Copper-Catalyzed Aerobic Oxidative C-H Functionalization of Substituted Pyridines: Synthesis of Imidazopyridine Derivatives

A novel, efficient, and practical method for the synthesis of imidazopyridine derivatives has been developed through the copper-catalyzed aerobic oxidative CH functionalization of substituted pyridines with N-(alkylidene)-4H-1,2,4-triazol-4-amines. The procedure occurs by cleavage of the NN bond in the N-(alkylidene)-4H-1,2,4-triazol-4-amines and activation of an aryl CH bond in the substituted pyridines. This is the first example of the preparation of imidazopyridine derivatives by using pyridines as the substrates by transition-metal-catalyzed CH functionalization. This method should provide a novel and efficient strategy for the synthesis of other nitrogen heterocycles.