Asymmetric synthesis of both enantiomers of point-difluorinated-eldanolide, analogues of insect sex pheromone

Substitution of two fluorine atoms on organic molecules is expected to alte r both chemical reactivity and biological activity due to the strong electr on-with drawing nature of fluorine. The synthesis of partly gem-difluorinat ed compounds remains a significant challenge to synthetic organic chemists. We report that [2,3]-Wittig rearrangement of 1,1,2-trifluoroallylic ether gave a new type of partly gem-difluorinated allylic alcohol: 6-methyl-4,4,5 -trifluorohept-1,5-dien-3-ol, 3, in a highly stereoselective fashion, and o ptical resolution of alcohol 3 was accomplished via lipase PS(PCL)-catalyze d reaction. Using this alcohol as the starting material, the first asymmetr ic synthesis of both enantiomers of point-fluorinated-eldanolides, 2,2,5,5, 6-pentafluoroeldanolide 1 and 5,5,6-trifluoroeldanolide 2, analogues of the sex pheromone of the male African sugarcane borer, has been demonstrated.