Mizoroki Heck Cross-coupling Reactions Research Articles

A silica-supported palladium-bis(oxazoline) complex efficiently catalyzes the synthesis of cinnamic acid derivatives via Mizoroki–Heck coupling reactions

A palladium(II)-bis(oxazoline) complex supported on silica (Pd-BOX-Si) was prepared, characterized and applied as a catalyst in Mizoroki–Heck cross-coupling reactions. The bis(oxazoline) (BOX) ligand has a hydroxyl group that can be anchored to 4-benzyl chloride-functionalized silica gel, followed by the coordination of palladium(II) chloride. The catalytic activity and the recyclability of Pd-BOX-Si have been investigated in the production of cinnamic acid derivatives via Mizoroki–Heck coupling reactions of acrylates with aryl halides; The Pd-BOX-Si catalyst demonstrated excellent catalytic activity. Characterization of the recycled Pd-BOX-Si catalyst revealed its good stability under the reaction conditions employed.

ChemInform Abstract: Novel Bis(benzothiazole‐oxime)‐Based Pd(II)‐Complex: Synthesis, Characterization, Quantum Chemical Calculations, and Catalytic Significance in Suzuki—Miyaura and Heck—Mizoroki Cross Coupling Reactions.

In the present work, a novel binuclear benzothiazole-oxime Pd(II) complex was synthesized, characterized (elemental analysis, infrared spectroscopy, thermogravimetric analysis, ultraviolet–visible spectroscopy, nuclear magnetic resonance, and conductance measurements), and explored for its catalytic activity in Suzuki–Miyaura and Heck–Mizoroki cross-coupling reactions of different aryl- and heteroaryl halides with arylboronic acids and styrene, respectively, using the microwave irradiation conditions. The electronic arrangement, type of hybridization, and nature of bonding in the Pd-complex were investigated by natural bond orbital analysis. Time-dependent density functional theory calculations were carried out to understand the electronic transitions in the related experimental observations.

Application of Carbohydrates with Methylene or Vinyl Groups in Heck–Mizoroki Cross-Coupling Reactions with O-Heterocycles

Structurally novel carbohydrate–O-heterocycle derivatives linked by various unsaturated carbon bridges were synthesized by palladium-catalyzed cross-coupling reactions.

Coumarin based novel ligands in the Suzuki–Miyaura and Mizoroki–Heck cross-couplings under aqueous medium

Coumarin-based novel ligands (benzylidine-bis-(4-hydroxycoumarin)-diethylamines) were easily synthesized using 4-hydroxycoumarin, aromatic aldehydes, and diethylamine. The ionic ligand structure was established by X-ray study. They are air and moisture stable ligands and have shown highly efficient catalytic activity with Pd(OAc)2 (0.1mol% loading) in the Suzuki–Miyaura and (0.3mol% loading) in the Mizoroki–Heck cross-coupling reactions in water or water/ethanol mixture. Pd-catalyst was reused efficiently without affecting variety of functional groups in the reaction.

Green and Efficient Procedure for Suzuki–Miyaura and Mizoroki–Heck Coupling Reactions Using Palladium Catalyst Supported on Phosphine Functionalized ZrO2 NPs (ZrO2@ECP-Pd) as a New Reusable Nanocatalyst

Abstract In this article, palladium supported on phosphine functionalized ZrO2 NPs (ZrO2@ECP-Pd) has been introduced as a novel and efficient nanocatalyst for Suzuki–Miyaura and Mizoroki–Heck reactions. This new catalyst was prepared from the reaction of Pd(OAc)2 and PPh2-functionalized ZrO2 NPs, and then characterized using FT-IR, XRD, SEM, TEM, TGA and ICP techniques. The above experimental results showed that the synthesized catalyst existed as spheres with a mean size range of 10–40 nm. The prepared ZrO2@ECP-Pd nanocatalyst was shown to be highly efficient in the Suzuki–Miyaura and Mizoroki–Heck cross-coupling reactions of a wide range of aryl halides including electron-rich and electron-poor aryl iodides/bromides, and heteroaryl iodides, affording the corresponding products in good to excellent yields in short reaction times. The notable feature of the present protocol is the use of water and [bmim]PF6 as environmentally benign solvents, which eliminate the need of toxic solvent. In addition to the aforementioned favorable properties, the nanocatalyst can be recovered and reused for the subsequent reactions (at least six times) without any appreciable loss of efficiency.

One-pot sequential functionalizations of meso-tetrathienylporphyrins via Heck–Mizoroki cross-coupling reactions

Synthesis and sequential functionalizations of a new meso-tetraiodo(thien-2-yl)porphyrin and its Ni(II) derivative are described. The reactions for the preparation of these new porphyrins were optimized. Subsequently, four successive one-pot Heck–Mizoroki cross-coupling reactions were studied using two acrylates and varied reaction conditions. We describe an optimized protocol for the preparation of highly conjugated thienylporphyrins with the potential to be used as dyes in solar cell devices as demonstrated in our preliminary studies.

Functionalized β-cyclodextrin as supramolecular ligand and their Pd(OAc)2 complex: highly efficient and reusable catalyst for Mizoroki–Heck cross-coupling reactions in aqueous medium

A novel class of water soluble palladium complexes with recognition abilities based on functionalized β-cyclodextrin has been synthesized. The complex demonstrated high catalytic activity and a supramolecular platform for phosphine-free Mizoroki–Heck cross-coupling reactions in water. The efficient arylation of alkenes was carried out using different iodo- and bromo-arenes with good to excellent yields (up to 96%). The advantages, like recyclability of catalysts, operational simplicity and accessibility in aqueous medium, make this protocol eco-friendly.

Preparation, characterization and catalytic reactivity of WO3@PdO core@shell nanospheres in the Mizoroki–Heck reaction

Palladium oxide nanoparticles supported on tungsten oxide nanospheres were synthesized in one pot using an impregnation method. The prepared catalyst was thoroughly characterized by various physico-chemical methods. TEM images showed uniform dispersion of palladium oxide nanoparticles onto WO3 (~170–205 nm). The obtained WO3@PdO core@shell nanospheres exhibited excellent reactivity and stability in the Mizoroki–Heck cross-coupling reactions with different aryl halides and olefins. This catalyst can be easily recovered and reused in several runs.

Novel bis(benzothiazole-oxime)-based Pd(II)-complex: synthesis, characterization, quantum chemical calculations, and catalytic significance in Suzuki–Miyaura and Heck–Mizoroki cross coupling reactions

In the present work, a novel binuclear benzothiazole-oxime Pd(II) complex was synthesized, characterized (elemental analysis, infrared spectroscopy, thermogravimetric analysis, ultraviolet–visible spectroscopy, nuclear magnetic resonance, and conductance measurements), and explored for its catalytic activity in Suzuki–Miyaura and Heck–Mizoroki cross-coupling reactions of different aryl- and heteroaryl halides with arylboronic acids and styrene, respectively, using the microwave irradiation conditions. The electronic arrangement, type of hybridization, and nature of bonding in the Pd-complex were investigated by natural bond orbital analysis. Time-dependent density functional theory calculations were carried out to understand the electronic transitions in the related experimental observations.

Ultrafine palladium nanoparticles immobilized into poly(4-vinylpyridine)-based porous monolith for continuous-flow Mizoroki–Heck reaction

Ultrafine Pd nanoparticles (dm=2.3nm), obtained by metal vapor synthesis technique, were immobilized into a poly(4-vinylpyridine)-based porous monolith by means of a new synthetic approach. The synthesis involves stabilization of Pd nanoparticles with 4-vinylpyridine ligand and their subsequent immobilization into the monolith by radical co-polymerization of the resulting metal-embedding monomer with ethylene glycol dimethacrylate in presence of porogenic agents (i.e. DMF and PEG-400) inside stainless-steel columns (HPLC type). The hybrid monolithic reactors containing highly dispersed Pd nanoparticles were effectively used as catalyst for Mizoroki–Heck cross-coupling reactions carried out under continuous-flow conditions. The devices showed long life-time (>65h) and very low Pd leaching (<2ppm).

ChemInform Abstract: An Expedient Approach to Enhance Mizoroki—Heck Coupling Reaction by Infrared Irradiation Using Palladacycle Compounds.

An alternative and environmentally friendly strategy to promote the Mizoroki–Heck cross-coupling reaction by the use of infrared irradiation using palladacycles as precatalysts is reported. Coupling products are obtained in high yield and short reaction time. A comparison with the classical use of reflux conditions, and commercial sources of palladium complexes, shows the advantages of this new alternative for promoting coupling reactions. Copyright © 2015 John Wiley & Sons, Ltd.

Pd- and Ni-Pyridyl Complexes Deposited as Films for Suzuki–Miyaura and Mizoroki–Heck Cross Coupling Reactions

A pyridyl fluorene ligand, 2,7-bis(4-pyridyl)-9,9-diethylfluorene (1), has been synthesized by a simple route. The ability of the two linearly terminal pyridyl nitrogen atoms of 1 to coordinate with the Pd(II) or Ni(II) ions has enabled the use of 1 as a linking ligand in the preparation of (PdCl2/1) n , (Ni(NO3)2/1) n films, PdCl2/1 and Ni(NO3)2/1 complex. The resulting films and complexes were characterized by UV–vis spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectrometer. The application of films and complexes as catalysts for Suzuki–Miyaura and Mizoroki–Heck reactions was carried out. (PdCl2/1) n films show high catalytic activity in the reactions with the Pd loading of ppm. (Ni(NO3)2/1) n multilayers as the active catalytic moieties for these reactions were investigated with very low Ni(II)-loading. The (Pd or Ni/1) n multilayer films were used as high active catalysts for the C-C formation with extremely low M(II)-loading in ppm level.

Developing chitosan-based composite nanofibers for supporting metal catalysts

Using electrospinning technique to prepare chitosan (CS) nanofibers from an inexpensive solvent such as acetic acid has been a challenge, due to the lack of sufficient entanglements in these semi-rigid polyelectrolytes. Incorporating polymers such as poly(methacrylic acid) (PMAA) into the solution lowers the entanglement concentration of the polymers, and make all three morphology regimes (polymer droplets, beaded nanofibers and nanofibers with uniform thickness) accessible to electrospinning method. Uniform composite nanofibers are found at concentrations well above the entanglement concentration. The thickness and morphology of nanofibers can be regulated by addition of small amount of organic solvents such as dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). The composite nanofibers are subsequently crosslinked at an elevated temperature to improve their thermal and solvent stability. The mechanical properties of the crosslinked CS/PMAA fibers can be modulated by varying the amount and molecular weight of PMAA incorporated in the blend. The composite fiber materials provide a useful platform to support a variety of catalysts. As a demonstration, palladium catalyst has been immobilized on the crosslinked CS/PMAA nanofibers to carry out Mizoroki–Heck cross-coupling reactions of aromatic halides and acrylates. We found remarkable catalytic efficiency and stability in these materials. We also demonstrate that, by the “post-modification” of the nanofibers with ligands that chelate metal catalysts, a variety of metal catalysts can be incorporated into the fiber platform, with further improved stability and activity.

Reactions of nitroxides 15. Cinnamates bearing a nitroxyl moiety synthesized using a Mizoroki-Heck cross-coupling reaction.

Cinnamic acid derivatives bearing a nitroxyl moiety (2,2,6,6-tetramethyl-1-oxyl-4-piperidyl 3-E-aryl acrylates) were synthesized in 30–100% yield using a Mizoroki–Heck cross-coupling reaction between 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl and iodobenzene derivatives in the presence of palladium(II) acetate coordinated with a tri(o-tolyl)phosphine ligand immobilized in a polyurea matrix.

Di- and tri-nuclear-palladium complexes bearing piperidoimidazolin-2-ylidenes: synthesis, characterization, and catalytic applications

A series of di- and tri-nuclear Pd(II) complexes with piperidoimidazolin-2-ylidenes anchored to benzene ring via methylene spacers were synthesized. The obtained complexes were fully characterized by IR, 1H NMR, 13C NMR spectroscopy and elemental analysis. Molecular structures of two of the products have been determined by means of X-ray crystallography. Their catalytic performances in Suzuki-Miyaura and Mizoroki-Heck cross-coupling reactions were thoroughly investigated. The catalytic reactivity of new di- and tri-metallic complexes was compared with the monometallic systems. It is observed that the activities of the tri-nuclear Pd(NHC) complexes were higher than the corresponding mono- and di-nuclear complexes under the same conditions.

ChemInform Abstract: Palladium Nanoparticles Supported on Triazine Functionalized Mesoporous Covalent Organic Polymers as Efficient Catalysts for Mizoroki—Heck Cross Coupling Reaction.

AbstractA novel class of mesoporous covalent organic polymers is synthesized by nucleophilic substitution of cyanuric chloride with 2,2′‐dihydroxybiphenyl.

Pd-functionalized MCM-41 nanoporous silica as an efficient and reusable catalyst for promoting organic reactions

Pd-functionalized MCM-41 nanoporous silica has been explored as an efficient and recyclable catalyst to effect Suzuki and Mizoroki–Heck cross-coupling reactions, under solvent-free conditions.

Synthesis, characterization, and microwave-assisted catalytic activity in Heck, Suzuki, Sonogashira, and Buchwald--Hartwig cross-coupling reactions of novel benzimidazole salts bearing N-phthalimidoethyl and benzyl moieties

Five novel benzimidazole salts (1-5) having N-phthalimidoethyl and 4-substituted benzyl were synthesized and identified by $^{1}$H NMR, $^{13}$C NMR, and IR spectroscopic methods and microanalysis. A mixture of the benzimidazole salts (1-5), Pd(OAc)$_{2}$, and K$_{2}$CO$_{3}$ in DMF-H$_{2}$O catalyzed, in high yield, the Suzuki-Miyaura and the Heck-Mizoroki cross-coupling reactions assisted by microwave irradiation in 5 min. The novel benzimidazole salts (1-5), Pd(OAc)$_{2}$, Cs$_{2}$CO$_{3}$, PEG, and Cu nanoparticles catalyzed, in high yield, the Sonogashira coupling reaction promoted by microwave irradiation in 10 min. The same benzimidazole salts (1-5), Pd(OAc)$_{2}$, Cs$_{2}$CO$_{3}$, and TBAB catalyzed, in moderate or low yield, the Buchwald-Hartwig reaction assisted by microwave irradiation in 60 min. The efficiency of the catalyst system in these four reactions was discussed as well as the electron-releasing and withdrawing substituent effects on the benzimidazole ligands.

C(sp2)–C(sp2) cross coupling reactions catalyzed by an active and highly stable magnetically separable Pd-nanocatalyst in aqueous media

A new magnetite Pd-nanoparticle supported (4,5-diazafluoren-9-one)-derived palladium chloride (7) was synthesized, characterized and introduced. The nanocatalyst exhibited an efficient activity in Suzuki cross-coupling reactions with an environmentally-friendly (H2O/DMF) solvent system for 1–3 h at 100 °C and Mizoroki–Heck cross-coupling reactions. The catalyst can easily be recovered from the reaction system by using an external magnet and reused several times with high yields.

Ordered interface mesoporous immobilized Pd pre-catalyst: En/Pd complexes embedded inside the SBA-15 as an active, reusable and selective phosphine-free hybrid catalyst for the water medium Heck coupling process

A series of Pd-complexes of amine and diamine ligands embedded into the ordered silica mesoporous (PdX2@SBA-15/NY, Y=1, 2) are synthesized. Among them, the covalently bonded Pd(OAc)2/ethylenediamine complex into the SBA-15 exhibit higher activity and selectivity toward Mizoroki–Heck cross-coupling reaction. The Pd(OAc)2@SBA-15/En pre-catalyst could be separated easily from reaction products and used repetitively several times, showing the superiority over the homogeneous catalysts for industrial and chemical applications.