Gold-Catalyzed Intramolecular Regioselective 7-exo-dig Cyclization To Access 3-Methylene-3,4-dihydrobenzo[b]oxepinones.

An efficient gold-catalyzed synthesis of substituted 3-methylene-3,4-dihydrobenzo[b]oxepinones from ortho-O-propargyl substituted aryl enaminones has been achieved. In this transformation a new C-C bond formation occurred regioselectively via 7-exo-dig cyclization. Benzooxepinone derivatives were obtained in good to excellent yields in a one-pot synthesis at ambient temperature.