Catalytic palladium nanoparticles supported on nanoscale MOFs: a highly active catalyst for Suzuki–Miyaura cross-coupling reaction

Pd nanoparticles have been successfully supported on nanoscale metal-organic frameworks (NMOFs) by using a simple and effective microwave-assisted impregnation process. The resulting composite, representing as a highly active NMOFs supported metal nanoparticles catalyst for the Suzuki cross-coupling reaction between aryl/heteroaryl halides and arylboronic acids, is well characterized, and its high activity and good recyclability are discussed in details. It reveals that, compared to the corresponding bulk MOFs and conventional active carbon materials, nanoscale MOFs as novel support materials for heterogeneous catalysts can exhibit superior performance in the catalytic reactions.     

Pd salen complex@CPGO as a convenient,effective heterogeneous catalyst for Suzuki–Miyaura and Heck–Mizoroki cross-coupling reactions

Research on Chemical Intermediates - A Pd(II) Schiff base complex supported on graphene oxide nanosheets (Pd(II) salen@CPGO) has been synthesized and characterized by FT-IR, ICP-AES, XRD, SEM/EDX...     

A highly efficient memantine-modified palladium catalyst for Suzuki–Miyaura cross-coupling reaction

A new simple Pd(memantine)₂Cl₂ complex was synthesized and characterized by ¹H NMR, ¹³C NMR and X-ray single crystal structure determination. The Suzuki–Miyaura reaction of aryl bromides catalyzed by Pd(memantine)₂Cl₂ complex was investigated in air with different temperature. The high turnover numbers of 650,000 have been obtained in the reaction of 4-bromonitrobenzene with phenylboronic acid at 80 °C. At room temperature, the complex also showed high activity for Suzuki–Miyaura cross-coupling reaction of aryl bromides with a wide range of functional groups under air, and the turnover number of up to 99,000 was achieved. The catalytic system also gives good yields toward the reaction of several heteroaryl bromides with thiophenylboronic acid.     

Pd–S-methylisothiourea supported on magnetic nanoparticles as an efficient and reusable nanocatalyst for Heck and Suzuki reactions

Supported Pd–S-methylisothiourea on magnetic nanoparticles (Pd–SMU-MNPs) as an efficient and magnetically reusable nanocatalyst was prepared and applied for the Heck and Suzuki cross-coupling reactions. All coupling reactions proceeded in short reaction times with good to excellent yields. After completion of reactions, the catalyst was easily separated from the reaction mixture using an external magnetic field and reused for several consecutive runs without significant loss of its catalytic efficiency and activity. This nanomagnetic catalyst was characterized by FT-IR spectroscopy, XRD, VSM, ICP-OES, TEM and SEM techniques. The leaching of the catalyst has been examined by a hot filtration test and ICP-OES analysis.     

Preparing Pd catalysts based on urea ligand via electrospinning for Suzuki–Miyaura cross-coupling reactions

Pd-catalyzed Suzuki–Miyaura cross-coupling (SMC) reactions are important in chemistry. In this work, using electrospinning technology, we prepared a novel type of composite catalyst with ligand structures such as urea-Pd/PAN (polyacrylonitrile) and used them to catalyze SMC reactions in nontoxic systems and “green” conditions (air atmosphere, low temperature, and short reaction time). This method of preparing hybrid materials is simple and easy to operate. The higher catalytic activity of the catalysts is attributed to active centers with rich electrons transferred from ligands with unique structures, which can decrease the activation energy of the rate-determining step (oxidative addition). In addition, urea-Pd/PAN composite catalysts exhibit higher catalytic performance than those reduced by H₂ because of the smaller size of active species and the more-efficient oxidative addition to Pd⁰–ligand complexes compared to Pd⁰.     

Imidazolium supported palladium–chloroglycine complex: recyclable catalyst for Suzuki–Miyaura coupling reactions

1-Glycyl-3-methyl imidazolium chloride–palladium(II) complex [[Gmim]Cl–Pd(II)] was found to be a catalyst for the Suzuki–Miyaura reaction with excellent yields with high turnover number (6.5 × 10²–9.4 × 10²).     

Mono- and dinuclear cyclopalladates as catalysts for Suzuki–Miyaura cross-coupling reactions in predominantly aqueous media

Suzuki–Miyaura cross-coupling reactions of aryl halides with arylboronic acids were performed in predominantly aqueous media employing two mono- and two dinuclear cyclopalladated complexes as catalysts. These complexes are [Pd(HL)Cl] (I), [Pd(L)(PPh₃)] (II), [Pd₂(μ-dppb)(L)₂] (III) and [Pd₂(μ-dppf)(L)₂] (IV); where H₂L, dppb and dppf represent 4-methoxy-N′-(mesitylidene)benzohydrazide, 1,4-bis(diphenylphosphino)butane and 1,1′-bis(diphenylphosphino)ferrocene, respectively. The reactions were conducted using potassium carbonate as base in presence of tetrabutylammonium bromide (TBAB) at 70/90 °C in dimethylformamide–water (1:20) mixture. Among the four catalysts used, the dinuclear complex IV turned out to be the most effective and afforded moderate to excellent yields with broad substrate scope.     

Pd nanoparticles supported on reduced graphene oxide as an effective and reusable heterogeneous catalyst for the Mizoroki–Heck coupling reaction

A general method for the synthesis of palladium nanoparticles loaded on reduced graphene oxide functionalized with diethylenetriamine (PdNPs/rGO-NH₂) using a sonochemical procedure is described. The heterogeneous nanocomposite was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray, thermogravimetric analysis, high-angle annular dark field scanning transmission electron microscopy, X-ray photoelectron spectroscopy, UV–visible absorption, and inductively coupled plasma optical emission spectrometry. The PdNPs/rGO-NH₂ was very effective for the Mizoroki–Heck coupling reaction of several aryl iodide compounds with different alkenes in the presence of triethylamine. The reaction provides the coupling products in good to excellent yields (59–100%). Additionally, the PdNPs/rGO-NH₂ catalyst can be reutilized for six successive runs without any apparent diminution of its catalytic reactivity.     

Immobilization of palladium nanoparticles as a recyclable heterogeneous catalyst for the Suzuki–Miyaura coupling reaction

This work describes the synthesis of Pd nanoparticles that are stabilized on CaAl-layered double hydroxide functionalized with Tris (tris(hydroxymethyl)aminomethane). The synthesized catalyst is characterized by several different analyses and has been successfully applied to the Suzuki–Miyaura reaction.     

Scyllo-inositol as a convenient protecting group for aryl boronic acids in Suzuki–Miyaura cross-coupling reactions

Herein, we report air- and water-stable borate complexes between scyllo-inositol and aryl boronic acids. The complexes were less reactive than free aryl boronic acids under Suzuki–Miyaura cross-coupling reaction conditions; thus, the borate complexes were used as protected boronic acids. Although protecting groups for organoboronic acids are useful in coupling reactions, especially those used to produce π-conjugated molecules, only a few reports describing the use of protecting groups for boronic acids have been published. The proposed unique structural borate complex provides a novel protective method for aryl boronic acids.     

Stabilized catalyst comprising nickel and supported 12-tungstophosphoric acid: synthesis,characterization and aqueous-phase Suzuki–Miyaura cross-coupling

Transition Metal Chemistry - This work describes a simple impregnation and soaking method for designing of stabilized nickel exchanged supported 12-tungstophosphoric acid, its characterization and...     

Carbohydrate-based phosphines as supporting ligand for palladium-catalyzed Suzuki–Miyaura cross-coupling reaction

Carbohydrate-based mono-phosphines (1 and 2) derived from glucose have been explored as supporting ligand for palladium-catalyzed Suzuki–Miyaura reaction. The combination of phosphine to palladium in a ratio of 2:1 resulted in a longer-living system than that in a ratio of 1:1. Using K₂CO₃ as base, aryl bromides as well as active aryl chlorides can be coupled nearly quantitatively by 0.1–0.2 mol % of 1/Pd(OAc)₂ with 95–99% of isolated yields. The amount of the catalyst could be lowered to 0.01 mol % under the optimized condition with 80% yield at room temperature. The carbohydrate hydroxyl group in 1 was found to contribute to catalytic activity.     

Catalysts based on hyperbranched pyridylphenylene polymers and palladium nanoparticles for the Suzuki—Miyaura cross-coupling reaction

Synthesis of catalysts based on hyperbranched pyridylphenylene polymer and palladium nanoparticles (РРР-Рd) is described. Catalytic activity in the Suzuki—Miyaura cross-coupling reaction is studied for the interaction of bromobenzene with phenylboronic acid. Optimal reaction conditions providing maximum conversion (100%) of the initial compounds are established.     

Pd nanoparticles supported on Fe3O4@SiO2-Schiff base as an efficient magnetically recoverable nanocatalyst for Suzuki–Miyaura coupling reaction

Research on Chemical Intermediates - In this work, Pd nanoparticles (Pd-NPs) were decorated on modified magnetic nanoparticles (MNPs) and used as an efficient and recyclable catalyst for the Suzuki...     

A highly active and stable imidazolidine-bridged N,O-donor ligand for efficient palladium catalyzed Suzuki–Miyaura reactions in water

Abstract  

We have used the sterically hindered N,O-donor ligand 1,4-bis(2-hydroxy-3,5-di-tert-butyl-benzyl)-imidazolidine with various Pd salts as a catalyst for the Suzuki reaction. This system exhibited excellent catalytic activity in Suzuki reactions of arylboronic acids with aryl halides, including aryl iodides, aryl bromides and activated aryl chlorides, using aqueous methanol as solvent under mild conditions. The catalytic system can be reused once without significant loss of activity.     

Xylan-type hemicelluloses supported terpyridine–palladium(II) complex as an efficient and recyclable catalyst for Suzuki–Miyaura reaction

Xylan-type hemicelluloses supported terpyridine–palladium(II) as a novel biomass-supported catalyst was synthesized and characterized in terms of morphology, composition, and thermal stability. The nano-Pd catalyst was further explored for Suzuki–Miyaura reaction between arylboronic acid and aryl halide under aerobic condition, with a yield up to 98 %. In particular, the catalyst exhibited both high catalytic activity and stability for Suzuki–Miyaura reaction. Furthermore, the catalyst could be easily recovered by simple filtration and reused at least six times without significant loss of its catalytic activity. This work provides a novel and effective supported catalyst, and broadens the applications of polysaccharides in green catalysis.     

Substituted potassium internal vinyltrifluoroborates: preparation and use in Suzuki–Miyaura cross-coupling reactions

A collection of substituted potassium internal vinyltrifluoroborates was prepared and utilized in palladium-catalyzed cross-coupling reactions with aryl and heteroaryl halides. The cross-coupling reactions proceeded readily with Pd(PPh₃)₄ as a catalyst in toluene/H₂O under reflux in the presence of Cs₂CO₃. The process is regiospecific with regard to the internal vinyltrifluoroborate starting material and tolerates a variety of functional groups. This unique collection of substituted internal vinyltrifluoroborates can be readily utilized in research pharmaceutical applications.     

Green and scalable procedure for extremely fast ligandless Suzuki–Miyaura cross-coupling reactions in aqueous IPA using solid-supported Pd in continuous flow

An environmentally friendly continuous-flow protocol for the Suzuki coupling of boronic acids and aryl halides under ligand-free conditions using solid-supported Pd is presented. The process described herein uses very simple reaction conditions and equipment setup and can be readily scaled up to provide multigram quantities of products containing low levels of residual Pd.     

Pd-isatin Schiff base complex immobilized onγ-Fe2O3 as a magnetically recyclable catalyst for the Heck and Suzuki cross-coupling reactions

A Pd‐isatin Schiff base complex immobilized onγ‐Fe2O3 (Pd‐isatin Schiff base‐γ‐Fe2O3) was synthe‐sized and characterized by Fourier transform infrared, scanning electron microscopy, high resolu‐tion tr...