几种齐墩果酸糖缀合物的合成

报道了齐墩果酸与四种单糖和二糖（葡萄糖、半乳糖、乳糖及葡萄糖醛酸）进 行糖苷化制备糖缀合物的方法。在合成过程中首先将葡萄糖、半乳糖及乳糖转化成 相应的全苯甲酰三氯亚胺酯糖基供体（10a-10c），将葡萄糖醛酸转化成为1-溴代 乙酰葡萄糖醛酸甲酯糖基供体（10d）；在齐墩果酸的28-位羧基上进行酰胺化引入 ω-氨基羧酸甲酯得到其衍生物6。然后10a-10c在TMSOTf的催化下与化合物6的3-位 羟基进行β-糖苷化；10d在AgOTf的催化下与6进行β-糖苷化，最后脱掉保护基得 到相应的糖缀合物13a-13d，所有目的化合物均为新化合物，其结构经IR，^1H NMR，^13C NMR，2D-COSY，HMQC，DEPT及HRMS进行了确证。

Synthesis of Oleanolic Acid Glycoconjugates

Four glycoconjugates (D-glucose, D-galactose, D -lactose and D - glucuronic acid) of oleanolic acid were synthesized through a facile approach. Firstly, D -glucose, D -galactose and D-lactose were converted into benzoyl group protected glycosyl trichloroacetimidates (lOa ~ lOc) as donors. D-glucuronic acid was converted into methyl (tri- 0-acetyl-a-.D-glucopyranosyl bromide)-uronate (lOd) as donor. Secondly, oleanolic acid was converted into methyl A~r-(3-hydroxylolean-12-en-28- oyl)-6-aminohexanoate (6). Then the coupling of the sugar moieties (10a~ lOc) to 3-OH of 6 was promoted by trimethylsilyl trifluoromethanesulfonate (TMSOTf) . AgOTf was used as the promoter in the glycosylation of lOd with 6. Finally, deprotection of the corresponding glycocongjugates afforded the target products 13a ~ 13d. The structures of all products were characterized by IR,~1H NMR, ~13C NMR, DEPT, tow-dimensional shift-correlated spectra (COSY, HMQC) and HRMS.