Difluoropalmitic acids as potential inhibitors of the biosynthesis of the sex pheromone of the Egyptian armyworm Spodoptera littoralis--IV.

2,2-, 3,3- and 4,4-Difluoropalmitic acids (1-3) have been synthesized and fully characterized. Acids 2 and 3 were prepared through fluorination of the corresponding dithioacetal-protected ketoesters followed by enzymatic saponification. The acids 1-3 were evaluated in vivo as inhibitors of the beta-oxidation step of the biosynthesis of (Z,E)-9,11-tetradecadienyl acetate, the major component of the sex pheromone of the Egyptian armyworm Spodoptera littoralis. Only, the 2,2- and 3,3-derivatives, i.e. those containing the two fluorine atoms at the positions involved in the chain-shortened step, have been found to be active, the activity being similar to or lower than that displayed by the corresponding monofluorinated acids.