Construction of Imidazole-Fused-Ring Systems by Iron-Catalyzed C(sp 3 )-H Amination-Cyclization under Aerobic Conditions.

An iron-catalyzed efficient C-H amination for the construction of imidazole-fused-ring systems was developed under aerobic conditions. Compared to previous studies, this work exhibited green features. The reaction was conducted in the green solvent anisole, with water as the only byproduct. Four C(sp 3 )-H bonds were cleaved and three C-N bonds were formed in this transformation. Imidazo[1,5- a ]pyridine-, imidazo[5,1- b ]oxazole-, imidazo[5,1- b ]thiazole-, imidazo[1,5- a ]pyrazine-, and imidazo[1,5- a ]imidazole-related N -heterocycles were obtained in acceptable-to-excellent yield.