Nature of the reducing agent and mechanism of the reductive condensation of trichloromethylarenes with hydroxylamine and hydrazines in pyridine

Abstract

It was shown that during the reductive condensation of trichloromethylarenes with hydroxylamine or hydrazines in pyridine the event of reduction with replacement of one chlorine atom by a hydrogen atom occurs without the participation of hydroxylamine or hydrazine. The first step of the reaction is the formation of N-(α,α-dichloroarylmethyl)pyridinium chlorides, which are converted by the action of the chloride anion or a second pyridine molecule to the corresponding 4-substituted 1,4-dihydropyridines. The latter undergo further aromatization with transfer of hydrogen from the 4-position of the dihydropyridine ring to the benzyl dichloromethylene group and the formation of N-(α-chloroarylmethyl)-4-chloropyridinium chlorides or N-(α-chloroarylrnetluyl)-4-(pyridinio)pyridinium dichlorides, which give the corresponding aldehydes in hydrolysis or products of reductive condensation under the action of hydroxylamine or hydrazines.

How to Cite
Belen'kii, L. I.; Poddubnyi, I. S.; Krayushin, M. M. Chem. Heterocycl. Compd. 1995, 31, 726. [Khim. Geterotsikl. Soedin. 1995, 830.]

For this article in the English edition, see DOI https://doi.org/10.1007/BF01169070