ACTION OF BORON TRUFLUORIDE ETHERATE ON UNSATURATED EPOXYCOMPOUNDS

The reaction of methyl 12,13-epoxyoctadec-9-enoate (VII) and methyl 9,10-epoxyoctadec-12-enoate (VIII) with BF3-etherate yielded mixtures of cyclic and unsaturated acyclic compounds. The latter arise from usual reactions of epoxy compounds with Lewis acids. The main cyclic products were the cis- and trans-isomers of methyl 9-methylene-12-oxoheptadecanoate (V) and methyl 9-oxo-1 1-methylene-heptadecanoate (XX) obtained from the epoxy esters (VII) and (VIII) respectively. A minor quantity of the 2,4-disubstituted 3-oxabicyclo[3.1.0]hexane (XVI) was formed from each epoxy ester. The formation of the cyclic products is hypothesized as arising from cationic intermediates which are formed by the participation of the double bond in epoxide ring opening. The stereochemical course of the reaction is discussed. © 1969.