Syntheses of model compounds related to an antigenic epitope in pectic polysaccharides from Bupleurum falcatum L. Original Research Article

Stereocontrolled syntheses of model compounds related to a category of the major antigenic epitope against anti-bupleurum 2IIc/PG-1-IgG from an anti-ulcer pectic polysaccharide are described. Glycosylation of the glucuronic acid donors methyl(2,3-di-O-benzoyl-4-O-methyl-α-d-glucopyranosyl trichloroacetimidate)uronate and methyl (2,3-di-O-benzoyl-4-O-methyl-β-d-glucopyranosyl)uronate-(1→6)-2,3,4-tri-O-benzoyl-α-d-galactopyranosyl trichloroacetimidate with the common acceptor 2-(trimethylsilyl)ethyl 2,3,4-tri-O-benzyl-β-d-galactopyranoside in the presence of trimethylsilyl triflate (TMSOTf) gave the desired di- and trisaccharide derivatives. Furthermore the products were transformed into the oligo-valent clustering saccharides, N,N′,N′′-tri-{5-[4-O-methyl-β-d-glucopyranosyluronic acid-(1→6)-β-d-galactopyranosyloxy]pentylcarbonylaminoethyl}-1,3,5-benzenetriamide and N,N′,N′′-tri-{5-[4-O-methyl-β-d-glucopyranosyluronic acid (1→6)-β-d-galactopyranosyl-(1→6)-β-d-galactopyranosyloxy]pentylcarbonylaminoethyl}-1,3,5-benzenetriamide.