This paper reports a green magnetic quasiheterogeneous efficient palladium catalyst in which Pd⁰ nanoparticles have been immobilized in self‐assembled hyperbranched polyglycidole (SAHPG)‐coated magnetic Fe₃O₄ nanoparticles (Fe₃O₄‐SAHPG‐Pd⁰). This catalyst has been used for effective ligandless Pd catalyzed Suzuki–Miyaura coupling reactions of different aryl halides with substituted boronic acids at room temperature and in aqueous media. Herein, SAHPG is used as support; it also acts as a reducing agent and stabilizer to promote the transformation of Pd^II to Pd⁰ nanoparticles. Also, this environmental friendly quasiheterogeneous catalyst is employed for the first time in the synthesis of new pyrimido[4,5‐b]indoles via oxidative addition/CH activation reactions on the pyrimidine rings, which were obtained with higher yield and faster than when Pd(OAc)₂ was used as the catalyst. Interestingly, the above‐mentioned catalyst could be recovered in a facile manner from the reaction mixture by applying an external magnet device and recycled several times with no significant decrease in the catalytic activity.

中文翻译：

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Fe3O4‐SAHPG‐Pd0纳米颗粒：无配体且低Pd负载的准多相催化剂，对轻度的Suzuki–Miyaura偶联和C反应具有活性。嘧啶核的H活化

本文报道了一种绿色的准多相磁性高效钯催化剂，其中Pd ⁰纳米颗粒已固定在自组装超支化聚缩水甘油（SAHPG）涂层的磁性Fe ₃ O ₄纳米颗粒（Fe ₃ O ₄ -SAHPG-Pd ⁰）中。该催化剂已用于在室温下和在水介质中，不同芳基卤化物与取代硼酸的有效的无配体Pd催化Suzuki-Miyaura偶联反应。这里，SAHPG被用作支持；它还充当还原剂和稳定剂，以促进Pd ^II向Pd ⁰的转化纳米粒子。而且，这种环境友好的准多相催化剂首次用于通过嘧啶环上的氧化加成/ CH活化反应合成新的嘧啶并[4,5- b ]吲哚，这种方法获得的收率更高且比当使用Pd（OAc）₂作为催化剂时。有趣的是，可以通过应用外部磁体装置以容易的方式从反应混合物中回收上述催化剂，并循环几次，而催化活性没有明显降低。