Rh(III)-Catalyzed Strain-Release-Enabled C–H Alkenylation/[4+1] Annulation of Benzamides with Alkylidenecyclobutanes

A Rh(III)-catalyzed strain-release-enabled C-H alkenylation/[4+1] annulation of benzamides with alkylidenecyclobutanes is described, enabling the efficient construction of 3-methyleneisoindolin-1-one derivatives. This protocol uniquely integrates Rh(III)-catalyzed C-H activation with strain-release ring-opening of alkylidenecyclobutanes, representing a rare example in which alkylidenecyclobutanes serve as C1 synthons in [4+1] annulation. Moreover, by subtly modifying the reaction conditions, Rh(III)-catalyzed C-H alkenylation was also achieved. This strategy features broad substrate scope and holds promise for late-stage functionalization of pharmaceutically relevant scaffolds. Its synthetic utility is further highlighted by scaled-up experiments and diverse downstream transformations.