Stereoselective Glycosylation of Amino Sugars Enabled by Thiourea/Phosphoric Acid Dual Catalysis

We reported a stereocontrolled synthesis of 3-amino-3-deoxy-, 4-amino-4-deoxy-O-glycosides through a phosphoric acid (PA) and thiourea cooperative catalytic system under mild conditions. Utilizing strategically protected 3-/4-deoxy glycosyl trichloroacetimidates as donors, this protocol achieved high yields (up to 86% yield) and exceptional stereoselectivity (up to α only or β only) across diverse alcohol nucleophiles. Successful glycosylation of bioactive molecules and scale-up of the reaction without loss of yield or selectivity demonstrated the potential application of the methodology.