Stereoselective Synthesis of 2-Azido-2-deoxy-β-<scp>d</scp>-mannosides via Cs<sub>2</sub>CO<sub>3</sub>-Mediated Anomeric O-Alkylation with Primary Triflates: Synthesis of a Tetrasaccharide Fragment of <i>Micrococcus luteus</i> Teichuronic Acid
Cesium carbonate-mediated anomericO-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