- Polymetallic carbosilane dendrimers containing N, N'-iminopyridine chelating ligands: Applications in catalysis
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This overview covers the most relevant results obtained by our group in the last few years concerning the synthesis and catalytic applications of metal complexes anchored to the surface of carbosilane dendrimers functionalized with iminopyridine ligands.
- Martinez-Olid, Francisco,Benito, Jose,Flores, Juan,De Jesus, Ernesto
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- [Bis(pyrazolyl)methane]palladium complexes with a carbosilane dendritic structure
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A series of carbosilane dendritic ligands of general formula Gn-[CH(GiS-Me2PZ)2]m and their corresponding palladium(II) complexes Gn-[CH(3,5-Me2pz)2Pd(X)C1]m (X = Cl or Me) containing four (m = 1) or eight (m = 2) terminal bis(pyrazo-lyl)methane moieties, along with their corresponding mono-metallic counterparts (m = 0), have been synthesized. An appropriate choice of poly(pyrazolyl)methane ligand has allowed us to overcome the steric and solubility issues that previously limited the synthesis of polymetallic dendrimers containing (scorpionato) palladium complexes. The evaluation of these complexes as catalyst precursors in the Heck reaction between p-iodotoluene and methyl acrylate is also reported
- Sanchez-Mendez, Alberto,De Jesus, Ernesto,Flores, Juan C.,Gomez-Sal, Pilar
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- Synthesis, structure, and reactivity of palladacycles that contain a chiral rhenium fragment in the backbone: New cyclometalation and catalyst design strategies
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The bromocyclopentadienyl complex f(η5-C5H 4Br)Re(CO)3] is converted to racemic [(η5- C5H4Br)Re-(NO)(PPh3)(CH2PPh 2)] (1b) similarly to a publish
- Friedlein, Florian K.,Kromm, Kiemenz,Hampel, Frank,Gladysz
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- Phosphine-Functionalized Chitosan Microparticles as Support Materials for Palladium Nanoparticles in Heck Reactions
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Herein, we investigated the activation and stabilization of Pd nanoparticles using microparticles of chitosan-functionalized with phosphine moieties. The catalytic activity of the prepared material was assessed in a series of Heck reactions, which demonst
- Biajoli, André F. P.,Fajardo, André R.,Lemos, Thalia S. A.,de Souza, Jaqueline F.
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- Pd-Catalyzed desulfitative arylation of olefins by: N -methoxysulfonamide
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A novel Pd-catalyzed protocol for the desulfitative Heck-type reaction of N-methoxy aryl sulfonamides with alkenes was reported. The cross-coupling reaction was performed successfully with a variety of olefins to obtain aryl alkenes. Different substituents on the aromatic ring of N-methoxysulfonamides were also found to be compatible with the reaction conditions. Expectedly, the reaction proceeds through CuCl2-promoted generation of the nitrogen radical and subsequent desulfonylation under thermal conditions to afford the aryl radical for the Pd-catalyzed coupling reaction. N-Methoxysulfonamide was further exploited for the synthesis of symmetrical biaryls in the presence of CuCl2. This journal is
- Ojha, Subhadra,Panda, Niranjan
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p. 1292 - 1298
(2022/02/19)
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- Palladium and silk fibroin-containing magnetic nano-biocomposite: a highly efficient heterogeneous nanocatalyst in Heck coupling reactions
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Supported metal catalysts, for instance, palladium, are one of the foundations of chemical reactions, especially in C–C bond formation. The present study reports preparation of a magnetically separable palladium-supported nano-biocomposite with a low cost and easy immobilization technique. Fibroin, a natural biodegradable polymer, was used through an in situ method to cover the Fe3O4 nanoparticles to make a nano-biocomposite followed by anchoring palladium on the fibroin surface. The morphology and the structure of palladium-supported nano-biocomposite Fe3O4@fibroin-Pd were characterized by FT-IR, XRD, TGA, SEM, EDX, and TEM techniques. Consequently, the nanocatalyst activity was evaluated in the Heck coupling reactions. Only a very small amount of the nanocatalyst was employed in the reaction, and it showed excellent catalytic activity; in most cases more than 90% efficiency. The significant advantages of employing this nanocatalyst include high catalytic activity, short reaction times, easy separation of the nanocatalyst with an external magnet and great reusability. The results demonstrated that the used nanocatalysts were very active for four consecutive reaction rounds.
- Nouri Parouch, Ahmad,Koukabi, Nadiya,Abdous, Elham,Shobeiri, Seyed Amin
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p. 3165 - 3177
(2021/05/21)
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- Triazine-hyperbranched polymer-modified magnetic nanoparticles-supported nano-cobalt for C–C cross-coupling reactions
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Design of hyperbranched polymers (HBPs) and crafting them in catalytic systems especially in organic chemistry are a relatively unexplored domain. This paper reports the utilization of triazine-hyperbranched polymer (THBP)-coated magnetic chitosan nanoparticles (MCs) as stabilizing matrix for cobalt nanoparticles. Cobalt nanoparticles were fabricated by coordination cobalt(II) ions with amine-terminated triazine polymer and then reduced into Co(0) using sodium borohydride in aqueous medium. The Co(0)-THBP@MCs were fully characterized by FT-IR, SEM–EDX, TEM, and TGA analyses. The presence of metallic cobalt was determined by ICP and XRD techniques. This novel hyperbranched polyaromatic polymer-encapsulated cobalt nanoparticles showed high catalytic activity in Mizoroki–Heck and Suzuki–Miyaura cross-coupling reactions. Heck and Suzuki reactions were carried out using 0.35 and 0.4?mol% of cobalt nanoparticles in which the turnover number (TON) values were calculated as 271 and 225, respectively. In addition, the produced heterogeneous catalyst could be recovered and reused without considerable loss of activity. Oxygen stability and high reusability over 7 runs with trace leaching of the cobalt into the reaction media as well as moisture stability of the immobilized cobalt nanoparticles are their considerable worthwhile advantages.
- Hajipour, Abdol R.,Sadeghi, Shaghayegh
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p. 3219 - 3233
(2021/08/06)
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- Valorisation of urban waste to access low-cost heterogeneous palladium catalysts for cross-coupling reactions in biomass-derived γ-valerolactone
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Herein we report a simple protocol for the valorisation of a common urban biowaste. The lignocellulosic biomass obtained after the pre-treatment of pine needle urban waste is efficiently transformed into a low-cost support (PiNe) for the immobilization of Pd nanoparticles. The final Pd/PiNe heterogeneous catalyst features a small particle size (4.5 nm) and a metal loading (9.9 wt%) comparable with most commercially available and generally used counterparts. In this contribution, we tested the catalytic efficiency of the Pd/PiNe system in two representative cross-couplings, Heck and Hiyama reactions, and compared the results obtained with commercial Pd/C catalyst. The good reactivity in the biomass-derived solvent (GVL) confirms that the Pd/PiNe heterogeneous catalyst is a valid system that can be integrated into a waste valorization chain within a circular economy approach. In addition, the efficiency of the catalyst has also been extended to perform the challenging consecutive Hiyama-Heck reaction to afford differently substituted (E)-1,2-diarylethenes.
- Valentini, Federica,Ferlin, Francesco,Lilli, Simone,Marrocchi, Assunta,Ping, Liu,Gu, Yanlong,Vaccaro, Luigi
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p. 5887 - 5895
(2021/08/23)
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- Coordination from Heteroscorpionate Ligand Towards Pd(II) via Pd???Hδ?C(sp3) Interaction: Structural and Catalytic Studies
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The coordination ability of the heteroscorpionate ligand 2,2-bis(3,5-dimethylpyrazol-1-yl)-1-p-tolylethanol (1) towards palladium (II) dihalides was evaluated. The structures of the respective palladium complexes (2 and 3) were elucidated in solution by NMR spectroscopy, and their molecular structures were established by single crystal X-ray diffraction analyses. Both studies revealed the existence of Pd???Hδ?C(sp3) anagostic interactions. The molecular structure of complexes 2 and 3 displays coordination of ligand 1 to palladium in a κ3-NNH tridentate fashion via two nitrogen atoms and one δ-anagostic H???Pd interaction. The metal center exhibits a square pyramidal geometry. The distances of anagostic Hδ???Pd interactions ranged from 2.566 to 2.576 ?. The δ-anagostic H???Pd interactions in complexes 2 and 3 were also identified by Bader's quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) analysis. The catalytic efficiencies of complexes 2 and 3 in the Suzuki-Miyaura cross-coupling reactions were evaluated and the results showed that palladium (II) dibromide complex is the most efficient of the series. Complex 3 was also evaluated in Mizoroki-Heck cross-coupling reactions.
- Castillo-Moreno, Miguel ángel,Cruz-Borbolla, Julián,González-Montiel, Simplicio,Ignacio Sandoval-Chávez, César,Manuel Vásquez-Pérez, José,Mendoza-Espinosa, Daniel,Salazar-Pereda, Verónica
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p. 2661 - 2668
(2021/07/06)
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- A Practice of Reticular Chemistry: Construction of a Robust Mesoporous Palladium Metal-Organic Framework via Metal Metathesis
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Constructing stable palladium(II)-based metal-organic frameworks (MOFs) would unlock more opportunities for MOF chemistry, particularly toward applications in catalysis. However, their availability is limited by synthetic challenges due to the inertness of the Pd-ligand coordination bond, as well as the strong tendency of the Pd(II) source to be reduced under typical solvothermal conditions. Under the guidance of reticular chemistry, herein, we present the first example of an azolate Pd-MOF, BUT-33(Pd), obtained via a deuterated solvent-assisted metal metathesis. BUT-33(Pd) retains the underlying sodalite network and mesoporosity of the template BUT-33(Ni) and shows excellent chemical stability (resistance to an 8 M NaOH aqueous solution). With rich Pd(II) sites in the atomically precise distribution, it also demonstrates good performances as a heterogeneous Pd(II) catalyst in a wide application scope, including Suzuki/Heck coupling reactions and photocatalytic CO2 reduction to CH4. This work highlights a feasible approach to reticularly construct noble metal based MOFs via metal metathesis, in which various merits, including high chemical stability, large pores, and tunable functions, have been integrated for addressing challenging tasks.
- He, Tao,Kong, Xiang-Jing,Li, Jian-Rong,Lv, Xiu-Liang,Nie, Zuo-Ren,Si, Guang-Rui,Wang, Kecheng,Wu, Xue-Qian,Zhao, Chen,Zhou, Jian
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p. 9901 - 9911
(2021/07/21)
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- Oxoammonium-Mediated Allylsilane–Ether Coupling Reaction
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A new C(sp3)?H functionalization reaction consisting of the oxidative α-allylation of allyl- and benzyl- methyl ethers has been developed. The C?C coupling could be carried out under mild conditions thanks to the use of cheap and green oxoammonium salts. The scope of the reaction was studied over 27 examples, considering the nature of the substituents on the two coupling partners.
- Carlet, Federica,Bertarini, Greta,Broggini, Gianluigi,Pradal, Alexandre,Poli, Giovanni
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p. 2162 - 2168
(2021/04/02)
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- Mizoroki-Heck Reaction of Unstrained Aryl Ketones via Ligand-Promoted C-C Bond Olefination
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Mizoroki-Heck reaction of unstrained aryl ketone with acrylate/styrene is accomplished via palladium-catalyzed ligand-promoted C-C bond cleavage. Various (hetero)aryl ketones are compatible in the reaction, affording the alkene product in good to excellent yields. Further applications in the late-stage olefination of some drugs, natural products, and fragrance-derived aryl ketones demonstrate the synthetic utility of this protocol. By employing ketone as both the directing group and the leaving group, 1,2-bifunctionalization is achieved via sequential ortho-C-H alkylation/ipso-Heck olefination.
- Wang, Mei-Ling,Xu, Hui,Li, Han-Yuan,Ma, Biao,Wang, Zhen-Yu,Wang, Xing,Dai, Hui-Xiong
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p. 2147 - 2152
(2021/04/05)
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- Visible-Light Induced C(sp2)?H Amidation with an Aryl–Alkyl σ-Bond Relocation via Redox-Neutral Radical–Polar Crossover
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We report an approach for the intramolecular C(sp2)?H amidation of N-acyloxyamides under photoredox conditions to produce δ-benzolactams with an aryl-alkyl σ-bond relocation. Computational studies on the designed reductive single electron transfer strategy led us to identify N-[3,5-bis(trifluoromethyl)benzoyl] group as the most effective amidyl radical precursor. Upon the formation of an azaspirocyclic radical intermediate by the selective ipso-addition with outcompeting an ortho-attack, radical–polar crossover was then rationalized to lead to the rearomative ring-expansion with preferential C?C bond migration.
- Chang, Sukbok,Jeong, Jiwoo,Jung, Hoimin,Keum, Hyeyun,Kim, Dongwook
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p. 25235 - 25240
(2021/10/25)
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- Synthesis and characterization of mesoporous organosilica supported palladium (SBA-Pr-NCQ-Pd) as an efficient nanocatalyst in the Mizoroki–Heck coupling reaction
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In the present study, the modification of a mesoporous organosilica nanocomposite SBA-15 (Santa Barbara Amorphous 15) was carried out in two steps, first through the surface functionalization of SBA-Pr-NH2 with 2-chloroquinoline-3-carbaldehyde to form SBA-Pr-NCQ, and then through a post-modification process with palladium ions. The target nanocompound structure of SBA-Pr-NCQ-Pd was characterized by different techniques (thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, Energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy). The catalytic performance of the porous inorganic–organic hybrid nanocomposite (SBA-Pr-NCQ-Pd) in one of the most important carbon–carbon bond-forming processes, the Mizoroki–Heck coupling reaction of aryl halides and methacrylate in water/ethanol media, was examined. Compared to previous reports, this protocol afforded some advantages, such as high yields of products, short reaction times, catalyst stability without leaching, simple methodology, easy workup, and greener conditions. Also, the nanocatalyst can be easily separated from the reaction mixture and reused several times without a significant decrease in activity and promises economic as well as environmental benefits.
- Moradi, Razieh,Mohammadi Ziarani, Ghodsi,Badiei, Alireza,Mohajer, Fatemeh
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- Highly effective cellulose supported 2-aminopyridine palladium complex (Pd(II)-AMP-Cell?Al2O3) for Suzuki-Miyaura and Mizoroki–Heck cross-coupling
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In the present work, a novel, highly efficient, retrievable organo–inorganic hybrid heterogeneous catalyst (Pd(II)-AMP-Cell?Al2O3) has been prepared by covalent grafting of 2-aminopyridine on chloropropyl modified cellulose-alumina composite followed by complexation with palladium acetate. The catalyst was characterized by techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), inductive coupled plasma-atomic emission spectroscopy (ICP-AES) and thermo gravimetric analysis (TGA). The catalyst has been successfully employed in Suzuki-Miyaura as well as Mizoroki–Heck cross-coupling reactions. The reactions proceed smoothly resulting in the high yields of cross-coupling products (81 to 95%) within short reaction times. The catalyst can be efficiently recovered by simple filtration and reused for multiple cycles without considerable loss in the catalytic activity. The key-features of the present protocol include mild reaction conditions, simple work-up procedure, high stability of the catalyst, high turnover number (TON) and frequency (TOF), ease recovery and reusability of the catalyst.
- Mhaldar, Pradeep,Pore, Dattaprasad,Rashinkar, Gajanan,Vibhute, Sandip
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- Biogenic synthesis of palladium nanoparticles using Boswellia sarrata and their applications in cross-coupling reactions
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A facile and green route for biogenic synthesis of palladium nanoparticles (PdNPs) using aqueous extract of nontoxic and renewable Boswellia sarrata leaves is reported. The as-synthesized PdNPs were systematically characterized by using ultraviolet (UV)–visible spectroscopy, X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The PdNPs were crystalline and cubic in nature with average particle size of ~6 nm and successfully employed as heterogeneous catalyst in the Suzuki–Miyaura and Mizoroki–Heck cross-coupling reactions. The PdNPs could be recycled up to five times with modest change in the catalytic activity.
- Arde, Satyanarayan M.,Rashinkar, Gajanan S.,Jadhav, Sanjay N.,Patil, Audumbar D.,Salunkhe, Rajashri S.
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- Synthesis and characterization of a new bis-NHC palladium complex and its catalytic activity in the Mizoroki–Heck reaction
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A new bis-N-heterocyclic carbene palladium complex, (C13H9N2F2)2PdCl2, is synthesized by a three-step reaction and characterized by 1H NMR and 13C NMR spectroscopy as well as by X-ray crystallography. This new bis-N-heterocyclic carbene palladium complex has excellent stability and is capable of efficiently catalyzing the Mizoroki–Heck coupling reaction of aryl halides with acrylates.
- Cui, Jin,Feng, Can,Liu, Cheng-Xin,Wang, Yu-Fang,Zhang, Ming-Jie
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p. 684 - 688
(2020/05/22)
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- C–C Cross-Coupling Reactions of Organosilanes with Terminal Alkenes and Allylic Acetates Using PdII Catalyst Supported on Starch Coated Magnetic Nanoparticles
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Starch coated magnetic nanoparticles supported palladium catalyst has been explored to perform C–C cross coupling reactions, such as oxidative Heck coupling and Tsuji–Trost allylic coupling using organosilicon compounds as one of the coupling partners. The biopolymer coated magnetic catalyst was very easy to recover magnetically and was efficiently recycled in the subsequent batches. All the reactions were performed in air and thus the necessity of air and moisture free reaction condition is avoided. The present protocols show wide substrate scope and good yields of the products.
- Patra, Debabrata,Panja, Subir,Saha, Amit
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p. 878 - 883
(2020/02/13)
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- Palladium-Based Catalysts Supported by Unsymmetrical XYC–1 Type Pincer Ligands: C5 Arylation of Imidazoles and Synthesis of Octinoxate Utilizing the Mizoroki–Heck Reaction
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A series of new unsymmetrical (XYC–1 type) palladacycles (C1–C4) were designed and synthesized with simple anchoring ligands L1–4H (L1H = 2-((2-(4-methoxybenzylidene)-1-phenylhydrazinyl)methyl)pyridine, L2H = N,N-dimethyl-4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazono)methyl)aniline, L3H = N,N-diethyl-4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazono)methyl) aniline and L4H = 4-(4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazono) methyl)phenyl)morpholine H = dissociable proton). Molecular structure of catalysts (C1–C4) were further established by single X-ray crystallographic studies. The catalytic performance of palladacycles (C1–C4) was explored with the direct Csp2–H arylation of imidazoles with aryl halide derivatives. These palladacycles were also applied for investigating of Mizoroki–Heck reactions with aryl halides and acrylate derivatives. During catalytic cycle in situ generated Pd(0) nanoparticles were characterized by XPS, SEM and TEM analysis and possible reaction pathways were proposed. The catalyst was employed as a pre-catalyst for the gram-scale synthesis of octinoxate, which is utilized as a UV-B sunscreen agent.
- Maji, Ankur,Singh, Ovender,Singh, Sain,Mohanty, Aurobinda,Maji, Pradip K.,Ghosh, Kaushik
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p. 1596 - 1611
(2020/04/29)
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- A photocatalytic ensemble HP-T?Au-Fe3O4: Synergistic and balanced operation in Kumada and Heck coupling reactions
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A supramolecular catalytic ensemble HP-T?Au-Fe3O4 supported by highly branched assemblies of hexaphenylbenzene (HPB) derivatives has been developed. The as-prepared HP-T?Au-Fe3O4 nanohybrid material serves as an efficient catalytic system to prepare biaryl derivatives through the Kumada cross-coupling reaction using aryl chlorides as one of the coupling partners under mild reaction conditions (visible light irradiation, aqueous media, aerial conditions, short reaction time). Through the cooperative effect of Au NPs and Fe3O4 NPs, dual activation of aryl chlorides for the generation of aryl radical intermediates is achieved. On the other hand, oligomeric assemblies contributed significantly to the enhancement of the reaction rate and yield of the product by facilitating the reductive elimination step. Different mechanistic studies confirm the involvement of Au NPs, Fe3O4 NPs and oligomeric assemblies in the synergistic and balanced operation of HP-T?Au-Fe3O4 nanohybrid materials in the efficient completion of the catalytic cycle of the Kumada coupling reaction. Being magnetic, the catalytic ensemble could be recycled for up to five catalytic cycles. The as-prepared supramolecular photocatalytic ensemble also works efficiently in Heck coupling reactions involving aryl chlorides and aryl iodides as the coupling partner.
- Bhalla, Vandana,Kaur, Harpreet,Kumar, Manoj
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supporting information
p. 8036 - 8045
(2020/11/30)
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- Amidoxime modified PAN supported palladium complex: A greener and efficient heterogeneous catalyst for heck reaction
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Development of a facile and greener approach for Heck reaction using a modified PAN supported palladium catalyst is described. The preparation of the catalyst involves a simple process through amidoxime modification of nitrile group in Polyacrylonitrile (PAN), followed by the complexation with Palladium chloride (PdCl2). The resulting supported catalyst was characterized by spectroscopic analyses and further by computational studies. This polymer supported Palladium complex displayed excellent catalytic activity in Heck coupling reaction of a series of activated alkenes and aryl halides and afforded the corresponding coupling products upto 96% isolated yield. After the reaction, the catalyst was easily recovered by simple filtration and recycled with excellent stability and activity even after 5 runs. This is the first report on the use of amidoxime functionalized PAN- Palladium (II) complex as a heterogeneous catalyst in Heck coupling reaction.
- Sruthi, Pambingal Rajan,Sarika, Vijayalekshmi,Suku, Arya,Krishnan, Aravind,Anas, Saithalavi
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- Extended architectures constructed of thiourea-modified SBA-15 nanoreactor: A versatile new support for the fabrication of palladium pre-catalyst
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We designed and synthesized a novel catalyst consisting of ordered mesoporous silica (SBA-15) functionalized with bis(thiourea) (BTU) linker. The regular and unique pore channels of BTU-SBA-15 ensure proper control of the size and homogeneous distribution of palladium nanoparticles. The physiochemical properties of the hybrid Pd?BTU-SBA-15 pre-catalyst were investigated using various techniques. The proposed catalyst is found to be very active, reusable, stable and scalable, and has excellent reactivity and selectivity for Suzuki and Heck coupling reactions under very mild and sustainable reaction conditions.
- Alamgholiloo, Hassan,Noroozi Pesyan, Nader,Rostamnia, Sadegh
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- Highly Regio- A nd Enantioselective Hydrogenation of Conjugated α-Substituted Dienoic Acids
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Highly regio- A nd enantioselective hydrogenation of conjugated α-substituted dienoic acids was realized for the first time using Trifer-Rh complex, providing a straightforward method for the synthesis of chiral α-substituted ?,?′-unsaturated acids. DFT calculations revealed N+H-O hydrogen bonding interaction is formed to stabilize the transition state and the coordination of 4,5-double bond to Rh(III) center would facilitate the reductive elimination process. This hydrogenation provided a gram-scale synthesis of the precursor of sacubitril.
- Liu, Xian,Liu, Song,Wang, Quanjun,Zhou, Gang,Yao, Lin,Ouyang, Qin,Jiang, Ru,Lan, Yu,Chen, Weiping
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supporting information
p. 3149 - 3154
(2020/04/09)
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- Palladium Ion Catalysed Oxidative C–C Bond Formation Reactions in Arylboronic Acid: Application of Cordierite Monolith Coated Catalyst
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Abstract: Catalytic efficiency of palladium ion substituted in TiO2, Ti0.97Pd0.03O1.97 is successfully exploited for the oxidative homocoupling of arylboronic acid and oxidative Heck coupling reactions between arylboronic acid and olefins. The reaction protocol provides direct approach to synthesize biphenyls and cinnamates from moderate to good yield with good functional group tolerance. As a result, 11 symmetrical biaryls and 14 cinnamates were synthesized from readily available arylboronic acids. Ti0.97Pd0.03O1.97 powder catalyst is synthesized by solution combustion method and characterized by powder X-ray diffraction. The C–C bond formation reactions were carried out by catalyst cartridge method using Ti0.97Pd0.03O1.97 catalyst coated cordierite monolith. Coating of the catalyst on a cordierite monolith enhanced the applicability of the catalyst and made handling and recycling of the catalyst very easy. Catalyst was recovered and recycled for eight times in both homocoupling and oxidative Heck coupling reactions. The turnover number for both the reactions found to be 443 and 424, respectively. Graphic Abstract: [Figure not available: see fulltext.].
- Bhat, Shrikanth K.,Prasanna,Dasappa, Jagadeesh Prasad,Hegde
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p. 2911 - 2927
(2020/03/31)
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- Sodium pyruvate as a peroxide scavenger in aerobic oxidation under carbene catalysis
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NHC-Catalyzed aerobic oxidative reactions of imines and aldehydes have been developed by using sodium pyruvate as a novel and efficient peroxide scavenger. A structurally diverse set of imidates and amidines has been prepared from imines using this strategy. This general and efficient strategy features the use of sodium pyruvate as a novel and efficient peroxide scavenger and ambient air as the sole oxidant to efficiently control the NHC-catalyzed aerobic reaction pathway (selective realization of the oxidative pathway) under mild and green conditions. This journal is
- Fu, Zhenqian,Hong, Xianfang,Huang, Wei,Wang, Guanjie,Wei, Chenlong
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supporting information
p. 6819 - 6826
(2020/11/09)
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- Novel and efficient polymer supported copper catalyst for heck reaction
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A novel polymer supported copper complex (m-PAN-Cu) is prepared by immobilizing Cuprous Iodide (CuI) on amidoxime modified Polyacrylonitrile (mPAN) and characterised by FTIR, XRD, EDX, ICP-MS and XPS analyses. This complex was further explored as a general and efficient heterogeneous catalyst for Heck coupling reaction of a series of aryl halides with olefins and afforded the corresponding coupling products in moderate to good yields. This catalyst offers easy preparation, good stability, excellent catalytic activity and reusability. This is the first study involving an amidoxime modified PAN supported copper catalyst towards greener and efficient Heck reaction.
- Anas, Saithalavi,Anjali, Suresh,Sruthi, Pambingal Rajan,Varghese, Nicy
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- Pd nanoparticles supported on reduced graphene oxide as an effective and reusable heterogeneous catalyst for the Mizoroki–Heck coupling reaction
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A general method for the synthesis of palladium nanoparticles loaded on reduced graphene oxide functionalized with diethylenetriamine (PdNPs/rGO-NH2) using a sonochemical procedure is described. The heterogeneous nanocomposite was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray, thermogravimetric analysis, high-angle annular dark field scanning transmission electron microscopy, X-ray photoelectron spectroscopy, UV–visible absorption, and inductively coupled plasma optical emission spectrometry. The PdNPs/rGO-NH2 was very effective for the Mizoroki–Heck coupling reaction of several aryl iodide compounds with different alkenes in the presence of triethylamine. The reaction provides the coupling products in good to excellent yields (59–100%). Additionally, the PdNPs/rGO-NH2 catalyst can be reutilized for six successive runs without any apparent diminution of its catalytic reactivity.
- Mirza-Aghayan, Maryam,Mohammadi, Marzieh,Addad, Ahmed,Boukherroub, Rabah
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- 4-Aryl Pyrrolidines as a Novel Class of Orally Efficacious Antimalarial Agents. Part 1: Evaluation of 4-Aryl- N-benzylpyrrolidine-3-carboxamides
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Identification of novel chemotypes with antimalarial efficacy is imperative to combat the rise of Plasmodium species resistant to current antimalarial drugs. We have used a hybrid target-phenotype approach to identify and evaluate novel chemotypes for malaria. In our search for drug-like aspartic protease inhibitors in publicly available phenotypic antimalarial databases, we identified GNF-Pf-4691, a 4-aryl-N-benzylpyrrolidine-3-carboxamide, as having a structure reminiscent of known inhibitors of aspartic proteases. Extensive profiling of the two terminal aryl rings revealed a structure-activity relationship in which relatively few substituents are tolerated at the benzylic position, but the 3-aryl position tolerates a range of hydrophobic groups and some heterocycles. Out of this effort, we identified (+)-54b (CWHM-1008) as a lead compound. 54b has EC50 values of 46 and 21 nM against drug-sensitive Plasmodium falciparum 3D7 and drug-resistant Dd2 strains, respectively. Furthermore, 54b has a long half-life in mice (4.4 h) and is orally efficacious in a mouse model of malaria (qd; ED99 ~ 30 mg/kg/day). Thus, the 4-aryl-N-benzylpyrrolidine-3-carboxamide chemotype is a promising novel chemotype for malaria drug discovery.
- Meyers, Marvin J.,Liu, Jianguang,Xu, Jing,Leng, Fang,Guan, Jiantong,Liu, Zhijun,McNitt, Sarah A.,Qin, Limei,Dai, Linglin,Ma, Hongwei,Adah, Dickson,Zhao, Siting,Li, Xiaofen,Polino, Alex J.,Nasamu, Armiyaw S.,Goldberg, Daniel E.,Liu, Xiaorong,Lu, Yongzhi,Tu, Zhengchao,Chen, Xiaoping,Tortorella, Micky D.
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supporting information
p. 3503 - 3512
(2019/03/29)
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- In situ synthesis of carbon nanotube-encapsulated cobalt nanoparticles by a novel and simple chemical treatment process: Efficient and green catalysts for the Heck reaction
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In this study, we present a novel, fast and easy method for supporting metal nanoparticles onto the internal surface of multi-walled CNTs; these CNT-encapsulated nanoparticles as heterogeneous, efficient, inexpensive and green catalysts promote the Heck cross-coupling of a large library of functional substrates under mild and sustainable conditions. Remarkably, the introduced catalytic system could be reused for at least nine successive runs without a discernible decrease in its catalytic activity.
- Hajipour, Abdol R.,Khorsandi, Zahra,Farrokhpour, Hossein
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supporting information
p. 8215 - 8219
(2019/06/07)
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- Threonine stabilizer-controlled well-dispersed small palladium nanoparticles on modified magnetic nanocatalyst for Heck cross-coupling process in water
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We report the synthesis of magnetically separable Fe3O4@Silica-Threonine-Pd0 magnetic nanoparticles with a core–shell structure. After synthesis of Fe3O4@Silica, threonine as an efficient stabilizer/ligand was bonded to the surface of Fe3O4@Silica. Then, palladium nanoparticles were generated on the threonine-modified catalyst. The threonine stabilizer helps to generate palladium nanoparticles of small size (less than 4?nm) with high dispersity and uniformity. Magnetically separable Fe3O4@Silica-Threonine-Pd0 nanocatalyst was fully characterized using various techniques. This nanocatalyst efficiently catalysed the Heck cross-coupling reaction of a variety of substrates in water medium as a green, safe and inexpensive solvent at 80°C. The Fe3O4@Silica-Threonine-Pd0 catalyst was used for at least eight successful consecutive runs with palladium leaching of only 0.05%.
- Sarvi, Iraj,Gholizadeh, Mostafa,Izadyar, Mohammad
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- Cobalt supported on dendronized magnetic nanoparticles: A new highly efficient and recyclable catalyst for the Mizoroki–Heck cross-coupling reaction
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Polyamidoamine (PAMAM) is one of the most interesting types of hyperbranched polymers that carry a large number of amino groups on its surface. PAMAM has gained significant attention from synthetic organic chemists due to its structural characteristics, controllable structure, inner porosity, and ability to trap a wide range of ions and molecules. So, in this work, the PAMAM dendrimer was synthesized, grafted onto the surface of magnetite nanoparticles, and the resulting hybrid nanoparticles were then employed as suitable host for immobilizing cobalt nanoparticles. The newly developed catalyst was well characterized by Fourier transform-infrared, X-ray diffraction, thermogravimetric analysis, field emission-scanning electron microscopy, transmission electron microscopy, atomic absorption spectroscopy, element mapping and energy-dispersive X-ray analysis. The efficiency of the as-prepared nanocatalyst was evaluated for the Mizoroki–Heck cross-coupling reactions. The MNP@PAMAM-Co represented perfect catalytic efficiency and high selectivity for the Mizoroki–Heck cross-coupling reaction compared with previously reported catalysts. The catalyst separation from the reaction mixture was easily achieved with the assistance of an external magnetic field, and its recycling was also investigated for five consecutive runs. Hot filtration confirmed no leaching of the active metal during the Heck coupling.
- Arghan, Maryam,Koukabi, Nadiya,Kolvari, Eskandar
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- Ionic Pd/NHC Catalytic System Enables Recoverable Homogeneous Catalysis: Mechanistic Study and Application in the Mizoroki–Heck Reaction
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N-Heterocyclic carbene (NHC) ligands are ubiquitously utilized in catalysis. A common catalyst design model assumes strong M–NHC binding in this metal–ligand framework. In contrast to this common assumption, we demonstrate here that lability and controlled cleavage of the M?NHC bond (rather than its stabilization) could be more important for high-performance catalysis at low catalyst concentrations. The present study reveals a dynamic stabilization mechanism with labile metal–NHC binding and [PdX3]?[NHC-R]+ ion pair formation. Access to reactive anionic palladium intermediates formed by dissociation of the NHC ligands and plausible stabilization of the molecular catalyst in solution by interaction with the [NHC-R]+ azolium ion is of particular importance for an efficient and recyclable catalyst. These ionic Pd/NHC complexes allowed for the first time the recycling of the complex in a well-defined form with isolation at each cycle. Computational investigation of the reaction mechanism confirms a facile formation of NHC-free anionic Pd in polar media through either Ph–NHC coupling or reversible H–NHC coupling. The present study formulates novel ideas for M/NHC catalyst design.
- Eremin, Dmitry B.,Denisova, Ekaterina A.,Yu. Kostyukovich, Alexander,Martens, Jonathan,Berden, Giel,Oomens, Jos,Khrustalev, Victor N.,Chernyshev, Victor M.,Ananikov, Valentine P.
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supporting information
(2019/11/14)
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- β-Carboline and N-hydroxycinnamamide hybrids as anticancer agents for drug-resistant hepatocellular carcinoma
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In an effort to develop anticancer agents that may overcome drug resistance, the number one reason in caner death, we have developed a series of novel hybrids of β-carboline and N-hydroxycinnamamide as histone deacetylase (HDAC) inhibitors. Most of the hybrids 13a-p showed strong antiproliferative effects with low-micromolar IC50 values against four human cancer cells. The most potent compound of series 13p exhibited high HDAC1/6 inhibitory effects, and also increased the acetylation levels of histone H3, H4 and α-tubulin. Importantly, 13p demonstrated high anticancer potency against drug-sensitive HepG2 and Bel7402 cells and drug-resistant Bel7402/5FU cells. Hybrid 13p triggered significant apoptosis by regulating apoptotic relative proteins expression in these Bel7402/5FU cells. Finally, 13p induced a substantial amount of autophagic flux activity by the accretion of the expression of LC3-II and the degeneration of expression of p62 and LC3-I in Bel7402/5FU cells. Overall, 13p is a novel β-carboline/N-hydroxycinnamamide hybrid with significant anticancer potency that warrants further evaluation for the treatment of drug-resistant hepatocellular carcinoma.
- Ling, Yong,Gao, Wei-Jie,Ling, Changchun,Liu, Ji,Meng, Chi,Qian, Jianqiang,Liu, Siqun,Gan, Huiling,Wu, Hongmei,Tao, Jinhua,Dai, Hong,Zhang, Yanan
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p. 515 - 526
(2019/03/08)
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- PdII/Novel Chiral Cinchona Alkaloid Oxazoline-Catalyzed Enantioselective Oxidative Cyclization of Aromatic Alkenyl Amides
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A highly enantioselective PdII-catalyzed aza-Wacker oxidation tandem cyclization of aromatic nitrogen-containing dienes has been achieved in the presence of novel chiral cinchona alkaloid oxazoline ligands for the first time, affording chiral dihydroindole nitrogen-containing polycyclic compounds with good yields (up to 83 %), high diastereoselectivities (> 95:5 dr), and excellent enantioselectivities (up to 97 % ee).
- Tian, Qinqin,Liu, Yulong,Wang, Xiaoyun,Wang, Xie,He, Wei
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supporting information
p. 3850 - 3855
(2019/06/08)
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- Utilization of Synthetic Calcium-Phyllosilicates as Bifunctional Bases in the Matsuda-Heck Reaction
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Calcium-phyllosilicates can successfully be used as novel bases in the Matsuda-Heck reaction using methanol as solvent. The new experimental set-up distinguishes itself by higher reactivity and better selectivity compared to other systems.
- Brunner, Heiko,Vedder, Lennart
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p. 698 - 702
(2019/01/04)
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- Mizoroki–Heck cross-coupling reactions using palladium immobilized on DABCO-functionalized silica
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A heterogeneous palladium catalyst supported on silica modified by DABCO has been prepared by post-synthetic modification of silica gel. This heterogeneous catalytic system exhibits high activity and stability in the Mizoroki–Heck cross-coupling reaction of various aryl halides with olefins. The reaction proceeds efficiently under efficiently under mild mild reaction conditions and high yield, with the formation of E-isomers selectively. Moreover, we successfully established a gram-scale synthesis, and the catalyst was reused for up to ten catalytic cycles.
- Jadhav, Sanjay,Patil, Seema,Kumbhar, Arjun,Kamble, Santosh,Salunkhe, Rajashri
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p. 507 - 514
(2019/04/25)
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- Synthesis and Catalytic Applications of [N,N]-Pyrrole Ligands for the Regioselective Synthesis of Styrene Derivatives
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We report the synthesis of two [N,N]-donor ligands (5 a–b) containing a 2-chalcogenazoline as the structural motif. These compounds were synthesized from a common intermediate Fischer type aminocarbene complex (3). The palladium-complexes of these [N,N]-donor ligands were successfully used as catalytic precursors in the Mizoroki-Heck coupling reaction between aryl halides and methyl acrylate, styrene and ethylene. For methyl acrylates, high yields with TOF values between 0.6 and 5.5×105 h?1 were obtained. In the case of ethylene, we reached high regioselectivities to obtain a diversity of styrene derivatives under soft pressure conditions, with good values of TON and TOF. (Figure presented.).
- Hochberger-Roa, Frank,Cortés-Mendoza, Salvador,Gallardo-Rosas, David,Toscano, Ruben A.,Ortega-Alfaro, M. Carmen,López-Cortés, José G.
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supporting information
p. 4055 - 4064
(2019/07/31)
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- Pd–Schiff base complex supported on Fe3O4 magnetic nanoparticles: A new and highly efficient reusable catalyst for C–C bond formation in water
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A protocol is introduced for the preparation of a new cage-like Pd–Schiff base organometallic complex supported on Fe3O4 nanoparticles (Fe3O4@Schiff-base-Pd). The structure of the nanomagnetic catalyst was comprehensively characterized using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller measurements, scanning electron microscopy (SEM), transmission electron microscopy, X-ray mapping, thermogravimetric analysis, vibrating sample magnetometry and inductively coupled plasma atomic emission spectroscopy. In the second stage, the catalytic activity of this catalyst was studied in the Suzuki and Heck cross-coupling reactions in water as a green solvent. In this sense, simple preparation of the catalyst from commercially available materials, high catalytic activity, simple operation, short reaction times, high yields and use of green solvent are some advantages of this protocol. Finally, the nanocatalyst was easily recovered, using an external magnet, and reused several times without significant loss of its catalytic efficiency. In addition, the stability of the catalyst after recycling was confirmed using SEM, XRD and FT-IR techniques.
- Lei, Lei
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- PdII Immobilized on Ferromagnetic Multi-Walled Carbon Nanotubes Functionalized by Aminated 2-Chloroethylphosphonic Acid with S -Methylisothiourea (FMMWCNTs@CPA@SMTU@PdII NPs) Applied as a Highly Efficient and Recyclable Nanostructured Catalyst for Suzuki-Miyaura and Mizoroki-Heck Cross-Coupling Reactions in Solvent-Free Conditions
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The new ferromagnetic nanostructured FMMWCNTs@CPA@SMTU@PdII NPs (IV) as an eco-friendly heterogeneous nanocatalyst with a particle size of ~20-30 nm reported earlier by our group has been found to be very effective for Suzuki-Miyaura and Mizoroki-Heck cross-coupling reactions at ambient temperature. The procedure has been applied for a wide range of aryl halides, arylboronic acids, and alkenes. The magnetic separation by an external magnetic field, mild reaction conditions, and catalyst reusability up to four times without significant decrease in catalytic activity (reduced catalytic activity from 11 to 18 % in the fifth, sixth, and seventh cycles) made the present method sustainable and economically viable for C-C cross-coupling reactions.
- Ghasemzadeh, Maryam Sadat,Akhlaghinia, Batool
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p. 674 - 692
(2019/07/12)
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- A tailored polymeric cationic tag-anionic Pd(ii) complex as a catalyst for the low-leaching Heck-Mizoroki coupling in flow and in biomass-derived GVL
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The [PdCl4]2- palladium complex has been immobilized on a polystyrene-type resin loaded with pincer-type imidazolium ionic tag binding sites. The catalytic system (Pd(ii)-POLI-TAG) has proved to be highly active in the definition of an efficient protocol for the Heck-Mizoroki coupling reaction under batch and flow conditions. Importantly, it is shown to be highly robust in combination with a safe non-toxic reaction medium, i.e. biomass-derived GVL, since it could be reused for multiple runs without significantly losing its activity.
- Mahmoudi, Hamed,Valentini, Federica,Ferlin, Francesco,Bivona, Lucia Anna,Anastasiou, Ioannis,Fusaro, Luca,Aprile, Carmela,Marrocchi, Assunta,Vaccaro, Luigi
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supporting information
p. 355 - 360
(2019/01/28)
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- Facile synthesis of a recyclable Pd-rGO/CNT/CaFe2O4 nanocomposite with high multifunctional photocatalytic activity under visible light irradiation
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We report a facile method to synthesize a magnetically separable Pd-rGO/CNT/CaFe2O4 photocatalyst. The incorporation of CNTs into rGO can form a conductive network structure to bridge the gaps between rGO sheets. This conductive netw
- Bagherzadeh, Mojtaba,Kaveh, Reyhaneh,Mahmoudi, Hamed
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p. 16257 - 16266
(2019/07/16)
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- A Bipyridine-Palladium Derivative as General Pre-Catalyst for Cross-Coupling Reactions in Deep Eutectic Solvents
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A versatile and DES-compatible bipyridine palladium complex has been developed as a general pre-catalyst for different cross-coupling reactions (Hiyama, Suzuki-Miyaura, Heck-Mizoroki and Sonogashira) in deep eutectic solvents. Hydrogen bond capacity of the ligand allows to keep the excellent level of results previously obtained in classical organic solvents. Palladium pre-catalyst showed a high catalytic activity for many cross-coupling reactions, demonstrating a great versatility and applicability. Also, this methodology employs sustainable solvents as a reaction medium and highlights the potential of DES as alternative solvents in organometallic catalysis. The catalyst and DES were easily and successfully recycled. The formation of PdNPs in DES has been confirmed by TEM and XPS analysis and their role as catalyst by mercury test. The dynamic coordination of bipyridine-type ligand in the palladium complex formation has been studied via UV/Vis. (Figure presented.).
- Saavedra, Beatriz,González-Gallardo, Nerea,Meli, Alessandro,Ramón, Diego J.
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supporting information
p. 3868 - 3879
(2019/07/12)
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- Templating effect of carbon nanoforms on highly cross-linked imidazolium network: Catalytic activity of the resulting hybrids with Pd nanoparticles
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Two different carbon nanoforms (CNFs), namely multi-walled carbon nanotubes (MWCNTs) and carbon nanohorns (CNHs), have been chosen as support for the direct polymerization of a bis-vinylimidazolium salt. Transmission electron microscopy analyses revealed a templating effect of the CNFs on the growth of the polymeric network, which perfectly covers their whole surfaces creating a cylindrical or spherical coating for MWCNTs and CNHs, respectively. Subsequently, the CNFs-polyimidazolium have been used as stabilizers for Pd nanoparticles (Pd NPs), and the obtained materials have been characterized by means of analytical and spectroscopic techniques and then employed as easily recoverable and recyclable catalysts for Suzuki and Heck reactions. Quantitative conversions have been obtained in almost all the explored reactions, even employing low loading of catalyst (down to 0.007 mol%). Suzuki reactions were carried out in pure water under aerobic conditions. Both materials showed excellent activity and recyclability for the investigated C-C coupling reactions, with the CNHs-based material resulting slightly more active than the MWCNTs-based one due to a higher superficial exposure of Pd NPs.
- Campisciano, Vincenzo,Calabrese, Carla,Liotta, Leonarda Francesca,La Parola, Valeria,Spinella, Alberto,Aprile, Carmela,Gruttadauria, Michelangelo,Giacalone, Francesco
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- SBA-15/POSS-Imidazolium Hybrid as Catalytic Nanoreactor: the role of the Support in the Stabilization of Palladium Species for C?C Cross Coupling Reactions.
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Supported imidazolium modified polyhedral oligomeric silsesquioxanes (POSS) on SBA-15 have been used as platform for Pd(II) species. The so-obtained material was firstly characterized by means of TGA, solid state NMR, TEM, XPS, SAXS, porosimetry and ICP-OES and it was successfully tested as pre-catalyst in C?C cross couplings, namely Suzuki-Miyaura and Heck reactions. In both cases, the solid proved to be highly efficient and easily recoverable from the reaction mixture. The recyclability was verified for up to seven cycles without showing any activity decrease. Interestingly, only Pd(II) was detected in the reused catalyst in the Heck reaction. Therefore, the versatility of the material was investigated by using various aryl halides. Our palladium nanocomposite was able to promote both Suzuki and Heck reactions down to 0.0007 mol% showing outstanding turnover frequency (TOF) values of 114,286 and 32,381 h?1, respectively. Comparison with the palladium catalyst on SiO2-POSS-imidazolium support showed interesting differences in terms of stabilization of Pd species and recyclability. The excellent outcome of the reactions could be ascribed to the textural properties of the SBA-15 support and the presence of the imidazolium-POSS nanocage within the pores of SBA-15, that worked as a sort of nanoreactor. (Figure presented.).
- Calabrese, Carla,Campisciano, Vincenzo,Siragusa, Fabiana,Liotta, Leonarda F.,Aprile, Carmela,Gruttadauria, Michelangelo,Giacalone, Francesco
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p. 3758 - 3767
(2019/05/15)
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- Evaluating aryl esters as bench-stable C(1)-ammonium enolate precursors in catalytic, enantioselective Michael addition-lactonisations
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An evaluation of a range of aryl, alkyl and vinyl esters as prospective C(1)-ammonium enolate precursors in enantioselective Michael addition-lactonisation processes with (E)-trifluoromethylenones using isothiourea catalysis is reported. Electron deficient aryl esters are required for reactivity, with 2,4,6-trichlorophenyl esters providing optimal product yields. Catalyst screening showed that tetramisole was the most effective isothiourea catalyst, giving the desired dihydropyranone product in excellent yield and stereoselectivity (up to 90 : 10 dr and 98 : 2 er). The scope and limitations of this process have been evaluated, with a range of diester products being generated after ring-opening with MeOH to give stereodefined dihydropyranones with excellent stereocontrol (10 examples, typically ~90 : 10 dr and >95 : 5 er).
- Young, Claire M.,Taylor, James E.,Smith, Andrew D.
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supporting information
p. 4747 - 4752
(2019/05/24)
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- Enantioselective Copper-Catalyzed 1,5-Cyanotrifluoromethylation of Vinylcyclopropanes
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A copper-catalyzed enantioselective 1,5-cyanotrifluoromethylation of vinylcyclopropanes has been developed using a radical relay strategy. This asymmetric reaction has demonstrated high enantioselective control, broad substrate scope, and mild conditions. Initiated by the in situ generated CF3 radical from Togni's reagent, this method offers a new solution for remote enantioselective bifunctionalization of alkenes and thus provides a straightforward way for the synthesis of chiral CF3-containing internal alkenylnitriles.
- Zhang, Zi-Qi,Meng, Xiang-Yu,Sheng, Jie,Lan, Quan,Wang, Xi-Sheng
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supporting information
p. 8256 - 8260
(2019/10/16)
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- METHOD FOR THE SYNTHESIS AND PURIFICATION OF ARYL ACID ESTERS
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The general inventive concepts are directed to the discovery that certain aryl acids can be esterified under particular conditions to provide the resulting ester as a solid that precipitates in good yield from the reaction mixture. The esters may then be isolated and purified with relative ease. Accordingly, a method for the esterification, isolation, and purification of aryl acids is provided.
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Paragraph 0029-0030
(2019/10/17)
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- Synthesis and discovery of 18β-glycyrrhetinic acid derivatives inhibiting cancer stem cell properties in ovarian cancer cells
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Despite advances in ovarian cancer treatment, the five-year overall survival rate is less than 30% with the presence of cancer stem cells (CSCs). To develop CSC-targeting therapy, a series of 18β-glycyrrhetinic acid (GA) derivatives containing cinnamamide moiety have been designed, synthesized, and screened for their antiproliferative activity in SKOV3 and OVCAR3 cells. Most of the compounds exhibited stronger antiproliferative activity than GA, and compound 7c was the most active one. Further biological studies showed that compound 7c could induce apoptosis and suppress migration. In addition, compound 7c could not only observably decrease the colony formation and sphere formation ability, but also significantly reduce the CD44+, CD133+, and ALDH+ subpopulation in SKOV3 and OVCAR3 cells. In conclusion, these results indicate that compound 7c is a promising anti-CSC agent for further anti-ovarian cancer studies.
- Li, Xiaojing,Liu, Yihua,Wang, Na,Liu, Yuyu,Wang, Shuai,Wang, Hongmin,Li, Aihua,Ren, Shaoda
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p. 27294 - 27304
(2019/09/12)
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- Bis-quinoline-2-carboxylic acid Copper Salt as an Efficient Catalyst for Synthesis of Aryl Olefins by Heck Reaction
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Abstract: A bis-quinoline-2-carboxylic acid copper salt as a single crystal was prepared and characterized by X-ray single crystal analysis. The crystal as a catalyst was applied to the Mizoroki–Heck coupling reaction between arylboronic acids and α-olefins. A series of diarylethenes and aryl olefins were synthesized with good to excellent yields at room temperature. The catalytic system exhibited good functional group tolerance and low pollution. Graphic Abstract: A bis-quinoline-2-carboxylic acid copper salt as a single crystal was prepared and characterized by X-ray single crystal analysis. The crystal as a catalyst was applied to the Mizoroki–Heck coupling reaction between arylboronic acids and α-olefins[InlineMediaObject not available: see fulltext.].
- Zuo, Minghui,Li, Zhuofei,Fu, Wanyong,Guo, Rui,Hou, Chuanfu,Guo, Weihao,Sun, Zhizhong,Chu, Wenyi
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p. 3217 - 3223
(2019/07/17)
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- Pd-Colloids-Catalyzed/Ag2O-Oxidized General and Selective Esterification of Benzylic Alcohols
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Palladium colloids obtained from the degradation of Hermann–Beller palladacycle proved to be an efficient catalytic system in combination with silver oxide as a selective oxidant for the oxidative esterification of differently substituted benzyl alcohols in MeOH as solvent. Excellent reactivity exhibited by the catalytic system also allowed the alcoholic coupling partner to be changed from MeOH to a wide range of alcohols having diverse functionalities. The mildness of the developed protocol also made it possible to employ propargyl alcohol as the coupling partner without any observation of any interference of the terminal alkyne. Selective oxidative coupling of a primary alcoholic functional group over secondary in the case of glycols and glycerols was also made possible using the developed catalyst system. To test the relevancy of Pd/Ag combined catalysis mixed Pd/Ag colloids were synthesized, characterized by TEM, XRD and XPS and applied to oxidative-esterification successfully.
- Sable, Vaibhav,Shah, Jagrut,Sharma, Anuja,Kapdi, Anant R.
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supporting information
p. 2639 - 2647
(2019/07/08)
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- Carbonyl-Olefin Metathesis Catalyzed by Molecular Iodine
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The carbonyl-olefin metathesis reaction could facilitate rapid functional group interconversion and allow construction of complicated organic structures. Herein, we demonstrate that elemental iodine, a very simple catalyst, can efficiently promote this chemical transformation under mild reaction conditions. Our mechanistic studies revealed intriguing aspects of the activation mode via molecular iodine and the iodonium ion that could change the previously established perception of catalyst and substrate design for the carbonyl-olefin metathesis reaction.
- Tran, Uyen P. N.,Oss, Giulia,Breugst, Martin,Detmar, Eric,Pace, Domenic P.,Liyanto, Kevin,Nguyen, Thanh V.
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p. 912 - 919
(2019/01/14)
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- Homoleptic cis- and trans-palladium(II) bis(guanidinato) complexes derived from N-aryl-N′,N″-di(pyridin-2-yl)- and N-aryl-N′,N″-bis(6-methylpyridin-2-yl)guanidines: Catalysts for Heck-Mizoroki coupling reactions
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N-Aryl-N′,N″-di(pyridin-2-yl)- and N-aryl-N′,N″-bis(6-methylpyridin-2-yl)guanidines (1–4 and 5–7) were isolated in 75%–81% yields. Reactions of Pd(OAc)2 with guanidines 2–7 carried out separately in toluene at 60 °C for 3 h afforded 8–13 respectively in 69%–80% yields. Compounds 1–13 were characterized by elemental analyses, HR-MS, IR and NMR (1H and 13C) spectroscopy. Molecular structures of guanidines 1, 4, 5 and 6 and those of 8–13 were determined by single crystal X-ray diffraction. The Pd(II) atom in 8–10 revealed trans geometry while that in 11–13 revealed cis geometry. DFT calculations were carried out on model compounds 9a (trans) and its hypothetical cis isomer, 9b and 12a (cis) and its hypothetical trans isomer 12b which indicated a very small energy difference between the 9a/9b pair (1.28 kcal/mol) whereas a large energy difference was observed between the 12a/12b pair (26.38 kcal/mol) in CH2Cl2. The catalytic utility of 9 in Heck-Mizoroki coupling reactions involving styrene and methyl acrylate and aryl bromides/aryl chlorides in the presence of NaOAc and excess of tetrabutylammonium bromide (TBAB) at 120 °C was explored. Both activated and de-activated aryl bromides and aryl chlorides were coupled with styrene and in addition, the aryl chlorides were coupled with methyl acrylate in the presence of 9 to afford the respective coupling products in 68% ? >99% yields. Neat reaction carried out with 9 and TBAB under the optimized condition released the colloidal Pd black as verified by EDAX, PXRD and SEM techniques thereby implying the heterogeneous nature of catalysis.
- Mishra, Vishwesh,Thomas, Jisha Mary,Chinnappan, Sivasankar,Thirupathi, Natesan
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- Recyclable Pd ionic catalyst coated on cordierite monolith for high TOF Heck coupling reaction
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Abstract : Pd 2 + ionic catalyst, Ti 0.97Pd 0.03O 1.97 was coated over cordierite monolith by solution combustion method. The catalyst coated on the cordierite is nano-crystalline as seen from XRD studies. Coated catalyst was used for Heck coupling reactions with different substrates of aryl halides and olefins. Thus handling nano-crystalline catalyst powder is avoided by fixing it on a solid catalyst cartridge. Heck coupled products were characterized using 1H NMR, 13C NMR, Mass and FTIR spectroscopy. This catalyst showed high selectivity towards Heck coupling reaction. Turnover frequencies (TOF) for each of the reactions were found to be very high. The catalyst was recycled up to 7 times with total TOF 3017 h - 1, which is found to be a new green technique in the Heck coupling reaction. Graphical abstract: Ti 0.97Pd 0.03O 1.97 catalyst is coated on cordierite monolith honeycomb (HC) by solution combustion method and it is used in the Heck coupling reaction. Reactions are done in a specially designed flask. Catalyst is recycled for 7 times. The total turnover frequency (TOF) after 7 cycles was 3017 h - 1. [Figure not available: see fulltext.].
- Bhat, Shrikanth K,Prasad, Jagadeesh D,Hegde
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