Switchable ROS Species Regulation Facilitates the Selective Oxidation of Benzyl Alcohols Enabled by an Organic Photocatalyst

Benefiting from the regulation of ROS species through a simple and feasible strategy, an efficient and switchable photocatalytic protocol for the chemoselective synthesis of aldehydes and carboxylic acids via oxidation of primary alcohols under mild conditions has been developed. Using the pyridinium derivative as a metal-free organic photocatalyst, a variety of benzyl alcohols can be converted into aldehydes or carboxylic acids under an air atmosphere at room temperature with high selectivity and yield via simple solvent regulation. A feasible tandem reaction combining the pyridinium-catalyzed alcohol-to-aldehyde conversion and catalyst-free photoinduced oxidation of aromatic aldehydes provides a powerful and efficient approach for the one-pot oxidation of benzyl alcohols to carboxylic acids, while a small amount of water can effectively regulate the competition of electron transfer and energy transfer and inhibit the generation of carboxylic acids, facilitating highly efficient and selective oxidation of alcohols to aldehydes.