Palladium-Catalyzed Heteroannulation Route to Benzazepinones

Significance

Reported is a method for the ­synthesis of benzazepinone derivatives 3 by the hydroamination of the Baylis-Hillman acetate 1 with amines 2, followed by intramolecular cyclocarbonylation of the resulting allylamines under palladium catalysis. After screening of ligands and bases, the optimized conditions were found to require an excess of amine 2, 100 psi of CO, and Pd(OAc)₂/dppb as catalyst. The reaction was extended to a series of amines. Although both aromatic and aliphatic amines were found to be active for the reactions, the latter afforded lower yields of products than the former systems. Substituents R^¹, R^² and R^³ have a modest effect on the yield, but yields are higher when R^² = EDGs.