Synthesis of 2,3-diazido-2,3-dideoxy-β-d-mannosides and 2,3-diazido-2,3-dideoxy-β-d-mannuronic acid via stereoselective anomeric O-alkylation.

Stereoselective synthesis of 2,3-diazido-2,3-dideoxy-β-d-mannosides has been accomplished via CsCO-mediated anomeric O-alkylation of 2,3-diazido-2,3-dideoxy-β-d-mannoses with primary electrophiles. Selective oxidation of the C6 primary alcohol of the 2,3-diazido-2,3-dideoxy-β-d-mannoside successfully produced corresponding 2,3-diazido-2,3-dideoxy-β-d-mannuronic acid.

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.

Synthesis of 2-Amino-2-deoxy-β-d-mannosides via Stereoselective Anomeric -Alkylation of 2,3-Oxazolidinone-Protected d-Mannosamine: Synthesis of the Trisaccharide Repeating Unit of 19F Polysaccharide.

Cesium carbonate-mediated stereoselective anomeric -alkylation of a 2,3-oxazolidinone-protected d-mannosamine with sugar-derived primary or secondary alkyl triflates afforded the corresponding 2-amino-2-deoxy-β-d-mannosides in moderate to good yields and excellent stereoselectivity. The oxazolidinone ring can be opened with aqueous alkali hydroxide to liberate the amine functionality. This method has been successfully applied to the synthesis of the trisaccharide repeating unit of 19F polysaccharide.

Stereoselective Synthesis of 2-Azido-2-deoxy-β-d-mannosides via CsCO-Mediated Anomeric O-Alkylation with Primary Triflates: Synthesis of a Tetrasaccharide Fragment of Teichuronic Acid.

Cesium carbonate-mediated anomeric O-alkylation of various protected 2-azido-2-deoxy-d-mannoses with primary triflate electrophiles afforded corresponding 2-azido-2-deoxy-β-mannosides in good yields and excellent anomeric selectivity. In addition, 1,3-dibromo-5,5-dimethylhydantoin was found to be the optimal oxidant for preparation of those 2-azido-2-deoxy-d-mannoses from their corresponding thioglycosides. The utilization of this method was demonstrated in the synthesis of a tetrasaccharide fragment of teichuronic acid containing -acetyl-β-d-mannosaminuronic acid (ManNAcA).