OXIDATION OF ORGANIC SUBSTRATES BY MOLECULAR-OXYGEN ALDEHYDE HETEROPOLYOXOMETALATE SYSTEM

Heteropolyoxometalate-catalyzed oxidations of organic compounds such as olefins and cyclic ketones with molecular oxygen in the presence of an aldehyde were examined. Olefins were epoxidized with dioxygen in the presence of 2 equiv of 2-methylpropanal under the influence of a catalytic amount of the mixed heteropolyoxometalate NPV6Mo6 (3) to give the corresponding epoxides in moderate to good yields. This catalytic oxidation method was also applied to the epoxidation of allylic and homoallylic alcohols. In the absence of olefins, the aldehydes were efficiently converted into the corresponding carboxylic acids. In addition, the Baeyer-Villiger oxidation of cyclic ketones was accomplished by using benzaldehyde instead of 2-methylpropanal as the aldehyde.