Cobalt-Catalyzed Intermolecular Oxidative Isocyanide Insertion with Two Amines: An Approach to Guanidines

A novel and efficient cobalt-catalyzed oxidative isocyanide insertion with amines via two C-N bond formation reactions under ultrasound irradiation conditions has been developed. This protocol provides a simple, clean and general way to synthesize guanidines or their corresponding hydrochlorides from simple starting materials under ultrasonic conditions. This chemistry could also be applied to an efficient synthesis of optically active guanidines without loss of enantioselectivity.