Synthesis of Cyclic Ethers Utilizing a Cyclization–Fragmentation Strategy

A variety of cyclic ethers have been prepared via both solution phase and polymer-supported sequences of 3+2 cycloaddition of nitrile oxides to alkenes and dienes to give isoxazolines, followed by electrophile-induced cyclization. Library generation by alkylative elaboration of isoxazolines was unsuccessful, but both simple and substituted dienes were found suitable for polymer-supported formation of cyclic ethers of ring sizes five through seven.