A brief account of the application of glycosyl halide as glycosyl radical precursor towards glycosylation through visible light catalysis

Glycosylation is potentially one of the most important reactions in glycochemistry, where precise control over the anomeric selectivity is crucial for synthesizing biologically relevant glycoconjugates. Over the last two decades, the advent of visible light chemistry for the generation of glycosyl radicals and its application in the synthesis of glycosides has revolutionized the impact on the stereoselectivity of glycosylation. The visible light-driven radical-based reactions offer exceptional functional group tolerance, operate under mild reaction conditions, and have emerged as a powerful tool for synthesizing potent glycosyl compounds, which include aryl/alkyl glycosides, 2-deoxy sugar, glycosylamino acid, glycosylpeptides, and other glyco-conjugates. In this review article, a brief account of the evolution of glycosyl radical chemistry, with a focus on the visible light-mediated activation of glycosyl halides and its transformative impact on glycoside synthesis, has been discussed.