Department of Chemistry, National Changhua University of Education, Changhua, Taiwan 500.
Dalton Trans. 2022 Dec 6;51(47):18264-18276. doi: 10.1039/d2dt03118c.
Ligand precursors for amido/amidate-functionalized triazole-based MIC ligands were synthesized. An initial theoretical calculation confirmed that triazole-based MIC ligands were promising ligands in terms of their σ-donating and π-acidic properties. Based on these ligand precursors, three different types of palladium complexes were successfully obtained, namely (1) a PEPPSI-type MIC complex, (2) a complex containing both a bidentate ligand of a MIC and an amidate donor and a mondentate NHC derived from nitron, and (3) a complex featuring a tridentate ligand of a MIC, an amidate, and a phenoxy donor. The structures of all these complexes were established by single-crystal X-ray diffraction studies. Imidazole derivatives are important heterocycles with enormous medicinal value. The catalytic activities of these new palladium complexes in the green direct C-H arylation of imidazoles with aryl halides were investigated and compared to those delivered from palladium complexes with IMes and triazole-based normal NHC ligands. Among the new complexes, the PEPPSI-type palladium complex with the monodentate triazole-based MIC ligand was found to be a very promising precatalyst which was capable of utilizing electron-deficient aryl chlorides as coupling partners in the reaction.
酰胺/酰氨基功能化三唑基 MIC 配体的配体前体被合成。初步理论计算证实，三唑基 MIC 配体在 σ-给电子和 π-酸性方面具有很大的潜力。基于这些配体前体，成功地获得了三种不同类型的钯配合物，即（1）PEPPSI 型 MIC 配合物，（2）含有 MIC 的双齿配体和酰氨基供体以及源自硝酮的单齿 NHC 的配合物，和（3）具有 MIC 的三齿配体、酰氨基和苯氧基供体的配合物。所有这些配合物的结构均通过单晶 X 射线衍射研究确定。咪唑衍生物是具有巨大药用价值的重要杂环化合物。研究了这些新钯配合物在绿色直接 C-H 芳基化反应中催化咪唑与芳基卤化物的反应活性，并与 IMes 和基于三唑的正常 NHC 配体的钯配合物的反应活性进行了比较。在新的配合物中，具有单齿三唑基 MIC 配体的 PEPPSI 型钯配合物被发现是一种非常有前途的前催化剂，它能够利用缺电子的芳基氯化物作为反应中的偶联伙伴。
