Primary Benzamide as a Weakly Coordinating Directing Group for Ru(II)-Catalyzed Redox-Neutral C–H Annulation: Concise Synthesis of Quinisocaine

Herein, we report the first Ru(II)-catalyzed redox-neutral C-H annulation of primary benzamides with aliphatic sulfoxonium ylides via weak coordination. The reaction demonstrates a broad substrate scope, excellent functional group tolerance, and applicability to late-stage functionalization. Notably, the reaction exhibits chemo-selectivity, where only the primary amide undergoes C-H annulation, leaving the secondary amide functionality intact. Moreover, the developed protocol was successfully employed in the synthesis of the anesthetic drug Quinisocaine.