Addition reactions of heterocyclic compounds. Part XLIX. Reactions of benzimidazoles possessing an activated 2-methylene group with acetylenic esters

Abstract

Benzimidazole-2-acetonitrile, ethyl benzimidazole-2-acetate, and their 1-methyl derivatives were heated with methyl propiolate and with dimethyl acetylenedicarboxylate in acetonitrile. The resulting mixtures, on chromatography gave pyrrolo-, pyrido-, and azepino-[1,2-a]benzimidazoles, the structures of which were deduced from their spectral properties.