Visible Light-Mediated Anaerobic Oxidation of α-Glucoside: Site-Selective Dehydrogenation Promoted by Aromatic Aldehydes

Herein, we describe a novel photocatalytic strategy for the site-selective oxidation of unprotected α-glucosides using aromatic aldehydes. In this method, Na2HPO4 was used to form hydrogen bonds with the C3 hydroxyl group of α-glucoside, thereby generating C3 free radicals, and p-cyanobenzaldehyde was used to dehydrogenate the free radical intermediates to achieve site-selective oxidation. This approach achieves a high selectivity for both glycosidic bond configurations and glycosylated forms. Mechanistic studies suggest that the reaction proceeds through single-electron transfer and radical coupling with the quinuclidine playing a key role in hydrogen atom transfer. This method provides a powerful tool for site-selective glycan oxidation, offering significant potential for applications in carbohydrate chemistry and glycobiology.