Ru-catalysed stereoselective glycosylation of C-2 substituted glycals: an efficient route to 3-deoxy-1,2-difunctionalized pseudoglycals

The stereoselective formation of glycosidic bonds remains a key challenge in carbohydrate chemistry, with far-reaching implications for glycoscience, drug development, and materials research. We report a novel method for glycosylation of glycal-derived substrates mediated by Ru(II) catalysis. Glycosylation selectivity is modulated by the presence or absence of external nucleophiles in the reaction medium. This transformation is notable for its operational simplicity, scalability, and use of cost-effective, air-stable Ru(II) catalysts. Notably, the reaction exhibits exceptional β-selectivity, offering an efficient and streamlined approach for synthesising 3-deoxy-1,2-difunctionalized glycals.