Ferrocenyl palladacycles derived from unsymmetrical pincer-type ligands: evidence of Pd(0) nanoparticle generation during the Suzuki–Miyaura reaction and applications in the direct arylation of thiazoles and isoxazoles
作者:Ankur Maji、Anshu Singh、Aurobinda Mohanty、Pradip K. Maji、Kaushik Ghosh
DOI:10.1039/c9dt03465j
日期:——
Mechanistic investigation authenticated the generation of Pd(0) nanoparticles during the catalytic cycle and the nanoparticles were characterized by XPS, SEM and TEM analysis. Direct C–H arylation of thiazole and isoxazole derivatives employing these ferrocenyl-palladacycle complexes was examined. The reaction model for the arylation reaction implicating the in situ generation of Pd(0) nanoparticles was
Conditions for the palladium-catalyzed directarylation of a wide range of heterocycles with aryl bromides are reported. Those conditions employ a stoichiometric ratio of both coupling partners, as well as a substoichiometric quantity of pivalicacid, which results in significantly faster reactions. An evaluation of the influence of the nature of the aryl halide has also been carried out.
Direct C-H bond (Hetero)arylation of thiazole derivatives at 5-position catalyzed by N-heterocyclic carbene palladium complexes at low catalyst loadings under aerobic conditions
synthesis of 5-(hetero)arylated thiazole derivatives via an N-heterocyclic carbene palladium (Pd-NHC) complex catalyzed directC-Harylation reaction. Utilization of this methodology, the arylation of substituted thiazoles with (hetero)aryl bromides efficiently proceeded at low catalyst loading (0.1–0.05 mol%) and under aerobic conditions. A variety of (hetero)aryl bromides, even some strongly deactivated
A Robust and Efficient Catalyst Possessing an Electron-Deficient Ligand for the Palladium-Catalyzed Direct Arylation of Heteroarenes
作者:Alexandra Jakab、Zoltán Dalicsek、Tibor Soós
DOI:10.1002/ejoc.201402586
日期:2015.1
The exploration of the directarylation capacity of a unique, thermally stable, and air-stable Pd0–phosphine catalyst is reported. Besides decisively contributing to catalyst robustness, the electron-deficient trifluoromethyl-substituted triphenylphosphine ligands make the palladium center more electron-deficient and accelerate the directarylation step. The combination of only 0.5–2 mol-% of the catalyst
Aerobic and Efficient Direct Arylation of Five-Membered Heteroarenes and Their Benzocondensed Derivatives with Aryl Bromides by Bulky α-Hydroxyimine Palladium Complexes
作者:Bao-Tian Luo、Huan Liu、Zhi-Jie Lin、Jingxing Jiang、Dong-Sheng Shen、Rui-Zhi Liu、Zhuofeng Ke、Feng-Shou Liu
DOI:10.1021/acs.organomet.5b00181
日期:2015.10.26
In the present work, a series of alpha-hydroxyimine palladium complexes with bulky substituents (i.e., [Ar-N=C(R)-C(R)(2)-OH]PdCl2} (C1, R = Me, Ar = 2-diphenylmethyl-4,6-dimethylphenyl; C2, R = Me, Ar = 2,6-bis(diphenylmethyl)-4-methylphenyl; C3, R = Me, Ar = 2,6-bis(diphenylinethyl)-4-methyoxylphenyl; C4, R = Me, Ar = 2,6-bis(diphenylmethyl)-4-chlorophenyl; C5, R = Ph, Ar = 2,6-dimethylphenyl; C6, R = Ph, Ar = 2,6-diisopropylphenyl)) were synthesized and characterized. The structures of palladium complexes C1 and C2 were determined by X-ray diffraction. These bidentate N,O-palladium complexes were applied for direct arylation under aerobic conditions. The effects of the reaction conditions and ligand substitution on the catalytic activity were evaluated. Upon a low palladium loading of 0.5 mol %, the bulky palladium complex C6 was successfully used to catalyze the cross-coupling of a variety of five-membered heteroarenes and their benzo-condensed derivatives with (hetero)aryl bromides. The mechanistic investigation on the direct arylation supported the involvement of a Pd(0)/Pd(II) CMD process.