Reaction Of Various Aryl Halides Research Articles

Synthesis and characterization of D-2PA-Pd(II)@SBA-15 catalyst via “click chemistry”: highly active catalyst for Suzuki coupling reactions

Copper catalysed cycloaddition reaction between azide and terminal alkyne, called as “click reaction”, was found to be modular approach for the synthesis of facile, highly efficient and recoverable D-2PA-Pd(II)@SBA-15 catalyst. In efforts to synthesize the catalyst, the cycloaddition reaction between azido-functionalized mesoporous SBA-15 and N,N-dimethyl-2-propynylamine (D-2PA) has been carried out, followed by the complexation with PdCl2. To analyze physiochemical properties of synthesized materials, various characterization techniques such as CHN elemental analysis, X-ray diffraction, solid state 13C and 29Si NMR spectra, FT-IR, XPS, SEM, TEM and N2 sorption analysis, TGA and DTA, UV–Vis spectroscopy have been carried out. The synthesized catalyst, D-2PA-Pd(II)@SBA-15, exhibited excellent catalytic activities with good product yield and high TON towards Suzuki coupling reaction of various aryl halides with phenylboronic acid. The effect of solvent, base and temperature on coupling reactions has also been described. The developed protocol offers recyclability of catalyst for multiple (four) times without any appreciable loss in stability and catalytic reactivity.

Synthesis and X‐ray structural characterization of a bidendate phosphine (dppe) palladium(II) complex and its application in Stille and Suzuki cross‐coupling reactions

The synthesis, characterization, crystal structure and catalyst activity of the bidentate phosphine complex [1,2‐bis(diphenylphosphino)ethane]palladium(II) bromide, [PdBr2(dppe)], are presented. Treatment of 1,2‐bis(diphenylphosphino)ethane with palladium(II) bromide under mild conditions resulted in the compound in high yield and purity. The characterization of the synthesized compound was performed using spectroscopic methods, such as Fourier transform infrared and NMR, CHN analysis and X‐ray crystallography. The structure of the compound was slightly distorted square planar. This compound was found to work as an efficient catalyst for both Stille and Suzuki cross‐coupling reactions of various aryl halides with triphenyltin chloride and/or phenylboronic acid. Also, the catalyst could be recovered and reused several times without significant loss of its catalytic activity. Copyright © 2016 John Wiley & Sons, Ltd.

ChemInform Abstract: C(sp2)—C(sp2) Cross Coupling Reaction Catalyzed by a Palladacycle Phosphine Complex: A Simple and Sustainable Protocol in Aqueous Media.

AbstractA palladacycle phosphine complex is used as catalyst for the Heck reaction of various aryl halides with olefins.

Miswak mediated green synthesized palladium nanoparticles as effective catalysts for the Suzuki coupling reactions in aqueous media

Green and eco-friendly synthesis of palladium nanoparticles NPs is carried out under facile and eco-friendly conditions using an aqueous solution of Salvadora persica L. (SP) root extract (RE) as a bioreductant, which is commonly known as Miswak. The as-synthesized Pd NPs were characterized using various spectroscopic and microscopic techniques, including, UV–Vis spectroscopy, FT-IR spectroscopy, XRD, ICP-MS and TEM. Detailed investigations of the Pd NPs have confirmed that the polyphenolic phytomolecules present in the RE of Miswak not only act as a bioreductant by facilitating the reduction and growth of Pd NPs, but they also functionalize the surface of Pd NPs and stabilized them in various solvents. Furthermore, the catalytic activity of the green synthesized Pd NPs was also tested toward the Suzuki coupling reactions of various aryl halides in aqueous media. The as-prepared Pd NPs exhibited superior catalytic activity and reusability for the Suzuki coupling reaction in aqueous and aerobic conditions. The kinetics of the reaction studied by GC revealed that the conversion of various aryl halides to biphenyl takes place in a short time.

A new N–heterocyclic carbene palladium complex immobilized on nano silica: An efficient and recyclable catalyst for Suzuki–Miyaura C[sbnd]C coupling reaction

A new catalytic system based on Pd–NHC complex utilizing (4–pyridyl)bis(imidazolyl)methane as a bidentate NHC ligand supported on nano‒silica is introduced. The catalyst was characterized by FT–IR spectroscopy, thermogravimetric analysis, field emission scanning electron microscopy, energy dispersive X–ray analysis, transmission electron microscopy and elemental analysis. This heterogeneous catalytic system exhibited excellent activity in the Suzuki–Miyaura coupling reaction of various aryl halides with phenylboronic acid, and was reusable several times without significant loss of its catalytic activity.

Biguanidine‐functionalized chitosan to immobilize palladium nanoparticles as a novel, efficient and recyclable heterogeneous nanocatalyst for Suzuki–Miyaura coupling reactions

Biguanidine‐functionalized chitosan was synthesized and combined with palladium nanoparticles to yield a recyclable, environmentally benign, heterogeneous catalytic system for the Suzuki–Miyaura C–C coupling reaction. The catalyst was characterized using various techniques. The catalyst was used in Suzuki cross‐coupling reactions of various aryl halides, including less reactive chlorobenzenes, with phenylboronic acid to give biaryls without any additive or ligand. A reusability test demonstrated that the catalyst was highly efficient even after six runs. Solid‐phase poisoning and leaching tests indicated that the catalyst has a heterogeneous nature. Copyright © 2016 John Wiley & Sons, Ltd.

C(sp2)–C(sp2) cross coupling reaction catalyzed by a palladacycle phosphine complex: A simple and sustainable protocol in aqueous media

The Heck reactions of various aryl halides with olefins using {[Ph2PCH2PPh2CH = C(O)(C10H7)] PdCl2} as efficient catalyst has been investigated. The mononuclear palladacycle complex showed excellent activity in aqueous phase including the C(sp 2)–C(sp 2) cross coupling reactions. The advantages of the protocol are high yields, short reaction time, a cleaner reaction profile and notable simplicity. Application of the palladacycle complex in the Heck cross coupling reaction of various aryl halides with styrene and ethyl acrylate is reported.

Palladium-Schiff Base Complex Immobilized Covalently on Magnetic Nanoparticles as an Efficient and Recyclable Catalyst for Heck and Suzuki Cross-Coupling Reactions

A new palladium-Schiff base complex immobilized covalently on magnetic nanoparticles (Pd-imino-Py-γ-Fe2O3) was synthesized via the reaction of chloro-functionalized γ-Fe2O3 with iminopyridine followed by the reaction with palladium acetate. Characterization of Pd-imino-Py-γ-Fe2O3 was carried out by various techniques such as XRD, SEM, TEM, FT-IR, TGA, ICP, XPS, VSM and elemental analysis. Pd-imino-Py-γ-Fe2O3 was successfully applied as a magnetically recyclable heterogeneous catalyst in Heck and Suzuki cross-coupling reactions of various aryl halides (iodide, bromides and chlorides as challenging substrates) with olefins and phenylboronic acid, respectively. The synthesized catalyst was separated easily by using an external magnet and recycled eight runs without appreciable loss of its catalytic activity and leaching of the significant quantity of Pd.

A palladium–phosphine catalytic system as an active and recycable precatalyst for Suzuki coupling in water

The Suzuki–Miyaura reaction of various aryl halides with aryl boronic acids using {[Ph2PCH2PPh2CH=C(O)(C10H7)]PdCl2} as a catalyst has been investigated. The X-ray crystal structure of the catalyst reveals a five-membered chelate ring formed by coordination of the ligand through the phosphine group and the ylidic carbon atom to the metal center. This palladacycle exhibited excellent activities and reusability in the aqueous phase for the Suzuki cross-coupling reactions of arylboronic acids with aryl halides. The proposed protocol featured mild reaction conditions and notable simplicity and efficiency using Cs2CO3 as a base in water. The catalytic system could be reused four times without significant loss of activity.

Palladium particles from oxime-derived palladacycle supported on Fe3O4/oleic acid as a catalyst for the copper-free Sonogashira cross-coupling reaction

An oxime-derived palladacycle was synthesized using 4-bromobenzoxime and pyridine in CHCl3, and characterized by FT-IR and 1H NMR spectroscopy. This Pd complex was supported on Fe3O4/oleic acid and shown to be an efficient catalyst for the copper-free Sonogashira cross-coupling reaction of various aryl halides with phenylacetylene in air and in ethanol or mixed aqueous medium. The oxime-derived palladacycle gave highly active palladium nanoparticles for the organic synthesis. The coupling products were obtained in high yields with low Pd loading and the heterogeneous catalyst can be separated by an external magnet and reused six times without loss of its activity. The characterization of the catalyst was carried out by XRD, SEM and TEM. Both TEM and XRD revealed that the palladium nanoparticles were well dispersed with diameters from 5 to 10 nm and average size 9.97 nm.

Preparation and characterization of HypoGel-supported Pd nanocatalysts for Suzuki reaction under mild conditions

A new heterogeneous catalyst composed of Pd nanoparticles immobilized within a HypoGel resin has been prepared in the absence of any ligands using an extensive cross-linking method. This newly developed nanocatalyst was characterized by N2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy and inductively coupled plasma-mass spectrometer (ICP-MS) techniques. TEM and XRD results revealed that the Pd nanoparticles were well dispersed with diameters in the range of 4–12 nm, and an average size of about 8 nm. The cross-linked Pd catalyst demonstrated excellent catalytic activity towards the synthesis of a series of biaryl compounds by the reaction of various aryl halides (e.g., bromides andiodides) with phenylboronic acid in the presence of tetrabutylammonium bromide. ICP-MS analysis indicated that there was only 0.25% weight loss of Pd (0.55 ± 0.02 ppm) from the supported catalyst after the first cycle reaction. Furthermore, the catalyst showed excellent reusability (up to five uses) with consistently high levels of catalytic activity following its recovery by filtration.

Palladium supported on silica–chitosan hybrid material (Pd‐CS@SiO2) for Suzuki–Miyaura and Mizoroki–Heck cross‐coupling reactions

Palladium supported on silica–chitosan hybrid material was prepared and characterized using thermogravimetric and differential thermogravimetric analyses, scanning electron microscopy, and Fourier transform infrared, energy‐dispersive X‐ray and X‐ray photoelectron spectroscopies. The prepared Pd‐CS@SiO2 catalyst (1 mol%) was used for the Suzuki–Miyaura cross‐coupling reaction of various aryl halides and arylboronic acids in 95% ethanol at 80 °C and the Mizoroki–Heck reaction in dimethylformamide at 110 °C using K2CO3 as a base. The developed catalyst is well suitable for the 3R approach (recoverable, robust, recyclable) for cross‐coupling reactions without appreciable loss of its activity. Copyright © 2015 John Wiley & Sons, Ltd.

Exfoliated Pd decorated graphene oxide nanosheets (PdNP–GO/P123): Non-toxic, ligandless and recyclable in greener Hiyama cross-coupling reaction

Graphene oxide nanosheets were applied as a support for Pd nanoparticles in Hiyama reaction of various aryl halides and triethoxyphenylsilane to generate biaryl derivatives in aqueous conditions. Addition of surfactant during the catalysis caused a significant increase in yields of products through well-exfoliation of PdNP–GO. Among various studied surfactants, P123 showed superior activity rather to other surfactants, SDS and CTAB. This heterogeneous catalytic system has attained the advantages of being non-toxic, available, recyclable, ligand-free, and compatible to reaction medium.

PEPPSI‐Effect on Suzuki–Miyaura Reactions Using 4,5‐Dicyano‐1,3‐dimesitylimidazol‐2‐ylidene‐Palladium Complexes: A Comparison between trans‐Ligands

AbstractThe PEPPSI (Pyridine Enhanced Precatalyst Preparation, Stabilization and Initiation) complexes 12–15 with the structure [PdCl2{(CN)2IMes}(3‐R‐py)] (12: R = H; 13: R = Cl; 14: R = Br; 15: R = CN) bearing the maleonitrile‐based N‐heterocyclic carbene (NHC) (CN)2IMes ({(CN)2IMes}: 4,5‐dicyano‐1,3‐dimesitylimidazol‐2‐ylidene) were prepared. Solid state structures of 14 and 15 were obtained. Complexes 14 and 15 adopt a slightly distorted square‐planar coordination geometry in the solid state with the substituted pyridine ligand trans to the NHC. Catalytic activities of precatalysts 12–15 were studied and subsequently compared to complexes [PdCl2{(CN)2IMes}(PPh3)] (4) and [PdCl(dmba){(CN)2IMes}] (5) recently reported by our group in the Suzuki–Miyaura reaction of various aryl halides and phenylboronic acid. Reactions using previously reported [PdCl2(IMes)(py)] (IMes: 1,3‐dimesitylimidazol‐2‐ylidene) (1) were also carried out and their results contrasted to those involving 12–15, 4 and 5. Differences in initiation rates and the catalytically active species related to the seven complexes in regards to the “throw away ligand” were investigated. Poisoning experiments with mercury show that palladium nanoparticles are responsible for the catalytic activity.

A highly stable and efficient magnetically recoverable and reusable Pd nanocatalyst in aqueous media heterogeneously catalysed Suzuki C–C cross‐coupling reactions

Surface modification of Fe3O4 nanoparticles with triethoxyethylcyanide groups was used for the immobilization of palladium nanoparticles to produce Fe3O4/Ethyl‐CN/Pd. The catalyst was characterized using Fourier transform infrared, wavelength‐dispersive X‐ray, energy‐dispersive X‐ray and X‐ray photoelectron spectroscopies, field‐emission scanning electron and transmission electron microscopies, and X‐ray diffraction, vibrating sample magnetometry and inductively coupled plasma analyses. In this fabrication, cyano groups played an important role as a capping agent. The catalytic behaviour of Fe3O4/Ethyl‐CN/Pd nanoparticles was measured in the Suzuki cross‐coupling reaction of various aryl halides (ArI, ArBr, ArCl) with phenylboronic acid in aqueous phase at room temperature. Interestingly, the novel catalyst could be recovered in a facile manner from the reaction mixture by applying an external magnet device and recycled seven times without any significant loss in activity. Copyright © 2015 John Wiley & Sons, Ltd.

Reduced graphene oxide-supported CuPd alloy nanoparticles as efficient catalysts for the Sonogashira cross-coupling reactions.

Monodisperse CuPd alloy nanoparticles (NPs) were prepared by using a typical high-temperature organic solution phase protocol comprising the coreduction of copper(II) acetylacetonate and palladium(II) acetylacetonate by morpholine-borane complex in oleylamine and 1-octadecene solution at 80 °C. The presented synthesis protocol allows us to control the composition of CuPd alloy NPs by simply tuning the initial ratio of metal precursors and the Cu-rich Cu75Pd25 NPs and Pd-rich Cu32Pd68 were synthesized besides the Cu48Pd52 NPs. Transmission electron microscopy studies revealed that most of the CuPd alloy NPs are polyhedral with an average diameter of 3.0±0.3 nm. The alloy structure of CuPd NPs was confirmed by the detailed X-ray diffraction and X-ray photoelectron spectroscopy analysis. As-prepared CuPd NPs were deposited on reduced graphene oxide (rGO) by using a liquid self-assembly method (rGO-CuPd) and used as catalysts in the Sonogashira cross-couplings of various aryl iodides or bromides and phenyl acetylene under the optimized reaction conditions. Among the three compositions of CuPd alloy NPs tested in the Sonogashira couplings, the rGO-Cu48Pd52 gave the best yields in shorter reaction times and therefore it was used for further coupling reactions. The results demonstrated that rGO-Cu48Pd52 were efficient catalysts for the Sonogashira reaction of various aryl halides with phenylacetylene. The coupling reactions proceeded smoothly with both electron-rich and electron-deficient aryl iodides and aryl bromides, affording the desired biaryl products in high yields. This is the first example of the employment of monodisperse CuPd alloy NPs with composition control in the Sonogashira cross-coupling reactions.

Dimeric ortho-palladated complex of 2,3-dimethoxybenzaldehyde oxime catalyzed Suzuki–Miyaura cross-coupling reaction under microwave irradiation

The catalytic activity of dimeric [Pd{C6H2(–CH=NOH)–(OMe)2-2,3}(µ–Cl)]2 complex as an efficient, air, and moisture-tolerant catalyst was investigated in Suzuki cross-coupling reactions of various aryl halides. The combination of homogenous metal catalyst, microwave irradiation, and microwave-active polar solvents gave high yields of substituted biaryl products in short reaction times.

Facile construction of symmetric biaryls using (BeDABCO)2Pd2Cl6 as an efficient and highly active catalyst under microwave irradiation

An efficient catalytic system using (BeDABCO)2Pd2Cl6 (BeDABCO, benzyl‐1,4‐diazabicyclo[2.2.2]octane) was developed for the homo‐coupling reaction of various aryl halides. Due to the combination of ionic homogeneous metal catalyst and microwave irradiation, symmetric biaryls were produced in excellent yields and short reaction times in N‐methyl‐2‐pyrrolidone at 120 °C. BeDABCO as an efficient ligand and also a quaternary ammonium salt had an efficient stabilizing effect on the Pd(0) species in this coupling reaction. Copyright © 2015 John Wiley & Sons, Ltd.

Proline-functionalized chitosan–palladium(ii) complex, a novel nanocatalyst for C–C bond formation in water

An environmentally friendly palladium-based catalyst supported on proline-functionalized chitosan was successfully prepared and evaluated as a heterogeneous nanocatalyst in the Suzuki cross-coupling reaction of various aryl halides with phenylboronic acid.

Mesoporous Silica MCM‐41 Supported N‐Heterocyclic Carbene‐Pd Complex for Heck and Sonogashira Coupling Reactions

AbstractHeterocyclic carbene‐Pd complex was anchored onto the mesoporous silica MCM‐41 which exhibits high catalytic activity in Heck reaction under phosphine free reaction conditions for the reaction of iodo/bromoarenes with olefinic compounds such as butyl acrylate, isopropyl acrylate and styrene. This catalytic system also showed high activity for Sonogashira coupling reaction of various aryl halides under copper, phosphine and solvent‐free reaction conditions. The air and thermally stable catalyst were reused several times without significant loss of its activity. High efficiency of the catalyst along with its recycling ability and the rather low Pd‐loading demonstrated in both Heck and Sonogashira coupling reactions are the merits of the presented catalyst system.