Activation of superoxide

Abstract

New peroxy species, various peroxysulfur intermediates are generated by activating superoxide and examined as oxidizing agents for the various organic compounds which are inert to superoxide alone. As an activator of superoxide, p-tolylsulfinyl and p-nitrobenzenesulfinyl chloride are used, and 2-nitrobenzenesulfinyl chloride are reacted with superoxide to form peroxysulfinyl intermediates which are proven to be a good oxidizing agent for olefins and sulfides. Among them, the 2-nitrobenzenesulfinylperoxy intermediates are readily formed and oxidize olefins to the epoxides and sulfides to the sulfoxides respectively in excellent yields. The new peroxysulfinyl intermediates oxidize selectively sulfides to the corresponding sulfoxides in excellent yields together with traceable amount of sulfones under mild conditions at -25$^\circ$C. The 2-nitrobenzeneperoxysulfinyl intermediate seems to be stabilized by a neighboring group effect of the nitro group attached at 2-position of phenyl ring. The second type of an activator such as N-arylsulfonyl, N-isopropyl and N-carbamenthoxy p-tolylsulfonimidoyl chloride are also used to form peroxysulfonimidoyl intermediate which seems to be a new and promising oxidizing agent for the various organic substrates. All the peroxysulfonimidoyl intermediates generated form the sulfonimidoyl chloride with superoxide oxidize facile various sulfides to the sulfoxides and olefins to the epoxides under mild conditions in good yields. The optical active sulfonimidoyul chloride such as (+)-(S)-N-carbo-(-)-menthoxy p-tolylsulfonimidoyl chloride was prepared and reacted with superoxide to form chiral peroxysulfonimidoyl intermediate which was examined to oxidizeprochiral methyl p-tolyl sulfide to the optically active sulfoxide. However, no distinguishable enantiomeric excess of methyl p-tolyl sulfoxide is obtained. From the above, the new peroxysulfonimidoyl intermediate seems to be an electrophilic radical rather than a nucleophile. The peroxy...