Oxidations of benzyl and phenethyl phenyl sulfides. Implications for the mechanism of the microsomal and biomimetic oxidation of sulfides

Article abstract of DOI:10.1016/S0040-4020(97)00560-7

The study of the oxidation of 4-methoxyphenethyl phenyl sulfide and 3,4-dimethoxyphenethyl phenyl sulfide with potassium 12-tungstocobalt(III)ate [Co(III)W] suggests that in the radical cations of 3,4,5-(MeO)₃PhCH₂SPh (4) and 2,4,6(MeO)₃PhCH₂SPh (5) the positive charge is not localized on the sulfur atom, but in the benzylic aromatic ring. Nevertheless, in the biomimetic and microsomal oxidation of 4 and 5 the products observed are exclusively sulfoxides and sulfones, which appears in contrast with a mechanism involving the formation of an intermediate sulfide radical cation followed by a fast oxygen rebound. A direct oxygen transfer mechanism seems most likely.