Polymer-Supported Synthesis of Cyclic Ethers: Electrophilic Cyclization of Izoxazolines

Article abstract of DOI:10.1021/jo00118a041

Polymer-supported synthesis of 2,5-disubstituted tetrahydrofurans via tandem 1,3-dipolar cycloaddition/electrophilic cyclization has been accomplished using a five-step reaction sequence to give 2-(cyanomethyl)-5-(iodomethyl)tetrahydrofuran (cis:trans ratio 1:2) in 40percent overall yield.The corresponding 2-(cyanomethyl)-6-(iodomethyl)tetrahydropyran was similarly formed in a 7percent overall yield.The final electrophilic cyclization simultaneously releases the desired product and regenerates the initial polymer-bound functionality.In the process the desired cyclic ether is obtained exclusively; byproducts of the sequence are not cleaved from the polymer support.In addition the polymer support is sufficiently robust to by recovered and recycled through the reaction sequence.