Cationic Gold(I)-Catalyzed Glycosylation with Glycosyl N-1,1-Dimethylpropargyl Carbamate donors

A mild and efficient cationic gold(I)-catalyzed O-glycosylation methodology involving the use of bench stable glycosyl N-1,1-dimethylpropargyl carbamate donors has been developed. In the presence of 1-2 mol% [tris(2,4-di-tert-butylphenyl)phosphite]gold(I) chloride and 5 mol% silver triflate, both “armed” and “disarmed” glycosyl N-1,1-dimethylpropargyl carbamate donors react with various sugar acceptors at room temperature to afford corresponding gly-cosides in good to excellent yields. This glycosyl N-1,1-dimethylpropargyl carbamate donors are found to be orthogonal to regular phenyl thioglycoside donors. The utilization of this method has demonstrated in the synthesis of a trisaccharide.