Blaha Ines, Weber Stefan, Dülger Robin, Veiros Luis F, Kirchner Karl
Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163-AC, A-1060 Wien, Austria.
Centro de Química Estrutural, Institute of Molecular Sciences, Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049 001 Lisboa, Portugal.
ACS Catal. 2024 Aug 17;14(17):13174-13180. doi: 10.1021/acscatal.4c03364. eCollection 2024 Sep 6.
An additive-free manganese-catalyzed isomerization of terminal alkenes to internal alkenes is described. This reaction is implementing an inexpensive nonprecious metal catalyst. The most efficient catalyst is the borohydride complex -[Mn(dippe)(CO)(κ-BH)]. This catalyst operates at room temperature, with a catalyst loading of 2.5 mol %. A variety of terminal alkenes is effectively and selectively transformed into the respective internal -alkenes. Preliminary results show chain-walking isomerization at an elevated temperature. Mechanistic studies were carried out, including stoichiometric reactions and in situ NMR analysis. These experiments are flanked by computational studies. Based on these, the catalytic process is initiated by the liberation of "BH" as a THF adduct. The catalytic process is initiated by double bond insertion into an M-H species, leading to an alkyl metal intermediate, followed by β-hydride elimination at the opposite position to afford the isomerization product.
本文描述了一种无添加剂的锰催化末端烯烃异构化为内烯烃的反应。该反应采用了一种廉价的非贵金属催化剂。最有效的催化剂是硼氢化物配合物-[Mn(dippe)(CO)(κ-BH)]。该催化剂在室温下运行，催化剂负载量为2.5 mol%。多种末端烯烃能有效且选择性地转化为相应的内烯烃。初步结果表明在高温下会发生链行走异构化。进行了机理研究，包括化学计量反应和原位核磁共振分析。这些实验辅以计算研究。基于这些，催化过程由作为四氢呋喃加合物的“BH”的释放引发。催化过程通过双键插入M-H物种开始，生成烷基金属中间体，随后在相反位置进行β-氢消除以得到异构化产物。
