Light-Driven Site-Selective Glycosylation of Native Carbohydrates

Carbohydrates constitute the largest source of biomass on Earth, but their synthetic modification is challenging due to their high content in oxygen functionalities. The site- and stereoselective modification of native sugars is a definite goal of glycochemistry research. Recent efforts to bypass the need for protecting groups, leveraging selective activation through photochemical mechanisms for site-selective C-C bond formation from native sugars, are likely to largely impact all glycochemistry-related areas. Davis, Koh, and co-workers have recently presented their use of photocatalysis to develop a "cap and glycosylate" approach for the site- and stereoselective C-glycosylation of native sugars. A modernized direct radical functionalization of in situ formed thioglycoside using photocatalysis was used in the synthetic manipulation of unprotected carbohydrates. This allowed reaching complex saccharides, and post-translational modification of proteins.