The use of Pd(OAc)₂ and a mixture of the cooperating ligand [2,2′-bipyridin]-6(1H)–one (bipy-6-OH) and PCy₃ in an optimal mol ratio of Pd/bipy-6-OH/PCy₃ = 1 : 0.5 : 1 leads to a more active system for the non-chelate-assisted direct arylation of simple arenes. The system operates at a temperature 30 °C lower than that for the Pd/bipy-6-OH system, and it is active for aryl chlorides as arylating partners. Mechanistic experiments support the operation of a bimetallic pathway via two connected catalytic cycles: a Pd/PCy₃ system responsible for the oxidative addition and reductive elimination steps and a Pd/bipy-6-OH system that enables C–H activation. Both cycles are connected by a transmetalation step. The phosphine ligand is not directly involved in the C–H activation, but compared to the monoligand system, the occurrence of the bimetallic route changes the nature of the key intermediate species in the C–H activation, favoring this turnover limiting step and the overall reaction rate.

中文翻译：

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双配体系统 [2,2′-联吡啶]-6（1H）–one/PCy3 的金属-配体合作和协同钯催化：芳烃无向 C-H 芳基化的较温和条件


使用 Pd（OAc）₂ 和配合配体 [2,2′-联吡啶]-6（1H）-one （bipy-6-OH） 和 PCy₃ 的混合物，以 Pd/bipy-6-OH/PCy₃ = 1 ： 0.5 ： 1 的最佳摩尔比导致更活跃的简单芳烃的非螯合辅助直接芳基化系统。该系统在比 Pd/bipy-6-OH 系统低 30 °C 的温度下运行，并且它对芳基氯化物作为芳基化配偶体具有活性。机理实验支持通过两个连接的催化循环操作双金属途径：负责氧化加成和还原消除步骤的 Pd/PCy₃ 系统和启用 C-H 活化的 Pd/bipy-6-OH 系统。两个循环通过金属转移步骤连接。膦配体不直接参与 C-H 活化，但与单配体系统相比，双金属路线的发生改变了 C-H 活化中关键中间体的性质，有利于这一周转限制步骤和总反应速率。