甜菊糖苷Rebaudioside_省略_udioside_S的全合成研究.pdf

摘 要 以简单易得的单糖和甜菊醇为原料完成了Rebaudioside R 和 Rebaudioside S 的首次全合成。采用线性和汇聚式的方式合成了Rebaudioside R 中C13-OH 上的 双支链三糖，在线性合成的过程中，发现了羟基邻位的保护基对糖苷化的发生有 重要影响；汇聚式的合成通过三糖俞氏给体以及乙腈的溶剂效应来构建关键的三 糖β 糖苷键，保证了整体的合成效率。通过模块化的策略，不仅完成了对文献提 出的Rebaudioside S 及其类似物的全合成，同时完成了其结构修正，通过对2 支 链的二糖俞氏给体与甜菊醇的糖苷化系统研究发现 2 位支链糖糖苷键的构型对 二糖给体糖苷化产物的立体选择性有重要影响。 关键词：Rebaudioside R ；Rebaudioside S ；糖苷化；结构修正；立体选择 性。 I Abstract With easy available monosaccharides as well as steviol as starting materials, the first total synthesis of rebaudioside R and Rebaudioside S were accomplished. Trisaccharide sugar chain in the C13-OH of rebaudioside R was formed via linear and convergent strategies. During the linear synthetic study, the effect of protecting groups (PGs) at vicinal hydroxy group on the reactivity of OH acceptors was illustrated. Trisaccharide Yu donors and nitrile solvent effect were used to forge the key β configuration glucosidic bond in the C13-OH via a convergent strategy, securing the overall synthetic efficiency.Through the modular strategy, the total synthesis of rebaudioside S and its analogues were achieved, at the same time the originally proposed structure was also revised. the effect of the internal glycosidic linkage configuration on the glycosylation stereoselectivity of disaccharide donors was disclosed during the systematic study of the glcosylation between C2-branched disaccharide Yu donors concerned and C13-OH of steviol. Key words : Rebaudioside R ，Rebaudioside S ，glycosylation, structure revision, stereoselectivity. II 目 录 摘 要 I Abstract II 第一章 前言 1 1.1.糖的生物学意义1 1.2.糖苷化反应的研究进展3