Asymmetric synthesis of long chain α-methyl-β-thiotrifluoromethyl ketones employing the SAMP-/RAMP-hydrazone alkylation methodology

The enantioselective synthesis of both enantiomers of (Z)-1,1,1-trifluoro-3-methyl-4-thia-13-octadecen-2-one and (Z)-1,1,1-trifluoro-3-methyl-4-thia-13-hexadecen-2-one (ee ⩾90%), potential inhibitors of the pheromone action of two major maize pests Sesamia nonagrioides and Ostrinia nubilalis, is described. The key step is based upon a stereoselective alkylation with methyl iodide using the SAMP-/RAMP-chiral auxiliary methodology, followed by deprotection under non-racemization conditions.