Stereoselective β-mannosylation via anomeric O-Alkylation: Concise synthesis of β-D-Xyl-(l→2)-β-D-Man-(1→4)-α-D-Glc-OMe, a trisaccharide oligomer of the <i>hyriopsis schlegelii</i> glycosphingolipid

<p>Synthesis of β-D-Xyl-(l→2)-β-D-Man-(1→4)-α-D-Glc-OMe (<b>1</b>), a tr-isaccharide oligomer of the <i>Hyriopsis schlegelii</i> glycosphingolipid is described. The synthesis involves a key β-mannosylation via cesium carbonate-mediated anomeric <i>O</i>-alkylation for direct synthesis of partially protected disaccharide β-D-Man-(1→4)-α-D-Glc-OMe (<b>4</b>) bearing a free C<sub>2</sub>˭OH in the mannose moiety. In addition, a silver triflate-promoted glycosylation of <b>4</b> with 2,3,4-tri-<i>O</i>-benzoyl-α-D-xylopyranosyl bromide (<b>5</b>) followed by deprotection affords the desired trisaccharide component (<b>1</b>) of the <i>Hyriopsis schlegelii</i> glycosphingolipid.</p>