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Novel acyl pyrazoles and acyl triazoles have been prepared by means of the oxidative amidation of aldehydes in the presence of the requisite azole. Yields range from modest to good in both cases, and some limitations of the substrate scope have been discovered. Acyl pyrazoles were prepared by treatment of a mixture of aldehyde and pyrazole with an oxoammonium salt bearing the nitrate anion. In the case of acyl triazoles, the oxidative functionalization was performed using sodium persulfate as a terminal oxidant in the presence of a catalytic quantity of a nitroxide.

This review article summarizes the electron transfer reactions of piperidine aminoxyl radicals. Electrochemical studies revealed the single electron transfer nature of piperidine aminoxyl radicals. In solution, piperidine aminoxyl radicals serve as single electron transfer oxidation reagent to react with various biologically interesting molecules such as glutathione, cysteine, ascorbic acid, and amines. The reaction product distribution, reaction kinetics, intermediates, and the reaction features in biological mimic environments including micelles and cyclodextrins were investigated. Oxoammonium salts, the one-electron transfer oxidation products of piperidine aminoxyl radicals, are agents of organic synthesis to selectively generate ketones or di-ketones from alcohols or ketones bearing a-methylene group under mild conditions. The new reactions of oxoammonium salts with aromatic amines, phenols, heterocycles including phenothiazines, papaverine, and bilirubin are also illustrated. [ABSTRACT FROM AUTHOR]