Oxidation with superoxide & sulfate-anion radical

Abstract

Potassium superoxide converted nitro compounds to the corresponding carbonyl compounds very efficiently. Due to the dual role of superoxide anion, the one-step conversion of nitro groups to ketones was possible. Nitro olefine was treated with superoxide anion in benzene to give nitroepoxides in good yields. Tetrabutyl ammonium peroxydisulfate ($\mbox{(TBA)_2S_2O_8}$) is turned out to be a good source of sulfate anion radical which is utilized for the generation of 1,3-dioxolan-2-yl radical. Reaction of alcohols in tetrahydropyran and tetrahydrofuran gives tetrahydropyranly- and tetrahydrofuranly- ether respectively. The $\beta$-masked formylation products were obtained from the reaction of electron deficient olefins and $\mbox{(TBA)_2S_2O_8}$ in 1,3-dioxolane. But, it was shown that nitro olefins were converted to the carbonyl compounds which have the masked formyl group at $\alpha$-position. This reaction can be a good method of the preparation of $\alpha$-formylating ketones. Chiral butenolide was treated in this way to give $\beta$-masked formylation products in a stereoselective manner Compounds which have a C=N bond such as N,N-dimethyl hydrazones were treated with $\mbox{(TBA)_2S_2O_8}$ in 1,2-dichloroethane to gives the ketones in good yields.