A convergent strategy for the synthesis of polycyclic ethers by using oxiranyl anions

A new X+2+Y]-type for the convergent synthesis of polycyclic ethers based on an oxiranyl anion strategy was developed. The sequence involves nucleophilic substitution of a triflate with an oxiranyl anion followed by 6-endo cyclization, ring expansion, and reductive etherification. The protocol features a flexible approach toward trans-fused polycyclic arrays consisting of six- and seven-membered ether rings from the same starting materials.