- Design of a capillary-microreactor for efficient Suzuki coupling reactions
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A Pyrex glass capillary (0.4 mm internal diameter) microreactor was developed and used for Suzuki coupling reactions. Capillary-microreactors are more attractive than photolithographic microfluidic devices in terms of simplicity, low cost and ease of handling. Compared with the conventional synthesis procedure, our approach of using a capillary-microreactor offers a convenient and highly efficient means to optimize reaction conditions and the performance of catalysts. The procedure exhibits good precision, reproducibility and high reaction yield for a range of reactants investigated.
- Basheer, Chanbasha,Jahir Hussain, Fathima Shahitha,Lee, Hian Kee,Valiyaveettil, Suresh
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- Selective heating of pd-modified ordered mesoporous carbon CMK-3 by microwave irradiation
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Various microwave-heated heterogeneous catalytic reactions can be accelerated by choice of the catalyst supports and solvents. In this work, heterogeneous Pd catalysts supported on ordered mesoporous carbon CMK-3 and related catalysts were prepared. In the presence of these catalysts, the effect of microwave heating on Pd-catalyzed SuzukiMiyaura coupling as a probe reaction was investigated. The CMK-3 worked efficiently as a "carbon nanoflask" under microwave irradiation, especially in nonpolar solvents such as toluene and o-xylene with a lower ratio of dielectric constant (δ′) to dielectric loss (δ″) (=tan δ).
- Inagaki, Satoshi,Onodera, Kenzo,Tani, Kensaku,Kubota, Yoshihiro
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- Suzuki-miyaura reaction in water, catalyzed by palladium nanoparticles stabilized by pluronic F68 triblock copolymer
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Palladium nanoparticles stabilized by Pluronic F68 triblock copolymer effectively catalyzed Suzuki-Miyaura reaction in water. The reactions with water-soluble aryl iodides and aryl bromides containing electron-withdrawing or electron-donating substituent occurred at room temperature. The catalytic efficiency was found to depend on the size of palladium nanoparticles and their morphology. Pleiades Publishing, Ltd., 2011.
- Kashin,Beletskaya
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- One-pot hydrothermal synthesis of Pd/Fe3O4 nanocomposite in HEPES buffer solution and catalytic activity for Suzuki reaction
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The Pd/Fe3O4 nanocomposite integrates versatile Pd nanocatalysts with magnetic separation, and has great potential in fine chemical and pharmaceutical synthesis. Its preparation usually involves multi-steps. Herein it was prepared via a facile one-pot hydrothermal synthesis in 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer solution with the assistant of polyvinylpyrrolidone (PVP). HEPES plays multi-functions, particularly as a ligand to enhance the oxidation of Fe2+ to Fe3+ and as a buffer to control the pH value at slightly basic conditions (ca. 7.4) for the formation of crystalline Fe3O4 phase via Fe2+/Fe3+ co-precipitation. PVP works as a dispersant to prevent the particle from aggregation. The obtained Pd/Fe3O4 nanocomposite comprised uniform Pd nanoparticles (ca. 5 nm) deposited on Fe3O4 nanocrystals (ca. 15 nm). It exhibited excellent catalytic activity and stability for various Suzuki coupling reactions, and could be efficiently recovered with a magnet and recycled for at least 10 cycles without losing catalytic activity.
- Li, Shaozhong,Zhang, Wei,Chen, Fengxi,Chen, Rong
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- Stabilized Palladium Nanoparticles: Synthesis, Multi-spectroscopic Characterization and Application for Suzuki–Miyaura Reaction
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The present article demonstrates a simple method for synthesizing the highly stabilized Pd(0) nanoparticles by using supported 12-tungstophosphoric acid as a stabilizer as well as a carrier. The obtained material was characterized by different methods and the presence of nanoparticles on the surface of the carrier was confirmed, especially by TEM and XPS. As an application, the use of material was explored for the well-known fascinating organic transformation, Suzuki–Miyaura cross coupling reaction in aqueous medium as well as in neat H2O. It was found that the material shows an outstanding activity as the heterogeneous catalyst (0.0096?mol% of Pd) for both aqueous medium (99% conversion, TOF 96958?h?1) and in neat H2O (89% conversion, TOF 46390?h?1) towards biphenyl. The catalyst was recovered by filtration only, regenerated and reused without any significant loss in conversion. Study shows that the present catalyst is truly heterogeneous and sustainable for the said reaction, in either of the medium. The viability of the catalyst was learned toward different substrates and found to be excellent in almost all cases. Graphical Abstract: Pd nanoparticles stabilized by supported 12-tungstophosphoric acid is proved to be sustainable and excellent for Suzuki–Miyaura reaction with very high catalyst to substrate ratio as well as TOF. [Figure not available: see fulltext.].
- Patel, Anish,Patel, Anjali
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- Highly active Pd-Ni nanocatalysts supported on multicharged polymer matrix
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In this article, we report the synthesis of mono- and bimetallic Pd-Ni nanocomposites supported on a multicharged polymeric matrix for catalytic applications. The morphology and catalytic properties of the composites depend on the Pd-Ni ratio. In the Suzuki-Miyaura coupling reaction, the composite with an equal amount of palladium and nickel is the most active and the reaction occurs within six hours in water at room temperature.
- Sultanova, Elza D.,Samigullina, Aida I.,Nastapova, Natalya V.,Nizameev, Irek R.,Kholin, Kirill V.,Morozov, Vladimir I.,Gubaidullin, Aidar T.,Yanilkin, Vitaliy V.,Kadirov, Marsil K.,Ziganshina, Albina Y.,Konovalov, Alexander I.
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- Anchoring of palladium(II) in chemically modified mesoporous silica: An efficient heterogeneous catalyst for Suzuki cross-coupling reaction
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The synthesis and characterization of a highly efficient and reusable catalyst, Pd(II) immobilized in mesoporous silica MCM-41, are described. Pd(II) Schiff-base moiety has been anchored onto mesoporous silica surface via silicon alkoxide chemistry. The catalyst has been characterized by small-angle X-ray diffraction (SAX), FTIR and electronic spectroscopy as well as elemental analysis. The catalyst is used in Suzuki cross-coupling reaction of various aryl halides, including less reactive chlorobenzene, and phenylboronic acid to give biaryls in excellent yields without any additive or ligand. High selectivity for the bi-aryl products containing both electron-donating and electron-withdrawing substituents, mild reaction conditions and possibility of easy recycle makes the catalyst highly desirable to address the industrial needs and environmental concerns.
- Bhunia, Susmita,Sen, Rupam,Koner, Subratanath
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- Magnetically recyclable Fe@Pd/C as a highly active catalyst for Suzuki coupling reaction in aqueous solution
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In this work, a novel catalyst Fe@Pd/C was synthesized by sequential reduction method. The core-shell catalyst exhibited efficient catalytic activity in Suzuki coupling reaction at mild condition in water. Moreover, the catalyst could be recycled by external magnetic field and the yields achieved above 86% after reused at least 5 times.
- Tang, Weijie,Li, Jing,Jin, Xiaodong,Sun, Jian,Huang, Jingwei,Li, Rong
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- Pd-sepiolite catalyst for Suzuki coupling reaction in water: Structural and catalytic investigations
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[Pd(NH3)4]2+-exchanged sepiolite clay (Pd-sepiolite) has been applied to the catalytic Suzuki-type carbon-carbon coupling reactions of 4-bromophenol with phenylboronic acid or sodium tetraphenylborate in water. The Pd-sepiolite effectively catalyzed the reaction under mild reaction conditions (at room temperature in air). The Pd-sepiolite system exhibits higher yield than unsupported Pd(II) salts, [Pd(NH 3)4]Cl2-impregnated SiO2 (Pd-SiO2), and a commercially available Pd/C consisting of Pd metal particles. The structure of Pd species in the catalysts before and after the reaction was well characterized by a combination of XRD, TEM, UV-Vis, Pd K-edge XANES/EXAFS, and Pd LIII-edge XANES. XAFS and TEM results confirmed the formation of metal particles after the reaction by unsupported Pd(II) salt and Pd-SiO2. In contrast, for Pd-sepiolite the change in the structure of Pd species after the reaction was not significant; the highly dispersed Pd(II) complex, present before the reaction, was still the main Pd species together with the small Pd clusters (2-7 nm) as minor species. As a result of the high stability, Pd-sepiolite was reused without losing its activity. Significantly high turnover numbers (TON=940,000) were also attained at reflux temperature. It is suggested that Pd metal precipitation during the reaction is inhibited by a strong electrostatic interaction of sepiolite with Pd(II) species.
- Shimizu, Ken-Ichi,Maruyama, Rei,Komai, Shin-Ichi,Kodama, Tatsuya,Kitayama, Yoshie
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- Chitosan as a support for heterogeneous Pd catalysts in liquid phase catalysis
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Four different chitosan-supported palladium catalysts were prepared, whereby two of them were modified as Schiff base by reaction with salicylaldehyde and 2-pyridinecarboxaldehyde before complexation with palladium. The remaining differ in their preparation method: co-precipitation or adsorption. The properties of the catalysts were characterized by FTIR, XPS, ICP-MS, and TGA. Comparison of the catalysts activity was assessed in microwave-assisted Suzuki reactions in aqueous media, resulting in good yields and excellent selectivities concerning cross-coupling product. Additionally, the catalysts prove their activity under conductive heating conditions. The study was extended to microwave-assisted Heck and Sonogashira reactions in DMF, confirming the efficiency of chitosan-supported palladium derivatives as catalysts for C-C couplings. Experiments revealed that catalysts prepared by co-precipitation furnished inferior yields concerning the employed C-C coupling reactions. Modification of chitosan with 2-pyridinecarboxaldehyde and subsequent palladium deposition resulted in highly active catalysts affording high product selectivities and yields.
- Leonhardt, Silke E.S.,Stolle, Achim,Ondruschka, Bernd,Cravotto, Giancarlo,Leo, Cristina De,Jandt, Klaus D.,Keller, Thomas F.
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- Imidazolium-urea low transition temperature mixtures for the UHP-promoted oxidation of boron compounds
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Different carboxy-functionalized imidazolium salts have been considered as components of low transition temperature mixtures (LTTMs) in combination with urea. Among them, a novel LTTM based on 1-(methoxycarbonyl)methyl-3-methylimidazolium chloride and urea has been prepared and characterized by differential scanning calorimetry throughout its entire composition range. This LTTM has been employed for the oxidation of boron reagents using urea-hydrogen peroxide adduct (UHP) as the oxidizer, thus avoiding the use of aqueous H2O2, which is dangerous to handle. This metal-free protocol affords the corresponding alcohols in good to quantitative yields in up to 5 mmol scale without the need of further purification. The broad composition range of the LTTM allows for the reaction to be carried out up to three consecutive times with a single imidazolium salt loading offering remarkable sustainability with an E-factor of 7.9, which can be reduced to 3.2 by the threefold reuse of the system.
- Martos, Mario,Pastor, Isidro M.
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- An Imidazole-Rich Pd(II)-Polymer Pre-catalyst for the Suzuki-Miyaura Coupling: Stability Influenced by Dissolved Oxygen and Reactants Concentration
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Herein a novel Pd(II)-polymeric pre-catalyst was prepared by coordinating Pd(II) ions to a low cost imidazole/carboxylate-rich polymer. The material displays good activity in the Suzuki-Miyaura coupling towards a range of aryl bromides and iodides in iPrOH/H2O mixtures at 25 or 60 °C. Catalyst longevity and recyclability proved to be sensitive to the concentration of the cross-coupling partners. When the concentration of PhBr is high ([PhBr]=250 mmol L?1), inactive Pd(0) aggregates were detected. On the other hand, when the reaction was performed at 20-fold dilution ([PhBr]=12.5 mmol L?1) the material could be reused up to 12 times without significant loss of catalytic activity. In this condition, minimum amount of Pd(0) was detected by XPS analysis and no Pd(0) aggregates were observed by XRPD. Importantly, it was found that the presence of oxygen is fundamental for avoiding formation of inactive Pd(0) aggregates.
- Nishida, Elvis N.,Leopoldino, Elder C.,Zaramello, Laíze,Centurion, Higor A.,Gon?alves, Renato V.,Affeldt, Ricardo F.,Campos, Carlos E. M.,Souza, Bruno S.
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- Synthesis of Fluorenes and Dibenzo[ g,p]chrysenes through an Oxidative Cascade
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We have developed robust, operationally simple syntheses of fluorenes and of dibenzo[g,p]chrysenes through oxidative cascade processes. These structures that are commonly encountered in optoelectronic materials, dyes, and pharmaceutical products are acces
- Dickinson, Cody F.,Tius, Marcus A.,Yap, Glenn P. A.
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supporting information
p. 1559 - 1563
(2022/02/07)
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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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- Production method and application of p-phenylphenol
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The invention discloses a production method and application of p-phenylphenol, and the production method comprises the following steps: heating biphenyl and sulfuric acid to carry out sulfonation reaction, then neutralizing 4-phenylbenzenesulfonic acid in sulfonation reaction products by using sodium sulfite to generate sodium 4-phenylsulfonate and sulfur dioxide, collecting sulfur dioxide gas, cooling after the neutralization is finished, filtering, washing and drying to obtain p-phenylphenol. Filtering to obtain a sodium 4-phenylbenzenesulfonate solid; carrying out alkali fusion reaction on the sodium 4-phenylbenzenesulfonate solid and molten solid sodium hydroxide to generate sodium p-phenylphenolate and sodium sulfite; diluting the alkali fusion material with water, introducing collected sulfur dioxide for acidification reaction to generate p-phenylphenol and sodium sulfite, standing and separating to obtain crude p-phenylphenol and mother liquor, and finally rectifying to obtain p-phenylphenol. The method provided by the invention has the advantages of simple and easily available raw materials, good reaction atom economy, high yield, high product quality and low industrial cost, and is a feasible industrial production method of p-phenylphenol.
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Paragraph 0063; 0066-0070; 0071; 0074-0078; 0079; 0082-0086
(2022/03/27)
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- Fe3O4-SAHPG-Pd0 nanoparticles: A ligand-free and low Pd loading quasiheterogeneous catalyst active for mild Suzuki–Miyaura coupling and C-H activation of pyrimidine cores
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This paper reports a green magnetic quasiheterogeneous efficient palladium catalyst in which Pd0 nanoparticles have been immobilized in self-assembled hyperbranched polyglycidole (SAHPG)-coated magnetic Fe3O4 nanoparticles (Fe3O4-SAHPG-Pd0). This catalyst has been used for effective ligandless Pd catalyzed Suzuki–Miyaura coupling reactions of different aryl halides with substituted boronic acids at room temperature and in aqueous media. Herein, SAHPG is used as support; it also acts as a reducing agent and stabilizer to promote the transformation of PdII to Pd0 nanoparticles. Also, this environmental friendly quasiheterogeneous catalyst is employed for the first time in the synthesis of new pyrimido[4,5-b]indoles via oxidative addition/C-H activation reactions on the pyrimidine rings, which were obtained with higher yield and faster than when Pd(OAc)2 was used as the catalyst. Interestingly, the above-mentioned catalyst could be recovered in a facile manner from the reaction mixture by applying an external magnet device and recycled several times with no significant decrease in the catalytic activity.
- Azizollahi, Hamid,Eshghi, Hossein,García-López, José-Antonio
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- Cu(OTf)2-Mediated Cross-Coupling of Nitriles and N-Heterocycles with Arylboronic Acids to Generate Nitrilium and Pyridinium Products**
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Metal-catalyzed C–N cross-coupling generally forms C?N bonds by reductive elimination from metal complexes bearing covalent C- and N-ligands. We have identified a Cu-mediated C–N cross-coupling that uses a dative N-ligand in the bond-forming event, which, in contrast to conventional methods, generates reactive cationic products. Mechanistic studies suggest the process operates via transmetalation of an aryl organoboron to a CuII complex bearing neutral N-ligands, such as nitriles or N-heterocycles. Subsequent generation of a putative CuIII complex enables the oxidative C–N coupling to take place, delivering nitrilium intermediates and pyridinium products. The reaction is general for a range of N(sp) and N(sp2) precursors and can be applied to drug synthesis and late-stage N-arylation, and the limitations in the methodology are mechanistically evidenced.
- Bell, Nicola L.,Xu, Chao,Fyfe, James W. B.,Vantourout, Julien C.,Brals, Jeremy,Chabbra, Sonia,Bode, Bela E.,Cordes, David B.,Slawin, Alexandra M. Z.,McGuire, Thomas M.,Watson, Allan J. B.
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supporting information
p. 7935 - 7940
(2021/03/03)
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- Nickel-catalyzed deallylation of aryl allyl ethers with hydrosilanes
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An efficient and mild catalytic deallylation method of aryl allyl ethers is developed, with commercially available Ni(COD)2 as catalyst precursor, simple substituted bipyridine as ligand and air-stable hydrosilanes. The process is compatible with a variety of functional groups and the desired phenol products can be obtained with excellent yields and selectivity. Besides, by detection or isolation of key intermediates, mechanism studies confirm that the deallylation undergoes η3-allylnickel intermediate pathway.
- Ding, Guangni,Fan, Sijie,Wang, Jingyang,Wang, Yu,Wu, Xiaoyu,Xie, Xiaomin,Yang, Liqun,Zhang, Zhaoguo
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supporting information
(2021/09/28)
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- A mild and practical method for deprotection of aryl methyl/benzyl/allyl ethers with HPPh2andtBuOK
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A general method for the demethylation, debenzylation, and deallylation of aryl ethers using HPPh2andtBuOK is reported. The reaction features mild and metal-free reaction conditions, broad substrate scope, good functional group compatibility, and high chemical selectivity towards aryl ethers over aliphatic structures. Notably, this approach is competent to selectively deprotect the allyl or benzyl group, making it a general and practical method in organic synthesis.
- Pan, Wenjing,Li, Chenchen,Zhu, Haoyin,Li, Fangfang,Li, Tao,Zhao, Wanxiang
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p. 7633 - 7640
(2021/09/22)
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- Nickel Hydride Catalyzed Cleavage of Allyl Ethers Induced by Isomerization
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This report discloses the deallylation of O - and N -allyl functional groups by using a combination of a Ni-H precatalyst and excess Bronsted acid. Key steps are the isomerization of the O - or N -allyl group through Ni-catalyzed double-bond migration followed by Bronsted acid induced O/N-C bond hydrolysis. A variety of functional groups are tolerated in this protocol, highlighting its synthetic value.
- Kathe, Prasad M.,Berkefeld, Andreas,Fleischer, Ivana
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supporting information
p. 1629 - 1632
(2021/02/09)
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- Ultrafine and Highly Dispersed Pd/SiO2 for Suzuki?Miyaura Cross-coupling Reactions
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Abstract: Construction of heterogeneous Pd/SiO2 catalyst via the pollution-free strategy marked strong electrostatic adsorption has been reported for the application to Suzuki–Miyaura cross-coupling reactions. The exposed negatively charged oxygen groups, which were converted from the hydroxyl groups on the surface of silica under the alkaline atmosphere, could effectively anchor palladium species to form ultrafine Pd nanoparticles (Pd NPs) with an average particle size of 1.3?nm and high dispersion (43%). Pd/SiO2 catalyst was endowed with the excellent catalytic performance which was that the yield of the Suzuki–Miyaura reaction between bromobenzene and phenylboronic acid at 40?°C was > 99% for 30?min and the TOF was ~ 80,000?h?1. The catalyst could be easily recovered and recycled by facile procedure without a significant decrease in catalytic activity, which was able to maintain the 90% yield after repeated for 8 times. In addition, a continuous flow reaction device was designed using the Pd/SiO2 catalyst to effectively improve the production efficiency of biphenyl. Graphic Abstract: Pd/SiO2 catalyst constructed with the strategy of strong electrostatic adsorption (SEA) possesses uniformly dispersed and highly exposed Pd sites which can be easily transformed into electron-deficient Pdδ+ and strengthened stability for itself due to its strong interaction with the front surface of the carrier, and has been endowed the outstanding catalytic performance for Suzuki?Miyaura cross-coupling reaction. [Figure not available: see fulltext.]
- Fan, Xizheng,Yang, Jingyi,Pang, Qingqing,Liu, Zhongyi,Zhang, Panke,Yang, Jing-He
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p. 2291 - 2301
(2021/01/04)
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- Anchoring of palladium onto the surface of porous MCM-41 modified with DL-pyroglutamic acid as a novel heterogeneous catalyst for Suzuki–Miyaura coupling reactions
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An environmentally friendly solid catalyst was synthesized by palladium (II) anchored to the silica MCM-41 after synthetic modification with DL-pyroglutamic acid (PCA). Palladium particles were immobilized on the surface of an acid-functionalized MCM-41 (MCM-41@PCA/Pd) and was identified using several analytical methods. In this method, the surface of MCM-41 was moderated by DL-pyroglutamic acid functional molecule, which assist the steady distribution of Pd particles. By electron donation from the acid molecule, the electron density of Pd particles increases. This extended catalyst displays excellent catalytic performance toward the Suzuki coupling reaction under mild reaction conditions with a large range of substrates for the reaction. The MCM-41@PCA/Pd catalyst offers eight reuse cycles without the loss of its activity. The immobilized complex did not leach or decompose through the catalytic reactions, indicating practical benefits over the homogeneous catalysis.
- Molaei, Somayeh,Ghadermazi, Mohammad
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- Magnetic covalently immobilized nickel complex: A new and efficient method for the Suzuki cross-coupling reaction
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In this study, an efficient procedure was reported to prepare Fe3O4@SiO2 magnetic nanoparticles (MNPs) with immobilized nickel NPs. In order to increase the activity of this catalyst, creatine as a ligand with high content of nitrogen atoms was linked onto the magnetic core–shell structure. Then, Ni(II) ions were coordinated on the surface of the silica-coated MNPs and reduced to Ni(0) NPs to obtain the final catalyst. The catalytic activity of the prepared catalyst was studied for the synthesis of biaryl derivatives via the Suzuki–Miyaura cross-coupling reaction in high yields. The catalyst could also be recovered and reused with no loss of activity over five successful runs.
- Keyhaniyan, Mahdi,Khojastehnezhad, Amir,Eshghi, Hossein,Shiri, Ali
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- Green and sustainable palladium nanomagnetic catalyst stabilized by glucosamine-functionalized Fe3O4@SiO2 nanoparticles for Suzuki and Heck reactions
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A novel magnetic and heterogeneous palladium-based catalyst stabilized by glucosamine-functionalized magnetic Fe3O4@SiO2 nanoparticle was synthesized. The strategy relies on the covalently bonding of glucosamine to cyanuric chloride-functionalized magnetic nanoparticles followed by complexation with palladium. The structure of magnetic nanocatalyst was fully determined by FT-IR, XRD, DLS, FE-SEM, TEM, ICP, UV-Vis, TGA, VSM, and EDX. The obtained results confirmed that the palladium nanoparticles stabilized by glucosamine immobilized onto the magnetic support exhibited high activity in cross-coupling reactions of Suzuki-Miyaura and Mizoroki-Heck. Various aryl halides were coupled with arylboronic acid (Suzuki cross-coupling reaction) and olefins (Heck reactions) under the green conditions to provide corresponding products in high to excellent yields. Interestingly, the catalyst can be easily isolated from the reaction media by magnetic decantation and can subsequently be applied for consecutive reaction cycles (at least seven times) with no notable reduction in the catalytic activity.
- Eslahi, Hassan,Sardarian, Ali Reza,Esmaeilpour, Mohsen
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- Hydrophilic role of deep eutectic solvents for clean synthesis of biphenyls over a magnetically separable Pd-catalyzed Suzuki-Miyaura coupling reaction
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The development of an efficient and sustainable catalytic system for the preparation of biphenyls through the Suzuki-Miyaura coupling reaction is still a great challenge to green chemistry. Encouraging the prevailing challenge, in the present work, a heterogeneous Pd catalyst was synthesized through a green method and used for the production of biphenyls in deep eutectic solvents (DESs) as green reaction media. In order to prepare the catalyst, magnetite-graphene oxide nanocomposite was modified with cellulose via the click reaction and applied as support for Pd nanoparticles. Cellulose acted as both reducing and stabilizing agent for Pd nanoparticles and eliminated the requirement of a reducing agent. The prepared catalyst was characterized by different methods such as FT-IR, EDX, EDX-mapping, XPS, SEM, TEM, XRD, VSM, and ICP-OES analyses. Catalytic properties of the obtained catalyst was explored in the coupling reaction of aryl halides with aryl boronic acids in different hydrophilic and hydrophobic DESs. The presence of cellulose with hydrophilic character on the structure of catalyst offered well dispersion of the catalyst in hydrophilic DESs, which led to enhancement of its catalytic activity. Among various hydrophilic DESs, the DES composed of dimethylammonium chloride and glycerol was verified as the most effective solvent for the preparation of biphenyls. The catalyst was compatible with a variety of substrates, with which all the Suzuki coupling products were achieved in high to excellent yields. Thanks to the low solubility of catalyst and DES in organic solvents, the separated aqueous phase containing both of the catalyst and DES could be readily recovered by evaporating water and reused up to five successive runs with a stable activity. This simple and new separation strategy provided a clean and highly efficient synthetic methodology for the synthesis of various biphenyls. Moreover, hot filtration test efficiently confirmed that the catalyst is heterogeneous and completely stable under reaction conditions.
- Karimi, Sabah,Masteri-Farahani, Majid,Niakan, Mahsa,Shekaari, Hemayat
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- Hexagonal Boron Nitride Supported N-Heterocyclic Carbene-Palladium(II): A New, Efficient and Recyclable Heterogeneous Catalyst for Suzuki–Miyaura Cross-Coupling Reaction
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Abstract: In this study, a new stable and powerful hexagonal boron nitride supported N-heterocyclic carbene-palladium(II) complex (h-BN@NHC-Pd) heterogeneous catalyst was designed and synthesized. The structure of the h-BN@NHC-Pd heterogeneous catalyst was characterized by various techniques such as Fourier transform infrared spectra (FT-IR), ultraviolet–visible spectroscopy (UV–Visible), inductively coupled plasma-optical emission spectroscopy (ICP-OES), energy-dispersive X-ray spectroscopy (EDS), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller surface area analysis (BET). Then catalytic activity of h-BN@NHC-Pd heterogeneous catalyst was studied in the Suzuki–Miyaura cross-coupling reactions between aryl halides and arylboronic acids in aqueous medium at room temperature. The effects of varying solvents, bases, temperature, time and catalytic ratios on the performance of the Suzuki–Miyaura cross-coupling reaction were investigated. Moreover, h-BN@NHC-Pd heterogeneous catalyst could be easily recovered through simple filtration or centrifugation method and could be reused five times without significant loss of its catalytic efficiency. Furthermore, stability of the h-BN@NHC-Pd heterogeneous catalyst after recycling was confirmed through FESEM and FT-IR techniques. The h-BN@NHC-Pd heterogeneous catalyst shows remarkable advantages such as simplicity of operation, excellent yields, short reaction times, heterogeneous nature, easily separable and high stability without leaching. Graphic Abstract: A new stable and powerful hexagonal boron nitride supported N-heterocyclic carbene-palladium(II) complex (h-BN@NHC-Pd) heterogeneous catalyst was designed, synthesized, characterized and catalytic activity was studied in the Suzuki–Miyaura cross-coupling reactions. [Figure not available: see fulltext.]
- Antony, Arnet Maria,Kandathil, Vishal,Kempasiddaiah, Manjunatha,Sasidhar,Patil, Shivaputra A.,Patil, Siddappa A.
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p. 1293 - 1308
(2020/10/06)
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- Green synthesis of Pd/Fe3O4 nanoparticles using Chamomile extract as highly active and recyclable catalyst for Suzuki coupling reaction
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In the present study, we demonstrate the synthesis of a novel biogenic nanocomposite by adorning in situ green synthesized Pd nanoparticles (Pd NPs) over the surface of magnetic nanoparticles by using Chamomileflower extract. It was physicochemically assigned by a number of analytical techniques. The as developed material was catalytically exploited in the synthesis of diverse biaryls via classical Suzuki-Miyaura coupling. Rigourness of the material was further validated by the study of reusability, hot-filtration and leaching test.
- Hamelian, Mona,Kamangar, Sheida Ahany,Karmakar, Bikash,Saremi, Shokoufeh Ghahri,Varmira, Kambiz,Veisi, Hojat,Zohrabi, Arezu
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- Photochemical (Hetero-)Arylation of Aryl Sulfonium Salts
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The construction of (hetero)biaryls, which are ubiquitous scaffolds among medical substances, functional materials, and agrochemicals, constitutes a key application of cross-coupling methods. However, these usually require multiple synthetic steps. Herein, we report a simple photoinduced and catalyst-free C-H/C-H (hetero)arylation cross-coupling through aryl thianthrenium salts, which are formed site-selectively by direct C-H functionalization. The key to this approach is the UV-light, which can disrupt the C-S bond to form thianthrene radical cations and aryl radicals.
- Zhao, Yue,Yu, Congjun,Liang, Wenjing,Patureau, Frederic W.
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p. 6232 - 6236
(2021/08/23)
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- Palladium supported on structurally stable phenanthroline-based polymer nanotubes as a high-performance catalyst for the aqueous Suzuki-Miyaura coupling reaction
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Though the Suzuki-Miyaura coupling reaction has intrinsic advantages in organic synthesis, it is still a challenging task to develop a highly active and truly heterogeneous catalyst for the aqueous Suzuki-Miyaura coupling reaction (SMR). In this work, a series of phenanthroline-based polymers (PBPs; PBP1 to PBP8) were synthesized by a simple one-step AlCl3-catalyzed Friedel-Crafts polymerization method. Systematic measurements of PBPs by N2adsorption-desorption isotherms, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) show that most of the PBPs have a nanosheet morphology, except PBP8 which has both one-dimensional nanotubular morphology and large surface area (745 m2g?1). Benefitting from the porous nanotube morphology and the two N atoms contained in the phenanthroline unit of the polymer structure, polymer PBP8 shows adsorption effects and strong chelating stabilization on the Pd active metal (size, 2-5 nm). The Pd/PBP8 catalyst exhibits superior catalytic activity within 2 h (TOF value: 3077 h?1) and reusability (7 cycles) in the SMR with typical reactants such as bromobenzene, phenylboronic acid and the base of K3PO4.3H2O at 30 °C in a solvent mixture of water and ethanol (VH2O?:?Vethanol= 3?:?2).
- Yang, Didi,Wang, Shuhui,Dan, Ting,Gao, Dashuang,Au, Chaktong,Zhang, Wanju,Zhang, Yan
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p. 12120 - 12128
(2021/07/19)
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- C(acyl)-C(sp2) and C(sp2)-C(sp2) Suzuki-Miyaura cross-coupling reactions using nitrile-functionalized NHC palladium complexes
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Application of N-heterocyclic carbene (NHC) palladium complexes has been successful for the modulation of C-C coupling reactions. For this purpose, a series of azolium salts (1a-f) including benzothiazolium, benzimidazolium, and imidazolium, bearing a CN-substituted benzyl moiety, and their (NHC)2PdBr2 (2a-c) and PEPPSI-type palladium (3b-f) complexes have been systematically prepared to catalyse acylative Suzuki-Miyaura coupling reaction of acyl chlorides with arylboronic acids to form benzophenone derivatives in the presence of potassium carbonate as a base and to catalyse the traditional Suzuki-Miyaura coupling reaction of bromobenzene with arylboronic acids to form biaryls. All the synthesized compounds were fully characterized by Fourier Transform Infrared (FTIR), and 1H and 13C NMR spectroscopies. X-ray diffraction studies on single crystals of 3c, 3e and 3f prove the square planar geometry. Scanning Electron Microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), metal mapping analyses and thermal gravimetric analysis (TGA) were performed to get further insights into the mechanism of the Suzuki-Miyaura cross coupling reactions. Mechanistic studies have revealed that the stability and coordination of the complexes by the CN group are achieved by the removal of pyridine from the complex in catalytic cycles. The presence of the CN group in the (NHC)Pd complexes significantly increased the catalytic activities for both reactions.
- ?akir, Sinem,Karabiyik, Hande,Kavukcu, Serdar Batikan,Rethinam, Senthil,Türkmen, Hayati
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p. 37684 - 37699
(2021/12/09)
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- Photohomolysis and Photoheterolysis in Aryl Sulfonates and Aryl Phosphates
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The photochemical behaviour of selected aryl sulfonates and phosphates (ArOX) in polar and nonpolar media has been investigated by laser flash photolysis (LFP) experiments. Two main pathways have been identified, namely the photohomolysis of the ArO?X bon
- Bonesi, Sergio,Protti, Stefano,Fagnoni, Maurizio
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p. 6315 - 6323
(2021/03/16)
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- Isotruxene-based porous polymers as efficient and recyclable photocatalysts for visible-light induced metal-free oxidative organic transformations
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Two new isotruxene-based porous polymers were prepared and demonstrated to be highly efficient, metal-free heterogeneous photocatalysts for oxidative transformations using air as the mild oxidant under visible-light irradiation. Both catalysts show excellent recyclability. In addition, the reactions can be performed in water, further indicating the greenness of this method. This journal is
- Zhang, Haowen,Zhang, Xiao,Zheng, Ying,Zhou, Cen
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supporting information
p. 8878 - 8885
(2021/11/27)
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- Blacklight-Induced Hydroxylation of Arylboronic Acids Leading to Hydroxyarenes Using Molecular Oxygen and Tetrabutylammonium Borohydride
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A new simple protocol for the conversion of arylboronic acids to hydroxyarenes was achieved using molecular oxygen in the presence of tetrabutylammonium borohydride under blacklight irradiation (360 nm). A radical chain mechanism in which a superoxide ion (O2?.) plays a key role is proposed.
- Kawamoto, Takuji,Ryu, Ilhyong
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- Double Insurance of Continuous Band Structure and N-C Layer Induced Prolonging of Carrier Lifetime to Enhance the Long-Wavelength Visible-Light Catalytic Activity of N-Doped In2O3
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Nonmetallic doped metal oxides can be broad in their visible-light-response range. However, the half-filled or isolated impurity state can also be the new recombination center for photogenerated electrons/holes, which seriously influence the photocatalytic activity of the catalyst in the visible-light region. Therefore, how to prolong the photogenerated carrier life of nonmetallic doping metal oxides is the difficult and challenging topic in the field of photocatalysis. In this work, the hexagonal nanosheets assembled by N-doped C (N-C)-coated N-doped In2O3 (N-In2O3) nanoparticles (N-C/N-In2O3 HS) was obtained by simply pyrolyzing the In(2,5-PDC) hexagonal sheets. The N-C/N-In2O3 HS catalyst exhibit good photocatalytic activity and cycle stability in the long-wavelength region of visible light (λ = 520 and 595 nm). The effective utilization of long-wavelength visible light for N-C/N-In2O3 HS was mainly attributed to the acceptor-donor-acceptor compensation mechanism between the oxygen vacancy (VO) and substitutional N-doping (Ns) sites, which made the N-C/N-In2O3 HS possess a continuous band structure, without the half-filled or isolated impurity state in the band gap, and extended its light absorption edge to 733 nm. The compensation mechanism of nitrogen doping on In2O3 can promote the photocatalytic activity under longer-wavelength yellow light (595 nm) irradiation. The N-C layer coated on the N-In2O3 nanoparticles acted as a good acceptor of photogenerated electrons, facilitating the effective spatial separation of photogenerated carriers and extend photogenerated carrier lifetimes. The comparative photocatalytic experiments (N-In2O3 HS and N-C/N-In2O3 HS) show that the presence of N-doped C layer can enhance the photocatalytic efficiency by nearly 10-fold. This double-doping and carbon-coating strategy provided a novel research idea to solve the problem that nonmetal atoms doped metal oxides led to the secondary combination of photogenerated electrons/holes.
- Sun, Liming,He, Xiaoxiao,Zeng, Suyuan,Yuan, Yusheng,Li, Rong,Zhan, Wenwen,Chen, Jinquan,Wang, Xiaojun,Han, Xiguang
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supporting information
p. 1160 - 1171
(2021/01/18)
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- A copper nitride catalyst for the efficient hydroxylation of aryl halides under ligand-free conditions
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Copper nitride (Cu3N) was used as a heterogeneous catalyst for the hydroxylation of aryl halides under ligand-free conditions. The cubic Cu3N nanoparticles showed high catalytic activity, comparable to those of conventional Cu catalysts with nitrogen ligands, demonstrating that the nitrogen atoms in Cu3N act as functional ligands that promote hydroxylation.
- Mitsudome, Takato,Mizugaki, Tomoo,Xu, Hang,Yamaguchi, Sho
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supporting information
p. 6593 - 6597
(2021/08/10)
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- Radical-anion coupling through reagent design: hydroxylation of aryl halides
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The design and development of an oxime-based hydroxylation reagent, which can chemoselectively convert aryl halides (X = F, Cl, Br, I) into phenols under operationally simple, transition-metal-free conditions is described. Key to the success of this approach was the identification of a reducing oxime anion which can interact and couple with open-shell aryl radicals. Experimental and computational studies support the proposed radical-nucleophilic substitution chain mechanism.
- Chechik, Victor,Greener, Andrew J.,James, Michael J.,Oca?a, Ivan,Owens-Ward, Will,Smith, George,Ubysz, Patrycja,Whitwood, Adrian C.
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p. 14641 - 14646
(2021/11/17)
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- Photocatalytic Reductive C-O Bond Cleavage of Alkyl Aryl Ethers by Using Carbazole Catalysts with Cesium Carbonate
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Methods to activate the relatively stable ether C-O bonds and convert them to other functional groups are desirable. One-electron reduction of ethers is a potentially promising route to cleave the C-O bond. However, owing to the highly negative redox potential of alkyl aryl ethers (Ered -2.6 V vs SCE), this mode of ether C-O bond activation is challenging. Herein, we report the visible-light-induced photocatalytic cleavage of the alkyl aryl ether C-O bond using a carbazole-based organic photocatalyst (PC). Both benzylic and non-benzylic aryl ethers underwent C-O bond cleavage to form the corresponding phenol products. Addition of Cs2CO3 was beneficial, especially in reactions using a N-H carbazole PC. The reaction was proposed to occur via single-electron transfer (SET) from the excited-state carbazole to the substrate ether. Interaction of the N-H carbazole PC with Cs2CO3 via hydrogen bonding exists, which enables a deprotonation-assisted electron-transfer mechanism to operate. In addition, the Lewis acidic Cs cation interacts with the substrate alkyl aryl ether to activate it as an electron acceptor. The high reducing ability of the carbazole combined with the beneficial effects of Cs2CO3 made this otherwise formidable SET event possible.
- Yabuta, Tatsushi,Hayashi, Masahiko,Matsubara, Ryosuke
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p. 2545 - 2555
(2021/02/01)
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- Selective C-O Bond Reduction and Borylation of Aryl Ethers Catalyzed by a Rhodium-Aluminum Heterobimetallic Complex
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We report the catalytic reduction of a C-O bond and the borylation by a rhodium complex bearing an X-Type PAlP pincer ligand. We have revealed the reaction mechanism based on the characterization of the reaction intermediate and deuterium-labeling experiments. Notably, this novel catalytic system shows steric-hindrance-dependent chemoselectivity that is distinct from conventional Ni-based catalysts and suggests a new strategy for selective C-O bond activation by heterobimetallic catalysis.
- Hara, Naofumi,Nakao, Yoshiaki,Saito, Teruhiko,Seki, Rin
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supporting information
p. 6388 - 6394
(2021/05/31)
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- Supported phosphine free bis-NHC palladium pincer complex: An efficient reusable nanocatalyst for Suzuki-Miyaura coupling reaction
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A periodic mesoporous organosilica material functionalized with a bis-NHC palladium pincer complex was synthesized by sol-gel process. The resulting organic-inorganic hybrid nano material was characterized by XRD, TEM, SEM, TGA analysis, and BET measurements. The hybrid nanomaterial act as highly active catalysts for the Suzuki–Miyaura cross-coupling between deactivated aryl chlorides and phenylboronic acid under heterogeneous and aerobic conditions. The supported catalyst exhibited excellent activity and stability and it could be reused at least ten times without any significant loss of activity. Furthermore, the SEM image revealed that high order mesostructure of the recycled nanocatalyst. After ninth run, catalyst showed almost similar structure as compared to the fresh catalyst. ICP-AES detected no Pd contamination in the products, and leaching tests verified that the reaction was truly heterogeneous.
- Burange, Anand S.,Luque, Rafael,Rajabi, Fatemeh,Voskressensky, Leonid G.
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- Pd salen complex@CPGO as a convenient, effective heterogeneous catalyst for Suzuki–Miyaura and Heck–Mizoroki cross-coupling reactions
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A Pd(II) Schiff base complex supported on graphene oxide nanosheets (Pd(II) salen@CPGO) has been synthesized and characterized by FT-IR, ICP-AES, XRD, SEM/EDX and TEM. The synthesized nanocatalyst has been found to be an efficient heterogeneous catalyst for Suzuki–Miyaura and Heck–Mizoroki coupling reactions. Pd(II) salen@CPGO could be separated and recovered easily from the reaction mixture and recycled several times without a discernible decrease in its catalytic activity. The construction of a solid sheet-supported Pd catalyst would be expected to be a promising system to perform heterogeneous catalytic reactions.
- Ghabdian, Mahdieh,Nasseri, Mohammad Ali,Allahresani, Ali,Motavallizadehkakhky, Alireza
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p. 1713 - 1728
(2018/05/25)
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- 2-Phosphinoimidazole Ligands: N-H NHC or P-N Coordination Complexes in Palladium-Catalyzed Suzuki-Miyaura Reactions of Aryl Chlorides
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We report the synthesis of two palladium 2-(dialkylphosphino)imidazole complexes and demonstrate their activity as catalysts for Suzuki-Miyaura reactions with (hetero)aryl chlorides at room temperature. Our mechanistic studies demonstrate that these palladium complexes exist as an equilibrium mixture between the P-N coordinated and N-H NHC forms of ligand. Our studies suggest that the N-H NHC form may be important for high catalytic activity in Suzuki-Miyaura reactions with aryl chlorides. These reactions proceed at or near room temperature in good to excellent yields. Heteroaryl chlorides are also reactive at lower catalyst loadings.
- Martinez, Erin E.,Larson, Alexandra J. S.,Fuller, Sydney K.,Petersen, Kathryn M.,Smith, Stacey J.,Michaelis, David J.
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supporting information
p. 1560 - 1564
(2021/05/29)
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- Crosslinked polymer encapsulated palladium nanoparticles for catalytic reduction and Suzuki reactions in aqueous medium
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Acrylamide and N-isopropylacrylamide were copolymerized in the presence of a N,N-methylenebisacrylamide crosslinker to obtain poly(N-isopropylacrylamide-co-acrylamide) [P(NA)] polymer colloidal particles. Pd nano crystals with diameter of 4–8 nm were loaded into the [P(NA)] microgels by reduction of [PdCl4]-2 within dispersion of polymer microgels. The Pd NPs-loaded hybrid microgels were analysed by TEM, STEM, EDX and XRD. The catalytic ability of the Pd-[P(NA)] system was investigated towards reductive transformation of nitroarenes into corresponding aryl amines and Suzuki coupling transformation in a green solvent, H2O. The progress of catalytic reaction was examined by thin layer chromatography (TLC). Different reactants were effectively converted into their corresponding products with great to fabulous yields (extending from 75 to 97%) under gentle reaction conditions. The Pd-[P(NA)] catalyst is stable for long time and can be utilized numerous times without any notable loss in its catalytic action.
- Begum, Robina,Farooqi, Zahoor H.,Xiao, Jianliang,Ahmed, Ejaz,Sharif, Ahsan,Irfan, Ahmad
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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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- A new palladium heterogeneous complex (Pd-Gu@BOEH): chemoselective, phosphine-free and practical nanocatalyst in carbon–carbon cross-coupling reaction
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Herein, boehmite nanoparticles were synthesized via combination of Al(NO3)3·9H2O and NaOH in aqueous solution. This nanomaterial converted to Pd-Gu@BOEH in several sequences. Pd-Gu@BOEH was used as efficient and recoverable nanocatalyst for the chemoselective C–C band formation such as Mizoroki–Heck and Suzuki–Miyaura reactions without any phosphine ligands or inert atmosphere. This catalyst has been characterized by several analyses such as EDS, WDX, SEM, XRD, FT-IR, TEM, TGA, AAS and BET. Also, obtained products from C–C coupling reactions were identified by NMR spectroscopy and their melting points. This catalyst was recycled in described reactions without palladium leaching. The reused catalyst was characterized by EDS, WDX, XRD, FT-IR and AAS analysis, which showed good stability during reaction process.
- Jafari, Fariba,Ghorbani-Choghamarani, Arash,Hasanzadeh, Neda
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p. 1033 - 1049
(2020/11/05)
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- A facile and versatile electro-reductive system for hydrodefunctionalization under ambient conditions
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A general electrochemical system for reductive hydrodefunctionalization is described, employing the inexpensive and easily available triethylamine (Et3N) as a sacrificial reductant. This protocol is characterized by facile operation, sustainable conditions, and exceptionally wide substrate scope covering the cleavage of C-halogen, N-S, N-C, O-S, O-C, C-C and C-N bonds. Notably, the selectivity and capability of reduction can be conveniently switched by simple incorporation or removal of an alcohol as a co-solvent.
- Huang, Binbin,Guo, Lin,Xia, Wujiong
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supporting information
p. 2095 - 2103
(2021/03/26)
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- Aryl phenol compound as well as synthesis method and application thereof
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The invention discloses a synthesis method of an aryl phenol compound shown as a formula (3). All systems are carried out in an air or nitrogen atmosphere, and visible light is utilized to excite a photosensitizer for catalyzation. In a reaction solvent, ArNR1R2 as shown in a formula (1) and water as shown in a formula (2) are used as reaction raw materials and react under the auxiliary action of acid to obtain the aryl phenol compound as shown in a formula (3). The ArNR1R2 in the formula (1) can be primary amine and tertiary amine, can also be steroid and amino acid derivatives, and can also be drugs or derivatives of propofol, paracetamol, ibuprofen, oxaprozin, indomethacin and the like. The synthesis method has the advantages of cheap and easily available raw materials, simple reaction operation, mild reaction conditions, high reaction yield and good compatibility of substrate functional groups. The fluid reaction not only can realize amplification of basic chemicals, but also can realize amplification of fine chemicals, such as synthesis of drugs propofol and paracetamol. The invention has wide application prospect and use value.
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Paragraph 0253-0255
(2021/05/12)
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- Effect of Alkyl Structures on the Anti-stacking and Anchoring of Pd/Diamine-Functionalized Graphene Nanoparticles in Application in Suzuki Reaction
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Three diamines (1,8-diaminooctane/p-phenylenediamine/biphenylenediamine) with different alkyl groups were used to synthesize the functionalized graphene networks. Pd as the common metal catalyst was used to explore the effects of alkyl types of diamines on anti-stacking, metal anchoring ability of functional graphene and hence the catalytic performance. The results were discussed by characterization of the material and its catalytic properties. All catalysts showed excellent catalytic performance on the Suzuki cross-coupling reaction with a high yield of up to 100%. The p-phenylenediamine and biphenylenediamine functionalized graphene with larger specific surface area was beneficial to improve the stability of the graphene catalyst and maintain good catalytic activity after 5 cycles. The Pd nanoparticles in 1,8-octanediamine materials have smaller size and a smaller loading with the same or even better catalytic performance than p-phenylenediamine, biphenylenediamine materials, due to the stronger electron donating ability of N of octanediamine than that of p-phenylenediamine.
- Tian, Yinbing,Tang, Zijie,Ru, Yu,Wang, Yuanyuan,Dai, Liyi
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p. 2745 - 2754
(2021/08/09)
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- Decarboxylative Hydroxylation of Benzoic Acids
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Herein, we report the first decarboxylative hydroxylation to synthesize phenols from benzoic acids at 35 °C via photoinduced ligand-to-metal charge transfer (LMCT)-enabled radical decarboxylative carbometalation. The aromatic decarboxylative hydroxylation is synthetically promising due to its mild conditions, broad substrate scope, and late-stage applications.
- Ritter, Tobias,Su, Wanqi,Xu, Peng
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supporting information
p. 24012 - 24017
(2021/10/06)
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- Substituent and Surfactant Effects on the Photochemical Reaction of Some Aryl Benzoates in Micellar Green Environment?
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In this study, we carried out preparative and mechanistic studies on the photochemical reaction of a series of p-substituted phenyl benzoates in confined and sustainable micellar environment. The aim of this work is mainly focused to show whether the nature of the surfactant (ionic or nonionic) leads to noticeable selectivity in the photoproduct formation and whether the electronic effects of the substituents affect the chemical yields and the rate of formation of the 5-substituted-2-hydroxybenzophenone derivatives. Application of the Hammett linear free energy relationship (LFER) on the rate of formation of benzophenone derivatives, on the lower energy band of the UV-visible absorption spectra of the aryl benzoates and 5-substituted-2-hydroxybenzophenone derivatives allows a satisfactory quantification of the substituent effects. Furthermore, UV-visible and 2D-NMR (NOESY) spectroscopies have been employed to measure the binding constant Kb and the location of the aryl benzoates within the hydrophobic core of the micelle. Finally, TD-DFT calculations have been carried out to estimate the energies of the absorption bands of p-substituted phenyl benzoates and 5-substituted-2-hydroxybenzophenone derivatives providing good linear correlation with those values measured experimentally.
- Siano, Gastón,Crespi, Stefano,Bonesi, Sergio M.
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p. 1298 - 1309
(2021/05/07)
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- Method for synthesizing heteroatom- substituted aromatic compound from styrene compound
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The invention discloses a method for synthesizing a heteroatom-substituted aromatic compound from a styrene compound, which comprises the following steps of: mixing a styrene compound with a general formula (I) and a heteroatom-containing compound with a general formula (II), and reacting in the presence of an acid additive and an organic solvent to obtain a heteroatom-substituted compound with ageneral formula (III). According to the synthesis method disclosed by the invention, a large amount of styrene compounds are used as raw materials and react to generate aromatic amine or phenol compounds under the action of no metal catalysis; and compared with the traditional aromatic amine and phenol synthesis method, the method has the advantages of high yield, simple conditions, low waste discharge amount, no metal participation, simple reaction equipment, easiness in industrial production and the like.
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Paragraph 0304-0307; 0310-0311; 0313; 0315-0317
(2021/02/06)
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- Copper-catalysed synthesis of α-alkylidene cyclic carbonates from propargylic alcohols and CO2
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We report a N-heterocyclic carbene copper(i) complex-catalysed formal cycloaddition between readily available propargylic alcohols and carbon dioxide at room temperature. By using the combination of a sterically demandingBPDPrCuCl complex (BPDPr = 1,3-bis(2,6-diisopropylphenyl)-1,3-diazonine-2-ylidene) and CsF, as catalytic system, primary propargylic alcohols are efficiently converted to the corresponding α-alkylidene cyclic carbonates. Gram scale (up to 89% yield) and reusability experiments (74% global yield, turnover number value = 103) showcase the robustness of the catalytic system. This practically simple protocol also tolerates secondary and tertiary propargylic alcohols under CO2at atmospheric pressure, enabling the direct synthesis of substituted and unsubstituted α-alkylidene cyclic carbonates at room temperature.
- Cervantes-Reyes, Alejandro,Farshadfar, Kaveh,Rudolph, Matthias,Rominger, Frank,Schaub, Thomas,Ariafard, Alireza,Hashmi
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supporting information
p. 889 - 897
(2021/02/09)
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- Catalytic SNAr Hydroxylation and Alkoxylation of Aryl Fluorides
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Nucleophilic aromatic substitution (SNAr) is a powerful strategy for incorporating a heteroatom into an aromatic ring by displacement of a leaving group with a nucleophile, but this method is limited to electron-deficient arenes. We have now established a reliable method for accessing phenols and phenyl alkyl ethers via catalytic SNAr reactions. The method is applicable to a broad array of electron-rich and neutral aryl fluorides, which are inert under classical SNAr conditions. Although the mechanism of SNAr reactions involving metal arene complexes is hypothesized to involve a stepwise pathway (addition followed by elimination), experimental data that support this hypothesis is still under exploration. Mechanistic studies and DFT calculations suggest either a stepwise or stepwise-like energy profile. Notably, we isolated a rhodium η5-cyclohexadienyl complex intermediate with an sp3-hybridized carbon bearing both a nucleophile and a leaving group.
- Kang, Qi-Kai,Li, Ke,Li, Yuntong,Lin, Yunzhi,Shi, Hang,Xu, Lun
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supporting information
p. 20391 - 20399
(2021/08/13)
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- Cobalt-catalyzed cross-coupling reactions of aryl- And alkylaluminum derivatives with (hetero)aryl and alkyl bromides
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A simple cobalt complex, such as Co(phen)Cl2, turned out to be a highly efficient and cheap precatalyst for a host of cross-coupling reactions involving aromatic and aliphatic organoaluminum reagents with aryl, heteroaryl and alkyl bromides. New C(sp2)-C(sp2) and C(sp2)-C(sp3) bonds were formed in good to excellent yields and with high chemoselectivity, under mild reaction conditions.
- Dilauro, Giuseppe,Messa, Francesco,Bona, Fabio,Perrone, Serena,Salomone, Antonio
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supporting information
p. 10564 - 10567
(2021/10/19)
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- Method for hydrolyzing diarylether compound to generate aryl phenol compound
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The invention discloses a method for hydrolyzing a diarylether compound to generate an arylphenol compound. According to the method, visible light is utilized to excite a photosensitizer for catalysis. In a reaction solvent, the raw material in the formula (1) breaks a C (sp2)-O bond under the auxiliary action of acid, and hydrolysis is performed to obtain the bimolecular aryl phenol compounds in the formula (3) and the formula (4). The method can catalyze the reaction at room temperature, is green and environment-friendly, and is easy to operate; the universality is wide, the reaction yield is relatively high, and the tolerance of functional groups is strong; the synthesis method not only can realize small-scale hydrolysis conversion of various diarylether compounds, but also can realize hydrolysis of herbicidal ether, triclosan and a lignin template substrate, and even can realize large-scale hydrolysis of triclosan and the lignin template substrate to realize gram-level degradation. A new strategy is provided for recovering phenol derivatives through lignin hydrolysis, degrading pesticides and purifying wastewater containing a degerming agent or herbicide. The method has wide application prospect and use value.
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Paragraph 0127-0130
(2021/09/29)
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- Site-Selective Acceptorless Dehydrogenation of Aliphatics Enabled by Organophotoredox/Cobalt Dual Catalysis
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The value of catalytic dehydrogenation of aliphatics (CDA) in organic synthesis has remained largely underexplored. Known homogeneous CDA systems often require the use of sacrificial hydrogen acceptors (or oxidants), precious metal catalysts, and harsh reaction conditions, thus limiting most existing methods to dehydrogenation of non- or low-functionalized alkanes. Here we describe a visible-light-driven, dual-catalyst system consisting of inexpensive organophotoredox and base-metal catalysts for room-temperature, acceptorless-CDA (Al-CDA). Initiated by photoexited 2-chloroanthraquinone, the process involves H atom transfer (HAT) of aliphatics to form alkyl radicals, which then react with cobaloxime to produce olefins and H2. This operationally simple method enables direct dehydrogenation of readily available chemical feedstocks to diversely functionalized olefins. For example, we demonstrate, for the first time, the oxidant-free desaturation of thioethers and amides to alkenyl sulfides and enamides, respectively. Moreover, the system's exceptional site selectivity and functional group tolerance are illustrated by late-stage dehydrogenation and synthesis of 14 biologically relevant molecules and pharmaceutical ingredients. Mechanistic studies have revealed a dual HAT process and provided insights into the origin of reactivity and site selectivity.
- Zhou, Min-Jie,Zhang, Lei,Liu, Guixia,Xu, Chen,Huang, Zheng
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supporting information
p. 16470 - 16485
(2021/10/20)
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- Synthesis and catalytic application of cyclopentadienyl nickel(II) N-heterocyclic carbene complexes
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A series of ester-functionalized benzimidazolium salts 2a–c were prepared by quaternization of 1-{(ethoxycarbonyl)methyl}benzimidazole (1) with 3,5-dimethylbenzyl bromide, 2,5-dimethylbenzyl chloride and 3-methoxybenzyl chloride, respectively. Refluxing 2a–c with nickelocene in THF yielded the neutral cyclopentadienyl NHC nickel(II) complexes 3a–c. Their structures were defined by NMR, IR and elemental analysis techniques. Molecular weights of 3a–c were affirmed by MALDI-TOF mass spectrometry. Catalytic tests of 3a–c were performed in Kumada coupling of some aryl chlorides with phenylmagnesium bromide at 25 °C.
- Demir Atli, Deniz
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p. 1530 - 1537
(2020/07/13)
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- Core-shell iron oxide@cathecol-polymer@palladium/copper nanocomposites as efficient and sustainable catalysts in cross-coupling reactions
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Magnetic core-shell Fe2O3@polymer-Pd/Cu nanocomposites (NCs) were developed as efficient and sustainable nanocatalysts for cross-coupling reactions. The designed NCs consisted of three components: i) a magnetic core (Fe2O3 nanoparticle), which allowed the recovery and reuse of the NCs, enhancing thus their attractiveness as green catalysts; ii) a catechol-based polymer coating, chosen because of its strong chelating ability towards metal ions, and its potential to be obtained from biomass (lignin depolymerization); and iii) catalytically active metal nanoparticles (Pd and Cu NPs) immobilized via in situ formation onto the polymeric shell. As-prepared Pd-based NCs successfully catalyzed Suzuki-Miyaura cross-coupling reactions, achieving yields between 87% and 97% in only 20–40 min depending on the aryl halides and boronic acid derivatives. Similarly, Cu-based NCs exhibited a quite good catalytic efficiency (> 80%) in the synthesis of propargylamines via A3 coupling reaction of phenylacetylene with various aldehydes and amines. Importantly, these NCs presented a good reusability, without significant decrease in efficiency after several cycles. However, the major advantage of the designed NCs is the lower Pd or Cu content (1.5 wt% and 2.6 wt%, respectively) as compared to most of the reported similar catalysts (between 3 – 6 wt% for Pd and > 5 wt% for Cu), which is a key challenge in view of developing cost-effective and environment-friendly catalysts while maintaining a high efficiency.
- Ostovar, Somayeh,Rezvani, Alireza,Luque, Rafael,Carrillo-Carrión, Carolina
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- NHC-Pd complex heterogenized on graphene oxide for cross-coupling reactions and supercapacitor applications
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N-heterocyclic carbene (NHC)-palladium(II) complex (GO@NHC-Pd) was synthesized on graphene oxide (GO) support via a simple and cost-effective multistep approach. The spectroscopic, microscopic, thermal, and surface analyses of GO@NHC-Pd confirmed the successful formation of the catalyst. The investigation of catalytic activity showed that GO@NHC-Pd was very effective in Suzuki–Miyaura as well as Hiyama cross-coupling. Being heterogeneous in nature, GO@NHC-Pd was recovered after each reaction cycle easily and reused for up to nine and six cycles in Suzuki–Miyaura and Hiyama cross-coupling, respectively, without significant loss of activity. Further exploration of the supercapacitor performance of GO@NHC-Pd catalyst assembled in a two-electrode cell configuration shown a maximum attained capacitance of 105.26 F/g at a current density of 0.1 A/g with good cycling stability of 96.89% over 2,500 cycles.
- Kandathil, Vishal,Siddiqa, Aisha,Patra, Abhinandan,Kulkarni, Bhakti,Kempasiddaiah, Manjunatha,Sasidhar,Patil, Shivaputra A.,Rout, Chandra Sekhar,Patil, Siddappa A.
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- L-lysine-Pd Complex Supported on Fe3O4 MNPs: a novel recoverable magnetic nanocatalyst for Suzuki C-C Cross-Coupling reaction
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In this work, L-lysine-Pd Complex, immobilized onto the surface of Fe3O4 MNPs, was successfully prepared via simple and inexpensive procedure. The prepared nanocatalyst was considered as a robust and clean nano-reactor catalyst for the Suzuki and Heck C-C Cross-Coupling reactions in water as the green condition. This eco-friendly heterogeneous catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), X-Ray Diffractometer (XRD), energy-dispersive X-ray spectroscopy (EDS), inductively coupled plasma atomic emission spectroscopy (ICP), X-ray mapping, BET, thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) techniques. The use of a green medium, easy separation and workup, excellent reusability of the nanocatalyst and short reaction time are some outstanding advantages of this method.
- Ashraf, Muhammad Aqeel,Liu, Zhenling,Zhang, Dangquan,Alimoradi, Ashkan
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- Palladium-decorated o-phenylenediamine-functionalized Fe3O4/SiO2 magnetic nanoparticles: A promising solid-state catalytic system used for Suzuki–Miyaura coupling reactions
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Palladium-supported o-phenylenediamine-functionalized Fe3O4 magnetic nanoparticles are presented. A convenient synthetic route for the nanocatalyst and also its application in Suzuki–Miyaura coupling of various aryl halides with phenylboronic acids are described. A high reaction yield (98%) was been obtained in a short reaction time (10 min) through use of this highly efficient nanocatalyst. From a mechanistic aspect, firstly, effective electronic interactions between heteroatoms such as oxygen and Pd(II) provide a suitable condition for covalent bonding by the ingredients in the Suzuki–Miyaura coupling reaction. Secondly, Pd(II) is converted to Pd(0) by use of sodium borohydride in the presence of triphenylphosphine in basic conditions, and then it plays a main role in the catalytic process. However, the most distinguished properties of this catalytic system are the ease of catalyst separation and great reusability. The palladium-supported o-phenylenediamine-functionalized Fe3O4 nanoparticles can be easily recovered by use of an external magnet and can reused at least ten times with no significant decline in catalytic activity. This novel system was structurally characterized by various analytical methods, and the results obtained are well interpreted in the context.
- Maleki, Ali,Taheri-Ledari, Reza,Ghalavand, Reza,Firouzi-Haji, Razieh
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