Activation of glycosyl trichloroacetimidates with perchloric acid on silica (HClO(4)-SiO(2)) provides enhanced alpha-selectivity.

Obtaining high stereoselectivity in glycosylation reactions is often challenging in the absence of neighboring group participation. In this study, we demonstrate that activation of glycosyl trichloroacetimidate donors with immobilized perchloric acid on silica (HClO(4)-SiO(2)) provides higher alpha-selectivity than trimethylsilyl triflate (TMSOTf) for reactions that do not involve neighboring group participation.