Rhodium-catalyzed annulation between 2-arylimidazo[1,2-a]pyridines and alkynes leading to pyrido[1,2-a]benzimidazole derivatives

A rhodium-catalyzed annulation between 2-arylimidazo[1,2-a]pyridines and alkynes was developed, leading to pyrido[1,2-a]benzimidazole derivatives in moderate to excellent yields. Notably, the ring C in pyrido[1,2-a]benzimidazole and the naphthalene framework were constructed consecutively, which provided a potential pathway leading to such a structure. This procedure tolerated chloro, bromo, cyano and methoxycarbonyl groups.