Abstract
Organic nitroxyl radicals have attracted attention as useful catalysts for alcohol oxidation under mild, safe, and environmentally benign conditions. We have pursued the development of ideal alcohol oxidation methods on the basis of azaadamantane-type nitroxyl radical catalysts (AZADOs) , which we have developed as a highly efficient alcohol oxidation catalyst. By tuning the electrochemical and steric properties of nitroxyl radical catalysts, 5-F-AZADO (4) and Nor-AZADO (5) were identified as suitable catalysts for aerobic oxidation. These catalysts realize highly efficient aerobic alcohol oxidation systems with a remarkably broad range of substrate applicabilities under mild and simple conditions. Nor-AZADO (5) was also found to effectively catalyze alcohol oxidation with diisopropyl azodicarboxylate (DIAD) as the cooxidant as well as oxidation from silyl enol ether to 1,2-diketone.
