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Stereoselective synthesis of D-glycero-and L-glycero-β-D-mannoheptosides has been achieved by cesium carbonatemediated β-selective anomeric O-alkylation of the corresponding D-mannoheptoses. In addition, this method has been utilized in the total synthesis of a tetrasaccharide repeat unit of Bacillus thermoaerophilus surface-layer glycoprotein.

A total synthesis of the trisaccharide repeat unit of Salmonella serogroup E1 O‐antigen is reported. This synthesis features a key β‐mannosylation reaction through a cesium carbonate‐mediated anomeric O‐alkylation of a partially protected D‐mannose with an L‐fucose‐derived electrophile for the first time.

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.

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