Convergent and Modular Synthesis of Candidate Precolibactins. Structural Revision of Precolibactin A
作者:Alan R. Healy、Maria I. Vizcaino、Jason M. Crawford、Seth B. Herzon
DOI:10.1021/jacs.6b02276
日期:2016.4.27
Escherichia coli. The metabolites are encoded by the clb gene cluster as prodrugs termed precolibactins. clb(+) E. coli induce DNA double-strand breaks in mammalian cells in vitro and in vivo and are found in 55-67% of colorectal cancer patients, suggesting that mature colibactins could initiate tumorigenesis. However, elucidation of their structures has been an arduous task as the metabolites are obtained
大肠杆菌素是由某些共生和肠外致病性大肠杆菌菌株产生的混合聚酮化合物-非核糖体肽天然产物。代谢物由 clb 基因簇编码,称为前体药物。clb(+) 大肠杆菌在体外和体内诱导哺乳动物细胞 DNA 双链断裂,并且在 55-67% 的结肠直肠癌患者中发现,表明成熟的大肠杆菌素可以引发肿瘤发生。然而,阐明它们的结构一直是一项艰巨的任务,因为从细菌培养物中获得的代谢物数量极少 (μg/L),并且被认为是不稳定的。在此,我们描述了一种灵活且收敛的合成路线来制备先进的前大肠杆菌素和衍生物。合成通过两个复杂前体(例如,28 + 17 → 29a,90%),然后是碱诱导的双脱水级联反应,形成两个目标环(例如,29a → 30a,79%)。该序列提供了超过发酵获得的数量的先进候选前大肠杆菌素的数量,并且预计可以很容易地进行缩放。这些研究指导了预测代谢物 precolibactin A(从 5a 或 5b 到 7)的结构修订,并证实了分离的代谢物