Enzymic glycosphingolipid synthesis on polymer supports. III. Synthesis of GM3, its analog [NeuNAcα(2-3)Galβ(1-4)Glcβ(1-3)Cer] and their lyso-derivatives

Two water-soluble polymers, carrying 0.24 meq g−1 of lactosyl-β(1-1)-sphingosine (7) and 0.13 meq g−1 of lactosyl-β(1-3)-sphingosine (8) were prepared. The polymers served as acceptors in the α-(2-3)-sialyltransferase reaction (up to 55.3 and 38.5% transfer yields, respectively). Subsequent photolysis, released compounds 11 (lyso-GM3) and 12 (lyso-GM3 analog), respectively; acylation and chromatography afforded (5-acetamido-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosylonic acid)-(2-3)-β-D-galactopyranosyl-(1-4)-β-D-glucopyranosyl-(1-1)-(2S, 3R, 4E)-2-octadecanoylamino-4-octadecene-1,3-diol (13, GM3) and (5-acetamido-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosylonic acid)-(2-3)-β-D-galactopyranosyl-(1-4)-β-D-glucopyranosyl-(1-3)-(2S, 3R, 4E)-2-octadecanoylamino-4-octadecene-1,3-diol (14, GM3 analogue), respectively, thus presenting a route to glycosphingolipids possessing the unusual glycosyl-β(1-3)-spingosine linkage.