Selective rhenium-catalyzed oxidation of secondary alcohols with methyl sulfoxide in the presence of ethylene glycol, a convenient one-pot synthesis of ketals

[GRAPHICS] Secondary alcohols are oxidized preferentially by DMSO and the catalyst ReOCl3(PPh3)(2) in the presence of ethylene glycol and refluxing toluene, producing the corresponding ketals. The reactions are rapid, and proceed in very good to excellent yields. The byproducts of the reaction, methyl sulfide and water, are easily removed. No epoxidation or other common side reactions were observed. This direct oxidative transformation of alcohols to the protected ketal derivatives should have broad synthetic applicability.