Palladium-Catalyzed Cycloisomerization of Bicyclobutyl (BCB) Amides to Access Polycyclic Quinolinones

A novel palladium-catalyzed cycloisomerization of bicyclobutyl amides has been developed for the expedited construction of polycyclic quinolinone skeletons. The reaction proceeded well to furnish a variety of tetracyclic quinolinone derivatives in good yields. Additionally, scale-up reactions and derivatization of tetracyclic quinolinones were demonstrated as well.