Oxidations are important transformations in organic synthesis. In general, many oxidations are carried out with a large excess of chromium or manganese reagents. The metal residues are environmentally undesirable and often cause problems during work-up.2 In addition organic oxidations in the chemical industry have traditionally been performed in either aromatic or halogenated solvents.' One of the most attractive oxidants is molecular oxygen? since oxygen is highly soluble in subcritical water. Molecular oxygen has been used as the reagent for the oxidation of alkyl aromatic compounds in the presence of different catalysts, such as MnBr.