Pozsgay V, Jennings H J
Division of Biological Sciences, National Research Council of Canada, Ottawa, Ontario.
Carbohydr Res. 1988 Aug 15;179:61-75. doi: 10.1016/0008-6215(88)84110-7.
Condensation of methyl 2,3-O-isopropylidene-alpha-L-rhamnopyranoside with methyl 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-1-thio-beta-D-glucopyranoside activated by nitrosyl tetrafluoroborate gave an excellent yield of the protected disaccharide 9, which was transformed into glycosyl acceptor 11. Methyl 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-galactopyranoside, obtained from D-galactose penta-acetate and methyl trimethylsilyl sulfide, under catalysis by boron trifluoride etherate, was converted into glycosyl donor 25, which was condensed with 11 under halide-ion catalysis to give the trisaccharide derivative 26. Rhamnosylation with 28 of 27, obtained by selective deprotection of 26, gave the protected tetrasaccharide 29. Deprotection of 10, 26, and 29 gave di- (2), tri- (3) and tetra-saccharide (4) methyl glycosides which form part of the group-specific polysaccharide antigen of Group B Streptococci.
2,3 - O - 异亚丙基 - α - L - 鼠李吡喃糖苷与由四氟硼酸亚硝酰活化的3,4,6 - 三 - O - 乙酰基 - 2 - 脱氧 - 2 - 邻苯二甲酰亚氨基 - 1 - 硫代 - β - D - 吡喃葡萄糖苷缩合，以优异的产率得到受保护的二糖9，其被转化为糖基受体11。由D - 半乳糖五乙酸酯和甲基三甲基硅基硫醚制得的2,3,4,6 - 四 - O - 乙酰基 - 1 - 硫代 - β - D - 吡喃半乳糖苷，在三氟化硼乙醚催化下转化为糖基供体25，其在卤离子催化下与11缩合得到三糖衍生物26。通过对26进行选择性脱保护得到的27用28进行鼠李糖基化反应，得到受保护的四糖29。对10、26和29进行脱保护得到二糖（2）、三糖（3）和四糖（4）甲基糖苷，它们是B族链球菌群特异性多糖抗原的一部分。
