A Convenient One-Pot Synthesis of Triazolopyridine and Related Heterocycle Fused-Triazole Analogs Through Copper Catalyzed Oxidative Cyclization Strategy

One‐pot synthesis of heterocycle fused‐triazole analogs from the corresponding aldehydes and heteroarylhydrazines is demonstrated. Transformation of hydrazones to the desired systems was achieved by employing the oxidative cyclization with catalytic CuBr2 and oxone. This reaction condition is mild and selective, and a wide range of functional groups were able to sustain. An array of biologically important triazolopyridines, triazolopyridazines, triazolopyrimidines, and triazoloquinolines were obtained in fairly good yield.