Synthesis of Phosphorylated, Conjugation-Ready Di-, Tri- and Tetrasaccharide Fragments of the O-Specific Polysaccharide ofV. cholerae O139
作者:Bart Ruttens、Rina Saksena、Pavol Kováč
DOI:10.1002/ejoc.200700322
日期:2007.9
3-O-(3-O-benzyl-β-D-galactopyranosyl)-2-deoxy-β-D-glucopyranoside, which was regioselectively phosphorylated to give two isomeric 4,6-cyclic 2,2,2-trichloroethyl phosphates. The (R)-phosphate was subjected to catalytic hydrogenation/hydrogenolysis to give the fully deprotected title disaccharide fragment. Glycosylation of the (S)-phosphate diol with 2,4-di-O-benzyl-3,6-dideoxy-α-L-xylo-hexopyranosyl
所描述的片段包含一个带有环状 4,6-磷酸酯的半乳糖残基,并配有一个氨基功能化的间隔区,允许进一步衍生化或直接结合到合适的载体上。核心 Gal-(13)-GlcNAc 二糖是通过 8-azido-3,6-dioxaoctyl 2-acetamido-4,6-O-benzylidene-2-deoxy-β-D-glucopyranoside 与 2,3, 4,6-四-O-乙酰基-α-D-吡喃半乳糖基溴在 Helferich 条件下。亚苄基缩醛的还原开环,然后去乙酰化和选择性苄基化得到 8-azido-3,6-dioxaoctyl 2-acetamido-6-O-benzyl-3-O-(3-O-benzyl-β-D-galactopyranosyl) -2-脱氧-β-D-吡喃葡萄糖苷,经区域选择性磷酸化得到两个异构的 4,6-环状 2,2,2-三氯乙基磷酸酯。(R)-磷酸盐经过催化氢化/氢解得