Iridium(III)-Catalyzed Direct Arylation of C–H Bonds with Diaryliodonium Salts

By developing a new Ir­(III)-catalyzed
C–C cross-coupling,
a versatile method for direct arylation of sp2 and sp3 C–H bonds in ketoximes, nitrogen-containing heterocycles,
various arenes, and olefins has been established. The key to this
arylation depends on the appropriate choice of catalyst and the use
of diaryliodonium triflate salts as the coupling partners. This transformation
has good functional group compatibility and can serve as a powerful
synthetic tool for late-stage C–H arylation of complex compounds.
Mechanistic studies by density functional theory calculations suggested
that the sp3 C–H activation was realized by a triflate-involved
concerted metalation–deprotonation process, and the following
oxidation of Ir­(III) to Ir­(V) is the most favorable when a bistriflimide
is contained in the diaryliodonium salt. Calculations indicated that
both steps are enabled by initial anion exchange between the reactant
complexes.

通过开发一种新型铱(III)催化的C-C交叉偶联反应，本研究成功构建了一种通用性极强的方法，可实现酮肟、含氮杂环、各类芳烃以及烯烃中sp²与sp³杂化碳氢键的直接芳基化修饰。该芳基化反应的关键在于催化剂的合理筛选，以及以二芳基碘鎓三氟甲磺酸盐（diaryliodonium triflate）作为偶联配偶体。此转化反应具备优异的官能团兼容性，可作为一款高效的合成工具，用于复杂化合物的后期碳氢键芳基化修饰。通过密度泛函理论（density functional theory）计算开展的机理研究表明，sp³碳氢键的活化是通过三氟甲磺酸盐参与的协同金属化-去质子化过程实现；而当二芳基碘鎓盐中含有双三氟甲磺酰亚胺（bistriflimide）时，将Ir(III)氧化为Ir(V)的步骤为最优势反应路径。计算结果显示，上述两个步骤均通过反应物配合物间的初始阴离子交换得以实现。