors for iminyl radicals with a variety of acceptor side chains. Dihyropyrroles were made in good yields from O-phenyl oximes containing pent-4-ene acceptors. The analogous process with a hex-5-enyl acceptor did not yield a dihydropyridine, probably because the 6-exo-trig ring closure of the iminyl radical was too slow to compete with H-atom abstraction. The iminyl radical from a precursor with a pent-4-yne type side chain underwent ring closure followed by rearrangement to afford a pyrrole derivative. Suitably substituted iminyl radicals ring closed readily onto aromatic acceptors, thus enabling several polycyclic systems to be accessed. Quinolines were made from 3-phenylpropanones via their O-phenyl oximes. Syntheses of phenanthridines starting from 2-formylbiphenyls were particularly efficient, and this approach enabled the natural product trisphaeridine to be made. Starting from 2-phenylnicotinaldehyde derivatives, ring closures of the derived iminyl radicals onto the phenyl rings yielded benzo[h][1,6]naphthyridines. Similarly, ring closure onto a phenyl ring from a benzothiophene-based iminyl yielded a benzo[b]thieno[2,3-c]quinoline. By way of contrast, iminyl radical ring closure onto pyridine rings was not observed. However, iminyl radicals did cyclize onto indoles, enabling indolopyridines to be prepared. The latter route was exploited in a short formal synthesis of neocryptolepine starting from 2-((1H-indol-3-yl)methyl)cyclohexanone.

  3. Exposure to polycyclic aromatic hydrocarbons with special focus on cancer

    Directory of Open Access Journals (Sweden)

    Thamaraiselvan Rengarajan

    2015-03-01

    Full Text Available Polycyclic aromatic hydrocarbons (PAHs are a group of compounds consisting of two or more fused aromatic rings. Most of them are formed during incomplete combustion of organic materials such as wood and fossil fuels, petroleum products, and coal. The composition of PAH mixtures varies with the source and is also affected by selective weathering effects in the environment. PAHs are ubiquitous pollutants frequently found in a variety of environments such as fresh water and marine sediments, the atmosphere, and ice. Due to their widespread distribution, the environmental pollution due to PAHs has aroused global concern. Many PAHs and their epoxides are highly toxic, mutagenic and/or carcinogenic to microorganisms as well as to higher forms of life including humans. The main aim of this review is to provide contemporary information on PAH sources, route of exposure, worldwide emission rate, and adverse effects on humans, especially with reference to cancer.

  4. On -Coherent Endomorphism Rings

    Indian Academy of Sciences (India)

    Li-Xin Mao

    2008-11-01

    A ring is called right -coherent if every principal right ideal is finitely presented. Let $M_R$ be a right -module. We study the -coherence of the endomorphism ring of $M_R$. It is shown that is a right -coherent ring if and only if every endomorphism of $M_R$ has a pseudokernel in add $M_R; S$ is a left -coherent ring if and only if every endomorphism of $M_R$ has a pseudocokernel in add $M_R$. Some applications are given.

  5. A Beautiful Ring

    Institute of Scientific and Technical Information of China (English)

    王对成

    2000-01-01

    Helen bought a very nice ring(戒指)and she wore it to the office the next day. Nobody saw her ring. She moved her hand this way and that, but still nobbdy in the offiee saw the ring on her finger. At tea time when they were sitting'round,she suddenly (突然地) stood up. “it is very hot here,”she said. “I think I'll take off my ring.”

  6. Homorooty in Rings

    Directory of Open Access Journals (Sweden)

    M. H. Hooshmand

    2010-03-01

    Full Text Available The topic of ”Homorooty” (for integer numbers has been introduced and studied in [2]. There are some applications of the homorooty in studying and solving some Diophantine equations and systems, as an interesting and useful elementary method. As a continuation of the Homorooty, we consider it for arbitrary rings and will study its properties in different rings, especially UFD and homorooty rings (which will be introduced. At last we shall state some applications of homorooty in studying some equations over homorooty rings

  7. [Determination of aromatics in light petroleum products by comprehensive two-dimensional gas chromatography].

    Science.gov (United States)

    Li, Yanyan

    2006-07-01

    In recent years, comprehensive two-dimensional gas chromatography (GC x GC) have been used widely, and the applications of this technique to many fields have already been reported. In the standard method of oil analysis, the concentrations of aromatics and naphthalene hydrocarbons in light petroleum products must be detected by more than two methods. Mono-aromatics, di-aromatics etc. in light petroleum products were detected only by comprehensive two-dimensional gas chromatography. After the proper selection of column system and optimization of chromatographic conditions, the method can achieve the group separations of paraffins, olefins, naphthenes, aromatics with 1 to 2 rings and some target components in light petroleum products with good reproducibility and good precision. The recoveries of standard compounds were 89.5% - 106.1%, and the relative standard deviations of repeatedly detecting the components were all lower than 5.8%. It took only 30 min to finish a determination. PMID:17017165

  8. [Determination of aromatics in light petroleum products by comprehensive two-dimensional gas chromatography].

    Science.gov (United States)

    Li, Yanyan

    2006-07-01

    In recent years, comprehensive two-dimensional gas chromatography (GC x GC) have been used widely, and the applications of this technique to many fields have already been reported. In the standard method of oil analysis, the concentrations of aromatics and naphthalene hydrocarbons in light petroleum products must be detected by more than two methods. Mono-aromatics, di-aromatics etc. in light petroleum products were detected only by comprehensive two-dimensional gas chromatography. After the proper selection of column system and optimization of chromatographic conditions, the method can achieve the group separations of paraffins, olefins, naphthenes, aromatics with 1 to 2 rings and some target components in light petroleum products with good reproducibility and good precision. The recoveries of standard compounds were 89.5% - 106.1%, and the relative standard deviations of repeatedly detecting the components were all lower than 5.8%. It took only 30 min to finish a determination.

  9. 某些3-腙与22-腙胆甾烷芳杂环化合物的合成%Synthesis of 3-and 22-hydrazone cholestane aromatic heterocycle compounds

    Institute of Scientific and Technical Information of China (English)

    戚斌斌; 刘亮; 赵丹丹; 杨雷; 甘春芳; 黄燕敏; 崔建国

    2015-01-01

    The steroidal drugs were widely applied in the cure of various diseases because of their special bioactivity. Using cholest-4-en-3,6-dione and 22-seco-3β-hydroxycholest-5-en-22-al as starting materials,some steroidal aromatic heterocycle hydrazones were synthesized by the reaction with hydrazine hydrate and various aromatic aldehydes. The structures of all compounds were character-ized by IR,NMR and MS. The antiproliferative activity of compounds was evaluated against human gastric cancer(SGC-7901)and human liver cancer(Bel-7404)cells.%甾体类药物由于其特有的生理活性而被广泛应用于各种疾病的治疗。本文采用一锅法及分步合成法,通过胆甾-4-烯-3,6-二酮及22-降-3β-羟基胆甾-5-烯-22醛与水合肼反应,然后进一步与不同的芳香醛反应,合成了5个新的具有不同结构特征的甾体芳杂环腙化合物,合成物经IR、NMR及HRMS进行结构表征。同时对合成物进行了体外抑制肿瘤细胞生长增殖活性测试。

  10. 超声辐射下水溶液中离子液体催化合成芳醛缩氨基硫脲%Synthesis of aromatic aldehyde thiosemicarbazones catalyzed by ionic liquid in water under ultrasound irradiation

    Institute of Scientific and Technical Information of China (English)

    刘卉闵; 崔鹏雷; 魏俊萍; 张冬暖; 张英群

    2013-01-01

    A series of aromatic aldehyde thiosemicarbazones were synthesized by the condensation reactions of aromatic aldehydes with thiosemicarbazide in water with 3-methyl-l-(3-sulfopropyl)-imidazolium trifluoro acetate as catalyst under ultrasound irradiation.The yields were ranged from 60.0%-95.0%.The structures of the products were confirmed by 1HNMR spectroscopy,IR and elemental analysis.The Bronsted acidic ionic liquid could be recycled easily.It is shown that the proposed method is easy,efficient and environmental friendly.%在超声波辐射下水相中以酸性甲基咪唑丙烷磺酸-三氟乙酸离子液体催化芳醛和氨基硫脲进行反应,合成了系列芳醛缩氨基硫脲衍生物,产率为60.0%~95.0%.产物结构经1 HNMR,IR,元素分析表征,该反应具有反应时间短、产率高、环境友好、后处理方便、催化剂可回收重复使用的优点.

  11. Asymmetric reduction of α-hydroxy aromatic ketones to chiral aryl vicinal diols using carrot enzymes system

    Institute of Scientific and Technical Information of China (English)

    Xiang Liu; Yi Wang; Hai Yan Gao; Jian He Xu

    2012-01-01

    Asymmetric reduction of α-hydroxy aromatic ketones was carried out by using carrot enzymes system,yielding corresponding chiral vicinal diols with special functional groups.The optimum reaction conditions were obtained after investigation of various influencing factors.Chiral aryl vicinal diols were produced with good yields and excellent enantiomeric excesses under appropriate conditions,Meanwhile,the steric factors and electronic effects of the substituents on the aromatic ring were shown to have an interesting influence on both yield and enantioselectivity.

  12. Advances towards aromatic oligoamide foldamers

    DEFF Research Database (Denmark)

    Hjelmgaard, Thomas; Plesner, Malene; Dissing, Mette Marie;

    2014-01-01

    We have efficiently synthesized 36 arylopeptoid dimers with ortho-, meta-, and para-substituted aromatic backbones and tert-butyl or phenyl side chains. The dimers were synthesized by using a "submonomer method" on solid phase, by applying a simplified common set of reaction conditions. X......-ray crystallographic analysis of two of these dimers disclosed that the tert-butyl side chain invokes a cis amide conformation with a comparatively more closely packed structure of the surrounding aromatic backbone while the phenyl side chain results in a trans amide conformation with a more open, extended structure...... of the surrounding aromatic backbone. Investigation of the X-ray structures of two arylopeptoid dimers disclosed that the tert-butyl side chain invokes a cis amide conformation with a closely packed structure of the surrounding aromatic backbone while the phenyl side chain results in a trans amide conformation...

  13. Production of alkyl aromatic hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Bonacci, J.C.; Billings, R.P.

    1975-01-30

    An improved method is claimed for producing aromatic hydrocarbons from a hydrocarbon charge containing aromatic hydrocarbons including benzene and C/sub 8/ alkyl aromatics and aliphatic hydrocarbons which charge is rich in such aromatic hydrocarbons and lean in aliphatic hydrocarbons boiling above about 220/sup 0/F by reason of conversion under severe conditions which comprises subjecting said charge to distillation conditions of temperature and pressure such that at least a portion of the benzene content of said fraction is separated as vapor from an alkyl aromatic fraction containing aliphatic hydrocarbons and the major portion of C/sub 8/ aromatics in said charge, reacting said alkyl aromatic fraction in the presence of hydrogen in contact with a catalyst containing type ZSM-5 zeolite, zeolite ZSM-12, zeolite ZSM-21 or zeolite beta in combination with a hydrogenation/dehydrogenation component at conversion conditions to convert aliphatic hydrocarbons to lower boiling material of five carbon atoms and lighter separable from aromatics by distillation including a temperature of about 500/sup 0/ to 1000/sup 0/F, a pressure of about 100 to about 600 pounds, a hydrogen to hydrocarbon mol ratio of 0.2 to 8 and weight hourly space velocity of 0.5 to 15, concurrently contacting a mixture of hydrogen and toluene with a disproportionation catalyst under reaction conditions to disproportionate said toluene, combining the effluents of said contacting steps, separating hydrogen from the combined effluents of said contacting steps, separating hydrogen from the combined effluents, recycling at least a portion of said separated hydrogen to said contacting steps, distilling the hydrocarbon residue from said separation step to recover therefrom at least toluene and mixed xylenes, and recycling at least a portion of said recovered toluene as feed to the disproportionation step aforesaid.

  14. Micropropagation of different aromatic plants

    OpenAIRE

    Koleva Gudeva, Liljana; Iljovska Tusev, Jasmina; Trajkova, Fidanka

    2014-01-01

    Aromatic plants have been used for centuries as species, natural flavor, raw material for essential-oil industry and other purposes. Micropropagation has advantage over conventional propagation because of high multiplication rate, but it depends on the performance of the starting material, media composition, phytohormones and environmental factors. In this study, aromatic plants as peppermint (Menta piperita L.) and Menta sp., rosemary (Rosmarinus sp.), rocket (Eruca sativa Mill.), coriand...

  15. Ring Around a Galaxy

    Science.gov (United States)

    1999-01-01

    Space Telescope Science Institute astronomers are giving the public chances to decide where to aim NASA's Hubble Space Telescope. Guided by 8,000 Internet voters, Hubble has already been used to take a close-up, multi-color picture of the most popular object from a list of candidates, the extraordinary 'polar-ring' galaxy NGC 4650A. Located about 130 million light-years away, NGC 4650A is one of only 100 known polar-ring galaxies. Their unusual disk-ring structure is not yet understood fully. One possibility is that polar rings are the remnants of colossal collisions between two galaxies sometime in the distant past, probably at least 1 billion years ago. What is left of one galaxy has become the rotating inner disk of old red stars in the center. Meanwhile, another smaller galaxy which ventured too close was probably severely damaged or destroyed. The bright bluish clumps, which are especially prominent in the outer parts of the ring, are regions containing luminous young stars, examples of stellar rebirth from the remnants of an ancient galactic disaster. The polar ring appears to be highly distorted. No regular spiral pattern stands out in the main part of the ring, and the presence of young stars below the main ring on one side and above on the other shows that the ring is warped and does not lie in one plane. Determining the typical ages of the stars in the polar ring is an initial goal of our Polar Ring Science Team that can provide a clue to the evolution of this unusual galaxy. The HST exposures were acquired by the Hubble Heritage Team, consisting of Keith Noll, Howard Bond, Carol Christian, Jayanne English, Lisa Frattare, Forrest Hamilton, Anne Kinney and Zolt Levay, and guest collaborators Jay Gallagher (University of Wisconsin-Madison), Lynn Matthews (National Radio Astronomy Observatory-Charlottesville), and Linda Sparke (University of Wisconsin-Madison).

  16. On the Aliphatic versus Aromatic Content of the Carriers of the "Unidentified" Infrared Emission Features

    CERN Document Server

    Yang, Xuejuan; Li, Aigen; Zhong, Jianxin

    2016-01-01

    Although it is generally accepted that the so-called "unidentified" infrared emission (UIE) features at 3.3, 6.2, 7.7, 8.6, and 11.3 micrometer are characteristic of the stretching and bending vibrations of aromatic hydrocarbon materials, the exact nature of their carriers remains unknown: whether they are free-flying, predominantly aromatic gas-phase molecules, or amorphous solids with a mixed aromatic/aliphatic composition are being debated. Recently, the 3.3 and 3.4 micrometer features which are commonly respectively attributed to aromatic and aliphatic C-H stretches have been used to place an upper limit of ~2\\% on the aliphatic fraction of the UIE carriers (i.e. the number of C atoms in aliphatic chains to that in aromatic rings). Here we further explore the aliphatic versus aromatic content of the UIE carriers by examining the ratio of the observed intensity of the 6.2 micrometer aromatic C-C feature (I6.2) to that of the 6.85 micrometer aliphatic C-H deformation feature (I6.85). To derive the intrinsic...

  17. Synthesis of aminopyrimidylindoles structurally related to meridianins

    OpenAIRE

    Rossignol, Emilie; Youssef, Ali; Moreau, Pascale; Prudhomme, Michelle; Anizon, Fabrice

    2007-01-01

    The synthesis of new meridianin derivatives substituted at the C-5′ position of the 2-aminopyrimidine ring by various aryl groups and substituted or not by a methyl group on the indole nitrogen is described. The 2-aminopyrimidine ring was obtained via a Bredereck synthesis. Aryl groups were introduced by Suzuki cross-coupling after bromination of the 2-aminopyrimidine ring at the C-5′ position

  18. A series of novel metal–organic coordination polymers constructed from the new 5-(4-imidazol-1-yl-phenyl)-2H-tetrazole spacer and aromatic carboxylates: Synthesis, crystal structures, and luminescence properties

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Jiayin [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Zhang, Daojun, E-mail: zhangdj0410@gmail.com [College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang 455002 (China); Wang, Li [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Zhang, Renchun; Wang, Junjie; Zeng, Ying; Zhan, Jinling [College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang 455002 (China); Xu, Jianing [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Fan, Yong, E-mail: mrfy@jlu.edu.cn [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China)

    2013-10-15

    Using bifunctional organic ligand 5-(4-imidazol-1-yl-phenyl)-2H-tetrazole (HL) and different aromatic carboxylates as secondary ligands, four novel metal-organic coordination polymers, [Zn(L)(1,4-bdc){sub 0.5}] (1), [Zn{sub 1.5}(L)(2,5-pydc)] (2), [Zn(HL)(1,2,4,5-btec){sub 0.5}] (3), and [Cd(HL)(1,2,4,5-btec){sub 0.5}] (4) (1,4-bdc, 1,4-benzenedicarboxylate; 2,5-pydc, 2,5-pyridinedicarboxylate; 1,2,4,5-btec, 1,2,4,5-benzenetetracarboxylate) have been successfully synthesized and analyzed. Compound 1 features the 2D [Zn(L)]{sub n} layers built by μ{sub 3}-L bridging ligands and Zn(II) ions, which are further linked by pillared 1,4-bdc{sup 2−} ligands to form a 2-fold interpenetrating dmc framework. The 3D network of compound 2 can be simplified as a rare 2-nodal (3,6)-connected rtl (rutile) topology. Compound 3 possesses a 2D layer structure which is accomplished by connecting ladder-chains to L ligands. Compound 4 exhibits 2D [Cd(1,2,4,5-btec)] layers with infinite Cd–O–Cd rods and the adjacent 2D networks are further pillared by L with terminal bidentate coordination mode to generate the final 3D structure. The solid-state luminescent studies show that compounds 1–4 display intense fluorescent emissions. - Graphical abstract: Using bifunctional organic ligand 5-(4-imidazol-1-yl-phenyl)-2H-tetrazole (HL) and different aromatic carboxylates as secondary ligands, four novel metal-organic coordination polymers have been obtained. All compounds show good luminescence properties at room temperature. Display Omitted - Highlights: • Four Zn(II)/Cd(II)-MOCPs have been successfully prepared with the rigid bifunctional ligand 5-(4-imidazol -1-yl-phenyl) -2H-tetrazole and different aromatic carboxylates mixed ligands. • Compound 2 is a 2-nodal rtl (rutile) net and compound 4 is a binodal (5, 6)-connected net with yav topology. • Compounds 1-4 display intense fluorescent emissions at room temperature.

  19. [GC x GC measurements of atmospheric aromatic compounds near a busy high-speed road in Beijing].

    Science.gov (United States)

    Mao, Ting; Xu, Xiao-bin; Wang, Ying

    2009-10-15

    Comprehensive two-dimensional gas chromatography (GC x GC) is a powerful instrumental tool often used to analyze complex mixtures. An optimized GC x GC method had been applied to the quantitative analysis of aromatic compounds in air samples collected near a busy high-speed road in Beijing during the 2007 National Holidays. In the resulting GC x GC chromatograms, aromatic species were resolved from other compound classes and were grouped in a manner that facilitated identification and integration, showing more information of aromatic compounds compared to traditional one-dimensional GC. Totally more than 30 aromatic species were identified and quantified. The average concentrations of monocyclic aromatic compounds ranged from 0.75 x 10(-9) to 24.64 x 10(-9) C, with toluene having the highest concentration, followed by m, p-xylene and ethylbenzene. The average concentrations of the measured polycyclic aromatic compounds ranged from 0.03 x 10(-9) to 2.28 x 10(-9) C, with naphthalene having the highest concentration, followed by 2-methyl-naphthalene and 4-methyl-1, 1'-biphenyl. The four-ring and higher polycyclic aromatic compounds were not detectable in the gaseous samples. The levels of aromatic compounds were significantly influenced by meteorological parameters. Benzene and toluene were poorly correlated with higher aromatic compounds though the latter compounds were highly correlated among each other, suggesting that both were significantly influenced by sources other than vehicle exhaust and gasoline evaporation.

  20. Revocable Ring Signature

    Institute of Scientific and Technical Information of China (English)

    Dennis Y. W. Liu; Joseph K. Liu; Yi Mu; Willy Susilo; Duncan S. Wong

    2007-01-01

    Group signature allows the anonymity of a real signer in a group to be revoked by a trusted party called group manager. It also gives the group manager the absolute power of controlling the formation of the group. Ring signature, on the other hand, does not allow anyone to revoke the signer anonymity, while allowing the real signer to forma group (also known as a ring) arbitrarily without being controlled by any other party. In this paper, we propose a new variant for ring signature, called Revocable Ring Signature. The signature allows a real signer to form a ring arbitrarily while allowing a set of authorities to revoke the anonymity of the real signer. This new variant inherits the desirable properties from both group signature and ring signature in such a way that the real signer will be responsible for what it has signed as the anonymity is revocable by authorities while the real signer still has the freedom on ring formation. We provide a formal security model for revocable ring signature and propose an efficient construction which is proven secure under our security model.