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.

Reaction of amidyl radicals in sodium peroxydisulfate-metal chloride oxidation systems

Abstract: 1. Unsubstituted alkanoic acid amides R(CH2)4CONH2 (R=H or alkyl) convert in Na2S2O8-CuCl2 and Na2S2O8-NaCl oxidation systems via intermediate amidyl radicals R(CH2)4C(O)NH intoγ- and δ-lactones with a considerable predominance ofγ-lactones. 2. Monoalkyl amides of alkanoic acids are lactonized to an inappreciable extent by the action of the S2O82−-Cl− system; N,N-diethyl valeramide undergoes oxidative dealkylation into N-alkyl valeramide. 3. As the result of an oxidative, Hoffmann type rearrangement in a Na2S2O8-NaCl-NaOH system, unsubstituted alkanoic acid amides convert into amines containing one carbon atom less than the initial amides.

A new approach to the synthesis of cilastatin, an inhibitor of renal dipeptidase

Abstract: A convenient preparative synthesis of cilastatin, an inhibitor of renal dipeptidase used in drugs with the antibiotic imipenem, has been elaborated. The key intermediate in this synthesis is 2-amino-7-chloroheptanoic acid prepared by oxidative cleavage of cycloheptanone followed by bromination of 7-chloroheptanoyl chloride with subsequent amination of the 2-bromo-7-chloroheptanoic acid thus formed. All of the stages of the new synthesis are easily performed, as is the isolation of the intermediate products, and they do not require any organometallic reagents.

Free-radical reaction of alcohols with dimethyl maleate

Abstract: 1. An investigation was made of the free-radical addition of alcohols to dimethyl maleate initiated by t-butyl peroxide. On the basis of this reaction a method was developed for the synthesis of methyl 2-substituted paraconates in yields of 70–80%. 2. The reactivities of unsaturated compounds in reactions with alcohols fall along the series; dimethyl maleate > methyl acrylate > allyl alcohol ≥ 1-alkenes. 3. 1-Hydroxyalkyl radicals formed from aliphatic alcohols are nucleophilic in character.

Oxidation of aliphatic thioamides in a sodium peroxydisulfate-cupric chloride system

Abstract: 1. Oxidative cyclization of N-unsubstituted aliphatic thioamides in the Na2S2O8-CuCl2 system leads to 3,5-dialkyl-1,2,4-thiadiazoles in a yield of 50–60%. 2. N-Monoalkyl- and N,N-dialkyl-substituted thioamides quantitatively convert in this system into the corresponding O-amides. 3. The principal difference in the oxidative reactions of aliphatic thioamides and their oxygen analogs in a Na2S2O8-CuCl2 system is determined by the tendency of the S atom of the. thiocarbonyl group to add radicals formed in the oxidation process.

Electrochemical selective trimerization of malonic esters into esters of propane-1,1,2,2,3,3-hexacarboxylic acid in the presence of hydrobromic acid salts

Abstract: The electrochemical oxidation of malonic esters in methanol, ethanol, or acetonitrile in the presence of alkali metal bromides as catalyst-carriers, with the use of 1.8–2 F of electricity per mole of the starting malonic ester leads to esters of propane-1,1,2,2,3,3-hexacarboxylic acid in a yield of up to 90%.

I and i

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 …

Cobalt-Catalyzed C―H Activation

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.

Catalytic Enantioselective Transformations Involving C-H Bond Cleavage by Transition-Metal Complexes.

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.