Maulbetsch Theo, Jürgens Eva, Kunz Doris
Institut für Anorganische Chemie, University of Tübingen, Auf der Morgenstelle 18, 72076, Tübingen, Germany.
Chemistry. 2020 Aug 17;26(46):10634-10640. doi: 10.1002/chem.202002651. Epub 2020 Jul 23.
The use of carbon monoxide as a direct reducing agent for the deoxygenation of terminal and internal epoxides to the respective olefins is presented. This reaction is homogeneously catalyzed by a carbonyl pincer-iridium(I) complex in combination with a Lewis acid co-catalyst to achieve a pre-activation of the epoxide substrate, as well as the elimination of CO from a γ-2-iridabutyrolactone intermediate. Especially terminal alkyl epoxides react smoothly and without significant isomerization to the internal olefins under CO atmosphere in benzene or toluene at 80-120 °C. Detailed investigations reveal a substrate-dependent change in the mechanism for the epoxide C-O bond activation between an oxidative addition under retention of the configuration and an S 2 reaction that leads to an inversion of the configuration.
本文介绍了使用一氧化碳作为直接还原剂将末端和内环氧物脱氧为相应烯烃的方法。该反应由羰基钳形铱（I）配合物与路易斯酸助催化剂进行均相催化，以实现环氧化物底物的预活化，以及从γ-2-铱丁内酯中间体中消除一氧化碳。特别是末端烷基环氧化物在80-120°C的苯或甲苯中，在一氧化碳气氛下能顺利反应且不会显著异构化为内烯烃。详细研究表明，在构型保持下的氧化加成和导致构型翻转的S2反应之间，环氧化物C-O键活化机制存在底物依赖性变化。
