Department of Applied Chemistry, National Chiao Tung University, Taiwan, ROC, 1001, Ta Hsueh Road, Hsinchu, Taiwan, 300 Taiwan.
Chem Asian J. 2010 May 3;5(5):1152-62. doi: 10.1002/asia.200900765.
The beta-selectivity of mannosylation has been found to be dependent on the addition rate of the mannosyl trichloroacetimidate donor in an inverse-addition (I-A) procedure. This rate dependent I-A procedure can improve the selectivity of direct beta-mannosylation and is applicable to orthogonal glycosylations of thioglycoside acceptors. Further elaboration of this novel procedure enables the development of the contiguous sequential glycosylation strategy, which streamlines the preparation of oligosaccharides invoking beta-mannosidic bond formation. The synthetic utility of the contiguous glycosylation strategy was demonstrated by the preparation of the trisaccharide core of human N-linked glycoproteins and the trisaccharide repeating unit of the O-specific polysaccharide found in the cellular capsule of Salmonelle bacteria.
人们发现，在反加法（I-A）过程中，甘露糖基三氯乙酰亚胺供体的加成速率决定了甘露糖化的β选择性。这种依赖于速率的 I-A 程序可以提高直接β-甘露糖化的选择性，并且适用于硫代糖苷受体的正交糖基化。对该新程序的进一步阐述使连续顺序糖基化策略得以发展，从而简化了涉及β-甘露糖苷键形成的寡糖的制备。通过制备人 N-连接糖蛋白的三糖核心和在细菌细胞胶囊中发现的 O-特异性多糖的三糖重复单元，展示了连续糖基化策略的合成实用性。
