天然产物(包括抗生素)的糖基化通常在确定它们的物理特性和生物活性以及它们作为候选药物的潜力方面起着重要作用。芳霉素类抗生素抑制细菌 I 型信号肽酶,由三个相关系列的天然产物组成,脂肽尾连接到核心大环。之前,我们报道了几种具有未修饰核心大环的 A 系列衍生物和具有硝化大环的 B 系列衍生物的全合成。我们现在报告脂糖肽芳霉素变体的合成和生物学评估,其大环用脱氧-α-甘露糖取代基糖基化,并且在某些情况下也被羟基化。带有每种可能的脱氧-α-甘露糖对映体的衍生物的合成使我们能够确定天然产物中糖的绝对立体化学,并表明虽然糖基化不会改变抗菌活性,但它似乎确实提高了溶解度。脂糖肽芳霉素与其信号肽酶靶标结合的晶体结构研究揭示了抑制作用的分子相互作用,并且甘露糖从结合位点被引导到溶剂中,这表明可以在同一位置进行其他修饰以进一步增加溶解度从而减少蛋白质结合并可能优化支架的药代动力学。
Formal Total Synthesis of Diazonamide A by Indole Oxidative Rearrangement
作者:Nadège David、Raffaele Pasceri、Russell R. A. Kitson、Alexandre Pradal、Christopher J. Moody
DOI:10.1002/chem.201601605
日期:2016.7.25
A short formal total synthesis of the marine natural product diazonamide A is described. The route is based on indole oxidative rearrangement, and a number of options were investigated involving migration of tyrosine or oxazole fragments upon oxidation of open chain or macrocyclic precursors. The final route proceeds from 7‐bromoindole by sequential palladium‐catalysed couplings of an oxazole fragment
Two practical entries to arylomycin antibiotics core structures are investigated. In route A, the activation of L-Hpg for the key macrolactamization step is achieved in 89% yield in the presence of unprotected phenol and amine functionalities. Alternatively, a propanephosphonic acid anhydride (T3P)-promoted coupling between theL-Tyr and L-Ala moieties in route B led to a facile macrolactamization in 68% yield with a marked reduction in competing oligomerization.