(Diphenoxyphosphoryl)methyl p-tolyl sulfoxide: A new reagent for Z-selective synthesis of racemic and optically active vinyl sulfoxides

Racemic and optically active (+)-(S)-(diphenoxyphosphoryl)methyl p-tolyl sulfoxide were prepared and used as Horner olefination reagents. Their reaction with aromatic and aliphatic aldehydes afforded the corresponding racemic and enantiomeric alpha,beta-unsaturated sulfoxides with moderate to high Z-selectivity. The E/Z ratio was found to be dependent on the structure of aldehyde, nature of base, reaction conditions, and addition of 18-crown-6.