HBr-H2O2: A Facile Protocol for Regioselective Synthesis of Bromohydrins and α-Bromoketones and Oxidation of Benzylic/Secondary Alcohols to Carbonyl Compounds under Mild Aqueous Conditions

HBr-H2O2 is efficiently activated in water under mild conditions, allowing the bromohydroxylation of various styrenes. HBr-H2O2 is more economic and easy to handle and offers sufficiently high regioselectivity (100%) for bromohydrin synthesis. Further activation of bromohydrin with a catalytic amount of HBr (50 mol %) and H2O2 in water affords alpha-bromoketones in moderate to good yields in a single step. Oxidation of benzylic/secondary alcohols to the corresponding carbonyl compounds has been achieved with the HBr (10 mol %) and H2O2 efficiently in aqueous dioxane under ambient conditions.