Mulard L A, Glaudemans C P
NIDDK, National Institutes of Health, Bethesda, MD 20892, USA.
Carbohydr Res. 1998 Sep;311(3):121-33. doi: 10.1016/s0008-6215(98)00216-x.
The blockwise synthesis of methyl alpha tri- and tetrasaccharide analogs of the biochemical repeating unit of the Shigella dysenteriae type 1 O-polysaccharide is described. Modifications include deoxygenation and deoxyfluorination at position 3 of the galactopyranoside residue. Methyl 4,6-O-benzylidene-3-deoxy-alpha-D-xylo-hexopyranoside (8) and methyl 4,6-O-benzylidene-3-deoxy-3-fluoro-alpha-D-galactopyranoside (9) were condensed with (2,3,4-tri-O-benzoyl-alpha-L-rhamnopyranosyl)-(1-->3) -2,4-di-O-benzoyl-alpha-L-rhamnopyranosyl chloride to give, after deprotection, the target trisaccharide methyl alpha-L-rhamnopyranosyl-(1-->3)-alpha-L- rhamnopyranosyl-(1-->2)-3-deoxy-alpha-D-xylo-hexopyranoside and the corresponding fluorinated oligosaccharide. For the tetrasaccharide synthesis, the glycosyl acceptors 8 and 9 were condensed with the temporarily protected (2,4-di-O-benzoyl-3-O-chloroacetyl-alpha-L- rhamnopyranosyl)-(1-->3)-2,4-di-O-benzoyl-alpha-L-rhamnopyranosyl chloride. Removal of the chloroacetyl group was followed by condensation of the resulting selectively deblocked trisaccharides with 3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha-D-glucopyranosyl chloride. Reduction and deprotection then gave the free methyl 2-acetamido-2-deoxy- alpha-D-glucopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl- (1-->3)-alpha-L-rhamnopyranosyl-(1-->2)-3-deoxy-alpha-D-xylo-hexopyra noside and the fluorinated analog.
描述了痢疾志贺氏菌1型O -多糖生化重复单元的甲基α -三糖和四糖类似物的逐步合成。修饰包括在吡喃半乳糖残基的3位进行脱氧和脱氧氟化。将4,6 - O -亚苄基 - 3 -脱氧 - α - D -吡喃木糖甲基苷（8）和4,6 - O -亚苄基 - 3 -脱氧 - 3 -氟 - α - D -吡喃半乳糖甲基苷（9）与（2,3,4 - 三 - O -苯甲酰基 - α - L -吡喃鼠李糖基） - （1→3） - 2,4 -二 - O -苯甲酰基 - α - L -吡喃鼠李糖基氯缩合，脱保护后得到目标三糖甲基α - L -吡喃鼠李糖基 - （1→3） - α - L -吡喃鼠李糖基 - （1→2） - 3 -脱氧 - α - D -吡喃木糖苷和相应的氟化寡糖。对于四糖合成，将糖基受体8和9与临时保护的（2,4 -二 - O -苯甲酰基 - 3 - O -氯乙酰基 - α - L -吡喃鼠李糖基） - （1→3） - 2,4 -二 - O -苯甲酰基 - α - L -吡喃鼠李糖基氯缩合。除去氯乙酰基后，将所得的选择性脱保护的三糖与3,4,6 -三 - O -乙酰基 - 2 -叠氮基 - 2 -脱氧 - α - D -吡喃葡萄糖基氯缩合。然后进行还原和脱保护，得到游离的甲基2 -乙酰氨基 - 2 -脱氧 - α - D -吡喃葡萄糖基 - （1→3） - α - L -吡喃鼠李糖基 - （1→3） - α - L -吡喃鼠李糖基 - （1→2） - 3 -脱氧 - α - D -吡喃木糖苷和氟化类似物。
