involving acetamide groups were found to reduce the reactivity in glycosylations: the protection of NHAc as NAc2 dramatically improved the reactivity. The dodecasaccharide–asparagine framework was constructed via the (4 + 4) glycosylation and the (4 + 8) glycosylation using the tetrasaccharide donor and the tetrasaccharide–asparagine acceptor. An ether-type solvent enhanced the yields of these key glycosylations
实现了包含N-聚糖的核心岩藻糖的
化学合成。在合成的早期引入天冬酰胺,并且糖链会聚地延长。至于片段合成,我们重新研究了α-
唾液酸化,β-
甘露糖基化和N-糖基化,以揭示精确的温度控制对于这些糖基化至关重要。发现涉及乙酰胺基团的分子间氢键会降低糖基化反应性:NHAc作为NAc 2的保护大大提高了反应性。使用四糖供体和四糖-天冬酰胺受体,通过(4 + 4)糖基化和(4 + 8)糖基化构建十二糖-天冬酰胺框架。
醚类溶剂可提高大型底物之间这些关键糖基化的收率。在十二糖完全脱保护之后,获得目标N-聚糖。