New oxidation by peroxysulfur intermediates resulting from reaction of organosulfur compounds with superoxide anion

Abstract

Oxidations of various olefins containing two double bonds with peroxysulfur intermediates which are generated from the nitrobenzenesulfonyl chlorides and potassium superoxide afforded high regioselective epoxidations in excellent yields under mild conditions. Regioselective epoxidations of olefins containing an $\alpha,\beta$-unsaturated ketone moiety such as $\alpha$-ionone, $\beta$-ionone, and $\ell$-carvone afforded their corresponding epoxides in mostly quantitative yields: no epoxidation of the double bond in the $\alpha,\beta$-unsaturated ketone moiety was detected. Moreover, oxidations of chalcones or t-stilbene by the peroxysulfur intermediate yielded their epoxides in excellent yields (82-90\%) at -35$^\circ$C. These yields of epoxides are higher than these obtained by the known methods. Dimethyl sulfoxide, diphenyl sulfoxide, p-tolyl methyl sulfoxide were also oxidized by the corresponding sulfones in good yields (78-97.5\%) under mild conditions. Thiocarbonyl compounds such as substituted thioureas, thioamides, and thiocarbamates were found to react with the peroxysulfur intermediate to convert into the corresponding carbonyl compounds in quantitative yields. These reactions appear to be initiated via a nucleophilic attack of superoxide anion($O_2^{\bar{\cdot}}$) on the sulfonyl sulfur atom to form a peroxysulfur radical intermediate, which may be readily converted to the peroxysulfonate intermediate or cyclic sulfurane intermediate by one electron transfer from excess superoxide anion($O_2^{\bar{\cdot}}$). While, arylsulfenyl chlorides reacted with superoxide anion in tetrahydrofuran or acetonitrile to give the corresponding diarylsulfides or arylsulfonates depending upon the substrates used.