bromide. Thus, syntheses of the protected tri- and tetrasaccharides were achieved easily and efficiently using known building blocks. Of particular interest, we also report that these protected oligosaccharides were submitted to dissolving metal conditions (Na-NH(3)) to provide in one single step the corresponding deprotected compounds. Under these conditions all protecting groups (O-acyl, benzylidene
我们在这里描述了肿瘤相关的
碳水化合物抗原Le(a)Le(x)的两个
寡糖片段的合成。线性
乳糖N-三糖I:β-D-Galp-(1-> 4)-β-D-GlcNAcp-(1-> 3)-β-D-Galp-OMe是已知的化合物,这是第一个报道的支链四糖β-D-GlcNAcp-(1-> 3)-β-D-Galp-(1-> 4)-[α-1-Fucp-(1-> 3)]-β-D-GlcNAcp-OMe。我们的合成方案涉及使用在0摄氏度下用过量TMSOTf活化的N-三
氯乙酰化三
氯乙酰亚
氨酸酯
氨基葡萄糖供体在O-3上半
乳糖基残基的O-3糖基化和用过量BF(3).OEt(2)活化以糖基化的三
氯乙酰亚
氨基半
乳糖基供体的糖基化O-3或O-4的
氨基葡萄糖残基。
葡糖胺受体在O-3处的岩藻糖基化反应是通过用
溴化铜(II)和
溴化四丁基
铵活化的
硫代
葡糖苷供体完成的。因此,使用已知的结构单元容易且有效地实现了被保护的三糖和四糖的合成