WorldWideScience

Sample records for sydnones

  1. Environmentally benign synthesis of sydnone containing 1,3,4 ...

    Indian Academy of Sciences (India)

    TECS

    lop benign synthetic methods for sydnone deriva- tives,. 9 we report here a new series of sydnone containing 1,3,4-thiadiazines by microwave irradia- tion under solvent-free conditions. 2. Experimental. 2.1 General remarks. Melting points were determined by open capillary method and are uncorrected. All compounds were.

  2. Mesoionic Compounds

    Indian Academy of Sciences (India)

    Organic Chemistry. Kamatak University,. Dharwad. Her research interests are synthesis, reactions and synthetic utility of sydnones. She is currently working on electrochemical and insecticidal/antifungal activities for some of these compounds. Keywords. Aromaticity, mesoionic hetero- cycles, sydnones, tandem re- actions.

  3. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    3-[4-(Azidocarbonyl)]phenylsydnone (2) obtained from 3-(4-hydrazinocarbonyl) phenylsydnone (1) on Curtius rearrangement with alcohols, water and amines afforded the corresponding carbamates (3a-h), 4,4'-(sydnone-3-yl) diphenyl urea (4) and 4-(heterocyclyl)phenyl ureas (5a-l). Compounds (5a-l) on one-pot ring ...

  4. Cytochrome P-450 inactivation by 3-alkylsydnones. Mechanistic implications of N-alkyl and N-alkenyl heme adduct formation

    International Nuclear Information System (INIS)

    Grab, L.A.; Swanson, B.A.; Ortiz de Montellano, P.R.

    1988-01-01

    Incubation of 3-(2-phenylethyl)-4-methylsydnone (PMS) with liver microsomes from phenobarbital-pretreated rats or with reconstituted cytochrome P-450b results in loss of the enzyme chromophore. Chromophore loss is NADPH-dependent even though the sydnone decomposes by an oxygen- but not enzyme-dependent process to give pyruvic acid and, presumably, the (2-phenylethyl)diazonium cation. N-(2-Phenylethyl)protoporphyrin IX and N-(2-phenylethenyl)protoporphyrin IX have been isolated from the livers of rats treated with PMS. Both deuteriums are retained in the N-(2-phenylethyl) adduct derived from 3-(2-phenyl[1,1- 2 H]ethyl)-4-methylsydnone, but one deuterium is lost in the N-(2-phenylethenyl) adduct. The N-(2-phenylethyl) to N-(2-phenylethenyl) adduct ratio is increased by deuterium substitution. Electron paramagnetic resonance (EPR)-spin trapping studies show that carbon radicals are formed in incubations of the sydnones with liver microsomes but by a process that is independent of chromophore destruction. It is proposed that the 2-phenylethyl radical formed by electron transfer to the sydnone-derived (2-phenylethyl)diazonium cation adds to the prosthetic heme group to give the N-(2-phenylethyl) adduct. This alkylation reaction is similar to that observed with (2-phenylethyl)hydrazine. Autoxidation of the Fe-CH(CH 2 Ph)-N bridged species expected from insertion of 2-phenyldiazoethane into one of the heme Fe-N bonds is proposed to explain the unprecedented introduction of a double bond into the N-(2-phenylethenyl)adduct

  5. Bioorthogonal Cycloadditions with Sub-Millisecond Intermediates.

    Science.gov (United States)

    Qing, Yujia; Pulcu, Gökçe Su; Bell, Nicholas A W; Bayley, Hagan

    2018-01-26

    Tetrazine- and sydnone-based click reactions have emerged as important bioconjugation strategies with fast kinetics and N 2 or CO 2 as the only byproduct. Mechanistic studies of these reactions have focused on the initial rate-determining cycloaddition steps. The subsequent N 2 or CO 2 release from the bicyclic intermediates has been approached mainly through computational studies, which have predicted lifetimes of femtoseconds. In the present study, bioorthogonal cycloadditions involving N 2 or CO 2 extrusion have been examined experimentally at the single-molecule level by using a protein nanoreactor. At the resolution of this approach, the reactions appeared to occur in a single step, which places an upper limit on the lifetimes of the intermediates of about 80 μs, which is consistent with the computational work. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Radiation Laboratory quarterly report, January 1, 1977--March 31, 1977

    Energy Technology Data Exchange (ETDEWEB)

    1978-08-12

    Some of the studies in progress are: distribution of deposited energy around heavy-ion tracks; effect of trapping on the thermalization of electrons in hydrocarbon liquids; effect of field-dependent mobility on escape probability; kinetics of electron scavenging reactions; second-order optical properties of solvated electrons; model molecular orbital studies of the chemisorption of atomic hydrogen and oxygen on aluminum surfaces; calculation of sum rule moments for H/sub 2/O; early events in pulse-irradiated polar liquids; radiation chemical studies of reactions of SO/sub 4//sup -/ radicals with organic compounds; reactions of the phosphate and sulfate radicals with inorganic compounds; pulse radiolysis studies of antioxidants in fatty acid soap aggregates; spectrophotometric pulse radiolytic study of the radicals produced by reduction of cis- and trans-azobenzene; correlation of singlet energies of aromatic hydrocarbons with the rates of protonation of their anion radicals; the association rate of sodium laurylsulfate micelle-monomer equilibrium; transfer of an organic molecule between micelles in an aqueous environment; in-situ photolysis ESR study of some reactions of phosphate radicals; photochemistry of sydnones; differentiation of triplet state and biradical reactions; photoenolization of aromatic ketones; and studies of Ni(III) macrocyclic ligand complexes. (LK)