Heck Cross-coupling Reactions Research Articles

Palladium(II) Picoline Thiourea Complex as Homogenous Catalyst in Heck Cross-Coupling Reaction in the Formation of C=C Bond

Palladium (II) complex containing picoline thiourea (Pd-PTu) was prepared by reacting bis (benzonitrile) palladium (II) chloride (Pd-PhCN) withN’-2-(5-picolyl)-N-4-bromobenzoylthiourea (PTu). All synthesized compounds have been characterized via several selected typical spectroscopic and analytical techniques namely elemental analysis, Infrared (IR) spectroscopy, Ultraviolet-visible (UV-Vis) spectroscopy, Nuclear Magnetic Resonance (1H and13C NMR) and gas chromatography-flame ionization detector (GC-FID). For Pd-PTu, IR spectrum showed significant shift in the ν (C=N) on the pyridine ring and ν (C=S) stretching vibration at around 30cm-1compared to the free ligand. The finding indicated that the expected coordination of ligand to the palladium metal centre took place via N and S atoms. The catalytic reaction was monitored using GC-FID with conversion of 83.81 %, proved that Pd-PTu can be used as an ideal homogenous catalyst in any Heck cross-coupling reactions in the near future.

Three-Dimensional Graphene–Magnetic Palladium Nanohybrid: A Highly Efficient and Reusable Catalyst for Promoting Organic Reactions

In this work, graphene aerogel (GA) decorated with Fe3O4@SiO2@Pd nanoparticles (GA-FSNP@Pd) as a novel three-dimensional graphene–magnetic palladium nanohybrid catalyst. This catalyst showed high catalytic activity for the Suzuki and Heck cross-coupling reactions. This noteworthy catalyst activity can be due to the high dispersion of FSNP@Pd nanoparticles on GA. The nanohybrid exhibits an interconnected mesoporous framework of graphene sheets with uniform dispersion of FSNP@Pd nanoparticles. Interestingly, the catalyst could be recovered in a facile manner from the reaction mixture and recycled ten times without appreciable loss of activity. High yield, low reaction time, magnetic separation and non-toxicity of the nanohybrid catalyst are the main merits of this protocol.

Pd(0)‐ S‐propyl‐2‐aminobenzothioate immobilized onto functionalized magnetic nanoporous MCM‐41 as efficient and recyclable nanocatalyst for the Suzuki, Stille and Heck cross coupling reactions

The present work describes the use of Pd(0)‐ S‐propyl‐2‐aminobenzothioate Complex immobilized onto functionalized magnetic nanoporous MCM‐41(Fe3O4@MCM‐41@Pd‐SPATB) as efficient and recyclable nano‐organometallic catalyst for C–C bond formation between various aryl halides with phenylboronic acid (Suzuki reaction), aryl halides with triphenyltin chloride (Stille reaction), and aryl halides with n‐butyl acrylate (Heck reaction). All the reactions were carried out in PEG‐400 as green solvent with short reaction time and good to excellent yields. This catalyst was characterized by FT‐IR spectroscopy, XRD, TGA, VSM, ICP‐OES, TEM, EDX and SEM techniques. Ease of operation, high efficiency, recovery and reusability for five continuous cycles without significant loss of its catalytic activities or metal leaching are the noteworthy features of the currently employed heterogeneous catalytic system.

Pd(OAc)2 immobilized on imine-functionalized microporous covalent triazine polymer as efficient heterogeneous catalyst for Mizoroki–Heck cross-coupling reaction

A template consisting of Pd(OAc)2 immobilized on imine-functionalized microporous covalent triazine polymer network (Pd/TATAE) was synthesized and found to be an efficient and recyclable heterogeneous solid catalyst for Mizoroki–Heck C–C coupling of styrene with substituted aryl halides under mild reaction conditions and without addition of any ligand or additives. Furthermore, Pd/TATAE could be recycled for nine consecutive cycles with minor loss of catalytic activity. Finally, the Pd/TATAE catalyst showed good catalytic activity with excellent yield of 96 % and high turnover number of 3349.

Postsynthetic modification of single Pd sites into uncoordinated polypyridine groups of a MOF as the highly efficient catalyst for Heck and Suzuki reactions

A novel Pd-HoMOF catalyst was prepared, which displayed good thermal stability and high activity in Heck and Suzuki cross-coupling reactions.

Palladium-Catalyzed Heck Cross-Coupling Reactions in Water: A Comprehensive Review

Palladium-catalyzed cross-coupling reactions have emerged as one of the most versatile tools in organic chemistry. Extensive efforts were made to adapt these reactions to aqueous media, not only for the purpose of environmental conservation but also to expand the scope, increase the efficiency and implement bio-compatible protocols. Among different palladium cross-coupling reactions, the Heck reaction turned out to be the most challenging in an aqueous environment. This led to various original developments in catalyst design. This review summarizes the different approaches pursued to perform Heck reactions in neat water as well as aqueous mixtures. Both, homogeneous and immobilized catalysts, including nanoparticles are presented herein.

Catalytic Performance Studies of New Pd and Pt Schiff Base Complexes Covalently Immobilized on Magnetite Nanoparticles as the Environmentally Friendly and Magnetically Recoverable Nanocatalyst in C–C Cross Coupling Reactions

Synthesis and characterization of new magnetically recoverable and high-performance nanocatalysts of Pd and Pt Schiff base complexes on magnetite nanoparticles were considered. Catalytic activity of these nanocatalysts was explored in Suzuki and Heck cross coupling reactions. The catalysts can be easily reused fourth consecutive runs without significant loss of catalytic efficiency.

Merrifield’s Resin-Supported Palladium–Bis(oxazoline) Complex-Catalyzed Cross-Coupling Reactions of Aryl Bromides and Aryl Chlorides

The catalytic activity and the recycling ability of palladium–bis(oxazoline) (Pd–BOX-M) complex supported on Merrifield’s resin have been investigated in Suzuki–Miyaura and Mizoroki–Heck cross-coupling reactions of aryl bromides and aryl chlorides. The supported palladium–bis(oxazoline) catalyst demonstrated exceptional catalytic activity and excellent recycling ability. The characterization of the recycled palladium catalyst reveals no significant change in its structure, oxidation state and the amount of loaded palladium. This confirms the excellent stability of the palladium-supported catalyst.

Pd0.09Ce0.91O2-δ: A sustainable ionic solid-solution precatalyst for heterogeneous, ligand free Heck coupling reactions

A quick and easy method for the preparation of Pd2+ metal ion substituted in ceria, Pd0.09Ce0.91O2-δ solid solution oxide, is described. The Pd0.09Ce0.91O2-δ solid solution oxide was fully characterized by XRD, ICP-OES, BET, XPS, SEM, EDX, TEM, TGA and Raman spectroscopy. All characterization techniques strongly suggested that Pd2+ was successfully incorporated into the lattice structure of ceria. The effect of the reaction conditions on the catalytic properties of the Pd0.09Ce0.91O2-δ solid solution catalyst initially was studied in detail with the model Heck reaction of iodobenzene and methylacrylate to obtain optimum reaction conditions. The Pd0.09Ce0.91O2-δ solid solution catalyst then afforded substituted alkenes in good to excellent yields under these optimum reaction conditions. Steric and electronic effects were also studied, and were found to influence the catalytic activity. Characterization of the used catalyst suggests that Pd2+ in Pd0.09Ce0.91O2-δ is reduced in situ to Pd0 when employed in the Heck cross-coupling reactions. The catalyst was easily recovered by centrifuge and reused three times without significant loss of catalytic efficiency.

Heterogeneous h-BN@Cyclodextrin@Pd(II) nanomaterial: Fabrication, characterization and application as a highly efficient and recyclable catalyst for C—C coupling reactions

An efficient and ligand-free method for the Suzuki and Heck cross-coupling reactions has been successfully developed using h-BN-supported palladium as the catalyst. This green methodology represents a cost-effective and operationally convenient process for the synthesis of biaryls, stilbenes and acrylates. Wide scope of substrates, good to excellent yields, low reaction time, water as solvent, ligand-free, non-toxicity and recyclability of the catalyst are the main merits of these protocols. In addition, the h-BN@γ-CD@Pd(II) nanomaterial has been fully characterized by TG, SEM, IR, XRD, XPS and ICP-AES analysis. And it could be easily recovered and reused for at least nine times without any considerable loss of catalytic activity. Above all, this work demonstrates the possibility of using cyclodextrin-modified h-BN as an efficient support for the hydrophilic heterogeneous catalysts.

Palladium Nanoparticles Supported on Modified Hollow-Fe3O4@TiO2: Catalytic Activity in Heck and Sonogashira Cross Coupling Reactions

Palladium nanostructures have been extensively employed as versatile catalysts for a variety of transformations, such as the hydrogenation of alkenes and alkynes,1,2 carbon-fluorine bond formation3...

Pd/Indanone-Based Ligands: An Efficient Catalyst System for Ullmann­-Type, Suzuki–Miyaura, and Mizoroki–Heck Cross-Coupling Reactions with Aryl Tosylates and Aryl Halides

2-Hydroxyindan-1-ones have been efficiently synthesized and successfully applied as ligands in Pd-catalyzed Ullmann type, Suzuki–Miyaura, and Mizoroki–Heck cross-coupling reactions with aryl tosylates and aryl halides. The ligands are air- and moisture-stable and have shown high catalytic activity with Pd(OAc)2 in these cross-coupling reactions. The system tolerates a variety of functional groups in the product and can be re-used at least three times with maximum efficiency.

Magnetic nanoparticle-supported tetrazole-functionalized palladium catalyst: synthesis, DFT study and application for Sonogashira and Heck cross-coupling reactions

A novel magnetic catalyst-immobilized nano-palladium was efficiently prepared via a (2 + 3) cycloaddition pathway and characterized with different analyses, including FT-IR, FE-SEM, EDS, XRD, TEM and VSM methods. Also, topological and NBO analysis of a simple model of the catalyst with the M06/6-311 g(d,p)-LANL2DZ model chemistry have been introduced. In addition, the catalytic pursuit of this novel magnetic nanocatalyst was successfully evaluated in Sonogashira and Heck cross-coupling reactions. Furthermore, the catalyst could be easily separated by a conventional method using a permanent magnet and reused repeatedly in the model reaction without noteworthy loss of its catalytic activity.

A strategic approach to [6,6]-bicyclic lactones: application towards the CD fragment of DHβE.

We report an effective synthetic protocol to access [6,6]-bicyclic lactone moieties through a regio- and stereoselective intramolecular Mizoroki–Heck cross-coupling reaction followed by a 6π-electrocyclization. This method enabled the first synthesis of the elusive CD fragment of the Erythrina alkaloid DHβE. Preliminary pharmacological evaluations support the notion that the key pharmacophores of DHβE are located in the A and B rings.

Cellulose Sponge Supported Palladium Nanoparticles as Recyclable Cross-Coupling Catalysts.

Robust and flexible cellulose sponges were prepared by dual-cross-linking cellulose nanofiber (CNF) with γ-glycidoxypropyltrimethoxysilane (GPTMS) and polydopamine (PDA) and used as carriers of metal nanoparticles (NPs), such as palladium (Pd). In situ growth of Pd NPs on the surface of CNF was achieved in the presence of polydopamine (PDA). The modified sponges were characterized with FT-IR, XRD, EDX, SEM, TEM, and TGA. XRD, EDX, and TEM results revealed that the Pd NPs were homogeneously dispersed on the surface of CNF with a narrow size distribution. The catalysts could be successfully applied to heterogeneous Suzuki and Heck cross-coupling reactions. Leaching of Pd was negligible and the catalysts could be conveniently separated from the products and reused.

Carbazolyl-substituted quinazolinones as high-triplet-energy materials for phosphorescent organic light emitting diodes

A series of carbazolyl-substituted quinazolinones were designed and synthesized by the Pd-catalyzed Buchwald-Hartwig, Suzuki and Heck cross-coupling reactions. Their optical, photophysical, thermal, electrochemical, and electroluminescent properties were investigated. The characterization of the synthesized compounds was carried out using experimental and theoretical methods. The determined geometries of the compounds lead to the HOMO distribution on the quinazolinone moiety and the different donor substituents. The synthesized compounds form glasses with the glass transition temperatures ranging from 97 to 159 °C. Their solutions in tetrahydrofuran absorb electromagnetic radiation in the range of 210–420 nm and emit in the range of 350–600 nm. The Stokes shifts recorded for the dilute solutions of compounds ranged from 48 to 134 nm, while those observed for the solid films were similarly in the range of 46–113 nm. The highest fluorescence quantum yield of 44.3% was recorded for the solution of 3-(9-ethyl-9H-carbazol-3-yl)-5-((E)-2-(9-ethyl-9H-carbazol-3-yl)ethenyl)-2-methylquinazolin-4(3H)-one. The triplet energy levels established for the dilute solutions of the compounds from their phosphorescence spectra at 77 K were found to be in the range of 2.55–2.99 eV. The ionization potentials of the synthesized compounds established by photoelectron emission technique in air ranged from 5.35 to 5.66 eV. The electrochemical properties of the derivatives were studied by cyclic voltammetry. All the studied compounds showed irreversible oxidation and no reduction waves. Their repeated cyclic voltammetry scans displayed increasing changes in the cyclic voltammetry traces, proving that a series of electro-polymerization reactions of the radical cations occurred. Time-of-flight hole drift mobility of the solid layer of 5-(bis(4-tert-butyldiphenyl)amino)-3-(9-ethyl-9H-carbazol-3-yl)-2-methylquinazolin-4(3H)-one reached 1.1 × 10−3 cm2/Vs at an electric field of 8.1 × 105 V/cm. This compound was tested as a host in the green and blue phosphorescent organic light emitting diodes achieving maximum external quantum efficiencies of ca. 7.1 and 6.9%, respectively.

Mizoroki–Heck Cross-Coupling Reaction of Haloarenes Mediated by a Well-Controlled Modified Polyacrylamide Brush Grafted Silica/Pd Nanoparticle System

Abstract Modified polyacrylamide brushes including phosphinite functionality grafted onto silica supported Pd nanoparticles were synthesized via RAFT polymerization technique in a controlled manner with elucidated graft density and chain length. Proper activity of the catalyst was indicated in the Mizoroki–Heck coupling reaction of various haloarenes with olefins. Different aryl iodides with electron rich and electron deficient substituent and also ortho and heterocyclic substrate showed good reactivity to generate the corresponding coupled products in good to excellent yields using low Pd loading. The turnover number (TON) for this catalyst can be reduced up to 9.5 × 103. Simple filtration, appropriate reusability and negligible palladium leaching of this catalyst are among other advantages.

Pd/Cu-free Heck and Sonogashira cross-coupling reaction by Co nanoparticles immobilized on magnetic chitosan as reusable catalyst

Chitosan (CS) is a porous, self-standing, nanofibrillar microsphere that can be used as a metal carrier. Amino groups on CS enable to modulate cobalt coordination using a safe organic ligand (methyl salicylate).

A convenient, efficient and reusable N-heterocyclic carbene-palladium(ii) based catalyst supported on magnetite for Suzuki–Miyaura and Mizoroki–Heck cross-coupling reactions

In the present work, a new magnetic nanoparticle supported N-heterocyclic carbene-palladium(ii) (NO2-NHC-Pd@Fe3O4) nanomagnetic catalyst was synthesized by a facile multistep synthesis under aerobic conditions.

Efficient nickel(ii) naringenin-oxime complex catalyzed Mizoroki–Heck cross-coupling reaction in the presence of hydrazine hydrate

A novel nickel(ii) naringenin-oxime complex was designed, synthesized and characterized.