Selective Oxoammonium Salt Oxidations of Alcohols to Aldehydes and Aldehydes to Carboxylic Acids

The oxidation of alcohols to aldehydes using stoichiometric 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (1) in CH2Cl2 at room temperature Is a highly selective process favoring reaction at the carbinol center best able to accommodate a positive charge. The oxidation of aldehydes to carboxylic acids by 1 In wet acetonitrile Is also selective; the rate of the process correlates with the concentration of aldehyde hydrate. A convenient and high yield method for oxidation of alcohols directly to carboxylic acids has been developed.