Synthesis of a Tri- and Tetrasaccharide Fragment Specific for the <i>Shigella flexneri</i> Serotype 5a <i>O</i>-Antigen. A Reinvestigation
作者:Laurence A. Mulard、Joël Ughetto-Monfrin
DOI:10.1080/07328309908544033
日期:1999.1.1
Stereocontrolled, stepwise synthesis of methyl α-L-rhamnopyranosyl-(1→2)-[α-D-glucopyranosyl-(1→3)]-α-L-rhamnopyranoside (A(E)B, 1) and methyl 2-acetamido-2-deoxy-β-D-glucopyranosyl-(1→2)-α-L-rhamnopyranosyl-(1→2)-[α-D-glucopyranosyl-(1→3)]-α-L-rhamnopyranoside (DA(E)B, 2) is described; these constitute the methyl glycosides of fragments of the O-specific polysaccharide of Shigella flexneri serotype
立体控制逐步合成甲基α-L-鼠李吡喃糖苷-(1→2)-[α-D-吡喃葡萄糖基-(1→3)]-α-L-鼠李吡喃糖苷(A(E)B,1)和甲基2-乙酰氨基-2-脱氧-β-D-吡喃吡喃糖基-(1→2)-α-L-鼠李吡喃糖基-(1→2)-[α-D-吡喃吡喃糖基-(1→3)]-α-L-鼠李糖吡喃糖苷(描述了DA(E)B,2);这些构成了志贺氏志贺氏菌血清型5a的O-特异性多糖的片段的甲基糖苷。考虑了三糖1的两种途径。路线1涉及前体与残基A和二糖EB的偶联,而路线2基于前体与残基E和二糖的缩合。AB。出乎意料的是,后者提供了1的β-异头物,即甲基α-L-鼠李吡喃糖基-(1→2)-[β-D-吡喃吡喃糖基-(1→3)]-α-L-鼠李糖吡喃糖苷。 。首选路线1。总体而言,在这项研究中进行的一些观察表明,为了构建更高的片段,鼠李糖A的合适前体将需要在位置3和4处具有低膨松度的保护基团。因此,2- O-乙酰基3,