Insight into the Steric and Electronic Effects of Ancillary Ligands: Synthesis and Structure−Reactivity Relationship of Well-Defined, Air- and Moisture-Stable (NHC)Pd(sal)Cl Complexes (sal = Salicylaldimine)
摘要:
Synthesis of a series of (NHC)Pd(sal)Cl complexes, 1-5, bearing a salicylaldimine (sal) unit was described. The structure reactivity relationship, especially the steric and electronic effects of the salicylaldimine ligands on their catalytic activities, was investigated intensively in the Buchwald-Hartwig coupling reaction. Our study demonstrated that the sterically encumbered N-aryl groups in the salicylaldimine unit give rise to an obviously negative effect in the aryl amination reaction. Additionally, incorporating a steric substituent into the ortho-position of the phenoxide oxygen atom does not appear to be beneficial to their catalytic activity. Notably, the electronic nature of N-substituted aryl groups in the salicylaldimine ligands plays a significant role in their catalytic activities. An electron-rich N-aryl group causes an obviously decreasing yield, while an electron-deficient one, such as complex 5b, leads to enhanced reactivity. The aryl amination reaction with complex 5b was also found to be remarkably tolerant to both air and moisture. Under optimized reaction conditions, a range of aryl chlorides and amines could be coupled smoothly under aerobic conditions.
Mixed er-NHC/phosphine Pd(<scp>ii</scp>) complexes and their catalytic activity in the Buchwald–Hartwig reaction under solvent-free conditions
作者:Alexandra A. Ageshina、Grigorii K. Sterligov、Sergey A. Rzhevskiy、Maxim A. Topchiy、Gleb A. Chesnokov、Pavel S. Gribanov、Elizaveta K. Melnikova、Mikhail S. Nechaev、Andrey F. Asachenko、Maxim V. Bermeshev
DOI:10.1039/c9dt00216b
日期:——
A series of novel (NHC)PdCl2-PR3 complexes were synthesized and fully characterized by 1H, 13C, 31P NMR and FT-IR spectroscopy. These complexes showed high catalytic activity toward solvent-free Buchwald–Hartwig amination. Both primary and secondary amines were efficiently utilized under the same reaction conditions. The solvent-free synthesis of valuable N-aryl carbazoles and similar N-heterocyclic
合成了一系列新颖的(NHC)PdCl 2 -PR 3配合物,并通过1 H,13 C,31 P NMR和FT-IR光谱进行了全面表征。这些配合物对无溶剂的布赫瓦尔德-哈特维格胺胺化显示出很高的催化活性。在相同的反应条件下,伯胺和仲胺均得到有效利用。描述了有价值的N-芳基咔唑和类似的N-杂环体系的无溶剂合成。
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‐Heterocyclic carbene) ion‐pair palladium complexes: Suzuki–Miyaura cross‐coupling studies in neat water under mild conditions
作者:Ming‐Tsz Chen、Yu‐Hsuan Lin、Kun‐Han Jian
DOI:10.1002/aoc.5955
日期:2020.12
of a series of (N‐heterocyclic carbene)PdCl3−(NMe3H)+ ion‐pair complexes are presented. Applying the quaternary ammonium salt as the function with NHC–Pd(II) complexes yields the new ion‐pair complexes. The NHC–Pd(II) ion‐pair complexes work well by undergoing the Suzuki–Miyaura reaction with aryl chloride substrates in water under mild conditions in air at room temperature. Twenty products resulting
Mixed Phosphite/<i>N</i>-Heterocyclic Carbene Complexes: Synthesis, Characterization and Catalytic Studies
作者:Olivier Diebolt、Václav Jurčík、Rosenildo Correa da Costa、Pierre Braunstein、Luigi Cavallo、Steven P. Nolan、Alexandra M. Z. Slawin、Catherine S. J. Cazin
DOI:10.1021/om9011196
日期:2010.3.22
hydroxide bases and/or alcohols were necessary to achieve good catalytic activity. Mechanisticstudies were undertaken in order to gain insights into the role of alkoxide groups. These studies suggest that alcohols or alkoxide groups play a major role in the activation of the precatalyst to generate the catalytically active species. Catalyticstudies proved these systems to be efficient using 0.1 mol % of
Synthesis of N-heterocyclic carbene-PdCl-[(2-Pyridyl)alkyl carboxylate] complexes and their catalytic activities towards arylation of (benzo)oxazoles with aryl bromides
作者:Wei Chen、Jin Yang
DOI:10.1016/j.jorganchem.2018.07.029
日期:2018.10
diffraction. The catalytic performance of the complexes was screened and the obtained palladium (II) complexes shown effective catalytic activities for direct arylation of (benzo)oxazoles with aryl bromides. Moreover, the 2-(pyridin-2-yl)acetate stabilized NHC–Pd complexes were more efficient than the 3-(pyridin-2-yl)propanoate stabilized NHC–Pd analogues. Further studies exhibited that 2-(pyridin-2-yl)acetate
the synthesis, characterization, and reactivity of [(NHC)PdCl2(aniline)] complexes. These well-defined, air- and moisture-stable catalysts are highly active in the Suzuki–Miyaura cross-coupling of amides by N–C(O) activation as well as in the Suzuki–Miyaura cross-coupling of esters, aryl chlorides, and Buchwald–Hartwig amination. Most crucially, this study introduces broadly available anilines as stabilizing