A new versatile and recyclable NHC ligand precursor has been developed with ligand, base, and solvent functionalities for the efficient Pd-catalyzed Heck, Suzuki and Sonogashira cross-coupling reactions under mild conditions. Furthermore, NHC ligand precursor was immobilized on magnetite and its catalytic activity was also evaluated towards the coupling reactions as a heterogeneous catalyst. The NHC ligand precursor was prepared with imidazolium functionalization of TCT followed by a simple ion exchange by hydroxide ions. However, the results revealed an excellent catalytic activity for the both homogeneous and heterogeneous catalytic systems. 1.52 g.cm⁻³ and 1194 cP was obtained for the density and viscosity of the NHC ligand precursor respectively. On the other hand, the heterogeneous type could be readily recovered from the reaction mixture and reused for several times while preserving its properties. Heterogeneous nature of the magnetic catalyst was studied by hot filtration, mercury poisoning, and three-phase tests. High to excellent yields were obtained for all entries for the both homogeneous and heterogeneous catalysts, which reflects the high consistency of the catalyst.

Graphic Abstract

中文翻译：

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引入具有双（NHC）配体性质的可回收碱性离子溶剂，以及将磁铁固定在无配体和无碱Pd催化的Heck，Suzuki和Sonogashira交叉偶联反应中的可能性

已经开发了一种具有配体，碱和溶剂功能的新型通用且可回收的NHC配体前体，用于在温和条件下有效进行Pd催化的Heck，Suzuki和Sonogashira交叉偶联反应。此外，将NHC配体前体固定在磁铁矿上，并评估了其催化活性作为非均相催化剂对偶联反应的影响。NHC配体前体的制备是通过对TCT的咪唑鎓官能团进行反应，然后通过氢氧根离子进行简单的离子交换。然而，结果表明均相和非均相催化体系均具有优异的催化活性。1.52厘米^-3NHC配体前体的密度和粘度分别为1194 cP和1194 cP。另一方面，不均匀类型可以容易地从反应混合物中回收并重复使用几次，同时保留其性质。通过热过滤，汞中毒和三相试验研究了磁性催化剂的异质性。对于均相和非均相催化剂，所有条目均获得了高至优异的产率，这反映了催化剂的高稠度。

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