Polymethyl methacrylate micro-spheres supported palladium: A new catalyst for Heck and Suzuki reactions

Polymethyl methacrylate (PMMA) micro-spheres, a kind of commercially available polymeric material was treated with PdCl₂ and formaldehyde giving a reagent with a palladium loading of 0.79 (wt.%). The Pd-PMMA catalyzed the highly efficient Heck and Suzuki reactions. The reactions can be performed under ligand-free conditions in an air atmosphere. The palladium catalyst is easily separated and can be reusable with negligible leaching of palladium.     

碳负载钯催化剂对Heck反应的催化性能

研究了钯碳催化剂对芳基卤和取代芳基卤与丙烯酸和苯乙烯的Heck芳基化反应的催化性能.结果表明:在反应温度为80℃、反应时间为8h、四丁基溴化铵(TBABr)作为溶剂和三丁胺作为碱的条件下,钯碳催化剂对不同取代芳基卤与丙烯酸和苯乙烯的Heck芳基化反应具有良好的催化性能,产物收率在80%以上.     

Preparation and application of SBA-15-supported palladium catalyst for Heck reaction in supercritical carbon dioxide

A new method for the preparation of SBA-15-supported palladium catalyst for Heck reaction in supercritical carbon dioxide was presented.The newly formed SBA-15-supported palladium catalyst（Ph-SBA-15-PPh₃-Pd） exhibited high catalytic activity for the Heck reaction of 4-nitrobromobenzene with methyl acrylate.The catalyst can be reused several times without a loss of activity.     

First use of a palladium complex with a thiosemicarbazone ligand as catalyst precursor for the Heck reaction

A novel palladium complex with salicylaldehyde N(4)-ethylthiosemicarbazone has been synthesized and according to its crystal structure the ligand is bound to the metal in an O, N, S-terdentate coordination mode. This phosphorus-free system efficiently catalyzes the Heck reaction of aryl bromides (from electron-rich to electron-poor) with styrene under argon, with turnover numbers of up to 43,000, at 150 °C after 24 h, and with a selectivity toward trans-stilbenes ranging from 92 to 96%. In air, for activated aryl bromides and for a palladium concentration of 1 mM, the yields are essentially the same as those obtained when the reaction was performed under argon.     

Macroporous magnetic poly(GMA-EGDMA-DVB) microspheres supported palladium complex as an efficient catalyst for Heck reaction

<正>Macroporous magnetic poly(GMA-EGDMA-DVB) microspheres synthesized by suspension polymerization were used as supports for palladium catalyst.The results showed the novel magnetic catalyst can promote Heck reaction of aryl halides with acrylic acid efficiently without an inert atmosphere.In addition,the novel catalyst can be conveniently recovered by applying an external magnet and reused at least five times without significant loss of its activity.     

Bis-chelate tetracarbene palladium(II) complex as an efficient and recyclable catalyst precursor for Heck reaction

A homoleptic Pd(II) complex with two chelating di-N-heterocyclic carbene (NHC) ligands has been synthesized and its square planar molecular geometry has been determined by X-ray diffraction analysis. The complex proved to be an efficient catalyst having exceedingly high turnover number and good reusability in Heck reaction.     

Polystyrene-supported recyclable palladacycle catalyst for Heck, Suzuki and Sonogashira reactions

A new type of soluble polystyrene-supported palladium complex as an excellent and recyclable palladacycle catalyst was discovered for carboncarbon bond formation in Heck, Suzuki and Sonogashira reactions. Precipitation and filtration process for recycling the catalyst was also achieved.     

Preparation of a titania‐supported highly dispersed palladium nano‐catalyst and its application in Suzuki and Heck coupling reactions

In this work, palladium complexes nanoparticles in titania are prepared by a pH‐controlled adsorption and without pH‐controlled adsorption method. This method results in high‐dispersion palladium on the titania surface. We demonstrate the use of the titania‐supported palladium as an efficient catalyst for Suzuki and Heck reactions of a representative range of aryl bromides and chlorides. The reusability of catalyst was tested, and deactivation process of the catalyst was not observed after four recycles. The catalysts were characterized by FT‐IR, NMR, elemental analysis, field emission scanning electron microscopy, transmission electron microscopy and X‐ray diffraction. Copyright © 2013 John Wiley & Sons, Ltd.     

Polymer‐supported macrocyclic Schiff base palladium complex as an efficient catalyst for the Heck reaction

A polymer‐supported macrocyclic Schiff base palladium complex has been synthesized. In the Heck reaction of aryl iodides and bromides with ethyl acrylate or styrene, the complex has been proved to give the corresponding products in good to excellent yields. The reaction proceeded smoothly in the presence of 0.5 mol% of catalyst in DMF within 1–4 h. Recycling studies have shown that the catalyst can be readily recovered and reused for four cycles with only a slightly decrease in its activity. Copyright © 2011 John Wiley & Sons, Ltd.     

Applications of a monomeric orthopalladate complex containing mixed phosphorus-nitrogen donors in the Heck reaction

The [Pd{C₆H₂(CH₂CH₂NH₂)-(OMe)₂,3,4}Br(PPh₃)] monomeric orthopalladate complex of homoveratrylamine and triphenylphosphine was synthesized and its application in Heck coupling reactions was investigated. This complex had been demonstrated to be more active than the corresponding dimeric catalyst for Heck reactions of aryl iodides, bromides and even chlorides and also arenesulfonyl chlorides. The cross-coupled products were produced in excellent yields using catalytic amounts of [Pd{C₆H₂(CH₂CH₂NH₂)-(OMe)₂,3,4}Br(PPh₃)] as a thermally stable and oxygen insensitive complex in NMP at 130 °C.     

Reducing agents as components in catalytic systems of the Heck reaction

Using of reducing agents for arylation of alkenes has been found to increase the activity of the catalytic system and allow to avoid the use of traditional tertiary amines as bases in the Heck reaction.     

Synthesis and characterization of silica-supported Pd nanoparticles and its application in the Heck reaction

Well-dispersed palladium nanoparticles immobilized onto modified silica(SiO 2-pr-NH-cyanuric-SH) have been prepared in some facile steps.The catalyst exhibits high catalytic activity in the Heck reaction,and can be easily recovered and reused without significant loss of its activity in several runs.     

Assembled catalyst of palladium and non-cross-linked amphiphilic polymer ligand for the efficient heterogeneous Heck reaction

The efficient heterogeneous Heck reaction was achieved by a new networked and supramolecular catalyst PdAS-V (1b). Employing of PdAS-V in 5.0×10⁻⁵ mol equiv. efficiently progressed the heterogeneous Heck reaction of a series of aryl iodides with acrylates, styrenes and acrylic acid. PdAS-V was successfully recycled five times without any decrease in its activity, and showed good stability in toluene and water, and hence the Heck reaction was efficiently performed in both reaction media. The use of 8.0×10⁻⁷ mol equiv. of PdAS-V resulted in the coupling product in 92% yield with the turnover number (TON) and the turnover frequency (TOF) of PdAS-V reached up to 1,150,000 and 12,000, respectively. The efficient synthesis of resveratrol was achieved via the PdAS-V-promoted Heck reaction.     

Preparation of polystyrene-supported soluble palladacycle catalyst for Heck and Suzuki reactions

A polystyrene-supported palladium complex soluble in tetrahydrofuran and N,N-dimethylacetamide and precipitated in diethyl ether or acetonitrile was prepared from two routes as an excellent and recyclable palladacycle catalyst for carbon-carbon bond formation in Heck and Suzuki reactions to give high yields of the desired products.     

Palladium-catalyzed Heck reaction of in-situ generated benzylic iodides and styrenes

A palladium-catalyzed Heck reaction of in-situ generated benzylic iodides and styrenes has been achieved. The reaction proceeds in a one-pot manner through 1) addition perfluoroalkyl iodides to styrenes to give benzylic iodides, 2) followed by a palladium-catalyzed Heck coupling of the resulting benzylic iodides with the same alkenes in high regio- and stereoselectivity. A variety of perfluoroalkylated alkenes were obtained in moderate to excellent yields.     

Polymer (fiber)-supported palladium catalyst containing imidazolinyl rings and its application to the Heck reaction

A polymer (fiber)-supported palladium catalyst was synthesized simply from commercially available polyacrylonitrile(PAN) fiber. Its high activity and selectivity for Heck reactions were measured; its activity remained unchanged after being recycled 20 times.     

A ligand-free Heck reaction catalyzed by the in situ-generated palladium nanoparticles in PEG-400

<正>A ligand-free Heck reaction catalyzed by in situ-generated palladium nanoparticles in PEG-400 has been developed.This catalytic system is a simple and active protocol for the Heck reaction of aryl halides under mild conditions.Comparative experiments demonstrated that the Heck reaction catalyzed by the palladium nanoparticles in situ-generated under the Heck reaction conditions was carried out much quicker than that by the in ex situ-generated ones.     

Terephthalic acid derived ligand‐stabilized palladium nanocomposite catalyst for Heck coupling reaction: without surface‐modified heterogeneous catalyst

A new protocol is reported for the synthesis of a heterogeneous palladium nanocomposite stabilized with a terephthalic acid‐derived ligand (N ,N ‐bis(4‐hydroxy‐3‐methoxybenzylidene)terephthalohydrazide). This is a highly insoluble ligand in common organic solvents, except dimethylformamide and dimethylsulfoxide. The resulting palladium nanocomposite acts as an efficient catalyst precursor for Mizoroki–Heck coupling reactions conducted under various reaction conditions. The spectral data suggest that the rate, yield and recycling of the catalyst are more effective for C–C coupling reactions. Copyright © 2016 John Wiley & Sons, Ltd.     

Kinetic investigation of a PC(sp)P pincer palladium (II) complex in the Heck reaction

An investigation of the kinetics of the Heck reaction between 4-iodoanisole and styrene catalysed by {cis-1,3-bis[(di-tert-butylphosphino)methyl]-cyclohexane} palladium (II) iodide (1) has been performed in DMF-d₇ solution. Based on mercury poisoning experiments a heterogeneous palladium catalyst formed from the pre-catalyst is proposed. Saturation behaviour with respect to the olefin concentration suggests a mechanism consisting of a pre-equilibrium association of the olefin followed by a rate determining reaction with aryl halide. The equilibrium constant for the olefin association, K₁, and the rate constant for the subsequent oxidative addition step, k₂, were determined to (5.7 ± 2.5) × 10⁻³ and 18.4 ± 2.7 M⁻¹ s⁻¹, respectively.