SYNTHESIS OF A NEOGLYCOPROTEIN CONTAINING THE LEWIS-X ANALOGOUS TRISACCHARIDE GALPNAC-(1-]4)[ALPHA-L-FUCP-(1-]3)]-BETA-D-GLCPNAC

The trisaccharide allyl glycoside 36 and related disaccharide part str uctures have been prepared using the richloroacetamido-2-deoxy-alpha-D -galactopyranosyl trichloroacetimidate derivative 9 as glycosyl donor under promotion with TMSOTf or Sn(OTf)(2), respectively, to produce th e beta-(1-->4) linkage to suitably protected glucosamine derivatives i n fair yields. Fucosylation was effected employing the ethyl 1-thio gl ycosyl donor 20 in the presence of IDCP. Deprotection of the intermedi ates afforded the disaccharide allyl glycosides beta-D-GalpNAc-(1-->4) -beta-D-GlcpNAc 13, beta-D-GalpNClAc-(1-->4) -beta-D-GlcpNAc 14, alpha -L-Fucp-(1-->3)-beta-D-GlcpNAc 24, alpha-L-Fucp-(1-->4)-beta-D-GlcpNAc 31 and the branched trisaccharide allyl glycoside lpNAc-(1-->4)[alpha -L-Fucp-(1-->3)]-beta-D-GlcpNAc 36. The trisaccharide which correspond s to a. structural motif occurring in N-glycoprotein glycans from huma n urokinase, human recombinant protein C, phospholipase A(2) as well a s O-glycans, was converted into a neoglycoprotein following introducti on of a cysteamine-derived spacer group and subsequent activation with thiophosgene. (C) 1998 Elsevier Science Ltd. All rights reserved.