Rh I ‐Catalyzed CC Bond Activation: Seven‐Membered Ring Synthesis by a [6+1] Carbonylative Ring‐Expansion Reaction of Allenylcyclobutanes

Ever expanding: A RhI-catalyzed CC activation reaction of allenylcyclobutanes generates intermediate metallacycles that can be trapped with CO to produce a new [6+1] reaction. Functionalized monocyclic and bicyclic cycloheptenones are obtained in good-to-excellent yields with this [6+1] higher-order carbonylative cycloaddition reaction.