Stereoselective Synthesis of (E)-Vinyl Sulfoxides by the Horner−Wittig Reaction

The Horner−Wittig reaction of sulfinylmethyl-substituted diphenylphosphane oxides 1−3 with aldehydes is reported. In a straightforward synthesis, (E)-vinyl sulfoxides 4 (R1 = Ph), 5 (R1 = Me) and 6 (R1 = pTol) were formed, mostly with high configurational selectivity and in high yields. In less selective cases, the (E)/(Z) ratio could be improved by slightly modifying the procedure. The use of (SS)-(+)-diphenyl(p-tolylsulfinylmethyl)phosphane oxide (3) allowed the synthesis of enantiomerically pure (E)-vinyl sulfoxides.