Unnatural Oligoaminosaccharides with N-1,2-Glycosidic Bonds Prepared by Cationic Ring-Opening Polymerization of 2-Oxazoline-Based Heterobicyclic Sugar Monomers
Unnatural Oligoaminosaccharides with N-1,2-Glycosidic Bonds Prepared by Cationic Ring-Opening Polymerization of 2-Oxazoline-Based Heterobicyclic Sugar Monomers
复制标题
2-恶唑啉基杂双环糖单体阳离子开环聚合制备具有 N-1,2-糖苷键的非天然低聚氨基糖
DOI：
10.1021/acsmacrolett.9b00674
复制
发表时间：
2019
影响因子：
7.015
通讯作者：
Ouchi Makoto
中科院分区：
文献类型：
--
作者：
Koda Yuta;Terashima Takaya;Ouchi Makoto
糖异构体和糖共聚物（糖化合物）在维持生物系统的稳态中起着重要的作用。糖生物学是阐明生物系统的一个新兴领域，其中糖化合物的分子设计需要进一步多样化，包括天然和非天然糖化合物。在此，我们提出了一种基于故意设计的糖单体链聚合的合成策略。以2-恶唑啉基杂环糖单体为原料，采用阳离子开环聚合法合成了n -1,2-糖苷键的非天然低氨基糖。为此，设计了一种杂双环单体[Glc(MeOx)]，包括受保护的氨基葡萄糖（GlcN）和2-甲基-2-恶唑啉（MeOx）环。该单体采用碘化叔丁基（t-BuI）和gacl3二元引发体系聚合得到低聚物[Glc(MeOx)]。所得到的结构对应于GlcN在n -1,2-糖苷键内的缩合产物。低聚物[Glc(MeOx)]去保护后，得到的低聚氨基糖二级结构与受保护的低聚物[Glc(MeOx)]不同。由于存在then -1,2-糖苷键，几丁质酶无法降解低聚氨基糖，通过ho -1,4-糖苷键水解GlcN的缩合产物。
Glycooligomers and glycopolymers (glycocompounds) play important roles in maintaining homeostasis in biological systems. Glycobiology is a burgeoning area in the elucidation of biological systems for which the molecular design of glycocompounds requires further diversification, including both natural and unnatural glycocompounds. Herein, we proposed a synthesis strategy based on the chain polymerization of deliberately designed sugar monomers. Unnatural oligoaminosaccharides comprisingN-1,2-glycosidic bonds were synthesized without enzymes through the cationic ring-opening polymerization of 2-oxazoline-based heterobicyclic sugar monomers. To achieve this, a heterobicyclic monomer [Glc(MeOx)], comprising protected glucosamine (GlcN) and 2-methyl-2-oxazoline (MeOx) rings, was designed. This monomer was polymerized using a binary initiating system oftert-butyl iodide (t-BuI) and GaCl3to afford oligo[Glc(MeOx)]. The resulting structure corresponded to the condensation product of GlcN withN-1,2-glycosidic bonds. After deprotection of oligo[Glc(MeOx)], the resulting oligoaminosaccharide had a secondary structure different to that of protected oligo[Glc(MeOx)]. Owing to theN-1,2-glycosidic bonds, the oligoaminosaccharide was not degraded by chitinase, which hydrolyzes the condensation product of GlcN withO-1,4-glycosidic bonds.