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G. I. Nikishin

Bio: G. I. Nikishin is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Radical & Homolysis. The author has an hindex of 11, co-authored 280 publications receiving 540 citations.


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TL;DR: The free radical addition of methyl acetoacetate to 1-hexene, initiated by di-tert-butyl peroxide, leads main ly to the formation of the methyl ester of α-acetoxyoctanoic acid as discussed by the authors.
Abstract: The free radical addition of methyl acetoacetate to 1-hexene, initiated by di-tert-butyl peroxide, leads main ly to the formation of the methyl ester of α-acetoxyoctanoic acid. Together with the latter, small amounts of the carbomethoxymethyl ester of octanoic acid and the heptyl ester of acetoacetic acid are formed.
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TL;DR: In this article, the Na2S2O8-CuCl2 system converted primary aliphatic amines into nitriles RCH2CN, 2,2-dichloroalkanals RCCl2CHO, acids RCH 2COOH, and chloroalkanes R CH2CH2Cl.
Abstract: 1. Primary aliphatic amines RCH2CH2NH2 are converted by the action of the Na2S2O8-CuCl2 system into nitriles RCH2CN, 2,2-dichloroalkanals RCCl2CHO, acids RCH2COOH, and chloroalkanes RCH2CH2Cl. The formation of 2, 2-dichloroalkanals and chloroalkanes are new reactions of oxidative substitution of the amino group in primary aliphatic amines. 2. A mechanism for the reactions has been proposed, including the production of aminyl radicals RCH2-CH2NH and their oxidation into aldimines RCH2CH=NH, predecessors of all the reaction products.
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TL;DR: In this article, the relationship between the ability of these radicals to undergo oxidative cyclization to lactones and the number of methylene groups (n) and also the effect of copper ions on the oxidative cyclization process was investigated.
Abstract: 1. ω-Carboxyalkyl radicals HOOC(CH2)nCH2, where n=4–7, were generated by the oxidative decarboxylation of pentane-, hexane-, heptane-, and octanedicarboxylic acids at 60°C in aqueous solution by the action of Na2S2O8 in the presence of silver nitrate. The relation between the ability of these radicals to undergo oxidative cyclization to lactones and the number of methylene groups (n) and also the effect of copper ions on the oxidative cyclization process were investigated. 2. The main products from oxidative cyclization ofω-carboxyalkyl radicals in the absence of copper ions areγ-alkyl-γ-butyrolactones. In addition, alkanoic acids (84–95%) are formed as a result of abstraction of H atoms from the organic substrates by the radicals. 3. The main products from the oxidative cyclization of theω-carboxyalkyl radicals in the presence of copper ions areγ-alkyl-Δα,β-butenoiides.ω-Alkenoic acids (58–98%) are formed as a result of the oxidativeβ-deprotonation of the radicals by the action of Cu(II).
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TL;DR: In this article, it was shown on the basis of quantum-chemical analysis by the LCAO-MO SCF method in the INDO approximation that the complexation of acyloxyl radicals with copper(II) salts and also their combination with chlorine atoms are factors which lead to the stabilization of these radicals and to the possibility of the realization of reactions with retention of the carboxy function.
Abstract: 1. It was shown on the basis of quantum-chemical analysis by the LCAO-MO SCF method in the INDO approximation that the complexation of acyloxyl radicals with copper(II) salts and also their combination with chlorine atoms are factors which lead to the stabilization of these radicals and to the possibility of the realization of reactions with retention of the carboxy1 function. 2. In the radical-cation RC(O)OH+ generated during the one-electron oxidation of carboxylic acids RCOOH the unpaired electron is concentrated mainly at the carbonyl oxygen atom, while in the acyloxyl radical RC(O)O it is delocalized at both oxygen atoms.

Cited by
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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: Recent progress in the field of organometallic cobalt-catalyzed C–H activation is reviewed until November 2015.
Abstract: Catalytic C–H activation has emerged as a powerful tool for sustainable syntheses. In the recent years, notable success was achieved with the development of cobalt-catalyzed C–H functionalizations with either in situ generated or single-component cobalt-complexes under mild reaction conditions. Herein, recent progress in the field of organometallic cobalt-catalyzed C–H activation is reviewed until November 2015.

953 citations

Journal ArticleDOI
TL;DR: This analysis comprehensively review all asymmetric transition-metal-catalyzed methodologies that are believed to proceed via an inner-sphere-type mechanism, with an emphasis on the nature of stereochemistry generation.
Abstract: The development of new methods for the direct functionalization of unactivated C–H bonds is ushering in a paradigm shift in the field of retrosynthetic analysis. In particular, the catalytic enantioselective functionalization of C–H bonds represents a highly atom- and step-economic approach toward the generation of structural complexity. However, as a result of their ubiquity and low reactivity, controlling both the chemo- and stereoselectivity of such processes constitutes a significant challenge. Herein we comprehensively review all asymmetric transition-metal-catalyzed methodologies that are believed to proceed via an inner-sphere-type mechanism, with an emphasis on the nature of stereochemistry generation. Our analysis serves to document the considerable and rapid progress within in the field, while also highlighting limitations of current methods.

648 citations