Potassium permanganate/carboxylic acid/organic solvent: a powerful reagent for enone oxidation and aryl coupling reactions

The α′-acetoxylation of enones and the α-acetoxylation of aromatic ketones were carried out with potassium permanganate and acetic acid, in which acetoxylation products were obtained in 74–96% yields. The same reaction was carried out with carboxylic acids other than acetic acid, which furnished corresponding acyloxy ketones with the same regioselectivity. For the first time, formyloxylation products were synthesized in a 61–85% yield by using formic acid. The potassium permanganate and acetic acid method was also used for aryl coupling reactions. The reaction of arylboronic acids and arylhydrazines in benzene with potassium permanganate and acetic acid in turn furnished biaryls in 85–96% yield. We have shown that potassium permanganate/carboxylic acid/organic solvent behaves as manganese(III) acetate.