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  • Title: Synthesis of 2,3-epoxypropyl beta-glycosides of (1----6)-beta-D-galactopyranooligosaccharides and their binding to monoclonal anti-galactan IgA J539 and IgA X24.
    Author: Nashed EM, Glaudemans CP.
    Journal: Carbohydr Res; 1986 Dec 15; 158():125-36. PubMed ID: 3829036.
    Abstract:
    Reaction of 2,3,4-tri-O-acetyl-6-O-(bromoacetyl)-alpha-D-galactopyranosyl bromide (2) with allyl 2,3,4-tri-O-acetyl-beta-D-galactopyranoside gave allyl O-[2,3,4-tri-O-acetyl-6-O-(bromoacetyl)-alpha- and -beta-D-galactopyranosyl]-(1----6)-2,3,4-tri-O-acetyl-beta-D- galactopyranoside, 4 (4%) and 5 (88%), respectively. Selective removal of the bromoacetyl group from 5 gave allyl O-(2,3,4-tri-O-acetyl-beta-D-galactopyranosyl)-(1----6)-2,3,4-tri-O-a cet yl-beta - D-galactopyranoside (6), which, after condensation with 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl bromide (1) yielded both allyl O-(2,3,4,6-tetra-O-acetyl-alpha- and -beta-D-galactopyranosyl)-(1----6)-O-(2,3,4-tri-O-acetyl-beta-D- galactopyranosyl)-(1----6)-2,3,4-tri-O-acetyl-beta-D-galactopyranoside, 7 (10%) and 8 (70%), respectively. When 6 was condensed with 2, allyl O-[2,3,4-tri-O-acetyl-6-O-(bromoacetyl)-beta-D-galactopyranosyl]-(1----6 )-O- (2,3,4-tri-O-acetyl-beta-D-galactopyranosyl)-(1----6)-2,3,4-tri-O-acetyl -beta-D - galactopyranoside (75%) was obtained. This was selectively O-de(bromoacetyl)ated to yield the nonaacetate, which was condensed with bromide 1 to give allyl O-(2,3,4,6-tetra-O-acetyl-alpha- and -beta-D-galactopyranosyl)-(1----6)-O-(2,3,4-tri-O-acetyl-beta-D- galactopyranosyl)-(1----6)-O-(2,3,4-tri-O-acetyl-beta-D-galactopyranosyl )- (1----6)-2,3,4-tri-O-acetyl-beta-D-galactopyranoside, 14 (4%) and 15 (70%). Epoxidation of the allyl group of 8 and 15 with m-chloroperoxybenzoic acid, and removal of the acetyl protecting groups with sodium methoxide, gave, respectively, 2,3-epoxypropyl O-beta-D-galactopyranosyl-(1----6)-O-beta-D-galactopyranosyl-(1----6)-be ta-D- galactopyranoside (17) and the corresponding tetrasaccharide 19. Sequential acetylation and O-debenzylation of 6-O-benzyl-D-galactose, followed by coupling of the product with bromide 1, yielded O-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)-(1----6)-1,2,3,4-tetr a-O- acetyl-beta-D-galactopyranose (12). Conversion of 12 into the bromide by treatment with bromotrimethylsilane, and condensation of the product with nucleophile 6 also gave the beta-linked tetrasaccharide 15 of this series. Epoxidation of the allyl group, followed by removal of acetyl blocking groups in the latter compound, again gave 2,3-epoxypropyl O-beta-D-galactopyranosyl-(1----6)-O-beta-D-galactopyranosyl-(1----6)-O- beta-D- galactopyranosyl-(1----6)-beta-D-galactopyranoside (19).(ABSTRACT TRUNCATED AT 400 WORDS)
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