中文摘要：

目的通过化学合成的手段进行褐藻胶中甘露糖醛酸二糖的合成。方法以甘露糖为起始原料，利用α-甘露糖基三氟甲磺酸酯中间体经SN2亲核取代反应直接构建伊甘露糖苷键，然后选择性的氧化6-位羟基得到甘露糖醛酸二糖苷。结果利用4，6位苄又保护的甘露糖硫苷5作为糖基供体，高立体选择性的构建了伊（1，4）一甘露糖苷键，然后利用TEMPO／BAIB选择性的氧化6-位羟基得到了β-D-（1，4）-甘露糖醛酸二糖甲基苷15。结论该研究为下一步合成聚合度更高的系列褐藻胶寡糖及其衍生物提供了有效的合成策略和方法。

英文摘要：

Objective To prepare structure-well-defined alginate disaccharides by chemical synthesis method. Methods Starting from the D-mannose, the β-mannopyranoside was directly synthesized through α- mannosyl triflate under the mechanism of SN2 substitution. β-mannopyranoside was followed by selec- tive oxidation on 6-OH to give target compound mannuronic acid disaccharide. Results By using 4,6-di- O-benzylidene-protected 1-thio mannoside 5 as a glycosyl donor, the stereoselective/3-D-mannosylation protocol provided the/3-（1,4）-D-mannobiose derivative, which upon regioselective oxidation on 6-OH with TEMPO/BAIB yielded the corresponding methyl β-1,4-di-D-mannuronic acid 15. Conclusion The research provided method and protocols for the synthesis of more alginate oligosaccharides in the future.