TRANSPOSITION DES OXIRANNES-ETHANOLS PAR L'INTERMEDIAIRE D'ALCOXYETAINS

Article abstract of DOI:10.1016/0040-4020(82)85161-2

Oxiraneethoxytributyltins prepared from the corresponding oxiraneethanols, on heating at 200 deg C gave, after demetalation with isophthalic acid, 2-oxetanemethanols and/or 3-oxolanols.As appears from about thirty rearrangements the choice between oxetane and oxolane formation is dependent on: (1) the relative degree of substitution of the oxirane ring; cyclization occuring predominantly at the more substituted carbon; and (2) the configuration of the oxirane ring, when both its ends are equally substituted; cis form being more suitable for genaration of the smaller ring.The reaction is shown to proceed with inversion of configuration at the site of oxygen attack.The results of attempts to perform the rearrangement in dilute-phase or throught alkaline metal alkoxides in various media support the conclusion that there is a large contribution by electrophilic assistance to the oxirane ring opening.Such assistance can be efficiently provided by a tin atom in a push-pull mechanism which accomodates all the facts.The present method of oxiraneethanol rearrangement may offer a convenient route to functional oxetanes.