Synthesis and use of glycosyl phosphates as glycosyl donors

Differentially protected glycosyl phosphates prepared by a straightforward synthesis from glycal precursors are used as powerful glycosyl donors. Activation of beta-glycosyl phosphates by TMSOTf at -78 degrees C achieves the selective formation of beta-glycosidic linkages in excellent yields with complete stereoselectivity. Reaction with thiois results in the conversion of glycosyl phosphates into thioglycosides in nearly quantitative yield. An orthogonal coupling strategy using glycosyl phosphate donors and thioethyl glycoside accepters allows for the rapid synthesis of a trisaccharide.