title: [Synthesis of aminoethyl glycosides of the carbohydrate chains of glycolipids Gb3, Gb4 i Gb5].
abstract: 4-O-Glycosylation of 2-azidoethyl 2,3,6-tri-O-benzoyl-4-O-(2,3,6-tri-O-benzoyl-beta-D-galactopyranosyl)-beta- D-glucopyranoside with ethyl 2,3,4,6-tetra-O-benzyl- and ethyl 3-O-acetyl-2,4,6-tri-O-benzyl-1-thio-alpha-D-galactopyranoside in the presence of methyl trifluoromethanesulfonate led to trisaccharide 2-azidoethyl (2,3,4,6-tetra-O-benzyl-alpha-D-galactopyranosyl)-(1-->4)- (2,3,6-tri-O-benzoyl-beta-D-galactopyranosyl)-(1-->4)2,3,6-tri-O- benzoyl-beta-D-glucopyranoside and its 3"-O-acetylated analogue, 2-azidoethyl (3-O-acetyl-2,4,6-tri-O-benzyl- alpha-D-galactopyranosyl)-(1-->4)-(2,3,6-tri-O-benzoyl-beta-D- galactopyranosyl)-(1-->4)-2,3,6-tri-O-benzoyl-beta-D-glucopyranoside, in yields of 85 and 83%, respectively. Deacetylation of the latter compound and subsequent glycosylation with 4-trichloroacetamidophenyl 3,4,6-tri-O-acetyl-2-deoxy-1-thio-2-trichloroacetamido-beta-D- galactopyranoside and 4-trichloroacetamidophenyl 4,6-di-O-acetyl-2-deoxy-3-O-(2,3,4,6-tetra-O- acetyl-beta-D-galactopyranosyl)-1-thio-2-trichloroacetamido-beta-D- galactopyranoside in dichloromethane in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid resulted in the corresponding selectively protected derivatives of tetrasaccharide GalNAc(beta 1-->3)Gal(alpha 1-->4)Gal(beta 1-->4)Glc beta-OCH2CH2N3 and pentasaccharide Gal(beta 1-->3)GalNAc(beta 1-->3)Gal(alpha 1-->4)Gal(beta 1-->4)Glc beta-OCH2CH2N3 in 88 and 73% yields, respectively. Removal of O-protecting groups, substitution of acetyl group for N-trichloroacetyl group, and reduction of the aglycone azide group resulted in the target 2-aminoethyl globo-tri-, -tetra-, and -pentasaccharide, respectively.
authors.affiliation: Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninskii pr. 47, Moscow, 119991 Russia.
authors.forename: P E
authors.initials: PE
authors.lastname: Cheshev
authors.forename: E A
authors.initials: EA
authors.lastname: Khatuntseva
authors.forename: A G
authors.initials: AG
authors.lastname: Gerbst
authors.forename: Iu E
authors.initials: IuE
authors.lastname: Tsvetkov
authors.forename: A S
authors.initials: AS
authors.lastname: Shashkov
authors.forename: N E
authors.initials: NE
authors.lastname: Nifant'ev
mesh_terms: D002240:Carbohydrate Sequence; D005690:Galactose / Q000737:chemistry; D006017:Glycolipids / Q000138:chemical synthesis* / Q000737:chemistry; D006027:Glycosides / Q000138:chemical synthesis* / Q000737:chemistry; D006031:Glycosylation; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D015394:Molecular Structure
chemical_list: D006017:Glycolipids; D006027:Glycosides; D005690:Galactose