PRACTICAL SYNTHESIS OF TA-D-XYL-(1-]2)-BETA-D-MAN-(1-]4)-ALPHA-D-GLC-OME, A TRISACCHARIDE COMPONENT OF THE HYRIOPSIS-SCHLEGELII GLYCOSPHINGOLIPID

By employing the readily accessible (preceding paper in this issue) 3, 4,6-tri-O-benzyl-alpha-D-arabino-hexosyl bromide (1) as an indirect, b eta-specific mannosyl donor, a practical three-step synthesis was elab orated for methyl xylosyl-beta(1-->2)-mannosyl-beta(1-->4)-glucoside ( 11), a trisaccharide component of Hyriopsis schlegelii ceramide oligos accharides. Key steps were the silver aluminosilicate-induced, beta-sp ecific glycosidation of 1 with methyl 2,3,6-tri-O-benzyl-alpha-D-gluco side and the silver triflate-promoted beta-xylosylation with 2,3,4-tri -O-benzoyl-alpha-D-xylosyl bromide. The overall yield amounted to a sa tisfactory 47%.