Selective Transformations of 2,3-Epoxy Alcohols and Related Derivatives. Strategies for Nucleophilic Attack at Carbon-3 or Carbon-2

Article abstract of DOI:10.1021/jo00350a051

The ring-opening reactions of 2,3-epoxy alcohols 1 under nonisomerizing conditions were investigated.There is an inherent tendency for ring-opening at the C-3 position of 1 due to an electronic effect of the C-1 hydroxyl group.Since the hydroxyl group is a relatively weak inductively electron-withdrawing group, C-3 selective ring-opening reactions are observed only with certain simple 2,3-epoxy alcohols.Since an electronic effect of the C-1 hydroxyl group was found to promote ring-opening at the C-3-position of 1, the ring-opening reactions of 2,3-epoxy acetals and 2,3-epoxy amides were also explored, under the assumption that the acetal and amide groups might promote C-3 opening more strongly than the hydroxyl group.As expected, 2,3-epoxy acetals were opened with various nucleophiles exclusively at the C-3 position.However, the ring-opening reactions of 2,3-epoxy amides exhibited variable behavior, affording the C-3 ring-opened products with Mg(N3)2 and the C-2 ring-opened products with PhSK.