Cobalt-Catalyzed Regioselective (4+2)-Annulation of Benzamides with Allenyl Carbinol Acetates: Access to 3-Vinylisoquinolinones

Herein we disclose a Co-catalyzed regioselective (4+2)annulation of aryl-, heteroaryl-and acrylamides with allenyl acetates to access a diverse array of heterocyclic derivatives in high yields with excellent regioselectivity. The protocol employs inexpensive cobalt(II) salts and exhibits broad functional group tolerance. Solvent plays a crucial role in governing regioselective migratory insertion, facilitating the selective formation of elusive Co-alkenyl intermediate. Preliminary mechanistic experiments were performed to elucidate the plausible reaction pathway.