Diastereoselectivity in the Synthesis of m- and p-Substituted 3-Aryl-2-trichloromethyl-1,3-thiazolidin-4-one Sulfoxides With Oxone

S-Oxidation of 3-Aryl-2-trichloromethyl-1,3-thiazolidin-4-ones with Oxone was investigated. For all compounds evaluated, selective oxidation to the sulfoxide versus the sulfone was realized using 3 equivalents of Oxone at room temperature. The diastereoselectivity of sulfoxide formation always favored the anti product, but the extent of the selectivity varied according to the solvent used. Generally, higher selectivity was observed using acetone and acetonitrile, and lower selectivity was observed using methanol. Alternatively, sulfones were prepared by reaction with KMnO₄ at room temperature.