- A novel magnetic polyacrylonotrile-based palladium Core?Shell complex: A highly efficientcatalyst for Synthesis of Diaryl ethers
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The present article describes the synthesis of a new magnetic polyacrylonitrile-based Pd catalyst involving polyacrylonitrile modified via 2-aminopyridine as an efficient support to immobilize Pd nanoparticles. The simple reusability, easy separation and high stability of this Pd complex make it an excellent candidate to generate a C–O bond via Ph-X activation which is a really important subject in achieving biologically active compounds. It is worth to note access to good and high yields as well as broad substrate scope have resulted from superior reactivity of this catalyst complex. Furthermore, the structure of the magnetic polyacrylonitrile-based heterogeneous catalyst was characterized by fourier transmission infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM), X-ray diffraction (XRD). Also, its thermal properties were studied by thermogravimetric analysis (TGA).
- Eslami, Mohammad,Jarahiyan, Atefeh,Moghaddam, Firouz Matloubi,Pourjavadi, Ali
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- Mechanochemical synthesis of graphene oxide-supported transition metal catalysts for the oxidation of isoeugenol to vanillin
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Vanillin is one of the most commonly used natural products, which can also be produced from lignm-derived feedstocks. The chemical synthesis of vanillin is well-established in large-scale production from petrochemical-based starting materials. To overcome this problem, lignin-derived monomers (such as eugenol, isoeugenol, feruhc acid etc.) have been effectively used n the past few years. However, selective and efficient production of vanillin from these feedstocks still remains an issue to replace the existing process. In this work, new transition metal-based catalysts were proposed to investigate their efficiency in vanillin production. Reduced graphene oxide supported Fe and Co catalysts showed high conversion of isoeugenol under mild reaction conditions using H2O2 as oxidizing agent. Fe catalysts were more selective as compared to Co catalysts, providing a 63% vanillin selectivity at 61% conversion in 2 h. The mechanochemical process was demonstrated as an effective approach to prepare supported metal catalysts that exhibited high activity for the production of vanillin from isoeugenol.
- Franco, Ana,De, Sudipta,Balu, Alina M.,Garcia, Araceli,Luque, Rafael
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- Ligand-free catalytic system for the synthesis of diarylethers over Cu 2O/Cu-CNTs as heterogeneous reusable catalyst
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Various substituted diarylether derivatives were prepared by using heterogeneous reusable Cu2O- and Cu-coated carbon nanotubes (Cu 2O/Cu-CNTs) as catalyst under ligand-free conditions, which provided good to excellent yields. The catalyst was characterized by TEM, XRD, and AAS analysis. The effects of solvent, base, and amount of catalyst for the O-arylation were investigated. The catalyst could be recovered by simple filtration from the reaction mixture without further treatment and reused several times with consistent catalytic activity. In addition, CNTs could also be recovered from the used Cu2O/Cu-CNTs by a simple acid treatment.
- Zhang, Ying-Peng,Jiao, Ya-Cong,Yang, Yun-Shang,Li, Chun-Lei
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- Buchwald-Hartwig amination reaction of aryl halides using heterogeneous catalyst based on Pd nanoparticles decorated on chitosan functionalized graphene oxide
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In this work, graphene oxide was functionalized with chitosan (GO-Chit) followed by a simple approach for immobilization of palladium nanoparticles onto a chitosan grafted graphene oxide surface. The Pd-nanocomposite (GO-Chit-Pd) was characterized using Transmission Electron Microscopy (TEM), Fourier transforms infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) measurements. The catalytic activity of the prepared heterogeneous graphene oxide functionalized chitosan-palladium (GO-Chit-Pd) was investigated in term of C-N coupling reaction (Buchwald-Hartwig amination reaction of aryl halides) yielding products of N-arylamines. The easy purification, convenient operation, and environmental friendliness, combined with a high yield, render this method viable for use in both laboratory research and larger industrial scales. Studying the reusability of the catalyst in this work showed that it could be reused for five times without obvious loss in catalytic activity.
- Sarvestani, Mosayeb,Azadi, Roya
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- Carbon dioxide thermal system: An effective method for the reduction of carbon dioxide
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When carbon dioxide is in the supercritical state and reduced by Fe3O4, multicarbon bearing hydrocarbon molecules such as phenol (rather than CO or formate usually formed in electrochemical or photochemical techniques) can be obtaine
- Chen,Qian
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- Sulfonato-diketimine Copper(II) Complexes: Synthesis and Application as Catalysts in Chan-Evans-Lam Couplings
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Copper complexes bearing a diketimino-sulfonate ligand, LCu(NO3)(NCMe), were prepared and proved to be stable to water for several hours in solution. Prolonged standing in the presence of water or strong bases led to desulfonation of the ligand. LCu(NO3) was inactive in the polymerization of lactide (in the presence of benzyl alcohol), but showed high activity for the Chan-Evans-Lam coupling of a variety of amines and anilines. Couplings do not require addition of base, ligand, or molecular sieves. Mechanistic investigations indicate a catalytic cycle involving dioxygen as the required oxidant, precoordination of boronic acid to the sulfonate group, and transmetalation occurring prior to reaction with the nucleophile.
- Hardouin Duparc, Valérie,Schaper, Frank
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- Ullmann Reaction Catalyzed by Heterogeneous Mesoporous Copper/Manganese Oxide: A Kinetic and Mechanistic Analysis
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A heterogeneous copper oxide supported on mesoporous manganese oxide (meso Cu/MnOx) was explored for Ullmann-type cross-coupling reactions. An inverse micelle-templated evaporation-induced self-assembly method with in situ addition of copper was adopted to synthesize the mesoporous catalyst. Broad substrate scope and excellent functional group tolerability in C-O, C-N, and C-S bond formation reactions were observed using the optimized reaction conditions. The catalytic protocol was ligand free, and the catalyst was reusable without any significant loss of activity. The kinetic and Hammett analyses provided evidence for oxidative addition to a Cu(I) reaction center followed by nucleophilic addition and reductive elimination at the active copper oxide surface. Rate acceleration was observed for aryl halides with electron-withdrawing groups. The Hammett analysis determined ρ = +1.0, indicative of an oxidative addition, whereas the electronic effect in the phenol ring (ρ = -2.9) was indicative of coordination to a metal ion. Theoretically, the oxidative addition of the aryl halides is assisted by the ligand environment of the copper center. Relevant mechanistic implications are discussed on the basis of the experimental and computational results.
- Mullick, Kankana,Biswas, Sourav,Kim, Chiho,Ramprasad, Ramamurthy,Angeles-Boza, Alfredo M.,Suib, Steven L.
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- Light-driven activation of carbon-halogen bonds by readily available amines for photocatalytic hydrodehalogenation
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A straightforward protocol using readily available aromatic amines, N,N,N′,N′-tetramethyl- p-phenylenediamine or N,N′,N′-tetramethylbenzidine, as photocatalysts was developed for the efficient hydrodehalogenation of organic halides, such as 4′-bromoacetophenone, polyfluoroarenes, cholorobenzene, and 2,2′,4,4′-tetrabromodiphenyl ether(a resistant and persistent organic pollutant). The strongly reducing singlet excited states of the amines enabled diffusion-controlled dissociative electron transfer to effectively cleave carbon-halogen bonds, followed by radical hydrogenation. Diisopropylethylamine served as the terminal electron/proton donor and regenerated the amine sensitizers.
- Chen, Chuncheng,Duan, Ran,Meng, Di,Song, Wenjing,Wei, Yan,Zhao, Jincai,Zhen, Shengli,Zhu, Qian
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- The Transition-metal Catalyzed Dehalogenation of Aromatic Halides by NaOH-Alcohols. A Facile Method of Destroying Aromatic Polyhalides
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Aromatic halides are dehalogenated by heating with NaOH in alcoholic solvents in the presence of transition metal salts, such as rhodium(III) chloride or palladium(II) acetate and triphenylphosphine.Bis(pentabromophenyl) ether was converted into diphenyl ether in 2-propanol when treated for 5 h at 355 K with a catalytic cycle of more than 80.
- Okamoto, Tadashi,Oka, Shinzaburo
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- Highly Efficient C-O Cross-Coupling Reactions with Unactivated Halides by Ligandless, Heterogeneous Raney Ni-Al Alloy/Copper (I) Salts
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A general, novel, ligandless and efficient method was developed for the Raney Ni-Al alloy/copper co-catalyzed formation of diaryl ethers by C-O cross-coupling reaction from aryl iodides, bromides, and even aryl chlorides with phenols.
- Xu, Li-Wen,Xia, Chun-Gu,Li, Jing-Wei,Hu, Xiao-Xue
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- Tris-(2-aminoethyl) amine as a novel and efficient tripod ligand for a copper(I)-catalyzed C-O coupling reaction
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We have introduced a novel, efficient, commercially available and economically attractive N-donor tripod ligand, tris-(2-aminoethyl)amine for copper-catalyzed Ullmann diaryl ether synthesis. This catalyst system is highly active for both aryl iodides and aryl bromides. Variously substituted diaryl ethers have been synthesized in good to excellent yields.
- Jogdand, Nivrutti R.,Shingate, Bapurao B.,Shingare, Murlidhar S.
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- Formation of aryl-nitrogen, aryl-oxygen, and aryl-carbon bonds using well-defined copper(I)-based catalysts
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(Matrix Presented) We report mild synthetic protocols for the formation of aryl-carbon, aryl-nitrogen, and aryl-oxygen bonds based on soluble, well-defined copper(I) catalysts. These protocols do not require the use of palladium and/or expensive ligands.
- Gujadhur, Rattan K.,Bates, Craig G.,Venkataraman
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- Iron-catalyzed C-O cross-couplings of phenols with aryl iodides
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(Chemical Equation Presented) Low-price coupling: A versatile, practical, and cost-efficient iron-catalyzed O-arylation protocol is applied to the synthesis of a variety of diaryl ethers, which are formed in high yields. Best results were obtained by using FeCl3 and a β-diketo ligand.
- Bistri, Olivia,Correa, Arkaitz,Bolm, Carsten
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- Highly efficient copper-catalyzed O-arylation using readily available (S)-N-methylpyrrolidine-2-carboxamide as the ligand
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A highly efficient and readily available catalyst system for O-arylation of various phenols using CuI and (S)-N-methylpyrrolidine-2-carboxamide (Pro-NHMe) was developed. The reaction is widely applicable to the synthesis of diaryl ethers. Georg Thieme Verlag Stuttgart.
- Liu, Xianghao,Fu, Hua,Jiang, Yuyang,Zhao, Yufen
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- Cu-nanoparticle catalyzed O-arylation of phenols with aryl halides via Ullmann coupling
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Recyclable Cu-nanoparticles provide an efficient, economic, and novel method for the synthesis of diaryl ethers via Ullmann type coupling. This method provides a wide range of substrate applicability and avoids the use of a heavy metal co-catalyst and gives diaryl ethers in satisfactory yields.
- Kidwai, Mazaahir,Mishra, Neeraj Kumar,Bansal, Vikas,Kumar, Ajeet,Mozumdar, Subho
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- A recyclable heterogeneous copper(II) Schiff base catalyst for the O-arylation reaction of phenols with aryl halides
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Immobilisation of copper acetate onto a modified polystyrene provided a polymer-supported copper(II) Schiff base catalyst, which is effective in the O-arylation reaction of phenols with aryl halides to give diaryl ethers in high yields. This catalyst is air-stable and was recycled for five times with minimal loss of activity.
- Islam, Manirul,Mondal,Mondal,Roy,Mobarak,Hossain
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- CuCl heterogenized on metformine-modified multi walled carbon nanotubes as a recyclable nanocatalyst for Ullmann-type C-O and C-N coupling reactions
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Herein, a novel MWCNTs-Met/CuCl nanocatalyst synthesis method by metformine covalent grafting on the surface of carbon nanotubes and subsequent coordination with a CuCl catalyst is described. The nanocatalyst formation was analyzed by FTIR, energy dispersive spectroscopy (EDS), Raman spectroscopy and ICP analysis. The nanocatalyst morphology was examined by transmission and scanning electron microscopies (TEM and SEM). Moreover, in the N-arylation of anilines and indole, the nanocatalyst (MWCNTs-Met/CuCl) could be successfully used by formation of intermolecular C(aryl)-N bonds of the relevant aryl halides (Ar-I, Ar-Br, Ar-Cl) with amines by coupling reactions of Ullmann-type. The O-arylation of substituted phenols is also promoted by this heterogeneous copper catalyst with different aryl iodides and bromides. Additionally, without any considerable loss in activity, the novel catalyst was recovered and recycled several times.
- Akhavan, Elham,Hemmati, Saba,Hekmati, Malak,Veisi, Hojat
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- Thermolysis of phenoxyaluminum compounds and formation of PCDD/F and their precursors
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Within the study of the formation of chlorinated dioxins and dibenzofurans and their precursors the thermolysis of hexachloroethane over the aluminum melt was investigated. "De novo" synthesis of precursors of PCDD/F was studied in the model system AlCl3/elemental carbon. Totally chlorinated heterocyclic compounds have been detected parallel with the formation of organochlorine compounds. The possibility of inserting oxygen to aluminum organyls was presented. In order to gain more detailed knowledge of the catalytic behaviour of fly ash the chemistry of thermolysis of phenoxy- and chlorophenoxy aluminum compounds at 300°C with the presence and absence of Al2O3 was investigated. Reagent compounds and products of thermolysis were followed by mass spectrometry.
- Voncina,Medved,Zerjal
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- Evidence for weak base site participation in the vapour phase methylation of catechol over solid base catalysts
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The vapour phase alkylation of catechol over supported caesium catalysts gives good selectivity to guaiacol formation, and TPD studies indicate that this result can be correlated with the presence of weak basic sites on the catalyst.
- Vishwanathan,Ndou,Sikhwivhilu,Plint,Raghavan,Coville
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- A highly stable and active magnetically separable Pd nanocatalyst in aqueous phase heterogeneously catalyzed couplings
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An active and stable magnetically separable Pd nanocatalyst was prepared and characterized. The nanocatalyst exhibited excellent activities and reusabilities in aqueous phase processes including the O-arylation of phenols and Sonogashira cross-coupling reactions. The proposed protocol features mild reaction conditions and an extraordinary simplicity and efficiency using NaOH as base in water.
- Zolfigol, Mohammad Ali,Khakyzadeh, Vahid,Moosavi-Zare, Ahmad Reza,Rostami, Abed,Zare, Abdolkarim,Iranpoor, Nasser,Beyzavi, Mohammad Hassan,Luque, Rafael
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- Impregnated copper on magnetite as catalyst for the O-arylation of phenols with aryl halides
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Nanoparticle Fe3O4 encapsulated CuO, as a heterogeneous catalyst, is a facile system for the synthesis of diaryl ethers by the cross-coupling reaction of various substituted aryl halides with various substituted phenols, which avoids using any type of expensive ligand and can be recovered from the reaction mixture by using a simple magnet. Moreover, this catalyst can be reused three times with high catalytic activity.
- Zhang, Ying-Peng,Shi, Ai-Hong,Yang, Yun-Shang,Li, Chun-Lei
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- Pd based on 2-Aminopyrimidine and 1H-benzo[d]imidazol-2-amine functionalizedFe3O4 nanoparticles as novel recyclable magnetic nanocatalysts for Ullmann coupling reaction
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In this study, Pd based on 2-Aminopyrimidine and 1H-benzo[d]imidazol-2-amine functionalized Fe3O4 magnetic nanoparticles [(Pd-APM-PSi-Fe3O4) and (Pd-BIA-PSi-Fe3O4)] was designed and used for the synthesis of di aryl ether by Ulmann cross-coupling reactions. Ulmann reaction performed with mixing of the arylhalides and phenol derivatives in DMF solvent. The prepared catalysts were characterized with various analytical techniques such as FT-IR, XRD, TGA, SEM, TEM, EDX, ICP and VSM. Pd-APM-PSi-Fe3O4 and Pd-BIA-PSi-Fe3O4 catalysts demonstrated good to excellent yields catalytic efficiency for Ulmann reactions in comparison with to commercial palladium catalysts. The catalyst is easily recycled and reused without loss of the catalytic activity. The combined merits of reusable catalyst conditions make the condensation with safe operation, no leaching of pd into environment, low pollution, rapid access to products and simple workup. Also, these novel magnetic nanocatalysts are superior to the industry standard Pd in every relevant aspect. They feature a way higher initial activity, a much more convenient separation, better recycling, and less contamination of the products. Last but not least, they can be very easily prepared from commercially available Fe3O4 nanoparticles using standard laboratory equipment.
- Chen, Jin,Dai, Linfang,Li, Jiayu,Mohammadnia, Majid
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- Synthesis of diaryl ethers by CuI-catalyzed C-O bond formation via Ullman coupling: Assessing the reactivity of aryl halides
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Using cuprous iodide as the catalyst, aryl halides reacted with phenols to form diaryl ethers. The reaction conditions were optimized: aryl halides (1 equiv) reacted with phenol (1 equiv) at 130 °C in DMF for 16 h with cuprous iodide (10 mol %), cesium carbonate (2.5 equiv) as the base, and tetramethylenediamine (5 mol %) as the ligand. Under the optimum conditions, reaction conversion with time was summarized. The structural parameters of four types of aryl halides and the ionization energy of various C-X bond lengths in all aryl halides-CuI π-complexes were calculated at the B3LYP/LANL2MB level by using the Gaussian 03 program and the corresponding Ullman reaction conversion was determined by HPLC. Results suggested that different relationships existed between reactivity and the energy of the lowest unoccupied molecular orbital ELUMO, mean polarizability and dipole moment μ. Both experimental and theoretical results, all displayed Ullman coupling reactivity order of the four aryl halides: fluorobenzene ? chlorobenzene bromobenzene iodobenzene.
- Xuesheng Zhang,Liu, Fu,Wei, Zhongbo,Wang, Zunyao
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- Cellulose-supported N-heterocyclic carbene silver complex with pendant ferrocenyl group for diaryl ether synthesis
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A cellulose-supported N-heterocyclic carbene Ag(I) complex has been synthesized by covalent grafting of ferrocenyl ionic liquid in the matrix of cellulose followed by metallation with silver oxide. The complex was employed as a heterogeneous catalyst in the synthesis of diaryl ethers. Reactions of a variety of phenols with aryl halides afford corresponding diaryl ethers in moderate to good yields. Recyclability experiments were executed successfully for five consecutive runs.
- Jagadale, Megha,Salunkhe, Rajashri,Kumbhar, Arjun,Gajare, Shivanand,Rajmane, Mohan,Rashinkar, Gajanan
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- Copper-catalyzed etherification of aryl iodides using KF/Al 2O3: An improved protocol
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A simple and efficient method for the coupling of aryl iodides with aliphatic alcohols and phenols that does not require the use of alkoxide bases is described. This C-O bond forming procedure shows that the combination of air stable CuI and 1,10-phenanthroline in the presence of KF/Al2O 3 comprises an extremely efficient and general catalyst system for the etherification of aryl iodides. Different functionalized aryl iodides were coupled with alcohols and phenols using this method.
- Hosseinzadeh, Rahman,Tajbakhsh, Mahmood,Mohadjerani, Maryam,Alikarami, Mohammad
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- Synthesis and characterization of polymer anchored cu(II) complexes: Heterogeneous catalysts for preparation of diaryl ethers
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Polymer anchored Cu(II) Schiff base complexes have been prepared and characterized by using scanning electron microscope (SEM), elemental analysis, atomic absorption spectroscopy (AAS), thermogravimetric analysis (TGA), spectrometric methods like diffuse reflectance spectra of solid (DRS) and fourier transform infrared spectroscopy (FTIR). These catalysts show excellent catalytic activity in the O-arylation reaction of aryl halides with phenol in acetonitrile using Cs2CO3 at 70 °C under an open air condition to give diaryl ethers in high yields. The effects of various parameters such as solvent, catalyst from different copper salt and base on the reaction system have been studied. The reaction is applicable to a wide variety of substituted aryl halides and phenols with different steric and electronic properties. These catalysts are recovered by simple filtration and the reusability experiments show that these catalysts can be used five times without much loss in the catalytic activity.
- Islam, Manirul,Mondal, Sanchita,Mobarak, Manir,Singha Roy, Anupam,Mondal, Paromita,Hossain, Dildar
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- ACTIVATION OF REDUCING AGENTS. SODIUM HYDRIDE CONTAINING COMPLEX REDUCING AGENTS 26. -- NEW EFFICIENT DESULFURIZING NICKEL CONTAINING REAGENTS
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It is shown that nickel containing Complex Reducing Agents NaH-RONa-NiX2 as such or in the presence of ligands are very efficient in desulfurizing organic compounds such as sulfur containing heteroaromatic substrates, aryl thioethers, dithioketals, sulfoxides or sulfones.
- Becker, S.,Fort, Y.,Vanderesse, R.,Caubere, P.
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- Open air O-arylation reaction of phenols with aryl halides catalyzed by polymer-anchored copper(II) complexes
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Two copper complexes were synthesized from macroporous chloromethylated polystyrene beads. The first one was prepared by sequential attachment of imidazole and copper acetate with chloromethylated polystyrene-divinyl benzene copolymer, and the second one was prepared from 4-vinylpyridine and copper acetate with chloromethylated polystyrene-divinyl benzene copolymer. These catalysts showed excellent catalytic activity in O-arylation reaction of aryl halides with phenol in dimethylsulfoxide using potassium carbonate at 130 °C under open air conditions to give diaryl ethers in high yields. Less reactive aryl bromides and aryl chlorides have also been shown to react with phenols to give good yields of the diaryl ethers. The effects of various parameters such as solvent, catalyst from different copper salt and base on the reaction system were studied. The reaction is applicable to a wide variety of substituted aryl halides and phenols with different steric and electronic properties. These catalysts were recovered by simple filtration, and the reusability experiments showed that these catalysts can be used five times without much loss in the catalytic activity.
- Islam, Manirul,Mondal, Sanchita,Mondal, Paramita,Roy, Anupam Singha,Hossain, Dildar,Mobarak, Manir
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- Preparation and characterization of isatin complexed with Cu supported on 4-(aminomethyl) benzoic acid-functionalized Fe3O4 nanoparticles as a novel magnetic catalyst for the Ullmann coupling reaction
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Isatin complexed with Cu supported on 4-(aminomethyl) benzoic acid-functionalized Fe3O4 nanoparticles (Cu-IS-AMBA-MNPs) as a new catalyst was designed, prepared and characterized by appropriate analyses. The heterogeneous reusable catalyst was successfully used for the efficient and widespread syntheses of diaryl ethers and diarylamines via the Ullmann coupling reaction. This green catalyst was easily removed, reused several times with no significant loss of its activity, and provided a clean synthesis with excellent yield and reduced time.
- Khodaei, Mohammad Mehdi,Alizadeh, Abdolhamid,Haghipour, Maryam
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- Barberry fruit extract assisted in situ green synthesis of Cu nanoparticles supported on a reduced graphene oxide-Fe3O4 nanocomposite as a magnetically separable and reusable catalyst for the O-arylation of phenols with aryl halides under ligand-free conditions
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In situ synthesis of copper nanoparticles (NPs) supported on a reduced graphene oxide (RGO)-Fe3O4 nanocomposite was carried out with barberry fruit extract as a reducing and stabilizing agent. The morphology and structure of the Cu/RGO-Fe3O4 nanocomposite was fully characterized by means of X-ray diffraction (XRD), Fourier transformed infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), Raman, energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). Cu/RGO-Fe3O4 was a promising catalyst for the O-arylation of phenols with aryl halides under ligand-free conditions. A diverse range of diaryl ethers were obtained in a good to high yield. Furthermore, due to the magnetic separability and high stability of the composite the catalyst could be separated conveniently from the reaction mixtures by an external permanent magnet and recycled multiple times without loss of catalytic activity.
- Nasrollahzadeh, Mahmoud,Maham, Mehdi,Rostami-Vartooni, Akbar,Bagherzadeh, Mojtaba,Sajadi, S. Mohammad
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- Direct arylation of benzothiazoles and benzoxazoles with aryl boronic acids
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A breath of fresh air: Without the need for organohalide precursors, the convenient and general synthesis of aryl-substituted benzothiazoles and benzoxazoles can be achieved by use of aryl boronic acids through direct arylation reactions catalyzed by a bimetallic system (see scheme).
- Ranjit, Sadananda,Liu, Xiaogang
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- CuI-USY as a Ligand-Free and Recyclable Catalytic System for the Ullmann-Type Diaryl Ether Synthesis
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The catalytic potential of copper(I)-exchanged zeolites was evaluated in the Ullmann-type synthesis of diaryl ethers. Among four investigated zeolites (i.e., USY, MOR, β, and ZSM5), CuI-USY was the best catalyst and proved efficient under ligand-free conditions in toluene at 120 °C. CuI-USY was also easy to recover and was recyclable up to five times without significant loss of activity.
- Magné, Valentin,Garnier, Tony,Danel, Mathieu,Pale, Patrick,Chassaing, Stefan
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- Synthesis, structure, and catalytic activity of Keggin-type polyoxometalate coordinated Cu(I): {[Cu(py)2]4[SiW12O 40]}, via hydrothermal decarboxylation
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A Keggin-type polyoxometalate [SiW12O40]4- supported transition metal complex, {[Cu(py)2]4[SiW 12O40]} (py=pyridine), has been synthesized by hydrothermal decarboxylation and characterized by elemental analyses, IR spectra, thermal stability analyses, and singlecrystal X-ray diffraction. The compound is a 1-D chain containing an inorganic-organic backbone with alternating [SiW12O40]4- clusters and [Cu(py)2]+ along the c-axis, and with both three- and four-coordinate copper. The luminescence properties indicated that the emission peak is emission of pyridine, assigned to the Cu(I) to pyridine charge transfer. This air-stable Cu(I) complex can efficiently catalyze the O-arylation of both phenols and aryl halides.
- Yang, Rui,Liu, Shu-Xia,Tang, Qun,Li, Shu-Jun,Liang, Da-Dong
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- A green approach for arylation of phenols using iron catalysis in water under aerobic conditions
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The first efficient iron-catalyzed coupling of aryl iodides with phenols was developed exclusively with water as solvent. The reaction is performed with low cost and readily available FeCl3·6H2O and DMEDA catalytic system providing diaryl ethers in good to excellent yields. The effectiveness of this reaction was further revealed by compatibility with a wide range of functional groups. Moreover, the procedure is rendered simple as this transformation is carried out in the presence of air. Thus, the protocol represents a facile, economical and eco-friendly procedure to access diaryl ethers.
- Sindhu, Kallikkakam S.,Ujwaldev, Sankuviruthiyil M.,Keerthi Krishnan,Anilkumar, Gopinathan
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- Glyoxal bis(phenylhydrazone) as promoter for CuI-catalyzed O-arylation of phenols with bromoarenes
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A very simple bishydrazone-type ligand, glyoxal bis(phenylhydrazone) (L1), was found to effectively promote the CuI-catalyzed O-arylation of phenols with aryl bromides. This cross-coupling reaction proceeded in acetonitrile at 60-80 °C in the presence of K3PO4 as base. A diverse array of phenols and bromoarenes was employed as substrates to afford diaryl ethers in good to excellent yields, and some base-sensitive groups, such as ester, aldehyde, and ketone groups, can survive under the mild reaction conditions.
- Liu, Yu-Hua,Li, Gang,Yang, Lian-Ming
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- Mild conditions for copper-catalyzed coupling reaction of phenols and aryl iodides and bromides
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Coupling of phenols and aryl bromides can be efficiently performed by means of catalytic amounts of copper iodide and the inexpensive ligand 1 (structure given in Table 1). The reaction is applicable to a wide range of substrates and proceeds at 60-80 deg;C, the lowest temperatures reported to date for an Ullmann-type synthesis of diaryl ethers. Moreover, the use of aryl bromides and inexpensive K3PO4 as base make this method attractive for applications on an industrial scale.
- Ouali, Armelle,Spindler, Jean-Francis,Cristau, Henri-Jean,Taillefer, Marc
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- Heck Coupling Reaction of Iodobenzene and Styrene Using Supercritical Water in the Absence of a Catalyst
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Heck coupling reaction of iodobenzene and styrene proceeds rapidly and selectively in supercritical water even without any catalyst in the presence of base. Both the choice of base and the reaction conditions had a significant effect on the conversion and the selectivity of the coupling products. The addition of a relatively mild base such as potassium acetate facilitated the cross-coupling reaction, while the hydrolysis of phenyl halide was favored in the presence of a strong base. The conversion and the yields of coupling products increased with increasing temperature, reaching a maximum at 650 K near the critical temperature of water, and then decreased as the temperature was further increased. Water density had a significant influence on the reaction rate, showing nearly 30% augmentation with a slight increase in density from 0.45 to 0.56 gcm-3, but had less effect on the product selectivity. Two possibilities of the role of water responsible for the noncatalytic Heck coupling reaction in supercritical water, that is, ion and water-catalyzed mechanisms have been considered.
- Zhang, Rong,Sato, Osamu,Zhao, Fengyu,Sato, Masahiro,Ikushima, Yutaka
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- Immobilization of copper in organic-inorganic hybrid materials: a highly efficient and reusable catalyst for the Ullmann diaryl etherification
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The immobilization of copper in organic-inorganic hybrid materials catalyzing the Ullmann reaction has been described. Phenols reacted with aryl iodides, aryl bromides and aryl chlorides smoothly in the presence of a 3-(2-aminoethylamino)propyl functionalized silica gel immobilized copper catalyst. The protocol involved the use of DMSO as the solvent, and potassium fluoride as the base. The reactions generated the corresponding cross-coupling products in good to excellent yields. Furthermore, the silica-supported copper could be recovered and recycled by a simple filtration of the reaction solution and used for 10 consecutive trials without loss of its reactivity.
- Miao, Tao,Wang, Lei
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- Ni(II) complexes of tripodal N4 ligands as catalysts for alkane hydroxylation and O-arylation of phenol: Structural and reactivity effects induced by fluoro substitution
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Nickel(II) complexes [NiII(L1-2)(OAc)(H2O)][BPh4] (1–2) and [NiII(L3)(OAc)][BPh4] (3) derived from fluorinated tripodal ligands viz. N-((6-fluoropyridin-2-yl)methyl)(pyridin-2-yl)-N-(pyridin-2-ylmethyl)methanamine (L1 or FTPA), N,N′-bis((6-fluoropyridin-2-yl)methyl)(pyridin-2-yl)methanamine (L2 or F2TPA) and tris((6-fluoropyridin-2-yl)methyl)amine (L3 or F3TPA) have been synthesized and characterized by spectroscopic (UV–visible, FT-IR, paramagnetic NMR), elemental analysis, electrochemistry and X-ray diffraction techniques. In structurally similar complexes 1 and 2, Ni(II) center has a distorted octahedral coordination geometry constituted by all the four N atoms of the ligands, one acetate group and a water molecule. Complex 3 has different structural aspects. It does not have the water molecule in the coordination sphere and contains one acetate group bound with metal center in a bidentate mode. All the complexes exhibit a one-electron oxidation corresponding to the NiII/NiIII redox couple, the potential of which is influenced by the donor functionalities of ligand. These complexes catalyze the oxidation of cyclohexane efficiently (turn over number: 586–698) and selectively (alcohol to ketone ratio: 7.9:1 to 8.4:1). The study also includes the catalysis of adamantane oxidation to a mixture of ketones and alcohols. Catalytic potential of all the three complexes (1–3) has also been screened for C–O coupling reactions of phenol with aryl halides. Among them, complex 1 is more efficient than 2 and 3 for such reactions.
- Kerbib, Wissame,Kumar, Arun,Kumar, Sushil,Nautiyal, Divyanshu,Singh, Siddhant
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- Ligand free copper-catalyzed heterogeneous O-arylation reaction under green condition
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A highly porous Zn-based iso-reticular metal-organic framework (IRMOF-3) has been selected for covalent modification. Pyridine-2-aldehyde has been used to decorate the free amine group of IRMOF-3 in the porous matrix. Schiff base moiety thus generated has been availed to anchor copper(II) ions to prepare the desired catalyst that catalyzes O-arylation reactions heterogeneously under mild reaction conditions. Porous catalyst demonstrates size selectivity in products when various substrates undergo O-arylation with α and β-naphthol.
- Maity, Tanmoy,Saha, Debraj,Das, Soma,Bhunia, Susmita,Koner, Subratanath
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Read Online
- Synthesis and characterization of nano-cellulose immobilized phenanthroline-copper (I) complex as a recyclable and efficient catalyst for preparation of diaryl ethers, N-aryl amides and N-aryl heterocycles
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Functionalized nanocellulose was prepared and employed for immobilization of phenanthroline-copper(I) complex to afford cellulose nanofibril grafted heterogeneous copper catalyst [CNF-phen-Cu(I)]. This nanocatalyst was well characterized using FT-IR, NMR, XRD, CHNS, AAS, TGA, EDX and SEM. The activities of the synthesized catalyst were examined in the synthesis of diaryl ethers via C-O cross-coupling of phenols and aryl iodides, as well as, the preparation of N-aryl amides and N-aryl heterocycles through C-N cross-coupling of amides and N-H heterocycle compounds with aryl halides. In this trend, various substrates containing electron-donating and electron-withdrawing groups were exploited to evaluate the generality of this catalytic protocol. Accordingly, the catalyst demonstrated remarkable catalytic efficiency for both C-N and C-O cross-coupling reactions, thereby resulting in good to excellent yields of the desired products. Furthermore, the recoverability experiments of the catalyst showed that it can be readily retrieved by simple filtration and successfully reused several times with negligible loss of its catalytic activity.
- Aghili, Nora,Hosseinzadeh, Rahman,Mavvaji, Mohammad
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- Research on the decomposition kinetics and thermal hazards of aniline diazonium salt
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Diazotization reaction, strong exothermic characteristics and thermal instability of diazonium salts make the production process high risk. To research thermal hazards of aniline diazonium salt, dynamic experiments are carried out by the differential scanning calorimeter (DSC) to obtain thermodynamic parameters. Moreover, the kinetic parameters are analyzed by Advanced Kinetics and Technology Solutions (AKTS) software. Finally, the GC-MS and UV spectrum are used to further study the decomposition mechanism of the aniline diazonium salt. The results indicate that aniline diazonium salt is very easy to decompose. When the heating rate is 2 K/min, the onset decomposition temperature is only 27.21 ℃ (Tonset). The apparent activation energy of the decomposition process calculated by Friedman and Ozawa methods are respectively 98-85 kJ/mol and 110-100 kJ/mol. Under the ideal adiabatic conditions (φ = 1), the initial temperatures of TMRad for 24 h is only 6.2 ℃ (TD24), which is predicted by the AKTS software. The decomposition process of aniline diazonium salt is inconsistent with a single reaction mechanism.
- Du, Lei,Wang, Ben,Xie, Chuanxin,Yuan, Yucan
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- Magnetization of graphene oxide nanosheets using nickel magnetic nanoparticles as a novel support for the fabrication of copper as a practical, selective, and reusable nanocatalyst in C-C and C-O coupling reactions
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Catalyst species are an important class of materials in chemistry, industry, medicine, and biotechnology. Moreover, waste recycling is an important process in green chemistry and is economically efficient. Herein, magnetic graphene oxide was synthesized using nickel magnetic nanoparticles and further applied as a novel support for the fabrication of a copper catalyst. The catalytic activity of supported copper on magnetic graphene oxide (Cu-ninhydrin@GO-Ni MNPs) was investigated as a selective, practical, and reusable nanocatalyst in the synthesis of diaryl ethers and biphenyls. Some of the obtained products were identified by NMR spectroscopy. This nanocatalyst has been characterized by atomic absorption spectroscopy (AAS), scanning electron microscopy (SEM), wavelength dispersive X-ray spectroscopy (WDX), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM) techniques. The results obtained from SEM shown that this catalyst has a nanosheet structure. Also, XRD and FT-IR analysis show that the structure of graphene oxide and nickel magnetic nanoparticles is stable during the modification of the nanoparticles and synthesis of the catalyst. The VSM curve of the catalyst shows that this catalyst can be recovered using an external magnet; therefore, it can be reused several times without a significant loss of its catalytic efficiency. The heterogeneity and stability of this nanocatalyst during organic reactions was confirmed by the hot filtration test and AAS technique.
- Hajjami, Maryam,Moradi, Parisa
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p. 25867 - 25879
(2021/08/09)
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- Fe-MIL-101 modified by isatin-Schiff-base-Co: a heterogeneous catalyst for C-C, C-O, C-N, and C-P cross coupling reactions
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A metal-organic framework functionalized with a cobalt-complex is preparedviapost-synthetic modification of Fe-MIL-101-NH2. Initially, Fe-MIL-101-NH2reacted with isatin to produce Fe-MIL-101-isatin-Schiff-base, which can anchor the cobalt by the addition of cobalt acetate. The resulting MOF-Co catalyst is characterized by employing multiple techniques. This new modified MOF acts as a heterogeneous and recyclable catalyst for efficient Ullmann, Buchwald-Hartwig, Hirao, Hiyama and Mizoroki-Heck cross-coupling reactions of several aryl halides/phenylboronic acid/phenyltosylate with phenols, anilines/heterocyclic amines, triethyl phosphite, triethoxyphenylsilane and alkenes and generates the expected coupling products in good to high yields.
- Farrokhi, Alireza,Rouzifar, Majid,Sansano, José Miguel,Sobhani, Sara
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p. 19963 - 19976
(2021/11/12)
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- L-Proline N-oxide dihydrazides as an efficient ligand for cross-coupling reactions of aryl iodides and bromides with amines and phenols
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A novel catalytic system based on L-proline N-oxide/CuI was developed and applied to the cross-coupling reactions of various N- and O- nucleophilic reagents with aryl iodides and bromides. This strategy featured in the employment of an-proline derived dihydrazides N-oxide compound as the superior supporting ligand. By using this protocol, a variety of products, including N-arylimidazoles, N-arylpyrazoles, N-arylpyrroles, N-arylamines, and aryl ethers, were synthesized with up to 99% yield.
- Ding, Zhiqiang,Nie, Nan,Chen, Tian,Meng, Lingxin,Wang, Gongshu,Chen, Zhangpei,Hu, Jianshe
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supporting information
(2020/12/21)
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- Preparation and characterization of Cu based on 5,5'-bistetrazole as a recyclable metal-organic framework and application in synthesis of diaryl ether by the Ullmann coupling reaction
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Cu based on 5,5′-bistetrazole ([Cu2BT · 2H2O] n) as a recyclable metal-organic framework (MOF) heterogeneous catalyst was characterized by FT-IR, 13C NMR, XRD, SEM, EDX, BET, BJH, and ICP-AES analysis. The catalytic activity of the catalyst was probed through the Ullmann reaction for synthesis of diaryl ether derivatives from two component reactions of aromatic arylhalides and phenol derivatives in DMSO. Simple procedure, high yields, short reaction time, and environmentally benign methods are advantages of this protocol. The catalyst was readily separated by simple filtration and reusable without significant loss of its catalytic efficiency.
- Noorpoor, Zeinab,Tavangar, Saeed
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p. 1651 - 1662
(2021/05/10)
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- Bis(NHC)-Pd-catalyzed one-pot competitive C-C*C-C, C-C*C-O, C-C*C-N, and C-O*C-N cross-coupling reactions on an aryl di-halide catalyzed by a homogenous basic ionic liquid (TAIm[OH]) under base-free, ligand-free, and solvent-free conditions
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Bis(NHC)-Pd-catalyzed competitive asymmetrical C-C*C-C, C-C*C-O, C-C*C-N, and O-C*C-N cross-coupling reactions were performedviathe one-pot strategy in the presence of a new ionic liquid, which played the roles of solvent, base, and ligand simultaneously. The ionic liquid was prepared based on a methyl imidazolium moiety with hydroxyl counter anionsviaa Hofmann elimination on a 1,3,5-triazine framework (TAIm[OH]). Pd ions could be efficiently coordinated through the bis(NHC)-ligand moiety in the ionic liquid. Based on differences in the competitive kinetics of C-C cross-coupling reactions (Heck, Suzuki, and Sonogashira) with C-N and C-O cross-coupling reactions, and also differences in the kinetics of aryl halides, the coupling reactions could be selectively performed with a low amount of by-products. The competitive cross-coupling reactions were thus performed with high selectivity under mild reaction conditions.
- Zhu, Yanfang,Xu, Guiyang,Kazemnejadi, Milad
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p. 11662 - 11671
(2021/07/11)
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- Copper nanoparticle anchored biguanidine-modified Zr-UiO-66 MOFs: a competent heterogeneous and reusable nanocatalyst in Buchwald-Hartwig and Ullmann type coupling reactions
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We have designed a functionalized metal-organic framework (MOF) of UiO topology as a support, with an extremely high surface area, adjustable pore sizes and stable crystalline coordination polymeric structure and implanted copper (Cu) nanoparticles thereon. The core three dimensional Zr-derived MOF (UiO-66-NH2) was modified with a biguanidine moiety following a covalent post-functionalization approach. The morphological and physicochemical features of the material were determined using analytical methods such as FT-IR, SEM, TEM, EDX, atomic mapping, XRD and ICP-OES. The SEM and XRD results justified the unaffected morphology of Zr-MOF after structural modifications. The as-synthesized UiO-66-biguanidine/Cu nanocomposite was catalytically explored in the aryl and heteroaryl Buchwald-Hartwig C-N and Ullmann type C-O cross coupling reactions with excellent yields. A library of biaryl amine and biaryl ethers was synthesized over the catalyst under mild and green conditions. Furthermore, the catalyst was isolated by centrifugation and recycled 11 times with no significant copper leaching or change in its activity.
- Veisi, Hojat,Neyestani, Narges,Pirhayati, Mozhgan,Ahany Kamangar, Sheida,Lotfi, Shahram,Tamoradi, Taiebeh,Karmakar, Bikash
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p. 22278 - 22286
(2021/07/02)
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- Thermally stable and robust gadolinium-based metal-organic framework: Synthesis, structure and heterogeneous catalytic O-arylation reaction
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Hydrothermal treatment of gadolinium nitrate and 2,6-naphthalenedicarboxylic acid (H2NDC) afforded a new metal-organic framework compound, {[Gd4(NDC)6(H2O)6]·2H2O}n(1). Compound 1 has been characterized by single-crystal X-ray crystallography, elemental analysis, FT-IR spectroscopy, therrmogravimetric analysis (TGA) and powder X-ray diffraction analysis. It is crystallized in the monoclinic system with the P21/n space group. Four crystallographically distinct Gd (III) centres are interconnected with each other through bridged carboxylato oxygen atoms and water molecules to form tetranuclear secondary building units, which are further connected through the carboxylato ligand and the network propagates along the crystallographic ac plane to form a 2D structure. Subsequent reinforcement from the remaining carboxylato oxygen atoms gives rise to a robust 3D framework structure. Thermogravimetric analysis demonstrates that compound 1 is fairly stable after dehydration under a nitrogen atmosphere. Notably, compound 1 is capable of catalyzing the O-arylation reaction efficiently between substituted phenols and bromoarene under heterogeneous conditions at 80 °C to afford unsymmetrical diarylethers.
- Ghosh, Pameli,Maity, Tanmoy,Biswas, Saptarshi,Debnath, Rakesh,Koner, Subratanath
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- Synergistic effect of copper nanocrystals-nanoparticles incorporated in a porous organic polymer for the Ullmann C-O coupling r–eaction
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A quinoxaline-based porous organic polymer (Q-POP) as a mesoporous organic copolymer was developed as a new platform for the immobilization of CuNPs and copper nanocrystals. The prepared materials were characterized by FT-IR, XRD, N2 adsorption-desorption isotherms, ICP, TGA, SEM, HR-TEM, EDX, and single-crystal X-ray crystallography. The obtained catalyst presented extraordinary catalytic activity towards Ullmann C–O coupling reactions with high surface area, hierarchical porosity, and excellent thermal and chemical stability. Due to its high porosity, and synergistic effect of copper nanocrystals incorporated in the polymer composite, the as-synthesized catalyst was successfully utilized for the Ullmann C–O coupling reaction of phenols and different aryl halides to prepare various diaryl ether derivatives. All types of aryl halides (except aryl fluorides) were screened in the Ullmann C–O coupling reaction with phenols to produce diaryl ethers in good to excellent yields (70–97 %), and it was found that aryl iodides have the best results. Besides, due to the strong interactions between CuNPs, N, and O-atoms of quinoxaline moiety existing in the polymeric framework, the copper leaching from the support was not observed. Furthermore, the catalyst was recycled and reused for five consecutive runs without significant activity loss.
- Gorginpour, Forough,Zali-Boeini, Hassan
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- Palladium-catalyzed intramolecular aromatic C-H acylation of 2-arylbenzoyl fluorides
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The catalytic intramolecular cyclization of acyl fluorides using a Pd(OAc)2/PCy3 system is described. A wide range of 2-arylbenzoyl fluoride derivatives can be used as fluorenone precursors and the reaction proceeds via an intramolecular coupling between aromatic C-H bonds with acyl C-F bonds. The reaction can be applied to the synthesis of indenofluorenedione derivatives and to the construction of other molecules with fivemembered rings.
- Hayakawa, Kazuki,Ikai, Kana,Ogiwara, Yohei,Sakai, Norio,Sakurai, Yuka
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p. 1882 - 1893
(2021/08/13)
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- Mediator-Enabled Electrocatalysis with Ligandless Copper for Anaerobic Chan-Lam Coupling Reactions
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Simple copper salts serve as catalysts to effect C-X bond-forming reactions in some of the most utilized transformations in synthesis, including the oxidative coupling of aryl boronic acids and amines. However, these Chan-Lam coupling reactions have historically relied on chemical oxidants that limit their applicability beyond small-scale synthesis. Despite the success of replacing strong chemical oxidants with electrochemistry for a variety of metal-catalyzed processes, electrooxidative reactions with ligandless copper catalysts are plagued by slow electron-transfer kinetics, irreversible copper plating, and competitive substrate oxidation. Herein, we report the implementation of substoichiometric quantities of redox mediators to address limitations to Cu-catalyzed electrosynthesis. Mechanistic studies reveal that mediators serve multiple roles by (i) rapidly oxidizing low-valent Cu intermediates, (ii) stripping Cu metal from the cathode to regenerate the catalyst and reveal the active Pt surface for proton reduction, and (iii) providing anodic overcharge protection to prevent substrate oxidation. This strategy is applied to Chan-Lam coupling of aryl-, heteroaryl-, and alkylamines with arylboronic acids in the absence of chemical oxidants. Couplings under these electrochemical conditions occur with higher yields and shorter reaction times than conventional reactions in air and provide complementary substrate reactivity.
- Walker, Benjamin R.,Manabe, Shuhei,Brusoe, Andrew T.,Sevov, Christo S.
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supporting information
p. 6257 - 6265
(2021/05/07)
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- Nickel-Catalyzed Photodehalogenation of Aryl Bromides
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Herein, we describe a Ni-catalyzed photodehalogenation of aryl bromides under visible-light irradiation that utilizes tetrahydrofuran as hydrogen source. The protocol obviates the need for exogeneous amine reductants or photocatalysts and is characterized by its simplicity and broad scope, including challenging substrate combinations.
- Higginson, Bradley,Sanjosé-Orduna, Jesus,Gu, Yiting,Martin, Ruben
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supporting information
p. 1633 - 1636
(2021/04/23)
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- Photo-induced thiolate catalytic activation of inert Caryl-hetero bonds for radical borylation
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Substantial effort is currently being devoted to obtaining photoredox catalysts with high redox power. Yet, it remains challenging to apply the currently established methods to the activation of bonds with high bond dissociation energy and to substrates with high reduction potentials. Herein, we introduce a novel photocatalytic strategy for the activation of inert substituted arenes for aryl borylation by using thiolate as a catalyst. This catalytic system exhibits strong reducing ability and engages non-activated Caryl–F, Caryl–X, Caryl–O, Caryl–N, and Caryl–S bonds in productive radical borylation reactions, thus expanding the available aryl radical precursor scope. Despite its high reducing power, the method has a broad substrate scope and good functional-group tolerance. Spectroscopic investigations and control experiments suggest the formation of a charge-transfer complex as the key step to activate the substrates.
- K?nig, Burkhard,Wang, Hua,Wang, Shun
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supporting information
p. 1653 - 1665
(2021/06/17)
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- Heterogeneously Catalyzed Selective Decarbonylation of Aldehydes by CeO2-Supported Highly Dispersed Non-Electron-Rich Ni(0) Nanospecies
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Aldehyde decarbonylation has been extensively investigated, primarily using noble-metal catalysts; however, nonprecious-base-metal-catalyzed aldehyde decarbonylation has been hardly reported. We have established an efficient selective aldehyde decarbonylation reaction with a broad substrate scope and functional group tolerance utilizing a heterogeneous Ni(0) nanospecies catalyst supported on CeO2. The high catalytic performance is attributable to the highly dispersed and non-electron-rich Ni(0) nanospecies, which possibly suppress a side reaction producing esters and adsorbed CO-derived inhibition of the catalytic turnover, according to detailed catalyst characterization and kinetic evaluation.
- Matsuyama, Takehiro,Yatabe, Takafumi,Yabe, Tomohiro,Yamaguchi, Kazuya
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p. 13745 - 13751
(2021/11/17)
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- Diaryl Ether Formation Merging Photoredox and Nickel Catalysis
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Photoredox and Ni catalysis are combined to produce diaryl ethers under mild conditions. A broad range of aryl halides and phenol derivatives are cross-coupled in the presence of a readily available organic photocatalyst and NiBr2(dtbpy). Symmetrical diaryl ethers have also been directly obtained from aryl bromides in the presence of water. Mechanistic investigations support the involvement of Ni(0) species at the outset of the reaction and a Ni(II)/Ni(III)-photocatalyzed single electron transfer process preceding the productive C(sp2)-OAr reductive elimination.
- Liu, Le,Nevado, Cristina
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supporting information
p. 2188 - 2193
(2021/05/04)
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- CoII Immobilized on Aminated Magnetic-Based Metal–Organic Framework: An Efficient Heterogeneous Nanostructured Catalyst for the C–O Cross-Coupling Reaction in Solvent-Free Conditions
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Abstract: In this paper, we report the synthesis of Fe3O4?AMCA-MIL53(Al)-NH2-CoII NPs based on the metal–organic framework structures as a magnetically separable and environmentally friendly heterogeneous nanocatalyst. The prepared nanostructured catalyst efficiently promotes the C–O cross-coupling reaction in solvent-free conditions without the need for using toxic solvents and/or expensive palladium catalyst. Graphic Abstract: [Figure not available: see fulltext.].
- Mohammadinezhad, Arezou,Akhlaghinia, Batool
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p. 332 - 352
(2020/01/11)
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- Catalysis with magnetically retrievable and recyclable nanoparticles layered with Pd(0) for C-C/C-O coupling in water
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Nanoparticles layered with palladium(0) were prepared from nano-sized magnetic Fe3O4 by coating it with silica and then reacting sequentially with phenylselenyl chloride under an N2 atmosphere and palladium(ii) chloride in water. The resulting Fe3O4?SiO2?SePh?Pd(0) NPs are magnetically retrievable and the first example of NPs in which the outermost layer of Pd(0) is mainly held by selenium. The weight percentage of Pd in the NPs was found to be 1.96 by ICP-AES. The NPs were authenticated via TEM, SEM-EDX, XPS, and powder XRD and found to be efficient as catalysts for the C-O and C-C (Suzuki-Miyaura) coupling reactions of ArBr/Cl in water. The oxidation state of Pd in the NPs having size distribution from ~12 to 18 nm was inferred as zero by XPS. They can be recycled more than seven times. The main features of the proposed protocols are their mild reaction conditions, simplicity, and efficiency as the catalyst can be separated easily from the reaction mixture by an external magnet and reused for a new reaction cycle. The optimum loading (in mol% of Pd) was found to be 0.1-1.0 and 0.01-1.0 for O-arylation and Suzuki-Miyaura coupling, respectively. For ArCl, the required amount of NPs was more as compared to that needed for ArBr. The nature of catalysis is largely heterogeneous.
- Joshi, Hemant,Sharma, Alpesh K.,Singh, Ajai K.
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p. 6452 - 6459
(2020/02/25)
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- Hydrodebromination of Aromatic Bromides Catalyzed by Unsupported Nanoporous Gold: Heterolytic Cleavage of Hydrogen Molecule
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Unsupported nanoporous gold (AuNPore) is a highly efficient, practically applicable, and recyclable catalyst for hydrodebromination of aromatic bromides. The AuNPore-catalyzed hydrodebromination of aromatic bromides proceeded smoothly at relatively low hydrogen pressure and temperature to achieve good to excellent yields of the corresponding non-bromine variants. The selective hydrodebromination reaction occurred exclusively in the coexistence of chlorine atom. For the first time, a mechanistic study revealed that the H?H bond splits in a heterolysis manner on the surface of AuNPore to generate Au?H hydride species.
- Bao, Ming,Feng, Xiujuan,Yamamoto, Yoshinori,Zhang, Sheng,Zhao, Yuhui
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p. 4951 - 4957
(2020/09/09)
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- Discovery and characterization of an acridine radical photoreductant
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Photoinduced electron transfer (PET) is a phenomenon whereby the absorption of light by a chemical species provides an energetic driving force for an electron-transfer reaction1–4. This mechanism is relevant in many areas of chemistry, including the study of natural and artificial photosynthesis, photovoltaics and photosensitive materials. In recent years, research in the area of photoredox catalysis has enabled the use of PET for the catalytic generation of both neutral and charged organic free-radical species. These technologies have enabled previously inaccessible chemical transformations and have been widely used in both academic and industrial settings. Such reactions are often catalysed by visible-light-absorbing organic molecules or transition-metal complexes of ruthenium, iridium, chromium or copper5,6. Although various closed-shell organic molecules have been shown to behave as competent electron-transfer catalysts in photoredox reactions, there are only limited reports of PET reactions involving neutral organic radicals as excited-state donors or acceptors. This is unsurprising because the lifetimes of doublet excited states of neutral organic radicals are typically several orders of magnitude shorter than the singlet lifetimes of known transition-metal photoredox catalysts7–11. Here we document the discovery, characterization and reactivity of a neutral acridine radical with a maximum excited-state oxidation potential of ?3.36 volts versus a saturated calomel electrode, which is similarly reducing to elemental lithium, making this radical one of the most potent chemical reductants reported12. Spectroscopic, computational and chemical studies indicate that the formation of a twisted intramolecular charge-transfer species enables the population of higher-energy doublet excited states, leading to the observed potent photoreducing behaviour. We demonstrate that this catalytically generated PET catalyst facilitates several chemical reactions that typically require alkali metal reductants and can be used in other organic transformations that require dissolving metal reductants.
- MacKenzie, Ian A.,Wang, Leifeng,Onuska, Nicholas P. R.,Williams, Olivia F.,Begam, Khadiza,Moran, Andrew M.,Dunietz, Barry D.,Nicewicz, David A.
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- Palladium complexes of chalcogenoethanamine (S/Se) bidentate ligands: Applications in catalytic arylation of C[sbnd]H and O[sbnd]H bonds
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This report describes the syntheses of N,E (E = S, Se) coordinated bidentate palladium complexes, by the reaction of N-(2-bromobenzyl)-2-(phenylthio/selanyl)ethanamine (3, 4) with [PdCl2(CH3CN)2]. The new ligands and palladium complexes were characterized by techniques like 1H, 13C{1H} NMR, IR, and elemental analysis. The coordination modes of ligand with palladium precursor in complexes 5 and 6 were authenticated by single crystal X-ray diffraction. The complexes possess distorted square planar geometry around palladium center. Thermally robust and air stable complexes 5 and 6 were used as catalyst for regioselective arylation of imidazole and O-arylation of phenol. In case of regioselective arylation of imidazole, the reaction proceeds smoothly under mild reaction conditions, only 2.0 mol% of catalyst loading is required to achieve high yield (76–92%). This protocol is applicable to a broad substrate scope showing excellent tolerance towards different functional groups. Whereas for O-arylation of phenol also only 2.0 mol% catalyst loading is sufficient to give good yield (71–92%) with excellent tolerance towards a broad range of functional groups. Among sulfur and selenium coordinated ligands, selenium ligand coordinated complex, was found to outperform the catalytic reactions in both cases as compare to sulfur ligand. The mercury and triphenylphosphine poisoning tests suggest homogeneous nature of catalysis.
- Bhatt, Ramprasad,Bhuvanesh, Nattamai,Himanshi,Joshi, Hemant,Sharma, Alpesh K.
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- Synthesis method of 2-phenoxy phenylboronic acid
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The invention relates to a synthesis method of 2-phenoxy phenylboronic acid. The synthesis method comprises the following steps: using phenol and benzene ring-containing organic acid as initial raw materials and synthesizing diphenyl ether; and then performing hydrogen removal on the diphenyl ether and reacting the diphenyl ether subjected to hydrogen removal with boric acid ester to obtain 2-phenoxy phenylboronic acid. Compared with the prior art, the method has the advantages that the product is synthesized by directly removing hydrogen from aryl, the raw materials are cheap and easily available, the selectivity is good and the atom economy is good; the method is short in synthetic route, high in reaction efficiency and high in total yield; and thus the method is very suitable for industrial popularization.
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Paragraph 0018-0021
(2020/05/14)
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- Diaza crown-type macromocycle (kryptofix 22) functionalised carbon nanotube for efficient Ni2+ loading; A unique catalyst for cross-coupling reactions
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Raising the capability of supporting and suppressing the leaching possibility to a very insignificant level has still remained challenging for some class of transition metals, i.e. Ni2+. Here we present the covalent functionalisation of macrocyclic ligand, 4,13-diaza-18-crown-6 (kryptofix 22), on the surface of carbon nanotube (CNT), leading to a unique adsorptive capability for supporting Ni2+. This material was incorporated as a promising catalyst in coupling reactions including C[sbnd]C, CN, and CO[sbnd][sbnd] cross-coupling reactions. We demonstrate that the kryptofix 22 functionalisation on the surface of CNT has a key role in the enhancement of the adsorption capability Ni2+ and subsequent catalytic activity. We further prove that this ligand causes a significant boost in the recyclability of the reactions due to the extremely trivial Ni2+ leaching from the CNT's surface during the reactions.
- Aalinejad, Michael,Doustkhah, Esmail,Pesyan, Nader Noroozi
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- Palladium nanoparticles supported on cysteine-functionalized MNPs as robust recyclable catalysts for fast O- and N-arylation reactions in green media
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A magnetically robust recyclable nanocatalyst was fabricated by immobilizing of Pd onto the surface of cysteine-functionalized magnetic nanoparticles (MNPs?Cys-Pd). This nanocatalyst was characterized using various techniques such as FT-IR, XRD, TEM, SEM, EDX, VSM, and ICP. The application of catalyst (MNPs?Cys-Pd) was investigated for O-arylation and N-arylation reactions. This phosphine-free complex was found as highly efficient heterogeneous catalyst in green media and mild reaction conditions. In addition, it gave excellent recyclability without significant deactivation after ten cycles.
- Hajipour, Abdol R.,Khorsandi, Zahra,Fatemeh Mohammadi Metkazini
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- A new strategy to design a graphene oxide supported palladium complex as a new heterogeneous nanocatalyst and application in carbon–carbon and carbon-heteroatom cross-coupling reactions
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The palladium nanoparticles were successfully stabilized with an average diameter of 6–7?nm through the coordination of palladium and terpyridine-based ligands grafted on graphene oxide surface. The graphene oxide supported palladium nanoparticles were thoroughly characterized and applied as an efficient heterogeneous catalyst in carbon–carbon (Suzuki-Miyaura, Mizoroki-Heck coupling reactions) and carbon–heteroatom (C-N and C-O) bond-forming reactions. The catalyst was simply recycled from the reaction mixture and was reused consecutive four times with small drop in catalytic activity.
- Bahrami, Kiumars,Targhan, Homa
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- Design of BNPs-TAPC Palladium Complex as a Reusable Heterogeneous Nanocatalyst for the O-Arylation of Phenols and N-Arylation of Amines
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The thermally stable new heterogenous nanocatalyst BNPs@SiO2(CH2)3-TAPC-O-CH2CH2NH2-Pd(0) was synthesized, characterized and successfully applied in carbon-heteroatom (C–O and C–N) coupling reactions of aryl halides with phenols and amines. The formation of resultant nanocatalyst was approved by FT-IR, XRD, TGA, XPS and EDX techniques. The morphology of BNPs@SiO2(CH2)3-TAPC-O-CH2CH2NH2-Pd(0) was characterized using scanning and transmission electron microscopes. The leaching of palladium from the surface of the catalyst was studid by ICP-OES technique. Noteworthy, the highly active BNPs@SiO2(CH2)3-TAPC-O-CH2CH2NH2-Pd(0) can be easily recycled and reused for six times with negligible loss in its activity. Some remarkable advantages of this method are the shorter reaction times, milder conditions, no needs for an inert atmosphere, high yields and easy separation. Graphical Abstract: [Figure not available: see fulltext.].
- Bahrami, Kiumars,Khodamorady, Minoo
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p. 688 - 698
(2019/01/04)
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- Magnetically recyclable nano copper/chitosan in O-arylation of phenols with aryl halides
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Interaction of chitosan (CS) with Fe3O4, followed by embedding Cu nanoparticles (NPs) on the magnetic surface through adsorption of Cu2+, and its reduction to Cuo via NaBH4, offers a reusable efficient catalyst (Fe3O4/CS-Cu NPs) that is employed in cross-coupling reactions of aryl halides with phenols, which affords the corresponding diaryl ethers, with good to excellent yields. The catalyst is completely recoverable from the reaction mixture by using an external magnet. It can be reused four times, without significant loss in its catalytic activity.
- Mousavi Mashhadi, Seyed Ali,Kassaee, Mohamad Z.,Eidi, Esmaiel
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- Method for converting carbon halogen C-R to hydrocarbon/deuterium bond C-H/D of photocatalytic polyhalides
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The invention discloses a method for converting carbon halogen C-R to hydrocarbon/deuterium bond C-H/D of photocatalytic polyhalides. The method includes the following steps: adding a photocatalyst quantum dot/rod into a solvent to obtain a solution A; adding the polyhalides and an electronic sacrificial into the solution A to obtain a solution B; and irradiating the solution B with a light sourcefor catalysis for dehalogenation conversion of the polyhalides. The method is the first to use the nano quantum dots and the nano quantum rods for the dehalogenation conversion reaction of the polyhalides, is mild in reaction conditions and uses visible light as driving energy, products are completely dehalogenated hydrocarbon compounds, and the whole process is green, simple and efficient. The method combines the dehalogenation conversion of the polyhalides and a deuteration labeling process to completely complete the conversion of multiple C-R bonds to C-D bonds to realize the deuteration labeling of polyatoms in one step.
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Paragraph 0039; 0040
(2019/10/01)
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- Palladium–Borane Cooperation: Evidence for an Anionic Pathway and Its Application to Catalytic Hydro-/Deutero-dechlorination
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Metal–Lewis acid cooperation provides new opportunities in catalysis. In this work, we report a new type of palladium–borane cooperation involving anionic Pd0 species. The air-stable DPB palladium complex 1 (DPB=diphosphine-borane) was prepared and reacted with KH to give the Pd0 borohydride 2, the first monomeric anionic Pd0 species to be structurally characterized. The boron moiety acts as an acceptor towards Pd in 1 via Pd→B interaction, but as a donor in 2 thanks to B-H-Pd bridging. This enables the activation of C?Cl bonds and the system is amenable to catalysis, as demonstrated by the hydro-/deutero-dehalogenation of a variety of (hetero)aryl chlorides (20 examples, average yield 85 %).
- Kameo, Hajime,Yamamoto, Jun,Asada, Ayaka,Nakazawa, Hiroshi,Matsuzaka, Hiroyuki,Bourissou, Didier
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supporting information
p. 18783 - 18787
(2019/11/19)
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- Hydrodehalogenation of Aryl Halides through Direct Electrolysis
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A catalyst- and metal-free electrochemical hydrodehalogenation of aryl halides is disclosed. Our reaction by a flexible protocol is operated in an undivided cell equipped with an inexpensive graphite rod anode and cathode. Trialkylamines nBu3N/Et3N behave as effective reductants and hydrogen atom donors for this electrochemical reductive reaction. Various aryl and heteroaryl bromides worked effectively. The typically less reactive aryl chlorides and fluorides can also be smoothly converted. The utility of our method is demonstrated by detoxification of harmful pesticides and hydrodebromination of a dibrominated biphenyl (analogues of flame-retardants) in gram scale.
- Ke, Jie,Wang, Hongling,Zhou, Liejin,Mou, Chengli,Zhang, Jingjie,Pan, Lutai,Chi, Yonggui Robin
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supporting information
p. 6911 - 6914
(2019/05/10)
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- Method for selectively catalyzing hydrogenolysis of aryl group C-Br bond using nano porous metal
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The invention belongs to the fields of pharmaceutical chemical intermediate and related chemistry, and provides a method for selectively catalyzing the hydrogenolysis of an aryl group C-Br bond usingnano porous metal. The method comprises the steps that (1), a bromine-substituted aromatic compound, a nano porous metal catalyst, alkali and a solvent are added to a reaction kettle, hydrogen is added, and heating and stirring are conducted; (2), reaction liquid obtained in step (1) is added to water after reaction is completed, extracting is conducted, and a solvent is removed by vacuum distillation to obtained a target product debromination aromatic compound. Compared with the prior art, the nano porous metal catalyst is taken as a catalyst, the catalyst can be conveniently recycled, the catalyst can be reused after simple filtering and cleaning, the catalyst has a stable structure and high catalytic activity, the catalytic activity is not significantly reduced after being reused for multiple times, and the possibility of industrialization of the catalyst is achieved.
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Paragraph 0058; 0059; 0060; 0061; 0062-0069
(2019/04/26)
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- Preparation method of diarylamine compound
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The invention relates to a preparation method of a diarylamine compound. Specifically, under the catalysis of cuprous oxide supported by chitosan, the arylation reaction used for a nitrogen-containingheterocyclic compound is achieved, and the corresponding diarylamine compound is obtained. The preparation method of the diarylamine compound has the advantages that the process conditions are simple, the yield is good, the operability is strong, and the functional group tolerance is wide.
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Paragraph 0062; 0063; 0064; 0065; 0066; 0067; 0075; 0076
(2019/04/26)
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- Preparation method of diaryl ether compound
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The invention relates to a preparation method of a diaryl ether compound. Particularly, under catalysis of chitosan supported cuprous oxide, an arylation reaction used for phenols is achieved, the corresponding diaryl ether compound is obtained, the technological condition is simple, the yield is good, operability is high, and wide functional group durability is achieved.
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Paragraph 0051-0056
(2019/06/05)
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- URJC-1-MOF as New Heterogeneous Recyclable Catalyst for C-Heteroatom Coupling Reactions
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Guillermo Calleja and co-workers from @urjc describe URJC-1-MOF as a new heterogeneous recyclable catalyst for c-heteroatom coupling reactions. The capacity of copper-based URJC-1-MOF as a MOF catalyst in cross-coupling reactions has been evaluated, focusing on the Chan-Lam-Evans arylation-type reactions on amines and alcohols without extra additives or ligands. The extraordinary chemical and structural stability of URJC-1-MOF and its good specific surface, make this material a promising alternative to homogeneous Cu (II) catalysts for cross-coupling reactions. URJC-1-MOF showed a remarkable catalytic activity for cross-coupling C?N and C?O reactions, higher than other heterogeneous and homogeneous copper-based catalyst, such as CuO, HKUST-1, Cu?MOF-74, Cu(OAc)2 and CuSO4?5H2O. Moreover, its easy recovery by simple filtration and reusability in successive runs without any loss of activity and stability, demonstrates the potential of URJC-1-MOF as an alternative catalyst for this kind of reactions in different chemical media of industrial interest.
- Mu?oz, Antonio,Leo, Pedro,Orcajo, Gisela,Martínez, Fernando,Calleja, Guillermo
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p. 3376 - 3380
(2019/07/04)
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- Catalytic reduction of aryl trialkylammonium salts to aryl silanes and arenes
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A new approach for the reduction of aryl ammonium salts to arenes or aryl silanes using nickel catalysis is reported. This method displays excellent ligand-controlled selectivity based on the N-heterocyclic carbene (NHC) ligand employed. Utilizing a large NHC in non-polar solvents generates aryl silanes, while small NHCs in polar solvents promote reduction to arenes. Several classes of aryl silanes can be accessed from simple aniline building blocks, including those useful for cross-couplings, oxidations, and halogenations. The reaction conditions are mild, functional group tolerant, and provide efficient access to a variety of benzene derivatives.
- Rand, Alexander W.,Montgomery, John
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p. 5338 - 5344
(2019/05/29)
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- Thermal Stability of 4-tert-Butyl Diphenyl Oxide
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Abstract: In the temperature range of 703–763 K, the thermal stability of 4-tert-butyl diphenyl oxide (4?TBDPO) has been studied, the components of the thermolysis reaction mass have been identified, a kinetic model of the process has been proposed, and the rate constants and parameters of the Arrhenius equation for all reactions under consideration have been calculated. The predominant role of isomerization transformations of 4-TBDPO has been found. A mechanism for the radical isomerization of the tert-butyl substituent has been proposed.
- Shakun,Nesterova,Tarazanov,Spiridonov
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p. 2123 - 2130
(2019/11/11)
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- Base-Mediated O-Arylation of Alcohols and Phenols by Triarylsulfonium Triflates
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A mild and efficient protocol for O-arylation of alcohols and phenols (ROH) by triarylsulfonium triflates was developed under transition-metal-free conditions. Various alcohols, including primary, secondary and tertiary, and phenols bearing either electron-donating or electron-withdrawing groups on the aryl rings were smoothly converted to form the corresponding aromatic ethers in moderate to excellent yields. The reactions were conducted at 50 or 80 °C for 24 h in the presence of a certain base and showed good functional group tolerance. The base-mediated arylation with asymmetric triarylsulfonium salts could selectively transfer the aryl groups of sulfoniums to ROH, depending on their inherent electronic nature. The mechanistic studies revealed that the reaction might proceed through the nucleophilic attack of the in situ formed alkoxy or phenoxy anions at the aromatic carbon atoms of the C?S bonds of triarylsulfonium cations to furnish the target products.
- Ming, Xiao-Xia,Tian, Ze-Yu,Zhang, Cheng-Pan
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supporting information
p. 3370 - 3379
(2019/11/03)
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- C-N Cross-Couplings for Site-Selective Late-Stage Diversification via Aryl Sulfonium Salts
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We report diverse C-N cross-coupling reactions of aryl thianthrenium salts that are formed site-selectively by direct C-H functionalization. The scope of N-nucleophiles ranges from primary and secondary alkyl and aryl amines to various N-containing hetero
- Berger, Florian,Berger, Georg,Engl, Pascal S.,H?ring, Andreas P.,Pérez-Bitrián, Alberto,Ritter, Tobias
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supporting information
(2019/09/06)
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- The First C?Cl Activation in Ullmann C?O Coupling by MOFs
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It was found that introduction of only 0.03 mol % Ag(I) into the framework of Cu3(BTC)2 ? xH2O in maghemite anchored CuBTC activated the inert CuBTC astonishingly to exhibit unexpected high catalytic activity for C?Cl activation in coupling of chloroarenes with phenols without the use of expensive ligands. This is the first application of mixed-metal MOFs in the C?X activation. Putting reusability and activity together, a TON over 15000 was obtained which is the highest TON compared with all its precedents even better than the results by Pd catalysts.
- Ramezani, Leila,Yahyazadeh, Asieh,Sheykhan, Mehdi
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p. 4636 - 4651
(2018/09/21)
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- Immobilized palladium nanoparticles on MNPs@A-N-AEB as an efficient catalyst for C-O bond formation in water as a green Solvent
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Palladium nanoparticles immobilized on the magnetic nanoparticles@2-amino-N-(2-aminoethyl) benzamide (MNPs@A-N-AEB.Pd0) have been presented as an efficient, and reusable magnetically heterogeneous catalyst for the C-O coupling reaction, namely Ullmann condensation reactions in an aqueous medium. This heterogeneous catalyst shows superior reactivity for the C-O arylation of different aryl halide (chloride, bromide, and iodide) with phenol derivatives to afford the desired products in good to excellent yields within short reaction time. Moreover, the catalyst can be easily recovered and reused for seven runs without loss of catalytic activity. The catalyst was characterized by several techniques, such as FT-IR, SEM, TEM, EDS, XRD, TGA and ICP-OES.
- Moghaddam, Firouz Matloubi,Eslami, Mohammad
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- Zirconium oxide complex anchored on boehmite nanoparticles as highly reusable organometallic catalyst for C–S and C–O coupling reactions
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Boehmite nanoparticles were prepared by a simple and inexpensive procedure in water using commercially available materials without inert atmosphere. Then, the surface of the boehmite nanoparticles was modified using 3-mercaptopropyltrimethoxysilane and subsequently zirconium oxide was supported on the modified surface. Zirconium oxide supported on boehmite nanoparticles (Pr.S-ZrO@boehmite) was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and inductively coupled plasma technique. The catalytic application of Pr.S-ZrO@boehmite was studied in C–O and C–S coupling reactions for synthesis of valuable compounds such as ether and sulfide derivatives. All products were obtained in good to excellent yields and the catalyst could be recovered and reused several times without significant loss of catalytic efficiency. Furthermore, zirconium oxide is rarely used as catalyst for cross-coupling reactions.
- Ghorbani-Choghamarani, Arash,Seydyosefi, Zeinab,Tahmasbi, Bahman
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- Hydrodehalogenation of Polyhalogenated Aromatics Catalyzed by NiPd Nanoparticles Supported on Nitrogen-Doped Graphene
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Ni30Pd70 nanoparticles supported on nitrogen-doped graphene (NG) acts as a catalyst for the hydrodehalogenation of halogenated aromatics under mild reaction conditions. It reduces mono- or dichloroarenes to the corresponding dehalogenated arenes in >90 % yield in 10 % aqueous isopropanol solvent at or below 50 °C within 5 h. Tests on a variety of substrates containing various functional groups show that the catalyst is selective for reduction of C?Cl and C?Br bonds. In addition, this catalyst completely hydrodehalogenates high-concentration solutions of dioxin, polychlorinated biphenyls, chloroaromatic constituents of the defoliant agent orange, and polybrominated diphenyl ethers in 12 h. The catalyst is reusable and shows no morphological or compositional changes after 5 cycles. This methodology offers a powerful, low-cost, and safe technology for the degradation of polyhalogenated aromatics, and may be useful for preventing proliferation of these toxins in the environment from causing serious health issues.
- Guo, Xuefeng,Yu, Chao,Yin, Zhouyang,Sun, Shouheng,Seto, Christopher T.
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p. 1617 - 1620
(2018/06/15)
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- Efficient and selective hydrogenation of C-O bonds with a simple sodium formate catalyzed by nickel
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A Ni-catalyzed hydrogenation of C-O compounds with sodium formate is developed. Various esters, i.e. aryl, alkenyl, benzyl pivalates, and even the aryl ethers, were efficiently reduced with a loading of nickel catalysts down to 0.5 mol%. Reactive functional groups such as C-C double bonds, carbonyl, CN, MeS and halogen groups are tolerable. This reaction can be used for the modification of complex molecules and carried out at a large scale.
- Xi, Xiaoxiang,Chen, Tieqiao,Zhang, Ji-Shu,Han, Li-Biao
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p. 1521 - 1524
(2018/02/19)
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