Department of Chemistry, University of Rochester, B31 Hutchison Hall, 120 Trustee Road, Rochester, NY, 14627, USA.
Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
Angew Chem Int Ed Engl. 2020 Sep 21;59(39):17070-17076. doi: 10.1002/anie.202006639. Epub 2020 Jul 28.
N,N,N',N'-Tetramethylethylenediamine (TMEDA) has been one of the most prevalent and successful additives used in iron catalysis, finding application in reactions as diverse as cross-coupling, C-H activation, and borylation. However, the role that TMEDA plays in these reactions remains largely undefined. Herein, studying the iron-catalyzed hydromagnesiation of styrene derivatives using TMEDA has provided molecular-level insight into the role of TMEDA in achieving effective catalysis. The key is the initial formation of TMEDA-iron(II)-alkyl species which undergo a controlled reduction to selectively form catalytically active styrene-stabilized iron(0)-alkyl complexes. While TMEDA is not bound to the catalytically active species, these active iron(0) complexes cannot be accessed in the absence of TMEDA. This mode of action, allowing for controlled reduction and access to iron(0) species, represents a new paradigm for the role of this important reaction additive in iron catalysis.
N,N,N',N'-四甲基乙二胺（TMEDA）是铁催化中最常用和最成功的添加剂之一，在交叉偶联、C-H 活化和硼化等多种反应中都有应用。然而，TMEDA 在这些反应中所起的作用在很大程度上还没有被定义。本文通过研究 TMEDA 促进的苯乙烯衍生物的水合镁化反应，深入了解了 TMEDA 在实现有效催化中的作用。关键是 TMEDA-铁(II)-烷基物种的初始形成，这些物种经历受控还原，选择性地形成催化活性的苯乙烯稳定的铁(0)-烷基配合物。虽然 TMEDA 不与催化活性物种结合，但如果没有 TMEDA，就无法获得这些活性铁(0)配合物。这种作用模式允许受控还原并获得铁(0)物种，为这种重要的反应添加剂在铁催化中的作用提供了一个新的范例。
