Copper‐Catalyzed Aerobic Annulation of Hydrazones: Direct Access to Cinnolines

A novel method was developed for the construction of biologically active poly‐substituted cinnolines from easily accessible hydrazones in good to excellent yields. A simple copper catalyst could efficiently promote C−N bond formation through selective C−H functionalization and dehydrogenative amination. Furthermore, the inert C−Heteroatom (O/F/N) bonds are susceptible to cleavage in high selectivity in the newly developed aerobic annulation, in preference to the alternative C−H bond, which is left intact.