A Synthesis of 1H-Indazoles via a Cu(OAc)2-Catalyzed N–N Bond Formation

A facile synthesis of 1H-indazoles featuring a Cu(OAc)2-catalyzed N–N bond formation using oxygen as the terminal oxidant is described. The reaction of readily available 2-aminobenzonitriles with various organometallic reagents led to o-aminoaryl N–H ketimine species. The subsequent Cu(OAc)2-catalyzed N–N bond formation in DMSO under oxygen afforded a wide variety of 1H-indazoles in good to excellent yields.