Unexpected N-C bond fission of fused N-alkylbenzimidazolium salts. A new approach to pyrido[1,2-a]- or pyridazino[1,6-a]benzimidazoles

Abstract

The reaction of N-carboxymethylpyrido[1,2-a]- and pyridazino[1,6-a]benzimidazolium salts with thionyl chloride resulted in an N-C bond fission, yielding the corresponding pyrido[1,2-a]- and pyridazino[1,6-a]benzimidazoles. A similar dealkylation process was observed when analogous N-propargylic derivatives were treated with Cu (II) acetate.