Suzuki Reaction of Aryl Bromides Using a Phosphine-Free Magnetic Nanoparticle-Supported Palladium Catalyst

A palladium catalyst immobilized on superparaganetic nanoparticles was prepared with a palladium loading of 0.30 mmol/g. The catalyst was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, thermogravimetric analysis, Fourier transform infrared, atomic absorption spectrophotometry, and nitrogen adsorption. The immobilized palladium catalyst was an efficient catalyst without added phosphine ligands for the Suzuki cross-coupling reaction of several aryl bromides with phenylboronic acid. The recovery of catalyst was simply by magnetic decantation in the presence of a magnet. The immobilized palladium catalyst can be reused many times without significant degradation in catalytic activity. No leaching of active palladium species into the reaction solution was detected.

Suzuki reaction of bromoallenes with arylboronic acids using an air-stable palladium complex Pd(Ph_2PCH_2CO_2)_2 as a precatalyst

Suzuki reaction of bromoallenes with arylboronic acids was successfully performed by using an air-stable hemilabile P-O coordinated cyclopalladated complex Pd(Ph_2PCH_2CO_2)_2 as a precatalyst,and the corresponding coupling products were obtained in satisfactory to excellent yields.All products are unknown compounds which were characterized by ~1H NMR,^(13)C NMR,IR,and HRMS.

Simple synthesis of sub-nanometer Pd clusters:High catalytic activity of Pd/PEG-PNIPAM in Suzuki reaction

Ultra‐small metal nanoclusters have high surface energy and abundant active sites,and thereforetheir catalytic activities are usually significantly higher than those of larger nanoparticles.A temperature‐responsive copolymer,namely poly(ethylene glycol)‐co‐poly(N‐isopropylacrylamide)(PEG‐PNIPAM)was synthesized as the first step,and then ultra‐small Pd clusters stabilized withinPEG‐PNIPAM copolymer micelles were formed by direct reduction.Pd nanoclusters of size less than2nm showed outstanding catalytic activity in the Suzuki coupling reaction.The reaction betweeniodobenzene and phenylboronic acid was completed in as little as10s(turnover frequency=4.3×104h?1).A yield of64%was achieved in5min in the reaction between chlorobenzene and phenylboronicacid.The catalyst showed significant deactivation during three consecutive runs.However,this composite catalyst consisting of Pd/PEG‐PNIPAM can be easily recycled based on the reversiblephase transition of temperature‐responsive PEG‐PNIPAM.This catalyst therefore has good potentialfor practical applications.

Synthesis,Structural Characterization of Ferrocenyl Iminophosphines and Amidophosphines as Well as Their Application in the Suzuki Reaction

Ferrocenyliminophosphine 1 and 1,1′-bisferrocenyliminophosphine 2 were easily prepared from the condensation of formylferrocene or 1,1′-diformylferrocene with 2-（diphenylphosphino） aniline. The following reduction of imine group by LiAlH4 led to the formation of the corresponding ferrocenyl amidophosphines 3 and 4. The new ligands 2- 4 were well characterized by IR, ^1H NMR, ^31p NMR spectra, elemental analysis, and ESI-MS. The catalytic activity of all the ligands with palladium compounds in the Suzuki reaction was evaluated. Ligand 1, in combination with Pd （OAc）2, was found to be the most effective for the Suzuki reaction of aryl bromides with phenylboronic acid. Typically, the use of 0. 1% （molar fraction） of Pd（OAc）2/ligand 1 in the presence of two equivalents of K2CO3 as base in toluene at 110 ℃ provided good to excellent yields of the coupled products.

1,3-Dicarbonyl compounds as phosphine-free ligands for Pd-catalyzed Heck and Suzuki reactions

Some 1,3-dicarbonyl compounds (such as pentane-2,4-dione and 3-oxo-N-phenylbutanamide) were found to constitute highly efficient, yet low-priced and phosphine-free ligands for the Pd-catalyzed Heck and Suzuki reactions of aryl bromides and iodides with very high turnover numbers (ca. 103–104).

4-Amino-1,2,4-triazole Resin-supported Palladium Complex as Phosphine-free Catalyst for Suzuki Reaction in Aqueous Phase

1 Introduction The Suzuki cross-coupling reaction is a powerful and versatile method for the generation of unsymmetrical biaryls from arylboronic acids and aryl halides in a single step. However, the reaction is usually performed in the presence of Pd catalyst along with phosphine ligand, which sometimes creates practical problems because organophosphines tend to be expensive, poisonous, and air sensitive. Recently, phos-phine-free ligands,

Aqueous-Phase, Palladium-Catalyzed Suzuki Reactions under Mild Conditions

Water-soluble ionic liquid-supported diols have been used as phosphine-free ligands in Suzuki couplings of aryl idides/bromides/chlorides under mild conditions in aqueous solvent. It was found that 2,2-bis((1-hexylimidazolium)-mehyl) propane-1,3-diol hexafluorophosphate (4) in combination with palladium (II) salts gave the most significant catalyst. Suzuki couplings of aryl iodides/bromides occurred efficiently at room temperature in water/acetonitrile. Notably, the reactions of hydrophilic aryl bromides gave high yields in neat water. The catalyst PdCl2-4 was recycled five times in Suzuki couplings in water before catalyst activity began to significantly drop. The average yield of five cycles was >95% per cycle.

A Facile Synthesis of N-alkyl-4'-methyl-1,1'-biphenyl-2-sulfona-mide via Linking DoM Reaction with Suzuki Reaction

Six N-alkyl-4＇-methyl-1,1＇-biphenyl-2-sulfonamides were synthesized facilely and efficiently from low cost and readily available benzenesulfonyl chloride and C1-C4 fatty amines via linking DoM reaction with Suzuki reaction.The structures of the new compounds synthesized were confirmed by elemental analysis,IR,1H NMR and MS.This new method makes a feature of low cost and readily available starting material,fewer steps,mild condition,easiness to operate and higher yield.

Symmetrical Palladium (II) N,N,O,O-Schiff Base Complex: Efficient Catalyst for Heck and Suzuki Reactions

Palladium is arguably the most versatile and most widely applied catalytic metal in the field of fine chemicals due to its high selectivity and activity. Palladium catalyst offers an abundance of possibilities of carbon-carbon bond formation in organic synthesis. In this research, three different Schiff base ligands have been prepared by condensation reaction between appropriate aldehyde or ketone with amine namely 2,2-dimethyl-1,3-propanediamine in the molar ratio of 2:1. The corresponding palladium (II) Schiff base complexes were prepared through the reaction between the Schiff base ligand with palladium (II) acetate in a molar ratio 1:1. FTIR, 1H-NMR and 13C-NMR spectroscopic data revealed that the ligands are N,N,O,O-tetradentate coordinated to the Pd atom through both the azomethine N atoms and phenolic O atoms. From X-ray Crystallographic analysis, it showed that the complex exists as square planar geometry. The synthesized palladium (II) Schiff base complexes were then subjected in catalytic Heck and Suzuki reaction of iodobenzene.

Palladium Nanoparticle-Graphene Hybrids as Active Catalysts for the Suzuki Reaction

Graphene has been successfully modified with palladium nanoparticles in a facile manner by reducing palladium acetate [Pd(OAc)2] in the present of sodium dodecyl sulfate (SDS), which is used as both surfactant and the reducing agent. The palladium nanoparticle-graphene hybrids (Pd-graphene hybrids) are characterized by high- resolution transmission electron microscopy, atomic force microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and energy dispersive X-ray spectroscopy. We demonstrate that the Pd-graphene hybrids can act as an efficient catalyst for the Suzuki reaction under aqueous and aerobic conditions, with the reaction reaching completion in as little as 5 min. The influence of the preparation conditions on the catalytic activities of the hybrids is also investigated.

Pd embedded in porous carbon （Pd@CMK-3） as an active catalyst for Suzuki reactions： Accelerating mass transfer to enhance the reaction rate

Heterogeneous catalysts are promising candidates for use in organic reactions due to their advantages in separation, recovery, and environment compatibility. In this work, an active porous catalyst denoted as Pd embedded in porous carbon （Pd@CMK-3） has been prepared by a strategy involving immersion, ammonia- hydrolysis, and heating procedures. Detailed characterization of the catalyst revealed that Pd（0） and Pd（I1） species co-exist and were embedded in the matrix of the porous carbon （CMK-3）. The as-prepared catalyst has shown high activity toward Suzuki reactions. Importantly, if the reaction mixture was homogenized by two minutes of ultrasonication rather than magnetic stirring before heating, the resistance to mass transfer in the pore channels was significantly reduced. As a result, the reactions proceeded more rapidly and a four-fold increase in the turnover frequency （TOF） could be obtained. When the ultrasonication was employed throughout the entire reaction process, the conversion could also exceed 90% even without the protection of inert gas, and although the reaction temperature was lowered to 30 ℃. This work provides a method for fabricating highly active porous carbon encapsulated Pd catalysts for Suzuki reactions and proves that the problem of mass transfer in porous catalysts can be conveniently resolved by ultrasonication without any chemical modification being necessary.

Recoverable Palladium（O） on Poly（vinylpyrrolidone） Catalyzed Ligand-free Suzuki Reaction in Water

In the absence of any ligand, a recoverable palladium（O） on poly（vinylpyrrolidone） （PVP） catalyzed Suzuki reaction of aryl iodide and bromide with potassium aryltrifluoroborate was developed. The reaction conditions involved the use of water as the solvent, potassium carbonate as the base, and PVP supported palladium metal colloids as the catalyst. The palladium metal could be recovered and recycled for eight consecutive trials without significant loss of its activity.

Carbon nanotubes-supported palladium nanoparticles for the Suzuki reaction in supercritical carbon dioxide: A facile method for the synthesis of tetrasubstituted olefins

A facile and efficient method for the synthesis of tetrasubstituted olefins in supercritical carbon dioxide was developed by using carbon nanotubes-supported palladium nanoparticles (Pd/CNTs) as the catalyst. Compared with common Pd/C, Pd/CNTs could more effectively catalyze the reaction of dibromo-substituted olefins with boronic acids, affording the corresponding tetrasubstituted olefins with moderate to good yields. This environmentally benign route with an easy-to-handle catalyst provides an appealing alternative to the currently available methods.

Aryl-guanidine/Pd-catalyzed Suzuki Cross-coupling Reaction at Room Temperature

Four aryl-guanidines（AG） were synthesized and used for the palladium-catalyzed Suzuki cross-coupling reaction to test the catalytic activity.In the presence of steric bulk AG,when aryl bromide and arylboronic acid were used as the reactants,the Suzuki reaction could be carried out smoothly at room temperature in aqueous solvent to afford the cross-coupling product in high yield.This catalysis system was also successful for the coupling of activated aryl chlorides at room temperature.

Arylation of pyridine N-oxides via a ligand-free Suzuki reaction in water

We report a practical and highly efficient protocol for the arylation of pyridine N-oxides with arylboronic acid through palladium-catalyzed Suzuki reaction in water.This ligand-free Suzuki reaction is performed in the presence of diisopropylamine and gives 2-or 3-arylated pyridyl N-oxide derivatives in good to excellent yields within 1 h.

Rapid Microwave-promoted Base-free Suzuki Coupling Reaction of Sodium Tetraphenylborate with Hypervalent Iodonium Salts in Water

The palladium chloride-catalyzed Suzuki coupling reaction of sodium tetraphenylborate with hypervalent iodonium salts was achieved under microwave irradiation in water without base in excellent yield. A convenient and rapid method for formation of carbon-carbon bonds was afforded.

Microwave-assisted Palladium-micelle-catalyzed Suzuki Cross-coupling Reaction in Water

A microwave-accelerated Suzuki coupling procedure was developed via guanidinium ionic liquids（GILs） stabilized Pd-micelle.The Pd micelle/GILs play a key role in enhancing the activity,due to the highly dispersed Pd active sites and the phase transfer function of GILs,which ensures the adsorption of reactants and facilitates the translation of the intermediates to the surface of the micelle.

Synthesis and characterization of a Pd(0) Schiff base complex anchored on magnetic nanoporous MCM-41 as a novel and recyclable catalyst for the Suzuki and Heck reactions under green conditions

A Pd Schiff base complex was immobilized onto the surface of magnetic MCM‐41(Fe3O4@MCM‐41@Pd(0)‐P2C)as a novel,eco‐friendly,and recyclable heterogeneous nanocatalyst and fully characterized by FT‐IR,VSM,EDS,transmission electron microscopy,scanning electron microscopy,thermogravimetric analyses,ICP‐OES,and X‐ray powder diffraction analysis.The Fe3O4@MCM‐41@Pd(0)‐P2C was investigated as a catalyst for the one‐pot Suzuki and Heck reactions in PEG as a green solvent to provide the target products in excellent yields.The main advantages of using this catalyst include a short reaction time,green reaction conditions,a simple experimental procedure,non‐use of hazardous organic solvents,low loading of the catalyst,and the ability to use various substrates.More importantly,the catalyst could be easily separated from the reaction mixture with the assistance of an external magnet and could be recovered and reused several times without significant loss of stability and activity.

Highly efficient and recyclable amorphous Pd(II)/crystal Pd(0)catalyst for boosting Suzuki reaction in aqueous solution

Ultrafine and highly dispersed Pd nanoparticles have drawn considerable attention with high activity,selectivity and atomic efficiency.In this paper,amorphous Pd(II)-complex solid spheres with-5 nm Pd nanoparticles loaded on were successfully achieved through a simple and gentle one-pot solution method with vitamin B1 simultaneously as complexing agent and reducing agent.An ultrathin mesoporous SiO_(2) shell was then coated at the surface of Pd(II-O)spheres as the armor which could prevent the dissolution of Pd(II)during the catalytic process.The combination of Pd(II)and Pd(0)endowed Pd(II-0)@m-SiO_(2) catalyst an excellent performance in eco-friendly aqueous media Suzuki reactions.The high activity,productivity and recyclability were all comparable with the best Pd catalysts ever reported.The ingenious formation of amorphous Pd(II)/crystal Pd(0)with enhanced catalytic performances provides a new,scalable strategy to practical promotion of Suzuki cross-coupling reactions.