Reaction of 1, l'-Bis(methoxycarbonyl)divinylamine with Hydrazines

Abstract

The reaction of 1, 1'-bis(methoxycarbonyl)divinylamine (BDA) with hydrazines was investigated as an example of nucleophilic attack on a cross-conjugated dienamine.
The reactions of BDA with 80.5% hydrazine hydrate, methylh ydrazine, methoxycarbonylhydrazine and phenylhydrazine gave pyruvic acid hydrazide hydrazone [3], methyl pyruvate methylhydrazone [4], methyl pyruvate methoxycarbonylhydrazone [5] and methyl pyruvate phenylhydrazone [6], respectively, in high yields. The 'H-NMR spectra of BDA in various solvents indicated the predominant existence of enamine form between enamine and imine tautomers. In addition, the reaction of N-methyl-1, 1'-bis(methoxycarbonyl)divinylamine [8] with phenylhydrazine also gave methyl pyruvate phenylhydrazone [6].
An appropriate mechanism yielding above hydrazones, [3]-[6], is considered to involve a nucleophilic attack of hydrazines at the electron-deficient α-carbon atom of enamine form of BDA, followed by an elimination of methyl 2-aminoacrylate.