S. V. Borodaev

Ambidentate reactivity of 3-azapyrylium systems in nucleophilic attack reactions

It has been shown that recyclization of 4-acylmethyl-3-azapyrylium salts under the influence of primary amines affords 4-(β-hydrozystyryl)pyrimidinium salts, which, upon further heating with the amine, are recyclized to form 4-acylaminopyridinium salts. It has been established that nucleophilic attack of 6-acylmethyl-substituted 3-azapyrylium salts in aqueous NaOH solution leads to functionally substituted pyridines. By means of MNDO quantum-chemical calculations with an accounting for solvation effects, in a continuum model, it has been shown that two directions of nucleophilic attack of the azapyrylium ring — at positions 2 and 6 — are equally probable.

Condensation of 6-methyl-3-azapyrylium salts to pyrido[1,2-c]pyrimidinium derivatives

Under the influence of DMF/Ac2O 2,4-diphenyl-6-methyl-3-azapyrylium perchlorates undergo condensation to give pyrido[1,2-c]pyrimidinium perchlorates. The structure of one of the perchlorates was proved by x-ray diffraction analysis.

Acid-catalyzed acylation of 4-alkyl-3-azapyrylium salts and the synthesis of 4-acylaminopyrylium salts

Abstract4-Alkyl-3-azapyrylium salts undergo acylation at the alkyl group under acid-catalyzed conditions to give 4-acylmethyl-3-azapyrylium derivatives, which upon heating in proton-donating solvents recyclize to give 4-acylaminopyrylium salts.

Formation of γ-Pyrones by Acylation of Benzoylacetone.

The reaction between benzoylacetone (I) and the acyl hexachloroantimonates, generated in situ from the acyl chlorides (II) and SbCl5, yields the title compounds (III) after treatment with alkali.

Mechanism of the reaction of aldehydes of the furan series with secondary amines in methanol

The reaction of 5-halofurfurals with piperidine and morpholine in methanol under various reaction conditions was investigated by means of spectrophotometry. The kinetics of the stepwise addition of the amine to the aldehyde function of the halofurfural were studied in the case of a dilute solution, while the conversion of the aldehyde to a 5-N,N-dialkylaminofurfurylidene-N,N-dialkylimmonium salt, for which two autocatalysis mechanisms were observed, was investigated in the case of a concentrated solution. Reaction intermediates, viz., 5-halofurfurylidene-N,N-bis(dialkylamines), were isolated preparatively and investigated.

Effect of the nature of the halogen atom on the structure and reactivity of 5-halo-2-nitrofurans

Abstract5-Chloro-2-nitrofuran was obtained for the first time. A comparative study of the properties (UV, IR, and NMR spectra) of 5-X-2-nitrofurans (X=Cl, Br, I) was made, and the kinetics of their reaction with diethylamine in dioxane were studied. The ratio of the rate constants in the indicated order is 29∶23∶1.