Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA.
Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, USA.
Nat Chem. 2022 Jun;14(6):632-639. doi: 10.1038/s41557-022-00951-y. Epub 2022 Jun 2.
The controlled isomerization and functionalization of alkenes is a cornerstone achievement in organometallic catalysis that is now widely used throughout industry. In particular, the addition of CO and H to an alkene, also known as the oxo-process, is used in the production of linear aldehydes from crude alkene feedstocks. In these catalytic reactions, isomerization is governed by thermodynamics, giving rise to functionalization at the most stable alkylmetal species. Despite the ubiquitous industrial applications of tandem alkene isomerization/functionalization reactions, selective functionalization at internal positions has remained largely unexplored. Here we report that the simple W(0) precatalyst W(CO) catalyses the isomerization of alkenes to unactivated internal positions and subsequent hydrocarbonylation with CO. The six- to seven-coordinate geometry changes that are characteristic of the W(0)/W(II) redox cycle and the conformationally flexible directing group are key factors in allowing isomerization to take place over multiple positions and stop at a defined unactivated internal site that is primed for in situ functionalization.
烯烃的可控异构化和功能化是金属有机催化中的一项重要成就，现已广泛应用于各个行业。特别是，烯烃与 CO 和 H 的加成反应，也称为氧化过程，用于从粗烯烃原料生产直链醛。在这些催化反应中，异构化受热力学控制，导致最稳定的烷基金属物种发生功能化。尽管串联烯烃异构化/功能化反应具有普遍的工业应用，但内部位置的选择性功能化在很大程度上仍未得到探索。在这里，我们报告说，简单的 W(0)前催化剂 W(CO)催化烯烃异构化为非活化的内部位置，并随后与 CO 进行氢甲酰化。W(0)/W(II)氧化还原循环的六到七配位几何变化以及构象灵活的导向基团是允许异构化在多个位置进行并在预定义的非活化内部位置停止的关键因素，该位置适合进行原位功能化。
