A straightforward synthetic strategy was developed for the synthesis of the tetrasaccharide repeating unit corresponding to the O-specific polysaccharide of Azospirillum doebereinerae type strain GSF71^T in a very good yield adopting sequential glycosylation followed by removal of the p-methoxybenzyl (PMB) group in the same pot. Further, the synthetic strategy was modified by carrying out three stereoselective iterative glycosylations followed by in situ removal of the PMB group in one pot. The stereochemical outcome of the newly formed glycosidic linkages was excellent using thioglycoside derivatives as glycosyl donors and a combination of N-iodosuccinimide (NIS) and perchloric acid supported on silica (HClO₄-SiO₂) as the glycosyl activator.

中文翻译：

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利用线性和一锅式迭代糖基化方法合成杜氏固氮螺旋藻型菌株GSF71T的O特异性多糖的四糖重复单元。

开发了一种简单的合成策略来合成四糖重复单元，该四糖重复单元对应于doesberillneraeae型菌株GSF71 ^T的O特异性多糖，采用顺序糖基化，然后去除肽中的对甲氧基苄基（PMB）基团，具有很高的收率。同一个锅。此外，通过进行三个立体选择性迭代糖基化，然后在一锅中原位去除PMB基团，对合成策略进行了修改。使用硫代糖苷衍生物作为糖基供体以及N-碘代琥珀酰亚胺（NIS）和高氯酸负载在二氧化硅（HClO）上的组合，新形成的糖苷键的立体化学结果极好_4- SiO ₂）作为糖基活化剂。