SYNTHESIS OF KETODIENOIC COMPOUNDS FROM N ATURAL UNSATURATED FATTY-ACIDS .1. LINOLEIC-ACID

A preparative four-step procedure for converting the natural unsaturat ed fatty acids with the 1Z,4Z-pentadienoic fragment in 1-oxo-2E,4Z-die noic compounds is described using linoleic acid methyl ester as an exa mple, Natural linoleic acid methyl ester was oxidized with m-chloroper benzoic acid in ethanol to a mixture of epoxides, methyl esters of cor onaric and vernolic acids. Their subsequent treatment with anhydrous H Br in methanol yielded the mixture of bromohydrins oxidized by the Jon es reagent to a mixture of bromoketones, which then were dehydrobromin ated by 1,8-diazabicyclo[5.4.0]undecene-7. The separation of the resul ting products by HPLC gave the methyl esters of (10E,12Z)-9-oxooctadec adienoic and (9Z,11E)-13-oxooctadecadienoic acids with a total yield o f 30% per all the four stages. The structures of the compounds synthes ized were confirmed by UV, IR, and H-1 and C-13 NMR.