Bakewell Clare, White Andrew J P, Crimmin Mark R
Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK.
Angew Chem Int Ed Engl. 2018 May 28;57(22):6638-6642. doi: 10.1002/anie.201802321. Epub 2018 May 2.
A series of industrially relevant fluoroalkenes react with a monomeric Al complex. These reactions break strong sp and sp C-F bonds, and result in the formation of a diverse array of organoaluminium compounds. Mechanistic studies show that two mechanisms are likely in operation: 1) direct oxidative addition of the C-F bond to Al occurs with retention of alkene stereochemistry, and 2) stepwise formation and decomposition of a metallocyclopropane intermediate occurs with inversion of alkene stereochemistry. As part of this mechanistic analysis, we have isolated the first aluminium metallocyclopropane complex from oxidative addition of an alkene to Al . Remarkably this reaction is reversible and reductive elimination of the alkene occurs at higher temperature reforming Al . Furthermore, in selected cases the organoaluminium products are susceptible toward β-fluoride elimination to yield a double C-F activation pathway.
一系列与工业相关的氟代烯烃与一种单体铝配合物发生反应。这些反应会断裂强的sp和sp C-F键，并导致形成各种各样的有机铝化合物。机理研究表明可能有两种机制在起作用：1）C-F键向铝的直接氧化加成反应发生时烯烃立体化学得以保留，以及2）金属环丙烷中间体的逐步形成和分解反应发生时烯烃立体化学发生反转。作为这种机理分析的一部分，我们从烯烃向铝的氧化加成反应中分离出了首个铝金属环丙烷配合物。值得注意的是，该反应是可逆的，并且在较高温度下烯烃会发生还原消除反应，重新生成铝。此外，在某些特定情况下，有机铝产物易于发生β-氟消除反应，从而产生一条双重C-F活化途径。
