Substituted 2-(2''-pyridyl)benzimidazole palladium(II) complexes as an efficient catalytic system for Suzuki--Miyaura cross-coupling reactions
作者:Mahmut ULUSOY、Nurdal ÖNCEL、Emine AYTAR
DOI:10.3906/kim-1505-105
日期:——
A new series of $N,N$-type 2-(2'-pyridyl)benzimidazole ligands (2A$_\mathbf1}}$, 2A$_\mathbf2}}$, 3B$_\mathbf1}}$, 3B$_\mathbf2}}$, 3B$_\mathbf3}}$, and 4C$_\mathbf1}})$ and their Pd(II) complexes (5A$_\mathbf1}}$, 5A$_\mathbf2}}$, 6B$_\mathbf1}}$, 6B$_\mathbf2}}$, 6B$_\mathbf3}}$, and 7C$_\mathbf1}})$ were prepared and characterized by conventional spectroscopic methods and elemental analyses. The incorporation of $N$-coordinated benzimidazole complexes of palladium gave high catalytic activity in the Suzuki-Miyaura coupling of aryl halides substrates. After determining the best active catalyst as 5A$_\mathbf1}}$, bearing the mesityl substituent on the benzimidazole ring with the Pd(II) ion, optimization studies were carried out via changing the substrate, base, time, atmosphere, and the effect of water. The DMF:H$_2}$O (4/1) and Cs$_2}$CO$_3}$ as base were found to be critical for the efficiency of the reaction yield (100%).
制备了一系列新型$N,N$型2-(2'-吡啶基)苯并咪唑配体(2A$_\mathbf1}}$、2A$_\mathbf2}}$、3B$_\mathbf1}}$、3B$_\mathbf2}}$、3B$_\mathbf3}}$和4C$_\mathbf1}}$)及其Pd(II)配合物(5A$_\mathbf1}}$、5A$_\mathbf2}}$、6B$_\mathbf1}}$、6B$_\mathbf2}}$、6B$_\mathbf3}}$和7C$_\mathbf1}}$),并通过常规光谱方法和元素分析进行了表征。含有$N$配位的苯并咪唑配体使得钯催化剂在Suzuki-Miyaura偶联反应中展现出极高的催化活性。在确定具有甲基苯并咪唑环结构的5A$_\mathbf1}}$为最佳活性催化剂后,通过改变底物、碱、时间、气氛和水等因素进行了优化研究。发现使用DMF:H$_2}$O (4/1)溶剂和Cs$_2}$CO$_3}$作为碱对反应产率(100%)的提高至关重要。