Copper-Catalyzed Aerobic Oxidative Dehydrogenative Coupling to Access Benzo[]cinnolines.

In this paper, a highly efficient copper-catalyzed oxidative dehydrogenative coupling to obtain benzo[]cinnolines (up to 100% yield) was developed. It was found that DMAP was a highly efficient ligand for copper-catalyzed oxidation, and molecular oxygen was a green oxidizing agent. In this simple process, various functional groups were tolerated under mild reaction conditions, and the practicality of the process was demonstrated by the preparation of benzo[]cinnolines on a gram scale and later derivatization.