Selective Oxidation of Benzyl and Allyl Alcohols to Carbonyl Compounds or Acids Mediated by Iron Photocatalysts

This study presents a selective oxidation method for benzyl and allyl alcohols to aldehydes, ketones, or carboxylic acids using inexpensive iron salts as photocatalysts and molecular oxygen (air) as the sole oxidant under mild conditions. The process demonstrates high selectivity for the hydroxyl groups of benzyl and allyl alcohols, while minimizing the reactivity of other functional groups, thereby enhancing atom efficiency. The scalability and industrial applicability of the method are evidenced by its successful use in the modification of natural products and the synthesis of pharmaceutical intermediates, as well as through scale-up experiments, continuous-flow processes, and the successful implementation of tandem reactions. Mechanistic studies suggest that the reaction proceeds via a radical pathway, mediated by singlet oxygen and superoxide anions.