Synthesis of Bridged N,O‐Heterocyclic 1,6‐Epoxybenzo[c]azocines via Migration‐Annulation Cascade Reaction of α‐Imino Rhodium Carbenes

A rhodium‐catalyzed cascade migration‐annulation reaction of 1‐sulfonyl‐1,2,3‐triazole has been developed. As the key step, the 1,3‐sulfinate migration of α‐imino rhodium carbene yielded an extended zwitterion, which was intramolecularly trapped by aldehyde group furnishing bridged N,O‐heterocyclic 1,6‐epoxybenzo[c]azocine as the [5+2] cyclization product. This migration‐annulation strategy provides more flexibility for heterocycle synthesis and medium‐sized ring construction, especially for the construction of polycycles with complex skeletons. A method for synthesizing bridged N,O‐heterocyclic 1,6‐epoxybenzo[c]azocines has been developed using a rhodium‐catalyzed cascade reaction involving 1,3‐sulfinate migration‐annulation of 1‐sulfonyl‐1,2,3‐triazole.