The mechanism of anion-catalyzed C–H silylation by R₃SiCF₃ reagents has been investigated using homogeneous TBAT-initiation, in situ and stopped-flow ¹⁹F NMR spectroscopy ²H-KIE, LFER, deuterium-labeled crossover, structure-selectivity quantitation (TMSCF₃/TESCF₃), carbene trapping, and DFT-calculations. Analysis of the kinetics of reactions of 1,3-difluorobenzenes (2), and the generation of ArSiMe₃ and Me₃SiF as a function of the concentration of [2], [TMSCF₃], and [TBAT], show that a CF₃-anionoid is the active intermediate. The CF₃-anionoid is reversibly released from siliconate [(CF₃)₂SiMe₃]⁻ and undergoes partitioning through rate-limiting arene deprotonation (¹H/²H KIE 9.5) to generate ArSiMe₃ (via a transient aryl anionoid) and fluoroform (CF₃H), in competition with F-anion transfer to TMSCF₃ to generate CF₂ and TMSF. The [2]/[TMSCF₃] concentration ratio directly and proportionally controls the kinetics of the partition, in favor of C–H deprotonation. Higher concentrations of TBAT and lower concentrations of TMSCF₃ lead to faster rates of ArSiMe₃ generation. Use of the homologous TESCF₃ reagent leads to faster rates of anion catalysis and an increased selectivity toward C–H deprotonation. Perfluoroalkenes, generated in situ from CF₂, capture the CF₃-anionoid leading to progressive inhibition of the anion-catalysis. Inhibition is suppressed by using a styrene additive to trap the CF₂ and the efficiency of the process enhanced by slow-addition of TMSCF₃ (1) to maintain a high concentration ratio [2]/[1].

中文翻译：

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使用TMSCF ₃的阴离子催化C–H硅烷化的机理：以动力学控制的CF _3-阴离子分配为关键参数

使用均相的TBAT引发，原位和停止流¹⁹ F NMR光谱² H-KIE，LFER，氘标记的交叉，结构选择性，研究了R ₃ SiCF ₃试剂对阴离子催化的CHH甲硅烷基化的机理。定量分析（TMSCF ₃ / TESCF ₃），卡宾捕获和DFT计算。分析1,3-二氟苯（2）的反应动力学，以及ArSiMe ₃和Me ₃ SiF的生成与[ 2 ]，[TMSCF ₃ ]和[TBAT]浓度的关系，表明CF ₃-阴离子型是活性中间体。CF _3-阴离子可逆地从硅酸盐[（CF ₃）₂ SiMe ₃ ] ^-中释放出来^，并通过限速芳烃去质子化反应（¹ H / ² H KIE 9.5）进行分配，生成ArSiMe ₃（通过瞬态芳基阴离子）。氟仿（CF ₃ H），与F阴离子转移到TMSCF ₃中竞争，生成CF ₂和TMSF。[ 2 ] / [TMSCF ₃]浓度比可直接和成比例地控制隔板的动力学，有利于C–H去质子化。较高浓度的TBAT和较低浓度的TMSCF ₃导致ArSiMe ₃生成速度更快。使用同源TESCF ₃试剂可加快阴离子催化速率，并增加对CH去质子化的选择性。从CF ₂原位生成的全氟烯烃捕获CF _3-阴离子，导致阴离子催化的逐步抑制。通过使用苯乙烯添加剂捕获CF ₂可以抑制抑制作用，并且通过缓慢添加TMSCF ₃（1可以提高该过程的效率）以保持高浓度比[ 2 ] / [ 1 ]。