Syntheses and reactions of methyl ( Z)-9,10-epoxy-13-oxo-( E)-11-octadecenoate and methyl ( E)-9,10-epoxy-13-oxo-( E)-11-octadecenoate

Abstract

The syntheses and reactions of two epoxyketoacids (methyl ( Z)-9,10-epoxy-13-oxo-( E)-11-octadecenoate ( IV) and methyl ( E)-9,10-epoxy-13-oxo-( E)-11-octadecenoate ( V)) are described. The synthetic method is based on the stereoselective oxidation of linoleic acid by soybean lipoxygenase to produce the corresponding 13-hydroperoxide. Reduction of the hydroperoxide with sodium borohydride followed by oxidation, esterification and epoxidation yielded the compounds IV and V with a global yield of 14% and 3%, respectively, referred to the diasteromerically pure isolated compounds. Confirmation of the structures was carried out by reduction of the ketone group with sodium borohydride and by the opening of the oxirane ring with methanolic boron trifluoride. The reduction of compounds IV and V with hydrogen mainly yielded the tetrahydrofuranoid fatty acid, methyl 10,13-epoxyoctadecanoate. This reaction may be considered a new procedure to obtain tetrahydrofuranoid fatty acids.