Synthesis of potential inhibitors of the biosynthesis of the sex pheromone of Spodoptera littoralis. Part I: Monofluorinated fatty acids

Abstract

Several monofluorinated fatty acids, structurally related to palmitic acid, have been synthesized and fully characterized for the first time and assayed as inhibitors of the β-oxidation step, in the proposed biosynthesis of the sex pheromone of the Egyptian armyworm Spodoptera littoralis. Silver fluoride, diethylaminosulfur trifluoride (DAST) and dichlorofluoromethane were used as fluorination agents in the synthesis of 2-fluoropalmitic acid. 3- and 4-fluoropalmitic acid and ( Z)-5-fluoro-4-hexadecenoic acid, respectively. Stereoselective 1,4-reduction of the conjugated fluorodienic ester with sodium dithionite has been utilized to prepare the required fluorinated intermediate ester for the synthesis of ( Z)-5-fluoro-4-hexadecenoic acid. A preliminary account of the biological activity of the synthetic compounds along with 2-bromopalmitic acid is also reported.