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Investigations into the ligand steric and electronic effects of Ru-catalyzed C–H bond arylation directed by 8-aminoquinoline as a bidentate-directing group
Journal of Chemical Research ( IF 1.4 ) Pub Date : 2020-05-28 , DOI: 10.1177/1747519820920154
Hamad H. Al Mamari 1 , Yousuf Al Lawati 1
Affiliation  

In this study, we report an investigation into the steric (cone angle, θ) and electronic properties of ligands in Ru-catalyzed C–H arylation of aromatic benzamides bearing 8-aminoquinoline as an N,N’-bidentate-directing group. The study employs [RuCl2(p-cymene)]2 as a precatalyst, and a ligand, under study, as a cocatalyst. Various electronically and sterically different monodentate and bidentate phosphine ligands were examined. Other ligands such as phosphites and amines were also tested. The study reveals that while bidentate phosphines, phosphites, and aryl and alkyl amines were found to be ineffective, monodentate triarylphosphines represented by triphenylphosphine were found to be the most effective ligands in the Ru-catalyzed C–H arylation under the conditions specified. In addition, the study reveals that there is a correlation between the steric effects, cone angle (θ) and the reaction efficiency. Thus, for symmetrical phosphine ligands, as the cone angle increases, the yield of the CH arylation product gradually decreased. Moreover, the electronic properties of triarylphosphine ligands influenced the reaction as demonstrated by the decreased ability of electron-poor ligands to promote the reaction. The study also reveals a correlation between the electronic parameter, υCO, of the triarylphosphine ligand and the reaction efficiency. As the carbonyl stretching frequency increases, the reaction yield gradually decreased.

中文翻译:

研究由 8-氨基喹啉作为双齿导向基团引导的 Ru 催化的 C-H 键芳基化的配体空间和电子效应

在这项研究中,我们报告了对带有 8-氨基喹啉作为 N,N'-二齿导向基团的芳香苯甲酰胺在 Ru 催化的 C-H 芳基化中配体的立体(锥角,θ)和电子特性的研究。该研究使用 [RuCl2(p-cymene)]2 作为预催化剂,并将研究中的配体作为助催化剂。检查了各种电子和空间上不同的单齿和双齿膦配体。还测试了其他配体,例如亚磷酸酯和胺。该研究表明,虽然发现双齿膦、亚磷酸酯以及芳基和烷基胺无效,但发现以三苯基膦为代表的单齿三芳基膦是在指定条件下 Ru 催化的 C-H 芳基化反应中最有效的配体。此外,研究表明,空间效应、锥角 (θ) 和反应效率之间存在相关性。因此,对于对称膦配体,随着锥角的增加,CH芳基化产物的产率逐渐降低。此外,三芳基膦配体的电子特性影响了反应,这表现为缺电子配体促进反应的能力下降。该研究还揭示了三芳基膦配体的电子参数 υCO 与反应效率之间的相关性。随着羰基拉伸频率的增加,反应产率逐渐降低。三芳基膦配体的电子特性会影响反应,这表现为缺电子配体促进反应的能力下降。该研究还揭示了三芳基膦配体的电子参数 υCO 与反应效率之间的相关性。随着羰基拉伸频率的增加,反应产率逐渐降低。三芳基膦配体的电子特性会影响反应,这表现为缺电子配体促进反应的能力下降。该研究还揭示了三芳基膦配体的电子参数 υCO 与反应效率之间的相关性。随着羰基拉伸频率的增加,反应产率逐渐降低。
更新日期:2020-05-28
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