Efficient strategy for the iterative synthesis of trans-fused polycyclic ether via SmI2-induced reductive intramolecular cyclization

A highly efficient strategy for the iterative synthesis of a trans-fused polycyclic ether ring system has been developed. The new iterative method involves SmI2-induced reductive intramolecular cyclization of an aldehyde and a β-alkoxy acrylate as the key step, producing a 2,3-trans-tetrahydropyran or oxepane ring. The syntheses of trans-fused 6,6,6-tricyclic, 6,7,6-tricyclic, and 6,7,7,6-tetracyclic ethers were effectively achieved based on the newly developed method.