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.
Liu et al. (2025) studied this question.