Chemoselective Conversion from α-Hydroxy Acids to α-Keto Acids Enabled by Nitroxyl-Radical-Catalyzed Aerobic Oxidation

The chemoselective oxidation of a-hydroxy acids to alpha-keto acids catalyzed by 2-azaadamantane N-oxyl (AZADO), a nitroxyl radical catalyst, is described. Although alpha-keto acids are labile and can easily release CO2 under oxidation conditions, the use of molecular oxygen as a cooxidant enables the desired chemoselective oxidation.