A study of hydroxyl participation in acyclic epoxide systems. Acid-catalysed rearrangements of trans- and cis-3,4-Epoxypentan-1-ols, 4,5-Epoxyhexan-1-ols, and 5,6-Epoxyheptan-1-ols

Abstract

The acid-catalysed rearrangements of trans- and cis-4,5-epoxyhexan-1- ols and 5,6-epoxyheptan-1-ols demonstrate a preference for cyclic ether formation: tetrahydrofuran > tetrahydropyran > oxepan. The ether products arise by intramolecular hydroxyl displacement of the epoxide oxygen with inversion of configuration. Reactions of trans- and cis- epoxypentan-1-ols give a mixture of trans- and cis-2-methyl-tetrahydro- furan-3-ols (8) and (9). From each epoxide one methyltetrahydrofuranol must arise by nucleophilic displacement of the secondary epoxide oxygen with retention of configuration.