Combined Directed Ortho Metalation/Cross-Coupling Strategies: Synthesis of the Tetracyclic A/B/C/D Ring Core of the Antitumor Agent Camptothecin
作者:Tam Nguyen、Markus A. Wicki、Victor Snieckus
DOI:10.1021/jo049890h
日期:2004.11.1
A convergent synthesis of the A/B/C/D ring fragment 5 of camptothecin using a combination of directed ortho metalation and Negishicross-coupling is described. The key features of the synthetic sequence are an anionic ortho-Fries rearrangement (10 → 12), a Negishicross-coupling (7 → 6), and a terminal modified von Braun reaction (16 → 5) that leads to tetracyclic derivative 5 in 7 steps and 11% overall
描述了使用定向原位金属化和Negishi交叉偶联的组合喜树碱的A / B / C / D环片段5的会聚合成。合成序列的关键特征是阴离子邻位-弗里斯重排(10 → 12),Negishi交叉偶联(7 → 6)和末端修饰的von Braun反应(16 → 5),导致四环衍生物5在7个步骤,总收率11%。