Potassium carbonate-mediated -selective anomeric -alkylation with primary electrophiles: Application to the synthesis of glycosphingolipids.

Stereoselective construction of a variety of β-glycosides can be achieved using abundant and inexpensive KCO-mediated stereoselective anomeric O-alkylation of sugar lactols with primary electrophiles. In addition, application of this methodology to the synthesis of various azido-modified glycosphingolipids has been accomplished in good yields and excellent anomeric selectivity using sphingosine-derived primary triflate.

Cationic gold(I)-catalyzed glycosylation with glycosyl -1,1-dimethylpropargyl carbamate donors.

A 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.

Stereoselective β-Mannosylation via Anomeric -Alkylation with L-Sugar-Derived Electrophiles.

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

Stereoselective Synthesis of β-d-Manno-heptopyranoside via CsCO-Mediated Anomeric -Alkylation: Synthesis of a Tetrasaccharide Repeat Unit of Surface-Layer Glycoprotein.

Stereoselective synthesis of d-glycero- and l-glycero-β-d-mannoheptosides has been achieved by cesium carbonate-mediated β-selective anomeric -alkylation of the corresponding d-mannoheptoses. In addition, this method has been utilized in the total synthesis of a tetrasaccharide repeat unit of surface-layer glycoprotein.