title: Synthesis of octyl S-glycosides of tri- to pentasaccharide fragments related to the GPI anchor of Trypanosoma brucei.
abstract: The three oligosaccharide octyl-S-glycosides Man-α1,6-Man-α1,4-GlcNH(2)-α1,S-Octyl (19), Man-α1,6-(Gal-α1,3)Man-α1,4-GlcNH(2)-α1,S-Octyl (27) and Man-α1,2-Man-α1,6-(Gal-α1,3)Man-α1,4-GlcNH(2)-α1,S-Octyl (37), related to the GPI anchor of Trypanosoma brucei were prepared by a stepwise and block-wise approach from octyl 2-azido-2-deoxy-3,6-di-O-benzyl-1-thio-α-D-glucopyranoside (8) and octyl 2-O-benzoyl-4,6-O-(1,1,3,3-tetraisopropyl-1,3-disiloxane-1,3-diyl)-1-thio-α-D-mannopyransoside (9). Glucosamine derivative 8 was obtained from 1,3,4,6-tetra-O-acetyl-2-azido-2-desoxy-β-D-glucopyranose (1) in five steps. Mannoside 9 was converted into the corresponding imidate 12 and coupled with 8 to give disaccharide octyl-S-glycoside 13 which was further mannosylated to afford trisaccharide 19 upon deprotection. Likewise, mannoside 9 was galactosylated, converted into the corresponding imidate and coupled with 8 to give trisaccharide 25. Mannosylation of the latter afforded tetrasaccharide 27 upon deprotection. Condensation of 25 with disaccharide imidate 35 gave, upon deprotection of the intermediates, the corresponding pentasaccharide octyl-S-glycoside 37. Saccharides 19, 27 and 37 are suitable substrates for studying the enzymatic glycosylation pattern of the GPI anchor of T. brucei.
authors.affiliation: Institute of Organic Chemistry, University of Tuebingen, Auf der Morgenstelle 18, 72076 Tuebingen, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Dettmann
authors.forename: Thomas
authors.initials: T
authors.lastname: Ziegler
mesh_terms: D002240:Carbohydrate Sequence; D006027:Glycosides / Q000138:chemical synthesis* / Q000737:chemistry; D006031:Glycosylation; D017261:Glycosylphosphatidylinositols / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D014346:Trypanosoma brucei brucei / Q000737:chemistry*
chemical_list: D006027:Glycosides; D017261:Glycosylphosphatidylinositols; D009844:Oligosaccharides