Recent Advances and Development in Visible-Light-Mediated Glycosylation: An Expanding Research Area in Glycochemistry

In the last fifteen years, the development of visible-light photocatalysis, metal/photoredox dual catalysis has become the forefront as a new paradigm in organic synthesis as well as in carbohydrate chemistry. It led to the discovery of unprecedented transformations and also the improvement of known reactions under mild conditions, employing simple household light sources and bench-stable precursors, which meet the requirements of green chemistry and sustainable development in excellent yield and stereocontrol. In a general sense, the exploitation of photoredox catalysis hinges on the capability of photocatalyst or redox mediator to transform visible light into chemical energy via photo-irradiated SET (single electron transfer), PET (photoinduced electron transfer), HAT (hydrogen atom transfer), and XAT (halogen atom transfer) to potentially unlock unique reaction pathways, thereby generating a diverse array of reactive intermediates. In view of reaction type, mechanism, and status, this review will systematically summarize the latest advances in visible-light-promoted photocatalytic glycosylation reactions, which are driven by single or dual photoredox catalysis and by the photoactivity of electron donor-acceptor (EDA) complexes.