Substrate‐Controlled Divergent Synthesis of Oxadiazinoisoquinolines via Cobalt‐Catalyzed Regioselective Annulation of Epoxides

A substrate‐controlled regioselective annulation protocol via Co(II)‐catalyst for accessing structurally divergent oxadiazinoisoquinolines from epoxides and C , N ‐cyclic azomethine imines is disclosed. The specific and orthogonal regioselectivity is achieved for aromatic and aliphatic epoxides, respectively, which is supported by density functional theory (DFT) calculations and DIAS analysis. Mechanistic investigation indicates the formation of a key Co(II)–azomethine imine complex, showcasing the dual roles of azomethine imine. Broad substrate scope is demonstrated by 46 examples.