Cyclometalation of Aryl-Substituted Phosphinines through CH-Bond Activation: A Mechanistic Investigation
作者:Leen E. E. Broeckx、Sabriye Güven、Frank J. L. Heutz、Martin Lutz、Dieter Vogt、Christian Müller
DOI:10.1002/chem.201301693
日期:2013.9.23
A series of 2,4,6‐triarylphosphinines were prepared and investigated in the base‐assisted cyclometalation reaction using [Cp*IrCl2]2 (Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl) as the metal precursor. Insight in the mechanism of the CH bond activation of phosphinines as well as in the regioselectivity of the reaction was obtained by time‐dependent 31P1H} NMR spectroscopy. At room temperature, 2,4
制备了一系列2,4,6-三芳基膦亚胺,并在碱辅助环化反应中使用[Cp * IrCl 2 ] 2(Cp * = 1,2,3,4,5-戊五甲基环戊二烯基)作为金属前体进行了研究。通过依赖时间的31 P 1 H} NMR光谱获得了对膦亚胺CH键活化机理以及反应区域选择性的深入了解。在室温下,2,4,6- triarylphosphinines瞬间打开铱二聚体和在η坐标1 -时尚与金属中心。加热后,观察到向游离配体和Ir-乙酸盐物种的解离步骤,并被证明是活化能为ΔE的一级反应。对2,4,6-三苯基次膦发现A = 56.6 kJ mol -1。磷杂环基的邻苯基上的供电子取代基促进了随后的环金属化反应,表明了亲电的CH活化机理。事实证明,环金属化反应对空间效应非常敏感,因为即使很小的取代基也会对反应的区域选择性产生很大影响。环金属化产物通过NMR光谱进行表征,在某些情况下还通过单晶X射线衍射进