title: Synthesis of a selectively protected trisaccharide building block that is part of xylose-containing carbohydrate chains from N-glycoproteins.
abstract: The synthesis is reported of ethyl 4-O-[3-O-allyl-4,6-O-isopropylidene-2-O-(2,3,4-tri-O-acetyl-beta-D- xylopyranosyl)-beta-D-mannopyranosyl]-3,6-di-O-benzyl-2-deoxy-2-phthalim ido-1 - thio-beta-D-glucopyranoside (16), a key intermediate in the synthesis of xylose-containing carbohydrate chains from N-glycoproteins. Condensation of ethyl 3,6-di-O-benzyl-2-deoxy-2-phthalimido-1-thio-beta-D- glucopyranoside (5) with 2,4,6-tri-O-acetyl-3-O-allyl-alpha-D-glucopyranosyl bromide, using silver triflate as a promoter, gave the beta-linked disaccharide derivative 8 (84%). O-Deacetylation of 8 and then isopropylidenation afforded 10, which was converted via oxidation-reduction into ethyl 4-O-(3-O-allyl-4,6-O-isopropylidene-beta-D-mannopyranosyl)-3,6-di-O-benz yl-2- deoxy-2-phthalimido-1-thio-beta-D-glucopyranoside (12). Silver triflate-promoted condensation of 12 with 2,3,4-tri-O-acetyl-alpha-D-xylopyranosyl bromide gave 16 (71%). The Xylp unit in 16 and in de-isopropylidenated 16 (17) existed in the 1C4(D) conformation, but that in O-deacetylated 17 (18) existed in the 4C1(D) conformation.
authors.affiliation: Institute of Biochemistry, L. Kossuth University, Debrecen, Hungary.
authors.forename: J
authors.initials: J
authors.lastname: Kerékgyártó
authors.forename: J G
authors.initials: JG
authors.lastname: van der Ven
authors.forename: J P
authors.initials: JP
authors.lastname: Kamerling
authors.forename: A
authors.initials: A
authors.lastname: Lipták
authors.forename: J F
authors.initials: JF
authors.lastname: Vliegenthart
mesh_terms: D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D006023:Glycoproteins / Q000138:chemical synthesis / Q000737:chemistry*; D006027:Glycosides / Q000138:chemical synthesis*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D014312:Trisaccharides / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D006023:Glycoproteins; D006027:Glycosides; D009844:Oligosaccharides; D014312:Trisaccharides; C010807:xylosides