- Improving glycopeptide synthesis: A convenient protocol for the preparation of β-glycosylamines and the synthesis of glycopeptides
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(Chemical Equation Presented) Herein we apply a recently introduced protocol using ammonium carbamate in methanol to the amination of crude chitobiose leading to 1,β-aminochitobiose. This simple, one-step procedure allows a facile preparation of unstable glycosylamines in contrast to the commonly implemented ammonium bicarbonate based amination of water-soluble carbohydrates. The new amination protocol leads to an improved synthesis of the key chitobiosyl-asparagine building block for the SPPS of glycopeptides. The utility of the method is demonstrated with the synthesis of a 39-amino acid glycoprotein.
- Hackenberger, Christian P. R.,O'Reilly, Mary K.,Imperiali, Barbara
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p. 3574 - 3578
(2007/10/03)
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- Synthesis of trisaccharide determinants of enterobacterial common antigens
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In the presence of silver silicate, the reaction of 3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha-D-mannopyranosyl bromide with 1,6-anhydro-2-azido-3-O-benzyl-2-deoxy-beta-D-glucopyranose gave beta-glycosidically linked 1,6-anhydro-2-azido-3-O-benzyl-2-deoxy-4-O-(3,4,6- tri-O-acetyl-2-azido-2-deoxy-beta-D-mannopyranosyl)-beta-D- glucopyranose. After deacetylation and catalytic oxidation with oxygen and platinum, 1,6-anhydro-2-azido-4-O-[(2-azido-2-deoxy-beta-D-mannopyranosyl) uronic acid]-3-O-benzyl-2-deoxy-beta-D-glucopyranose was obtained. A series of intermediate steps led to the glycosyl donor 6-O-acetyl-2-azido-3-O-benzyl-4-O-[benzyl (3,4-di-O-acetyl-2-azido-2-deoxy-beta-D-mannopyranosyl)uronate]-2-deoxy- alpha, beta-glucopyranosyl chloride which was coupled with 8-methoxycarbonyloctyl 4-azido-2-O-benzyl-4,6-dideoxy-alpha-D-galactopyranoside to give 8-methoxycarbonyloctyl O-[benzyl (3,4-di-O-acetyl-2-azido-2-deoxy-beta-D-mannopyranosyl)uronate]- (1----4)-O-(6-O-acetyl-2-azido-3-O-benzyl-2-deoxy-alpha-D-glucopyranosyl )-(1----3)-4-azido-2-O-benzyl-4,6-dideoxy-alpha-D-galactopyranoside. Deblocking gave the spacer-linked repeating unit of the enterobacterial common antigen, beta-D-ManpNAcA-(1----4)-alpha-D-GlcpNAc-(1----3)-alpha- D-Fucp4NACO(CH2)8CO2CH3.
- Paulsen,Lorentzen
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