Formation of Enantiomerically Pure 1-Fluorovinyl and 1-Fluoromethyl Sulfoxides

(SS)-[Fluoro(p-tolylsulfinyl)methyl]diphenylphosphane oxide (2) was obtained with complete stereoselectivity from (fluoromethyl)diphenylphosphane oxide (3) and (S)-(−)-menthyl p-toluenesulfinate. 1-Fluorovinyl p-tolyl sulfoxides 1 were prepared in good yields by Horner−Wittig reaction of 2 with aldehydes, in excellent enantiomeric excess (ee). With ketones, yields were generally low. Stereoselectivity was high for aliphatic aldehydes, producing (Z) isomers, and for benzaldehydes, yielding the (E) isomers. A two-step, one-pot procedure for the conversion of 3 into 1 was also developed. Solvolysis of 2 provided the first route to enantiomerically pure (S)-1-(fluoromethyl)sulfinyl-4-methylbenzene (7).