A general and efficient strategy for synthesis of tri-, hexa- and heptasaccharidic substructures of the lipopolysaccharide of Providencia rustigianii O34 is described. For the heptasaccharide seven different building blocks were employed. Special features of the structures are an α-linked galactosamine and the two embedded α-fucose units, which are either branched at positions-3 and -4 or further linked
描述了一种通用且有效的策略,用于合成锈锈菌O34的脂
多糖的三糖,六糖和七糖亚结构。对于七糖,采用了七个不同的结构单元。该结构的特殊特征是一个α-连接的半乳糖胺和两个嵌入的α-岩藻糖单元,它们在3和-4位分支或在其2位进一步连接。收敛策略集中在[4 + 3],[3 + 4]和[4 + 2 + 1]耦合上。[4 + 3]和[3 + 4]耦合策略失败,而[4 + 2 + 1]策略成功。作为
单糖结构单元,使用了三
氯乙
酰亚胺酸酯和
磷酸盐。通过桦木反应实现了完全保护的结构的整体脱保护。