A novel efficient and stereoselective synthesis of cis- or trans-2,5-disubstituted tetrahydrofurans

摘要

A general route to either cis-or trans-2,5-alkyl or aryl disubstituted tetrahydrofurans is described, using the nucleophilic addition of organolithium derivatives to tricyclc lactones, followed by a highly stereocontrolled acid-assisted reduction with sodium cyanoboro-hydride of the hemiketals formmed. The stereoselectivity observed can be rationalized by the preferential approach of the hydride on the less hindered face of an oxonium ion intermediate.