Synthesis of 4H‐Indazol‐4‐ones and Fused Pyrazoles via Copper‐Catalyzed Annulation of Hydrazones with Cyclic Enones

Herein, we report the synthesis of cyclic ketone‐fused pyrazoles via [3+2] annulation reaction between hydrazones and cyclic enones (five‐, six‐ and seven‐membered) catalyzed by Cu(II) under aerobic conditions. These compounds were further functionalized by reactions such as Suzuki‐Miyaura cross‐coupling, Heck coupling, and Aldol reaction to afford diverse molecular scaffolds in good yield, selectivity and functional group tolerance.