Cu-Catalyzed Regioselective C–H Amination of 2H-Indazoles for the Synthesis of Indazole-Containing Indazol-3(2H)-ones

A copper-catalyzed C3 amination of 2 H -indazoles with 2 H -indazoles and indazol-3(2 H )-ones under mild conditions was developed. A series of indazole-containing indazol-3(2 H )-one derivatives were produced in moderate to excellent yields. The mechanistic studies suggest that the reactions probably proceed through a radical pathway.