Suzuki Reaction Of Aryl Bromides Research Articles

5,6-Membered CNN palladium pincer complexes of 3-benzyl-8-dimethylamino -3-azabicyclo[3.2.1]octane and 3-benzyl-9-dimethylamino-3-azabicyclo[3.3.1]nonane

The unsymmetrical CNN pincer ligand precursors 4 and 7b based on the structures of bicyclo[3.2.l]octane and bicyclo[3.3.l]nonane have been synthesized. The corresponding palladium pincer 5,6-membered complexes 5 and 9 were prepared by direct cyclopalladation of ligand precursors with Li2PdCl4 in MeOH. The molecular structure of the palladacycles was determined by 1H and 13C NMR and confirmed by X-ray diffraction analysis. The obtained complexes 5 and 9 exhibited good catalytic activity in the Suzuki reactions of aryl bromides with phenylboronic acid.

A simple and mild Suzuki reaction protocol using triethylamine as base and solvent

A simple and mild protocol for the palladium-catalyzed Suzuki reaction of aryl bromides and arylboronic acids is developed. The cross-coupling reactions can be performed at room temperature using 5.0 equiv. of Et3N as solvent and base without any ligands, and affording biaryl products in good yields. In addition, the chemoselecitive Suzuki reaction of bromo-N-methyliminodiacetic acid (MIDA) boronates with arylboronic acids can be achieved in this system, and various unsymmetrical terphenyls have been prepared in moderate yields by one-pot double Suzuki reactions.

Heterogenization of homogeneous NHC-Pd-pyridine catalysts and investigation of their catalytic activities in Suzuki-Miyaura coupling reactions

New generation, novel, environmentally safe polymeric heterogeneous catalysts which included catalytically active NHC-Pd-pyridine complexes were prepared by radical polymerization of NHC-Pd-pyridine complexes with Acrylamide (AAm) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) monomers in the presence of N,N′-methylenebisacrylamide (MBA) crosslinker. Structural characterization of NHC-Pd-pyridine complexes was conducted by using NMR, FT-IR while the structural characterization of crosslinked polymeric catalyst systems was made by using FT-IR, SEM, SEM-EDX, TEM and TGA analysis techniques. The synthesized polymer-based NHC-Pd-pyridine catalysts showed good catalytic activity for Suzuki reaction of aryl bromides with phenylboronic acid in aqueous media. They exhibited good stability and they could be reused at least five times without remarkable loss of catalytic activity.

A simple method for preparing imidazolium-based polymer as solid catalyst for Suzuki-Miyaura reaction

Polymers containing the structure of N-heterocyclic carbenes (NHCs) have attracted much interest due to their superior complexing ability to metal ions and good recyclability, which make them promising candidates as solid supporters. Herein, we developed an easy method to synthesize polyimidazolium chloride salt (PImCl) via one-step method in mild conditions. After PImCl was chelated with palladium chloride in 3-chloropyridine, this NHC-Pd polymer was employed as the solid catalyst for Suzuki reactions of aryl bromides and phenylboronic acid. The catalytic activity of the NHC-Pd polymer was high for many different substrates. Moreover, the Suzuki reaction of 4-bromoanisole with phenylboronic acid could be catalyzed by this NHC-Pd polymer in mild conditions. Furthermore, this solid catalyst could be easily isolated by centrifugal separation. After several recycling runs, the catalytic activity decreased little. Compared with the conventional methods, this method was much simpler and more efficient, which showed enormous potential in preparing new heterogeneous supporter of porous polyimidazolium chloride salt.

MCM-41-Immobilised Nitrogen and Sulfur Mixed Tridentate Palladium(0) Complex: A Highly Efficient and Recyclable Catalyst for the Suzuki Reaction of Aryl Bromides in Air

The novel MCM-41-immobilised nitrogen and sulfur mixed tridentate palladium(0) complex [MCM-41-2N,S-Pd(0)] was prepared from 3-(2-aminoethylamino)propyltrimethoxysilane by immobilisation on MCM-41, followed by reaction with thiophene-2-carboxaldehyde and PdCl2 and then reduction with hydrazine hydrate. This phosphine-free heterogeneous palladium(0) complex was a highly active catalyst for the Suzuki reaction of aryl bromides in air and could be recycled at least 8 times without significant loss of activity.

ChemInform Abstract: Recyclable N‐Heterocyclic Carbene/Palladium Catalyst on Graphene Oxide for the Aqueous‐Phase Suzuki Reaction.

Abstract Graphene oxide (GO) was functionalized with a N-heterocyclic carbene (NHC) precursor, 3-(3-aminopropyl)-1-methylimidazolium bromide ([APMIm][Br]) for the immobilization of palladium catalyst. The GO-supported NHC precursor (IMGO) formed a stable complex with Pd(OAc)2 (GO–NHC–Pd), which showed excellent catalytic activity and fast reaction kinetics in the aqueous-phase Suzuki reaction of aryl bromides and chlorides at relatively mild conditions (1 h at 50 °C). The GO–NHC–Pd catalyst was reused several times without any loss of its catalytic activity in the Suzuki reaction of aryl bromide.

Recyclable N-heterocyclic carbene/palladium catalyst on graphene oxide for the aqueous-phase Suzuki reaction

Graphene oxide (GO) was functionalized with a N-heterocyclic carbene (NHC) precursor, 3-(3-aminopropyl)-1-methylimidazolium bromide ([APMIm][Br]) for the immobilization of palladium catalyst. The GO-supported NHC precursor (IMGO) formed a stable complex with Pd(OAc)2 (GO–NHC–Pd), which showed excellent catalytic activity and fast reaction kinetics in the aqueous-phase Suzuki reaction of aryl bromides and chlorides at relatively mild conditions (1h at 50°C). The GO–NHC–Pd catalyst was reused several times without any loss of its catalytic activity in the Suzuki reaction of aryl bromide.

Cationic cyclopalladated ferrocenylpyrimidine complex as an efficient catalyst for the synthesis of substituted biarylmethanol by the Suzuki reaction in water

A new cationic cyclopalladated ferrocenylpyrimidine 2 has been synthesized and characterized by elemental analysis, IR, 1H and C13 NMR. Additionally, its detailed structure has been determined by single-crystal X-ray diffraction and intermolecular C–H⋯O hydrogen bonds were found in the its crystal. 2 was successfully used in Suzuki reaction of aryl bromides or chlorides excluding water-soluble group with 4-(hydroxymethyl)phenylboronic acid for the synthesis of substituted biarylmethanol in water. Complex 2 was found to be very efficient for these reactions. Typically, using 0.5–1mol% of catalyst in the presence of 3 equivalents of K3PO4·3H2O as base in water at 100°C provided coupling products in good yields.

Cyclopalladated Arylimine Self‐Assembly Films for Suzuki Reaction

AbstractA series of cyclopalladated arylimine self‐assembly films were prepared through chemical grafting to substrates and used to catalyze a Suzuki coupling reaction. Atomic force microscopy, water contact angle analysis, cyclic voltammetry, scanning electron microscopy, attenuated total‐reflectance infrared, and X‐ray photoelectron spectroscopy were used to analyze the morphology and composition of the heterogeneous catalysts. The results show that these cyclopalladated arylimine self‐assembly films immobilized on substrates could be used as efficient and reusable heterogeneous catalysts in the Suzuki reaction of aryl bromides under open air conditions in aqueous solution. These catalysts exhibited 10 times the catalytic performance of the homogeneous counterpart. The palladium catalysts were grafted onto the internal surface of the round‐bottomed flasks. The reaction flasks acted as both reaction vessels and catalysts, which simplified the reaction operations. The catalysts were run over 8 cycles without showing any sign of deactivation, suggesting the potential of the catalysts as advanced functional materials with applications in the heterogeneous catalysis of Suzuki reactions.

A conveniently synthesized polyethylene gel encapsulating palladium nanoparticles as a reusable high-performance catalyst for Heck and Suzuki coupling reactions

The synthesis of a polyethylene (PE) gel containing self-incarcerated palladium(0) nanoparticles is described. The PE gel matrix without any special functionality was synthesized by one-pot chain walking copolymerization of ethylene and 1,6-hexanediol diacrylate facilitated by a Pd–diimine complex (1). The Pd(II) species from 1 were immobilized in situ onto the gel matrix and further reduced to Pd(0) nanoparticles as a result of catalyst 1 deactivation during polymerization and methanol (a reducer) washing in the polymer purification process. The resulting Pd-containing PE gel (2) is shown to be a high-performance and facilely reusable heterogeneous catalyst for the Heck and Suzuki coupling reactions of iodobenzene or aryl bromides. An average TOF of 460 h−1 was achieved with an average 0.57 ppm Pd leaching in each cycle of the Heck reaction of iodobenzene when the PE gel 2 was recycled 10 times. A maximum TOF of 3.33 × 104 h−1 was reached and less than 0.64 ppm of Pd was leached in the Suzuki reactions of aryl bromides with water as solvent.

Suzuki reactions of aryl bromides catalyzed by amidoxime fibers-palladiumII complex

Amidoxime fibers-palladium II complexes [Pd II -AOFs] were synthesized by combining PdCl 2 with amidoxime fibers. Pd II -AOFs are novel phosphine-free recyclable heterogeneous catalysts for Suzuki coupling reaction of aryl bromides with phenylboronic acid to provide the corresponding products in high yields. The heterogeneous catalyst can be readily recovered by simple filtration and reused several times without significant loss in its activity. ► A novel phosphine-free amidoxime fibers-pd II catalyst has been synthesized. ► The catalyst exhibits good catalytic activity and stability for Suzuki reaction. ► XPS, XRD, SEM and EDS were used to guess the catalytic process.

Competing reaction method for identification of fast and slow steps of catalytic cycles: Application to heck and Suzuki reactions

A method for identification of fast and slow steps of catalytic cycles is suggested. This method provides reliable data for reactions conducted at an unsteady-state catalyst concentration. It has been used in the determination of the rate-determining step in the Heck reaction of aryl bromides and in the Suzuki reaction of aryl bromides and aryl iodides. The data obtained by this method are in agreement with the data obtained by other methods, including kinetic isotope effect measurements.

Simple kinetic method for distinguishing between homogeneous and heterogeneous mechanisms of catalysis, illustrated by the example of “ligand-free” Suzuki and Heck reactions of aryl iodides and aryl bromides

Using a simple method based on an analysis of the phase trajectories of competing reactions of several substrates, it has been established that the selectivity of catalytically active species in the Suzuki reaction of aryl bromides depends on the nature of the catalyst precursor. This indicates that there is a considerable contribution from heterogeneous catalysis. At the same time, in the reaction involving aryl iodides, when the catalyst concentration in the solution is much higher, the selectivity of the catalyst is precursor-independent, suggesting that homogeneous catalysis is dominant. In the Heck reaction of both aryl bromides and aryl iodides, pure homogeneous catalysis takes place.

Synthesis, structural characterization and catalytic activity of two N-heterocyclic carbene–phosphine palladium(II) complexes

Abstract Two new N-heterocyclic carbene (NHC)-phosphine palladium(II) complexes Pd(IMeo)PPh3I2 1 and Pd(IMeo) P(C6H4-p-Me)3I2 2 (IMeo = 1,3-di-4-methoxyphenyl- imidazolin-2-ylidene) have been easily prepared from the reaction of the corresponding iodide-bridged NHC dimer with phosphine ligands in high yields. Complexes 1 and 2 were characterized by elemental analysis, IR, 1H NMR, ESI-MS and single-crystal X-ray analysis. Complex 1 adopts a trans geometry in the solid state, while 2 is cis. The common features of the structures of these complexes are intermolecular C H⋯I and C H⋯O hydrogen bonds. These complexes were found to be efficient catalysts for the Suzuki reaction of aryl bromides.

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. A magnetically recoverable palladium catalyst was prepared, characterized, and employed for the Suzuki reaction of aryl bromides with phenylboronic acid. The catalyst can be reused many times.

An efficient and simple protocol for a PdCl2-ligandless and additive-free Suzuki coupling reaction of aryl bromides

A highly efficient, convenient, and environmentally friendly protocol was developed for the PdCl2-catalyzed ligandless and additive-free Suzuki reaction of aryl bromides with arylboronic acids in water/ethanol.

Oxygen-promoted PdCl2-catalyzed ligand-free Suzuki reaction in aqueous media

A simple and efficient protocol has been developed for the PdCl(2)-catalyzed ligand-free and aerobic Suzuki reaction of aryl bromides or nitrogen-based heteroaryl bromides with arylboronic acids in good to excellent yields in aqueous ethanol. A systematic investigation on the effect of different atmospheres on the reactivity of the palladium-catalyzed Suzuki reaction has been carried out, the results show that an aerobic atmosphere demonstrates a positive effect on the reactivity of the Suzuki reaction in an aqueous media and a negative effect in a pure organic solvent, which exhibits that the water plays a crucial role for the function of the atmosphere on the palladium-catalyzed ligand-free Suzuki reaction.

A simple and efficient protocol for a palladium-catalyzed ligand-free Suzuki reaction at room temperature in aqueous DMF

A convenient, effective and mild protocol has been developed for the palladium-catalyzed ligand-free Suzuki reaction of aryl bromides with arylboronic acids in aqueous N,N-dimethylformamide (DMF) in the presence of K2CO3 and a catalytic amount of PdCl2 in air at room temperature. It is noteworthy that the volume ratio of water–DMF and base play important roles in the reaction, and various functional groups are tolerated under the optimized conditions. Furthermore, this protocol could be extended to the cross-couplings of nitrogen-based heteroaryl halides with arylboronic acids in moderate to excellent yields.

Synthesis and application of ortho-palladated complex of (4-phenylbenzoylmethylene)triphenylphosphorane as a highly active catalyst in the Suzuki cross-coupling reaction

The ortho-metallated complex [Pd(μ-Cl){ κ 2( C, C)-[C 6H 4(PPh 2CHC(O)C 6H 4-Ph-4)}] 2 ( 2a) was prepared by refluxing of Pd(OAc) 2 and {(Ph) 3PCHCOC 6H 4-Ph-4} (PhBPPY) of in CH 2Cl 2 followed by addition of an excess of KCl in MeOH Complex ( 2a) reacts with triphenylphosphine to give the mononuclear derivative [Pd(Cl)(PhC 6H 4COCHPPh 2C 6H 4)(PPh 3)] ( 3a) whose crystal structure has been determined by single crystal X-ray diffraction. The Suzuki reactions of aryl bromides and chlorides of varying electron density using complex ( 3a) as an efficient catalyst were performed, giving the cross-coupling products in good to excellent yields.

Cyclopalladated complexes of 2-(m-nitrophenyl)imidazolines: synthesis, characterization and catalytic activity in the Suzuki reaction under mild conditions

Three cyclopalladated complexes of 2-(m-nitrophenyl)imidazolines have been easily prepared and characterized by spectroscopic analysis. The structure of one of the complexes has been determined by single-crystal X-ray analysis. The complexes are effective catalysts for the Suzuki reaction of aryl bromides with phenylboronic acid in aqueous solution at room temperature under air.