Synthesis of Two Diastereomers of Iriomoteolide-1a via a Tunable Four-Module Coupling Approach Using Ring-Closing Metathesis as the Key Step
作者:Wei-Min Dai、Yuanxin Liu、Gaofeng Feng、Jian Wang、Jinlong Wu
DOI:10.1055/s-0030-1260822
日期:2011.7
A tunable four-module coupling approach has been established for assembling the 20-membered macrolactone core related to the proposed structure of iriomoteolide-1a by using ring-closing metathesis as the key step. Two C1-C6 (2E)-diene acid fragments with (4R,5S)- and (4S,5R)-stereogenic centers, respectively, were synthesized via anti-selective aldol reaction and E-selective conjugate addition of Me2CuLi with an alkynoic ester in the presence of TMSCl. The ring-closing metathesis reaction was carried out in the presence of 10 mol% Grubbs second-generation initiator at room temperature to give exclusively the (6E)-cycloalkenes. Our four-module coupling strategy enables efficient synthesis of two diastereomers of the proposed iriomoteolide-1a with opposite chirality at C4 and C5.
通过使用闭环复分解作为关键步骤,建立了一种可调的四模块偶联方法,用于组装与 iriomoteolide-1a 的拟议结构相关的 20 元大环内酯核心。通过抗选择性羟醛反应和 Me2CuLi 与炔酸酯的 E 选择性共轭加成,合成了两个分别具有 (4R,5S)- 和 (4S,5R)-立体中心的 C1-C6 (2E)-二烯酸片段在 TMSCl 存在下。闭环复分解反应在 10 mol% Grubbs 第二代引发剂存在下于室温下进行,仅生成 (6E)-环烯烃。我们的四模块偶联策略能够有效合成所提出的 iriomoteolide-1a 的两种非对映异构体,在 C4 和 C5 处具有相反的手性。