Diastereoselective synthesis of substituted dihydropyrans via an oxonium–ene cyclization reaction

Abstract

Substituted dihydropyrans can be efficiently synthesized in good yields with excellent diastereoselectivity from the reaction of aldehydes or epoxides and ethyl 3-alkyl-3-hydroxy-5-methylhex-5-enoate via an oxonium–ene cyclization reaction catalyzed by trimethylsilyl trifluoromethanesulfonate (TMSOTf) under mild conditions.