Copper‐Catalyzed [3+2] Annulation of 2‐Arylidene‐1,3‐Indandiones with N‐Acetyl Enamides for the Synthesis of Spiropyrrolines

A copper‐catalyzed intermolecular [3+2] annulation of 2‐arylidene‐1,3‐indandiones with N‐acetyl enamides has been developed to assemble spirocyclic pyrrolines, which are important building blocks for organic synthesis and drug discovery. This heteroannulation protocol tolerates various functional groups and proceeds in good to excellent yields. Mechanistic studies reveal that the reactions might involve radical processes.