Chaudhury Aritra, Mukherjee Mana Mohan, Ghosh Rina
Department of Chemistry, Jadavpur University, 188, Raja S. C. Mullick Rd., Kolkata 700032, India.
Department of Chemical Sciences, Indian Institute of Science Education and Research, Kolkata, Mohanpur, 741246, West Bengal, India.
Beilstein J Org Chem. 2018 May 17;14:1095-1102. doi: 10.3762/bjoc.14.95. eCollection 2018.
(SPn) is a Gram-positive bacterium which causes life threatening diseases. The bacteria protect themselves against non-specific host defence by an external polysaccharide (PS) capsule which bears a repeating unit, α-D-Galp(1->3)-α-D-Glcp(1->3)-α-L-Rhap(1->3)-D-Rib (SPn 6A). A closer look at the structure reveals the presence of α-linked galactose and glucose residues. The synthesis of these 1,2- glycosidic linkages are considered challenging particularly in the context of a one-pot oligosaccharide synthesis. We have synthesized the aforesaid tetrasaccharide (SPn 6A) based on both stepwise and sequential one-pot glycosylation reactions using easily accessible common building blocks; eventually similar overall yields were obtained in both cases.
肺炎链球菌（SPn）是一种革兰氏阳性细菌，可引发危及生命的疾病。该细菌通过带有重复单元α-D-半乳糖（1->3）-α-D-葡萄糖（1->3）-α-L-鼠李糖（1->3）-D-核糖（SPn 6A）的外部多糖（PS）荚膜来抵御非特异性宿主防御。仔细观察其结构会发现存在α-连接的半乳糖和葡萄糖残基。这些1,2-糖苷键的合成被认为具有挑战性，特别是在一锅法寡糖合成的背景下。我们使用易于获得的常见构建块，基于逐步和连续一锅法糖基化反应合成了上述四糖（SPn 6A）；最终在两种情况下都获得了相似的总产率。
