Cai Yuanting, Hua Yuhui, Lu Zhengyu, Chen Jiangxi, Chen Dafa, Xia Haiping
College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
Shenzhen Grubbs Institute and Department of Chemistry, Southern University of Science and Technology, Shenzhen, 518005, China.
Adv Sci (Weinh). 2024 Oct;11(38):e2403940. doi: 10.1002/advs.202403940. Epub 2024 Aug 5.
Metallacyclobutadienes (MCBDs) are key intermediates of alkyne metathesis reactions. There are in principle two isomerization pathway from kinetic to thermodynamic MCBDs, intermolecular and intramolecular. However, systems that simultaneously isolate two kinds of MCBD isomers have not been achieved, thus restricting the mechanistic studies of the isomerization. Here the reactivity of a metallapentalyne that contains an M≡C bond within the aromatic ring, with alkynes to afford a series of MCBD-fused metallapentalenes is studied. In some cases, both kinetic and thermodynamic products are isolated in the same system, which has never been observed in previous MCBD reactions. Furthermore, the isomerization of MCBD-fused metallapentalenes is investigated both experimentally and theoretically, indicating that it is an intramolecular process involving a metallatetrahedrane (MTd) intermediate. This research provides experimental evidence demonstrating that one MCBD can undergo intramolecular rearrangement to transform into another.
金属环丁二烯（MCBDs）是炔烃复分解反应的关键中间体。原则上，从动力学MCBDs到热力学MCBDs有两种异构化途径，即分子间和分子内途径。然而，尚未实现同时分离出两种MCBD异构体的体系，因此限制了异构化的机理研究。本文研究了一种在芳环内含有M≡C键的金属戊搭炔与炔烃反应生成一系列MCBD稠合金属戊搭炔的反应活性。在某些情况下，动力学产物和热力学产物在同一体系中被分离出来，这在以往的MCBD反应中从未被观察到。此外，还对MCBD稠合金属戊搭炔的异构化进行了实验和理论研究，结果表明这是一个涉及金属四面体烷（MTd）中间体的分子内过程。该研究提供了实验证据，证明一种MCBD可以通过分子内重排转化为另一种MCBD。
