Organoboranes for synthesis. 3. oxidation of organoboranes with aqueous chromic acid. a convenient synthesis of ketones from alkenes via hydroboration

Abstract

Organoboranes react with alkaline hydrogen peroxide to provide a wide variety of alcohols. These alcohols can be taken up in ether solvent and converted without isolation into the corresponding ketones by treatment with chromic acid. Organoboranes can also be oxidized directly with chromic acid to the corresponding ketones. The chromic acid oxidation of organoboranes provides a new, convenient procedure for the synthesis of α-substituted cycloalkanones via hydroboration. The conversion of organoboranes into ketones proceeds through the intermediate alcohol. Representative cycloalkanones and α-methylcycloalkanones have been prepared from the corresponding alkenes via hydroboration, followed by chromic acid oxidation.