北京化工大学杨占会团队报道了铱催化氢化物转移制备非对开多环内酯γ。相关研究成果发表在2024年7月30日出版的国际学术期刊《中国化学》。

还原性内酯化策略提供了一种获得非对映体富集多环γ-内酯的有效途径。然而，开发一种具有良好非对映体控制水平的高效、通用的协议仍然是一项艰巨的挑战。

该文中，研究人员通过铱催化的氢化物转移策略，提供了一种高度非对映选择性和高效的非对映异构双和多环γ-内酯路线。该方法具有高水平的非对映体控制、宽底物范围和高催化剂效率（S/C=高达5000）。机理研究表明，氢化铱的形成可能是速率决定步骤，氢化物转移步骤是非对映体决定步骤。氢化铱物种的大空间位阻和分子内氢键是氢化物转移过程非对映控制的关键。

从构型分析和Duniz攻击角度来看，非对映体控制的性质是合理的。还提出了一种基于面部选择性分析的更通用的经验规则，用于解释和预测立体化学。

附：英文原文

Title: En Route to Diastereopure Polycyclic γ-Lactones by Iridium-Catalyzed Hydride Transfer†

Author: Yang Chen, Jingyu Zhang, Yecheng Wang, Hongguang Du, Jiaxi Xu, Zhanhui Yang

Issue&Volume: 2024-07-30

Abstract: The reductive lactonization strategy provides an efficient access to diastereoenriched polycyclic γ-lactones. However, it is still a formidable challenge to develop an efficient and versatile protocol with excellent levels of diastereocontrol. Herein, we provide a highly diastereoselective and efficient route to diastereopure bi- and polycyclic γ-lactones, by means of an iridium-catalyzed hydride transfer strategy. This method features high levels of diastereocontrol, broad substrate scope, and high catalyst efficiency (S/C = up to 5000). Mechanistic studies suggest that the iridium hydride formation might be the rate-determining step, and that the hydride transfer step be the diastereo-determining step. The large steric hindrance of the iridium hydride species and intramolecular hydrogen bonding are critically key to the diastereocontrol of the hydride transfer process. From the perspectives of configurational analysis and Duniz angles of attack, the nature of diastereocontrol is well rationalized. A more general empirical rule based on facial selectivity analysis for explaining and predicting the stereochemistry is also proposed.

DOI: 10.1002/cjoc.202400265

Source: https://onlinelibrary.wiley.com/doi/full/10.1002/cjoc.202400265