Synthesis of an antigenic tetrasaccharide repeating unit of the -polysaccharide of lipopolysaccharide has been accomplished. Those four monosaccharides were assembled stereoselectively by employing our recently developed cationic gold(I)-catalyzed glycosylation methodology involving various glycosyl -1,1-dimethylpropargyl carbamate donors. The newly formed α-anomeric stereochemical configuration was controlled by the axial C2-OBz of the glycosyl donors via anchimeric assistance.
View Article and Find Full Text PDFA mild and efficient cationic gold(I)-catalyzed -glycosylation methodology involving the use of bench-stable glycosyl -1,1-dimethylpropargyl carbamate donors has been developed. In the presence of 1-2 mol% [tris(2,4-di--butylphenyl)phosphite]gold(I) chloride and 5 mol% silver triflate, both "armed" and "disarmed" glycosyl -1,1-dimethylpropargyl carbamate donors react with various sugar acceptors at room temperature to afford the corresponding glycosides in good to excellent yields. These glycosyl -1,1-dimethylpropargyl carbamates are found to be orthogonal to regular phenyl thioglycoside donors.
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