A facile synthesis of pyrrolo[1,2-a]benzimidazoles and pyrazolo[3,4:4′,3′]pyrrolo[1,2-a]benzimidazole derivatives

Reaction of 2-cyanomethylbenzimidazole with hydrazonoyl halides led to formation of pyrrolo[1,2-a]benzimidazole derivatives . Similar reaction of with halides afforded 5-amino-4-(benzimidazol-2-yl)pyrazole derivatives or 1-amino-2-arylpyrazolo[3,4:4′,3′]pyrrolo[1,2-a]benzimidazol-4-one depending on the reaction conditions. The mechanisms of the studied reactions are discussed.