16939-08-5Relevant articles and documents
Pd-NHCs Enabled Suzuki-Miyaura Cross-Coupling of Arylhydrazines via C–N Bond Cleavage
Zeng, Xiao-Xiao,Li, Dong-Hui,Zhou, Zhen,Xu, Chang,Liu, Feng-Shou
supporting information, (2021/03/01)
We describe a highly efficient protocol for cross-coupling of phenylhydrazines with arylboronic acids by Pd-NHCs under aerobic reaction condition. A series of well-defined Pd-NHCs complexes were evaluated and the relationship between the structure and the catalytic properties was investigated. It was disclosed that the Pd-PEPPSI-IPr proved to be the robust precatalyst, providing access to a range of (hetero)biaryls in good to excellent yields.
Air-Stable Dinuclear Iodine-Bridged Pd(I) Complex - Catalyst, Precursor, or Parasite? the Additive Decides. Systematic Nucleophile-Activity Study and Application as Precatalyst in Cross-Coupling
Aufiero, Marialuisa,Scattolin, Thomas,Proutière, Fabien,Schoenebeck, Franziska
supporting information, p. 5191 - 5195 (2015/11/09)
Dinuclear Pd(I) complexes were recently shown to potentially adopt various possible roles in catalysis, being capable of functioning as catalyst via dinuclear catalysis cycles, precatalyst for Pd(0), or inhibitor. This report examines the factors that control the mechanistic role in catalysis. Our data suggest that the transformation to Pd(0) occurs via nucleophile-induced fragmentation of Pd(I)-Pd(I). A systematic study examining the nucleophilicity of additive versus activity was undertaken that revealed the minimum nucleophilicity necessary to activate two structurally very similar Pd(I) dimers, [Pd(μ-X)(PtBu3)]2 (X = I or Br). While the more labile bromine-bridged Pd(I) dimer is converted to Pd(0) with nucleophiles N ≥ 10.5, the iodine-bridged analogue requires N ≥ 16.1 (N according to Mayrs scale). Too strong nucleophiles generate a high concentration of unstable monoligated Pd(0) rapidly, leading to Pd loss (i.e., Pd black). On the other hand, careful tuning of nucleophilicity allows for a controlled release of well-defined Pd(0) species. These insights have led to the first application of the air-stable and previously thought unreactive iodine-bridged dimer [Pd(μ-I)(PtBu3)]2 as a precatalyst for monoligated Pd(0) in cross-coupling reactions. The reactions were performed without exclusion of oxygen-all reagents were handled in air without special precautions. Highly efficient Kumada couplings of aryl iodides and bromides were achieved in 5 min at room temperature.
General and highly efficient fluorinated-N-heterocyclic carbene-based catalysts for the palladium-catalyzed Suzuki-Miyaura reaction
Liu, Taoping,Zhao, Xiaoming,Shen, Qilong,Lu, Long
supporting information; experimental part, p. 6535 - 6547 (2012/08/28)
A general and highly efficient trifluoromethylated-N-heterocyclic carbene (NHC)-based catalyst for the palladium-catalyzed Suzuki-Miyaura reaction was reported. In the presence of the catalyst, reactions of non-activated aryl chlorides and triflates with aryl boronic acids occurred at room temperature with good to excellent yields (63-98%). In addition, catalysts generated from a combination of Pd(OAc)2/imidazolium salt 6a is not only effective for the coupling of heteroaryl boronic acid with aryl halides and heteroaryl halides, but also efficient for coupling of other heteroaryl halides and heteroaryl boronic acids. Finally, the catalyst is highly effective for Suzuki-Miyaura reaction of aryl bromides and chlorides with 0.01-0.1 mol % loading if the temperature was raised at refluxed THF/H2O.
