389091-50-3Relevant academic research and scientific papers
Catalysis with palladium colloids supported in poly(acrylic acid)-grafted polyethylene and polystyrene
Bergbreiter, David E.,Kippenberger, Andrew,Zhong, Zhenqi
, p. 1343 - 1350 (2006)
Grafts of poly(acrylic acid) on polyethylene powder (PE-g-PAA) or polystyrene (PS-g-PAA) can be used to support Pd(O) crystallites that function like a homogeneous Pd(O) catalyst in some reactions. These Pd-PE-g-PAA catalysts were active in allylic substitution reactions in the presence of added phosphine ligand. A catalyst analogous to the Pd-PE-g-PAA powder catalyst on polystyrene (Pd-PS-g-PAA) was similarly active for allylic substitution and could also be used in Heck reactions at 80-100°C in N,N-dimethylacetamide (DMA). Analysis of the product solutions for Pd leachate and a correlation of the Pd leaching with product formation in the allylic substitution chemistry for both types of catalysts suggests that the active catalysts in these reactions are leached from the support. In the case of the allylic substitution reaction, external triphenylphosphine and substrate together are required for the chemistry and Pd leaching.
Non-Chelate-Assisted Palladium-Catalyzed Aerobic Oxidative Heck Reaction of Fluorobenzenes and Other Arenes: When Does the C?H Activation Need Help?
Albéniz, Ana C.,Villalba, Francisco
supporting information, p. 4795 - 4804 (2021/09/06)
The pyridone fragment in the ligand [2, 2’-bipyridin]-6(1H)-one (bipy-6-OH) enables the oxidative Heck reaction of simple arenes with oxygen as the sole oxidant and no redox mediator. Arenes with either electron-donating or electron-withdrawing groups can be functionalized in this way. Experimental data on the reaction with toluene as the model arene shows that the C?H activation step is turnover limiting and that the ligand structure is crucial to facilitate the reaction, which supports the involvement of the pyridone fragment in the C?H activation step. In the case of fluoroarenes, the alkenylation of mono and 1,2-difluoro benzenes requires the presence of bipy-6-OH. In contrast, this ligand is detrimental for the alkenylation of 1,3-difluoro, tri, tetra and pentafluoro benzenes which can be carried out using just [Pd(OAc)2]. This correlates with the acidity of the fluoroarenes, the most acidic undergoing easier C?H activation so other steps of the reaction such as the coordination-insertion of the olefin become kinetically important for polyfluorinated arenes. The use of just a catalytic amount of sodium molybdate as a base proved to be optimal in all these reactions. (Figure presented.).
Palladium-Based Catalysts Supported by Unsymmetrical XYC–1 Type Pincer Ligands: C5 Arylation of Imidazoles and Synthesis of Octinoxate Utilizing the Mizoroki–Heck Reaction
Maji, Ankur,Singh, Ovender,Singh, Sain,Mohanty, Aurobinda,Maji, Pradip K.,Ghosh, Kaushik
, p. 1596 - 1611 (2020/04/29)
A series of new unsymmetrical (XYC–1 type) palladacycles (C1–C4) were designed and synthesized with simple anchoring ligands L1–4H (L1H = 2-((2-(4-methoxybenzylidene)-1-phenylhydrazinyl)methyl)pyridine, L2H = N,N-dimethyl-4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazono)methyl)aniline, L3H = N,N-diethyl-4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazono)methyl) aniline and L4H = 4-(4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazono) methyl)phenyl)morpholine H = dissociable proton). Molecular structure of catalysts (C1–C4) were further established by single X-ray crystallographic studies. The catalytic performance of palladacycles (C1–C4) was explored with the direct Csp2–H arylation of imidazoles with aryl halide derivatives. These palladacycles were also applied for investigating of Mizoroki–Heck reactions with aryl halides and acrylate derivatives. During catalytic cycle in situ generated Pd(0) nanoparticles were characterized by XPS, SEM and TEM analysis and possible reaction pathways were proposed. The catalyst was employed as a pre-catalyst for the gram-scale synthesis of octinoxate, which is utilized as a UV-B sunscreen agent.
Monodentate phosphorus-coordinated palladium(II) complexes as new catalyst for Mizoroki-Heck reaction of aryl halides with electron-deficient olefins
Zhao, Fang,Xin, Li,Zhang, Yingying,Jia, Xuefeng
supporting information, p. 493 - 496 (2017/09/06)
Four novel palladium(II) complexes coordinated by phosphorus atoms from both 3,5-disubstituted-1H-1,2,4-diazaphospholes in monodentate fashion were developed as efficient catalyst for the Mizoroki-Heck reaction of aryl halides with electron-deficient olefins. The coupling reaction of aryl halide bearig different functional groups with olefin derivatives took place and the corresponding products were isolated in good to excellent yields under optimal conditions. The procedure exhibits good functional group tolerance and wide substrate scope. This Mizoroki-Heck reaction was further achieved using Pd(OAc)2 and 3,5-di-isopropyl-1H-1,2,4-diazaphospholes as combined catalyst, which provide the convenient and alternative method in organic synthesis
A convenient, efficient and reusable N-heterocyclic carbene-palladium(II) based catalyst supported on magnetite for Suzuki-Miyaura and Mizoroki-Heck cross-coupling reactions
Kandathil, Vishal,Fahlman, Bradley D.,Sasidhar,Patil, Siddappa A.,Patil, Shivaputra A.
, p. 9531 - 9545 (2017/08/29)
In the present work, a new magnetic nanoparticle supported N-heterocyclic carbene-palladium(ii) (NO2-NHC-Pd@Fe3O4) nanomagnetic catalyst was synthesized by a facile multistep synthesis under aerobic conditions using inexpensive chemicals. The NO2-NHC-Pd@Fe3O4 nanomagnetic catalyst was characterized by various analytical techniques such as attenuated total reflectance infrared spectroscopy (ATR-IR), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), energy-dispersive X-ray spectroscopy (EDS), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller surface area analysis (BET). The synthesized NO2-NHC-Pd@Fe3O4 nanomagnetic catalyst showed excellent catalytic activity in both Suzuki-Miyaura and Mizoroki-Heck cross-coupling reactions for various substrates under mild reaction conditions. Recovery of the NO2-NHC-Pd@Fe3O4 nanomagnetic catalyst from the reaction mixture was easily accomplished by applying an external magnet. The recovered NO2-NHC-Pd@Fe3O4 nanomagnetic catalyst exhibited very good catalytic activity up to seven recycles in Suzuki-Miyaura and five recycles in Mizoroki-Heck cross-coupling reactions without considerable loss of its catalytic activity.
Cross-Coupling Catalysis by an Anionic Palladium Complex
Schroeter, Felix,Soellner, Johannes,Strassner, Thomas
, p. 3004 - 3009 (2017/05/31)
Recent studies have shown that anionic palladium complexes are viable catalysts for a range of catalytic cross-coupling reactions. We present a one-step synthesis of the anionic "ligandless" palladium complex [NBu4][Pd(DMSO)Cl3] together with its crystal structure. This compound has been shown to be an active precatalyst in the Mizoroki-Heck reaction. Under Jeffery conditions, activated aryl chlorides can be coupled in yields of up to 94% without the need of an additional ligand. The presence of a small amount of water was necessary for product formation. An Amatore-Jutand-type catalytic cycle is consistent with the results presented herein. For comparison with the known mixed complex [(pym-Im-Me)2PdCl][Pd(DMSO)Cl3], the cationic complex [(pym-Im-Me)2PdCl]PF6 (pym = pyrimidyl, Im = imidazolin-2-ylidene) has been synthesized and characterized using standard techniques.
An efficient palladium catalyzed Mizoroki-Heck cross-coupling in water
Jadhav, Sanjay N.,Rode, Chandrashekhar V.
supporting information, p. 5958 - 5970 (2017/12/26)
The homogeneous Pd-catalysed Mizoroki-Heck coupling reaction was successfully performed in water in the absence of any additives under aerobic conditions. The various key reaction parameters that affect the yield of the desired cross-coupling product were optimized. The Pd(PPh3)4/Et3N/H2O/98 °C catalyst system was found to be highly active (TOF = 12 to 14 h-1) towards achieving excellent yield of the Mizoroki-Heck coupling products for a wide range of electron-withdrawing as well as electron-donating aryl bromides and chlorides in the shortest reaction time. Pd(PPh3)4 catalyst deactivation during the Mizoroki-Heck coupling reaction was investigated and to evolve a strategy for achieving ten times Pd-metal recyclability without appreciable loss of its activity. Thus, the proposed mechanism provides access to a variety of olefins in aqueous medium, making this protocol eco-friendly.
Bench-Stable and Recoverable Palladium(I) Dimer as an Efficient Catalyst for Heck Cross-Coupling
Sperger, Theresa,Stirner, Christopher K.,Schoenebeck, Franziska
supporting information, p. 115 - 120 (2016/12/24)
The application of air- and moisture-stable dinuclear palladium(I) complex [Pd(μ-I)(Pt-Bu3)]2 as an efficient catalyst for the Heck cross-coupling reaction of aryl iodides and bromides with acrylates and styrenes is described. The de
Cyclodextrin-Grafted Silica-Supported Pd Nanoparticles: An Efficient and Versatile Catalyst for Ligand-Free C-C Coupling and Hydrogenation
Martina, Katia,Baricco, Francesca,Caporaso, Marina,Berlier, Gloria,Cravotto, Giancarlo
, p. 1176 - 1184 (2016/04/05)
Silica is an extremely versatile support, which is capable of hosting metal nanoparticles (NPs) and enhancing their stability and reactivity. In this study, a novel cyclodextrin/silica support for Pd NPs, which we have denoted Pd/Si-CD, has been prepared. The highly efficient and homogeneous impregnation of small palladium nanoparticles on this support has been carried out under conventional conditions, and ultrasound irradiation has been shown to have a beneficial effect on catalyst preparation. The catalyst exhibited excellent activity in ligand-free C-C Suzuki and Heck couplings with a large number of aryl iodide and bromides, in which microwave irradiation use cuts down reaction time. Pd/Si-CD have shown high activity and selectivity in the hydrogenation reaction, and the semihydrogenation of phenyl acetylene was also studied with excellent results.
An efficient trifunctional benzhydrazone ligated Pd(II) complex for Heck reaction of aryl bromides
Muthumari, Subramanian,Mohan, Nanjan,Ramesh, Rengan
supporting information, p. 4170 - 4174 (2015/06/22)
Synthesis of air and thermally stable trifunctional O, N, and O-terdentate benzhydrazone Pd(II) complex is reported and characterized by elemental analysis, spectral methods, and single crystal X-ray crystallographic technique. The new and reusable homogeneous catalyst has been effectively applied to the Mizoroki-Heck reaction of activated and deactivated aryl bromides with various olefins under mild reaction conditions in good to excellent yields up to 99%.
