Galacturonic Acid Lactones in the Synthesis of All Trisaccharide Repeating Units of the Zwitterionic Polysaccharide Sp1
作者:Alphert E. Christina、Leendert J. van den Bos、Herman S. Overkleeft、Gijsbert A. van der Marel、Jeroen D. C. Codée
DOI:10.1021/jo102363d
日期:2011.3.18
A modular approach toward the synthesis of all possible trimer repeating units of the type 1 capsular polysaccharide of Streptococcus pneumonia, Sp1, is described. This zwitterionic polysaccharide is built up from trisaccharide repeats, which in turn are composed of two galacturonic acid monomers and a 2,4,6-trideoxy-4-amino-2-acetamido-d-galactose moiety. All monomeric constituents are linked through
描述了一种模块化方法,用于合成肺炎链球菌Sp1的1型荚膜多糖的所有可能的三聚体重复单元。这种两性离子多糖选自三糖重复序列,而这又是由两个半乳糖醛酸的单体的建立和2,4,6-三脱氧-4-氨基-2-乙酰氨基d半乳糖基部分。所有单体成分均通过顺式连接-糖苷键。为了克服与有效立体选择性引入α-半乳糖醛酸键相关的困难,我们采用了半乳糖醛酸-[3,6]-内酯结构单元。当用作供体半乳糖苷时,这些结构单元不仅表现良好,而且当具有游离羟基功能时,它们还被证明是反应性受体糖苷。除高度例外,所有三个移码三聚体重复均通过高度立体选择性糖基化反应构建。在非选择性糖基化事件中形成的三糖的差向异构体混合物,在全局脱保护后,可以使用高效阴离子交换色谱(HPEAC)轻松分离。