The functionalization of otherwise unreactive C–H bonds adds a new dimension to synthetic chemistry, yielding useful molecules for a range of applications. Arylation has emerged as an increasingly viable strategy for functionalization of heteroarenes which constitute an important class of structural moieties for organic materials. However, direct bisarylation of heteroarenes to enable aryl-heteroaryl-aryl bond formation remains a formidable challenge, due to the strong coordination between heteroatom of N or S and transitional metals. Here we report Pd interstitial nanocatalysts supported on ordered mesoporous carbon as catalysts for a direct and highly efficient bisarylation method for five-membered heteroarenes that allows for green and mild reaction conditions. Notably, in the absence of any base, ligands, and phase transfer agents, high activity (turn-over frequency, TOF up to 107 h⁻¹) and selectivity (> 99%) for the 2,5-bisarylation of five-membered heteroarenes are achieved in water. A combination of characterization reveals that the remarkable catalytic reactivity here is attributable to the parallel adsorption of heteroarene over Pd clusters, which breaks the barrier to electron transfer in traditional homogenous catalysis and creates dual electrophilic sites for aryl radicals and adsorbate at C2 and C5 positions. The d-band filling at Pd sites shows a linear relationship with activation entropy and catalytic activity. The ordered mesopores facilitate the absence of a mass transfer effect. These findings suggest alternative synthesis pathways for the design, synthesis and understanding of a large number of organic chemicals by ordered mesoporous carbon supported palladium catalysts.

中文翻译：

---

介孔碳负载钯间隙催化剂在 CH 官能化中释放电子转移

否则不反应的 C-H 键的功能化为合成化学增加了一个新的维度，产生了适用于一系列应用的有用分子。芳基化已成为杂芳烃功能化越来越可行的策略，杂芳烃构成有机材料的一类重要结构部分。然而，由于 N 或 S 的杂原子与过渡金属之间的强配位，杂芳烃的直接双芳基化以形成芳基-杂芳基-芳基键仍然是一项艰巨的挑战。在这里，我们报告了负载在有序介孔碳上的 Pd 间隙纳米催化剂作为催化剂，用于五元杂芳烃的直接和高效双芳基化方法，允许绿色和温和的反应条件。值得注意的是，在没有任何碱、配体和相转移剂的情况下，^-1 ) 和 5 元杂芳烃 2,5-双芳基化的选择性 (> 99%) 在水中实现。表征的组合表明，此处显着的催化反应性归因于杂芳烃在 Pd 簇上的平行吸附，这打破了传统均相催化中电子转移的障碍，并在 C2 和 C5 位置为芳基和吸附物创造了双亲电位点。该dPd 位点的 - 带填充与活化熵和催化活性呈线性关系。有序的介孔有助于不存在传质效应。这些发现表明了通过有序介孔碳负载钯催化剂设计、合成和理解大量有机化学品的替代合成途径。