Selective Synthesis of Ortho-substituted 3-Cyclohexyl-2-phenyl-1,3-thiazolidin-4-one Sulfoxides and Sulfones by S-Oxidation with Oxone

S-oxidation of 3-aryl-2-phenyl-1,3-thiazolidin-4-ones with Oxone® was investigated. For all compounds evaluated, selective oxidation to the sulfoxide was realized using 3 equivalents of Oxone® at room temperature. Alternatively, the sulfone was prepared selectively in most of the compounds evaluated at high temperature by increasing the equivalents of Oxone® used; the extent of this selectivity was affected by the substituent and its position on the N3 aromatic ring. The ratio of the sulfoxide and sulfone products was quantified by isolating the products by liquid chromatography.