Mizoroki Heck Coupling Reaction Research Articles

Synthesis, structure determination of Schiff bases and their PdII complexes and investigation of palladium catalyzed cross-coupling reactions

Two Schiff base ligands, S1 and S2, were synthesized from the reaction of 2-amino-5-ethyl-4-methylthiophene-3-carbonitrile with 2-hydroxybenzaldehyde and 4-nitrobenzaldehyde were investigated for their coordination to PdCl2(CH3CN)2. The prepared ligands S1 and S2 and the PdII complexes 1 and 2 were characterized by using FT-IR, 1H-13C NMR, UV–Vis, TGA, elemental analysis, molar conductivity, mass, and magnetic susceptibility. The characterization data agree well with the formulation of ligands S1 and S2 and PdII complexes 1 and 2. The geometries of the metal chelate were discussed with the help of magnetic and spectroscopic measurements. Finally, the catalytic potential of the synthesized PdII complexes for Suzuki-Miyaura and Mizoroki-Heck coupling reactions was investigated using GC-MS. As a result, it was observed that the PdII complexes are the active catalysts in suitable Suzuki-Miyaura and Mizoroki-Heck C-C coupling reactions.

Stable Diamine Functionalized Graphene Supported Pd Nanoparticles Showing Excellent Catalytic Activity For Mizoroki–Heck Coupling Reactions

AbstractWe used a simple technique to create palladium nanoparticles on diamine functionalised graphene (Pd(0)‐AAPTMS@G) with an average particle size of 5.5 nm. Our earlier research described the Pd(0)‐AAPTMS@G material as an effective catalyst with outstanding conversion and yields for the Suzuki coupling reaction. We reported the characterisation data for Pd(0)‐AAPTMS@G catalysts previously. Here, we provide a narrative for the excellent selectivity and high yields (92–100 %) for the Mizoroki–Heck coupling product over the same Pd(0)‐AAPTMS@G catalyst. Six uses of the generated catalyst are possible without any activity loss. We also compared the catalyst characterisation for both fresh and reused catalysts.

Unique biomedical application of fluorescence derivatization based on palladium-catalyzed coupling reactions for HPLC analysis of pharmaceuticals and biomolecules.

Palladium-catalyzed coupling reactions are versatile and powerful tools for the construction of carbon-carbon bonds in organic synthesis. Although these reactions have favorable features that proceed selectively in mild reaction conditions using aqueous organic solvents, no attention has been given to their application in the field of biomedical analysis. Therefore, we focused on these reactions and evaluated the scope and limitations of their analytical performance. In this review, we describe the pros and cons and future trends of fluorescence derivatization of pharmaceuticals and biomolecules based on palladium-catalyzed coupling reactions such as Suzuki-Miyaura coupling, Mizoroki-Heck coupling, and Sonogashira coupling reactions for HPLC analysis.

An efficient palladium catalyzed mizoroki-heck cross-coupling in water: synthesis, characterization and catalytic activities

A series of new palladium complexes known as PEPPSI-type complexes 3 were successfully synthesized by reacting benzimidazolium salts 2a-e, potassium carbonate (K2CO3), and palladium chloride (PdCl2) in pyridine for 16 h at 80 °C. Both the benzimidazolium salts 2a-e and the resulting complexes 3 were characterized through spectroscopic data and elemental analysis. The Mizoroki-Heck coupling reaction, catalyzed by the homogeneous Pd, was effectively carried out in water without the need for any additional substances under aerobic conditions. The optimization of various key reaction parameters was performed to enhance the yield of the desired cross coupling product. The catalytic performance of these complexes in a catalytic system containing palladium complexes 3a, Et3N, and H2O was evaluated in the Mizoroki-Heck coupling reaction. The PEPPSI-type palladium complex 3a /Et3N/H2O/98 °C catalyst system exhibited high activity, with a turnover frequency (TOF) ranging from 12 to 14 /hour towards achieving the excellent yield of the Mizoroki-Heck coupling products for a wide range of electron withdrawing as well as electron donating aryl bromide and chlorides in shortest reaction time.

In-Flow Heterogeneous Triplet-Triplet Annihilation Upconversion.

Photon upconversion based on triplet-triplet annihilation (TTA-UC) is an attractive wavelength conversion with increasing use in organic synthesis in the homogeneous phase; however, this technology has not performed with canonical solid catalysts yet. Herein, a BOPHY dye covalently anchored on silica is successfully used as a sensitizer in a TTA system that efficiently catalyzes Mizoroki-Heck coupling reactions. This procedure has enabled the implementation of in-flow reaction conditions for the synthesis of a variety of aromatic compounds, and mechanistic proof has been obtained by means of transient absorption spectroscopy.

Nanocatalytic and antimicrobial potency of CQD@Pd nanoparticles: Experimental and theoretical approach

A single-pot approach has been developed for the fabrication of novel heterogeneous nanocatalyst of carbon quantum dots doped palladium (CQD@Pd-NPs) nanoparticles. Herein, Aegle marmelos fruit extract was utilized as a reducing and capping agent for the fabrication of CQD@Pd-NPs. Synthesis of metallic nanoparticles through green chemistry route is environment beneficial technology owing to its low cost and ecological compatibility. The formation of CQD-NPs and CQD@Pd-NPs was confirmed with high-end sophisticated techniques and theoretical studies. The computational analysis revealed a discernible decrease in the band gap value (Egap = ELUMO - EHOMO) from 0.08 eV to 0.03 eV upon the introduction of Pd atoms into carbon quantum dots (CQDs). Therefore, computational data also authenticates the stability of the CQD@Pd-NPs nanocatalyst which was predominantly supported by electrostatic interaction between Pd and CQDs. The developed nanocatalyst has vouched for an effective candidature in the Suzuki-Miyaura and Mizoroki-Heck coupling reactions with a superior selectivity for product formation. The excellent antibacterial properties against E. coli and S. aureus were further supported by visualizing bacterial growth, inhibition zone, FESEM results and molecular docking studies. Moreover, the nanocatalyst displayed facile separation from the reaction system and showcased efficient recyclability with minimal activity loss. This further supports an effective potential over existing commercial catalysts and holds immense future prospective in industrial applications.

Design and synthesis of versatile ligand precursors based on phosphonium ylides for palladalactam formation and catalytic investigation.

A new series of ligand precursors designed for the synthesis of palladalactams has been developed. These precursors are easily accessible through a one-step reaction involving 2-chloro-N-phenylacetamide and a wide choice of various monophosphines, offering tunable electronic and steric properties within the ligand framework. The stability of both ligand precursors and resulting palladalactams in ambient air enhances their practical applicability. A newly synthesized palladalactam, featuring an electron-donating triethylphosphine moiety on the anionic phosphonium ylide ligand scaffold exhibited promising catalytic activities in the Mizoroki-Heck coupling reaction between aryl chlorides and alkenes. Theoretical calculations further affirmed that the ligand system in the complex is the most electron-donating, forming the strongest Pd-C bond compared to other complexes with alternative phosphine moieties.

Well-defined (NHC)PdCl2(azetidine) complexes: Synthesis, characterization and catalytic activities

The synthesis of a series of well-defined (N-heterocyclic carbene)PdCl2(azetidine) complexes are presented. The structures of all complexes were fully characterized by 1H-NMR and 13C-NMR, which supported the proposed structures. The molecular structures of all complexes were further determined by single-crystal X-ray diffraction. The catalytic activities of the obtained Pd-complexes were then evaluated in Suzuki-Miyaura, Sonogashira and Mizoroki-Heck coupling reactions.

Synthesis of linear and branched poly(phenylacetylene)s through Mizoroki-Heck coupling reaction of vinyl bromides

Polyacetylene and its derivatives are a class of traditional conjugated polymers that started the era of conducting plastics. In this paper, we develop a new approach of synthesizing substituted poly(phenylacetylene)s through Mizoroki-Heck coupling of vinyl bromides. A series of α-bromostyrene derivatives are synthesized and used as the monomers for the polycoupling reaction. It is found that K2CO3 is the effective base while Et3N shows almost no catalytic reactivity. Gel permeation chromatography (GPC) results indicate that the molecular weight distribution is broad, which is typical for step growth polymerization. A kinetic study shows that electron withdrawing group on the phenyl ring increase the polymerization rate of the corresponding monomer. Furthermore, incorporating both aryl and vinyl halides into a single vinyl monomer allows the synthesis of branched polyacetylene possessing oligo(phenylene vinylene) at the branch points. The current approach may serve as a new tool for the molecular engineering of substituted polyacetylene materials.

(Fe3O4@SiO2/GO–NH2–CoII NPs): A Novel and Efficient Nanomagnetic Heterogeneous Cobalt Catalysis in the Sonogashira and Heck–Mizoroki Coupling Reactions

(Fe3O4@SiO2/GO–NH2–CoII NPs): A Novel and Efficient Nanomagnetic Heterogeneous Cobalt Catalysis in the Sonogashira and Heck–Mizoroki Coupling Reactions

Efficient and biocompatible new palladium-supported boehmite nanoparticles: synthesis, characterization and application in Suzuki-Miura and Mizoroki-Heck coupling reactions.

Palladium complex-supported on boehmite (Pd(0)-SMTU-boehmite) nanoparticles were synthesized and characterized by using XRD, SEM, EDS, TGA, BET, ICP and FT-IR techniques. When applied as a new catalyst for C-C coupling reactions of Suzuki-Miyaura and Mizoroki-Heck in PEG-400 solvent, the Pd(0)-SMTU-boehmite nanoparticles showed excellent activity and recyclability. The study of palladium leaching by the ICP-OES technique and hot filtration led to the catalyst exhibiting excellent stability and recyclability.

Nitron-derivative-based palladium carbene complexes: structural characterization, theoretical calculations, and catalytic applications in the Mizoroki-Heck coupling reaction.

New palladium(0) and palladium(ii) complexes with N-heterocyclic carbene (NHC) ligands derived from nitron and its derivatives were synthesized. The structures of most of these complexes were established by single-crystal X-ray diffraction studies. Among the new complexes, the palladium complex with a monodentate NHC ligand derived from nitron demonstrated the highest efficacy as a catalyst precursor in the Mizoroki-Heck coupling reaction of aryl chlorides with alkenes. Theoretical calculations provide valuable insights into the electronic parameters of both the ligands and the palladium complexes, highlighting the significance of a robust Pd-C bond and the π-accepting property of the NHC ligand in achieving enhanced catalytic activity. Notably, catalyst activation occurred much more rapidly with the preformed palladium(0) complex compared to its palladium(ii) counterpart.

Selective fluorescence labeling of myristicin using Mizoroki-Heck coupling reaction. Application to nutmeg powder, oil, and human plasma samples

Myristicin [5-allyl-1‑methoxy-2,3-(methylenedioxy)benzene] is the major constituent of the seasoning nutmeg oil and powder. Sometimes myristicin is abused via its ingestion at high doses to cause hallucination. In these high doses, myristicin could cause severe adverse health effects, including convulsion, delirium, and palpitation. Hence there is a strong need for a sensitive method for its analysis, such as fluorescence determination. Myristicin has a very weak fluorescence and also lacks derivatizable groups like the carboxylic, hydroxyl, or amino group in its structure, which makes its fluorescence derivatization challenging. In this research, we developed a fluorescence labeling method for myristicin based on the Mizoroki-Heck coupling reaction of its terminal alkene with a fluorescent aryl iodide derivative, 4-(4,5-diphenyl-1H-imidazol-2-yl)iodobenzene (DIB-I). Then, we developed an HPLC fluorescence detection method for the determination of myristicin utilizing this labeling reaction. The developed method showed a good linear response for myristicin (r = 0.995) in the range of 0.01–10 µmol/L with excellent sensitivity down to the detection limit of 2.9 nmol/L (9.6 fmol/injection). Finally, the developed method could be successfully applied to determine myristicin content in nutmeg powder, oil samples, and human plasma with simple extraction methods and good recoveries ranging from 89.3 to 106%.

Mizoroki–Heck coupling reaction on the surface of sepiolite clay-supported Pd/Cu nanoalloy

Well distributed Pd/Cu bimetallic nanoalloy supported on acid-modified sepiolite (ASEP) was prepared via a solvothermal process. The resulting system, Pd/Cu@ASEP, was characterized using spectroscopic data such as FT-IR, XRD, TEM and ICP-AES. The morphology characterization revealed that the crystalline bimetallic particles were dispersed on ASEP as nanoalloys with diameters ranged from 25 to 30 nm. This system was successfully used for ligand-free Mizoroki-Heck coupling in the presence of air, under mild conditions. This method has advantages compared to other systems, such as short reaction times, high yields, facile catalyst and easy separation and reusability of the catalyst. The catalyst was compatible with a variety of aryl and heteraryl iodides, which provides favorable products with good to high yields. Aryl and heteraryl bromides could also be activated for the Mizoroki-Heck reaction using Pd/Cu@ASEP catalyst, with good to moderate yields.

Synthesis and characterization of novel PEPPSI type bicyclic (alkyl)(amino)carbene (BICAAC)-Pd complexes

A series of bicyclic alkylamino carbenes (BICAAC) (where N-aryl = dipp, mes, 2,6-dimethyl-4-(dimethylamino)phenyl, 5a–d) and their novel air- and moisture-resistant pyridine (pyridine, 4-dimethylaminopyridine) containing palladium Pd(II) complexes (6a–e) were synthetized and characterized. As novel examples of the PEPPSI (“pyridine enhanced precatalyst preparation stabilization and initiation”)-Pd compounds, the reported complexes have shown high activity in Mizoroki–Heck coupling reaction even at as low as 100 ppm loading (TON up to 10000). Kinetic studies revealed that reactions carried out in the presence of elemental mercury resulted decrease in activity. It indicates that the coupling reaction may have both molecular and Pd(0)-mediated catalytic paths.

Experimental evidence for the direct involvement of Pd(0) and Pd(II) anionic phosphine complexes in the Mizoroki–Heck coupling reaction

The role of ionic Pd species in the catalytic systems used for cross-coupling reactions has been revised in recent years, mainly utilizing in situ analytical techniques to detect catalyst species in the reaction mixture. The possible inclusion of phosphine molecules in the active Pd complexes is still debated. We have carried out a comparative study on the differential selectivity of the Mizoroki–Heck reaction with competition between two aryl halides or two alkenes to elucidate the active Pd species in different types of catalytic systems, including those favoring the formation of ionic complexes. The sensitivity of the reaction differential selectivity of two competing aryl halides to the additives of tertiary phosphine and halide salts points to the catalytic activity of anionic Pd(0) complexes containing at least one phosphine ligand when the phosphine-containing catalytic systems are used. The changes of the reaction differential selectivity of two competing alkenes to phosphine and halide salt allow to propose the entrance of both phosphine and halide ions into the coordination sphere of active Pd(II) complexes possessing anionic character. In addition, evidence for the effect of phosphine ligand and salt additives on the composition of the active Pd complexes that determine the regioselectivity of the reaction is presented. The data obtained indicate the decisive role of anionic Pd species in the Mizoroki–Heck reaction using both phosphine-free and phosphine-containing catalytic systems.

Synthesis, crystal structure, and catalytic activity of bridged-bis(N-heterocyclic carbene) palladium(II) complexes in selective Mizoroki-Heck cross-coupling reactions

A series of three 1,3-propanediyl bridged bis(N-heterocyclic carbene)palladium(II) complexes (Pd-BNH1, Pd-BNH2, and Pd-BNH3), with + I effect order of the N-substituents of the ligand (isopropyl > benzyl > methoxyphenyl), was the subject of a spectroscopic, structural, computational and catalytic investigation. The bis(NHC)PdBr2 complexes were evaluated in Mizoroki-Heck coupling reactions of aryl bromides with styrene or acrylate derivatives and showed high catalytic efficiency to produce diarylethenes and cinnamic acid derivatives. The X-ray structure of the most active palladium complex Pd-BNH3 shows that the Pd(II) center is bonded to the two carbon atoms of the bis(N-heterocyclic carbene) and two bromide ligands in cis position, resulting in a distorted square planar geometry. The NMR data of Pd-BNH3 are consistent with a single chair-boat rigid conformer in solution with no dynamic behavior of the 8-membered ring palladacycle in the temperature range 25–120 °C. The catalytic activities of three Pd-bridged bis(NHC) complexes in the Mizoroki-Heck cross-coupling reactions were not found to have a direct correlation with +I effect order of the N-substituents of the ligand. However, a direct correlation was found between the DFT calculated absolute softness of the three complexes with their respective catalytic activity. The highest calculated softness, in the case of Pd-BNH3, is expected to favor the coordination steps of both the soft aryl bromides and alkenes in the Heck catalytic cycle.

Pd(II)/Pd(0) Anchored on Magnetic Organic–Inorganic Hybrid Mesoporous Silica Nanoparticles: A Nanocatalyst for Suzuki–Miyaura and Heck–Mizoroki Coupling Reactions

Pd(II)/Pd(0) Anchored on Magnetic Organic–Inorganic Hybrid Mesoporous Silica Nanoparticles: A Nanocatalyst for Suzuki–Miyaura and Heck–Mizoroki Coupling Reactions

Synthesis of new adamantyl-imine palladium(II) complexes and their application in Mizoroki-Heck and Suzuki-Miyaura C[sbnd]C cross-coupling reactions

Improving carbon–carbon cross-coupling reactions is an ongoing process and finding the most versatile and stable catalyst precursors has been of great interest. Ligand design has been proven to be important since it is responsible for providing electron density and steric saturation around the metal centre, thus contributing towards the stereo-electronic properties. The adamantyl moiety has been used to generate highly bulky and electron-rich ligands for application in palladium-catalysed cross-coupling reactions. Accordingly, we have prepared some Schiff-base adamantyl ligands (L1-L3) and complexed them with [PdCl2(MeCN)2] to afford the (pre)catalysts C1-C3, which were successfully applied in Mizoroki-Heck and Suzuki-Miyaura carbon–carbon cross-coupling reactions. The cross-coupling reaction products were obtained in good yields using 0.5 mol % Pd catalyst loading. C2 and C3 showed remarkable activity in the Mizoroki-Heck coupling reactions involving substrates with substituents on the olefin and aryl halide (including 4-Cl, 4-CH3, -CO2Me and -CO2Et). We also, observed that the Suzuki-Miyaura cross-coupling system was active towards challenging activated and deactivated aryl chlorides, with to up 70% conversions recorded. The mercury poisoning tests conducted revealed that the catalysts act as homogenous molecular active species in the Mizoroki-Heck reactions and act as both homogenous and heterogeneous catalysts in the Suzuki-Miyaura cross-coupling reactions.

Facile Synthesis and Characterization of Palladium@Carbon Catalyst for the Suzuki-Miyaura and Mizoroki-Heck Coupling Reactions

Palladium-based carbon catalysts (Pd/C) can be potentially applied as an efficient catalyst for Suzuki–Miyaura and Mizoroki–Heck coupling reactions. Herein, a variety of catalysts of palladium on activated carbon were prepared by varying the content of ‘Pd’ via an in situ reduction method, using hydrogen as a reducing agent. The as-prepared catalysts (0.5 wt % Pd/C, 1 wt % Pd/C, 2 wt % Pd/C and 3 wt % Pd/C) were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Brunauer–Emmett–Teller (BET) analyses. The catalysts were tested as a coupling catalyst for Suzuki–Miyaura coupling reactions involving aryl halides and phenyl boronic acid. The optimization of the catalyst by varying the palladium content on the activated carbon yielded Pd/C catalysts with very high catalytic activity for Suzuki reactions of aryl halides and a Mizoroki–Heck cross-coupling reaction of 4-bromoanisol and acrylic acid in an aqueous medium. A high ‘Pd’ content and uniform ‘Pd’ impregnation significantly affected the activity of the catalysts. The catalytic activity of 3% Pd/C was found to make it a more efficient catalyst when compared with the other synthesized Pd/C catalysts. Furthermore, the catalyst reusability was also tested for Suzuki reactions by repeatedly performing the same reaction using the recovered catalyst. The 3% Pd/C catalyst displayed better reusability even after several reactions.