Copper‐Catalyzed Aerobic Dehydrogenative Cyclization of N‐Methyl‐N‐phenylhydrazones: Synthesis of Cinnolines

O2 leading the way: The title reaction proceeds through an oxidation/cyclization sequence, thus representing the first copper-catalyzed coupling reaction of hydrazones through a CH bond functionalization process (see scheme; DMF=N,N′-dimethylformamide, Py=pyridine). The method provides an environmentally friendly and atom-efficient approach to biologically active cinnoline derivatives.