- Synthesis and catalytic activities of 1-alkoxycarbonyl- and 1-carbamoylmethyl-5-phenyl-3-aryl-3H-imidazol-1-yliden-Pd(II) complexes
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4-Phenyl-1-aryl-1H-imidazoles were reacted with α-haloesters and amides to give the corresponding imidazolium salts. The latter were used as starting materials for the synthesis of Pd(NHC) complexes. The catalytic activities of the newly prepared compounds were screened in a model coupling reaction. 1-Alkoxycarbonyl-5-phenyl-3-aryl-3H-imidazol-1-yliden-Pd(II) were shown to be better catalyst than the 1-carbamoylmethyl-5-phenyl-3-aryl-3H-imidazol-1-yliden-Pd(II) complexes. The catalysts were shown to be insensitive to the air oxygen and water.
- Koruk?u, Meliha ?etin,Co?kun, Necdet
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- New Pd(II) and Pt(II)-diaminophosphine complexes bearing cyclohexyl or isopropyl moiety: Use of Pd(II) complexes as precatalyst in Mizoroki-Heck and Suzuki-Miyaura cross-coupling reactions
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Two new diaminophosphine ligands, N, N′-bis(dicyclohexylphosphino)-2-(aminomethyl)aniline (1) and N, N′-bis(diisopropylphosphino)-2-(aminomethyl)aniline (2) were synthesized by the reaction of 2-(aminomethyl)aniline with two equivalents of Cy2P
- Aydemir, Murat,Durap, Feyyaz,Baysal, Akin
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- Efficient and ligand free palladium catalyst for Suzuki and Heck cross-coupling reactions
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A simple and efficient system for Suzuki cross-coupling reactions was developed using a ligandless catalyst of Pd nanoclusters generated in situ from Pd(acac)2. The cross-coupling reactions proceeded under mild reaction conditions with a high reaction rate (5 min) to give various biaryls in high yields. The system also exhibited catalytic potential for Heck reaction between aryl bromides and styrene.
- Luo, Bin,Wang, Jiaqing,Ge, Danhua,Li, Xinming,Cao, Xueqin,Pan, Yue,Gu, Hongwei
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- N-heterocyclic carbene palladium complexes with different N-coordinated ligands: Comparison of their catalytic activities in Suzuki-Miyaura and Mizoroki-Heck reactions
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In this paper, we have reported the synthesis and catalytic activities of four new anthracene substituted imidazole-based palladium N-heterocyclic carbene complexes. The synthesized complexes, 2a–d, were stabilized with different N-heterocycles, namely py
- Karata?, Mert Olgun,?zdemir, Nam?k,Al?c?, Bülent,?zdemir, ?smail
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- 5-Nitrobenzimidazole containing Pd(II)catalyzed C[sbnd]C cross-coupling reactions: The effect of the N-substituent of the benzimidazole structure on catalyst activity
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A series of Pd(II)complexes (1a-e)were successfully synthesized by reaction of N-substituted 5-nitrobenzimidazole with [PdCl2(CNCH3)2]in toluene under argon reflux condition. Their catalytic activity in the Suzuki-Miyaura
- Buldurun, Kenan,?zdemir, ?smail
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- Five complexes containing N, N -bis(2-hydroxyethyl)-ethylenediamine with tetracyanidopalladate(II): Synthesis, crystal structures, thermal, magnetic, and catalytic properties
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Five cyanide complexes, [Ni(N-bishydeten)Pd(CN)4] (1), [Cu(N-bishydeten)Pd(-CN)2(CN)2]n (2), [Cu(N-bishydeten)2][Pd(CN)4] (3), [Zn(N-bishydeten)Pd(CN) 4] (4), and [Cd(N-bishydeten)2][Pd(CN)4] (5) (N-bishydeten = N,N-bis(2-hydroxyethyl)-ethylenediamine), have been synthesized and characterized using various techniques. Different structures were formed when the M: L ratio was varied in copper complexes. The single-crystal X-ray diffraction analysis reveals that 2, a 1-D cyanide-bridged complex with 2,2-CT-type zigzag chain, was obtained by using 1: 1 M: L ratio whereas 3 was formed as a complex salt in a molar ratio of 1: 2. The thermal stabilities determined from DTGmax values of the first decomposition stages change in the order 1 > 5 > 4 > 3 > 2. Although an EPR signal was not observed for 1, the g parameters obtained from the EPR spectra of 2 and 3 indicate that CuII ions are located in tetragonally distorted octahedral sites (D4h), and the ground state of the unpaired electron is ( 2B1g). The magnetic behavior indicates a very small antiferromagnetic interaction below 10 K for 1-3. In 3, there is a temperature-independent paramagnetism (α) due to the orbital moments of the d electrons. 1-3 were tested as catalysts in Suzuki and Heck coupling reactions. 102013
- Korkmaz, S. Aslan,Karadag,Korkmaz,Andac,Guerbuez,Oezdemir,Topkaya
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- Microwave-assisted synthesis of novel perimidinium salts as N-heterocyclic carbene precursors: Involvement in palladium-catalyzed cross-coupling reactions
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[Figure not available: see fulltext.] In the current study, five novel perimidinium chlorides were synthesized in good yields by reaction of 1-(3-methylbenzyl)perimidine with five different alkyl chlorides under microwave irradiation in 30 minutes. Synthe
- Onar, Gulnihan,Karatas, Mert Olgun,Alici, Bülent,Cetinkaya, Engin
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- Preparation of a new clay-immobilized highly stable palladium catalyst and its efficient recyclability in the Heck reaction
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The immobilization of a series of bis-carbene-pincer complexes of palladium(II) on montmorillonite K-10 affords the preparation of effective catalysts for the C-C coupling in a standard Heck reaction. The supported catalysts so obtained, show catalytic activity similar to their homogeneous counterparts. The determination of Pd content on the supported catalysts by XPS and elemental analysis, before and after each catalytic reaction, shows that leaching is negligible. Once the reaction conditions were optimized, we were able to recycle the catalyst at least ten times, without significant loss of activity.
- Poyatos, Macarena,Marquez, Francisco,Peris, Eduardo,Claver, Carmen,Fernandez, Elena
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- Synthesis and catalytic application of palladium complexes with picoline-functionalized benzimidazolin-2-ylidene ligands
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The picoline-functionalized benzimidazolium salts N-alkyl- N'-picolylbenzimidazolium bromide [alkyl = methyl (1), ethyl (2), n-propyl (3), n-butyl (4)] and the dipicoline-function-alized benzimidazolium bromide 5 have been synthesized. Reaction of the sal
- Jahnke, Mareike C.,Pape, Tania,Hahn, F. Ekkehardt
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- Palladium Complexes with Phenoxy- And Amidate-Functionalized N-Heterocyclic Carbene Ligands Based on 3-Phenylimidazo[1,5- a]pyridine: Synthesis and Catalytic Application in Mizoroki-Heck Coupling Reactions with Ortho-Substituted Aryl Chlorides
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Mononuclear and tetranuclear palladium complexes with functionalized "abnormal"N-heterocyclic carbene (aNHC) ligands based on 3-phenylimidazo[1,5-a]pyridine were synthesized. All of the new complexes were structurally characterized by single-crystal X-ray diffraction studies. The new complexes were applied in the Mizoroki-Heck coupling reaction of aryl chlorides with alkenes in neat n-tetrabutylammonium bromide (TBAB). The mononuclear palladium complex with a tridentate phenoxy- and amidate-functionalized aNHC ligand displayed activity superior to that of the palladium complex with a bidentate amidate-functionalized aNHC ligand. The new tetranuclear complex with the tridentate ligand displayed the best activities, capable of the activation of deactivated aryl chlorides as substrates with a low Pd atom loading. Even challenging sterically demanding ortho-substituted aryl chlorides were successfully utilized as substrates. The studies revealed that the robustness of the catalyst precursor is crucial in delivering high catalytic activities. Also, the promising use of tetranuclear palladium complexes with functionalized aNHC ligands as the catalyst precursors in the Mizoroki-Heck coupling reaction in neat TBAB was demonstrated.
- Hung, Cheng-Hau,Zheng, Wei-Yuan,Lee, Hon Man
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p. 702 - 713
(2021/04/02)
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- Palladium Loaded Dendronized Polymer as Efficient Polymeric Sustainable Catalyst for Heck Coupling Reaction
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The palladium incorporated amine-functionalized dendronized polymer was synthesized by the addition of palladium acetate to dendronized polymer in methanol at room temperature. Palladium species are immobilized onto the dendritic structure by their coordination with amino functional groups. The newly developed dendritic system showed high palladium content in the low generation level itself, which was found to be 4.19?mmol/g. This was fairly higher than, the other palladium-based catalysts. Energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, UV–Visible spectroscopy, and X-ray photoelectron spectroscopy were used to confirm the successful synthesis of the new catalyst. It was used as a homogeneous palladium catalyst for Heck coupling reaction between olefins and differently substituted aryl halides and the products were isolated in high yield. The products isolated were in trans configuration, which indicated the selectivity of the newly developed catalytic system. Also, this catalyst system was reused up to nine times without a significant decrease in its catalytic activity. The easy accessibility of catalytic sites, stability, resistance to metal leaching, high catalytic activity and remarkable stereoselectivity with a low amount of catalyst are all due to the dendritic support. The docking study was carried out for all the stilbene derivatives obtained by the Heck coupling reaction against DprE1 protein to study its potential antitubercular activity. All the compounds displayed superior docking score values over the range ??6.5 to ??8.2?kcal/mol, compared to the standard drug isoniazid with docking score of ??6.1?kcal/mol against DprE1. Graphic Abstract: [Figure not available: see fulltext.]
- Hiba, K.,Krishna, G. Anjali,Prathapan, S.,Sreekumar, K.
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- Palladium supported aminobenzamide modified silica coated superparamagnetic iron oxide as an applicable nanocatalyst for Heck cross-coupling reaction
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An applicable palladium-based nanocatalyst was constructed through the immobilization of palladium onto 2-aminobenzamide functionalized silica coated superparamagnetic iron oxide magnetic nanoparticles. The nanocatalyst (named as Pd@ABA@SPIONs@SiO2) was characterized by several characterization methods, including scanning electron microscope (SEM), transmission electron microscopy (TEM), vibrating-sample magnetometry (VSM), energy-dispersive X-ray spectroscopy (EDS), dynamic light scattering (DLS), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma (ICP), and X-ray photoelectron spectroscopy (XPS) analyses. Microscopy results showed that the nanoparticles are spherical in shape with 20–25 nm size. The size of the nanoparticles was confirmed by the DLS method. The superparamagnetic nature of the catalyst was confirmed by the VSM method. The successful functionalization of SPIONs@SiO2 was confirmed by FT-IR spectroscopy. The presence of palladium in the structure of the nanocatalyst was illustrated by XRD and EDS analysis. Also using XPS technique, the oxidation state of palladium in Pd@ABA@SPIONs@SiO2 was determined zero before and after the catalyst was applied in Mizoroki-Heck reaction. Several aryl halides and alkenes were reacted in the presence of the nanocatalyst and formed the corresponding products in high isolated yields. The nanocatalyst showed very good reusability and did not decrease its activity after 10 sequential runs. Density functional theory (DFT) calculation was performed to provide a mechanism for the reaction and confirmed the role of the palladium catalyst in the reaction function.
- Fatahi, Yousef,Ghaempanah, Aram,Ma?mani, Leila,Mahdavi, Mohammad,Bahadorikhalili, Saeed
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- NiFe2O4@SiO2@ZrO2/SO42-/Cu/Co nanoparticles: A novel, efficient, magnetically recyclable and bimetallic catalyst for Pd-free Suzuki, Heck and C-N cross-coupling reactions in aqueous media
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The novel heterogeneous bimetallic nanoparticles of Cu-Co were synthesized based on magnetic nanoparticles, and the magnetic nanocatalyst was characterized by XRD, FE-SEM, EDX mapping, BET, TEM, HRTEM, FTIR, TGA, and VSM. This catalyst was successfully applied as a recyclable magnetically catalyst in Heck, Suzuki, and C-N cross-coupling reactions with various aryl halides (iodides, bromides, and chlorides as challengeable substrates), with olefins, phenylboronic acid, and amines, respectively. We considered the rise of synergetic effects from the different Lewis acid and Br?nsted acid sites present in the catalyst. The catalyst was synthesized with cheap, available materials and a simple synthesis method. The catalyst can be separated easily using an external magnet. It was recycled for more than ten runs without a sensible loss of its catalytic activity, and no significant leaching of the Cu and Co quantity was observed. The significant benefits of the method are high-level generality, simple operation, and there are no heavy metals and toxic solvents. This is a quick, easy, efficacious and environmentally friendly protocol, and no by-products are formed in the reaction. These features make it an appropriate practical alternative protocol. In comparison with recent works, the other advantage of this catalyst is the synthesis of a wide variety of C-C and C-N bond derivatives (more than 40 derivatives). The other significant advantage is the low temperature of the reaction and the use of the least possible amount of the catalyst (0.003 g). The efficiency was good to excellent and the catalyst selectivity has been high. We aspire that our study inspires more interest to design novel catalysts based on using low-cost metal ions (such as cobalt and copper) in the cross-coupling reactions. This journal is
- Alavi G., Seyyedeh Ameneh,Nasseri, Mohammad Ali,Kazemnejadi, Milad,Allahresani, Ali,Hussainzadeh, Mahdi
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p. 7741 - 7757
(2021/05/13)
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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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supporting information
p. 2661 - 2668
(2021/07/06)
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- Structural Effect of Pincer Pd(II)–ONO Complexes Modified with Acylthiourea on Sizes of the In Situ Generated Pd Nanoparticles During Heck Coupling Reaction
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Abstract: The Pd nanoparticles generated in situ from Pd–pincer complexes catalyzed Heck coupling reaction. For this purpose, new Pd(II)–ONO pincer complexes (1–4) containing acylthiourea ancillary ligand were obtained by treating [Pd(ONO)(CH3CN)] with the respective N-substituted carbamothioyl benzamide ligand (L1–L4). Formation of these complexes was confirmed by UV–Visible, FT-IR, NMR and mass spectroscopic techniques. The sizes of in situ formed Pd nanoparticles were greatly affected by the substituent in ancillary ligand, which in turn influenced their catalytic activity towards Heck coupling reaction. The in situ formed Pd nanoparticles during Heck reaction were removed from the reaction medium and analyzed using HR-TEM to estimate the sizes of the Pd nanoparticles. Complex [Pd(ONO)((N-benzylcarbamothioyl)benzamide)] (1) which does not possess any substituent on the benzyl moiety of acylthiourea produced the smallest Pd nanoparticles with the average particle size of 3.7?nm. Hence, complex 1 showed the utmost catalytic activity. With complex 1, 51–99% of conversion was observed during Heck coupling reaction of styrene with various aryl halides. XPS results confirmed that the recovered black particles were Pd(0). A reasonable recyclability results were achieved by these in situ generated Pd nanoparticles. Graphic Abstract: [Figure not available: see fulltext.]
- Jerome,Babu, S. Ganesh,Karvembu
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p. 1633 - 1645
(2020/10/15)
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- Bimetallic nano alloy architecture on a special polymer: Ni or Cu merged with Pd for the promotion of the Mizoroki–Heck reaction and the Suzuki–Miyaura coupling
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Abstract: Novel Ni-Pd and Cu-Pd bimetallic nano alloys was designed and heterogenized on the highly robust ABPBI [poly(2,5-benzimidazole)] polymer in high yields using NaBH4 as reducing agent. These were versatile ligand free catalysts for the Mizoroki–Heck reaction and Suzuki–Miyaura coupling. The bimetallic Ni-Pd-ABPBI catalyst for the Mizoroki–Heck reaction of 4-iodo anisole could be recycled 5 times with high yields. Aryl bromides could also be activated for the Mizoroki–Heck reaction using Cu-Pd-ABPBI NP catalysts, with moderate yields. Graphic abstract: Synopsis Novel bimetallic Ni-Pd and Cu-Pd nano alloys, heterogenized on the robust ABPBI [poly(2,5-benzimidazole)] polymer using NaBH4 as reducing agent, is described. These were versatile ligand free, noble metal conservative catalysts, for the Mizoroki–Heck reaction and the Suzuki–Miyaura coupling. Aryl bromides were activated for the Mizoroki–Heck reaction using the Cu-Pd-ABPBI catalyst.[Figure not available: see fulltext.]
- Patil, Vijay P,Kashid, Abhijit A,Solanki, Bhanupratap S,Kharul, Ulhas K,Iyer, Suresh
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- A Bis (BICAAC) Palladium(II) Complex: Synthesis and Implementation as Catalyst in Heck-Mizoroki and Suzuki-Miyaura Cross Coupling Reactions
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Carbenes are one of the most appealing, well-explored, and exciting ligands in modern chemistry due to their tunable stereoelectronic properties and a wide area of applications. A palladium complex (BICAAC)2PdCl2 with a recently discovered cyclic (alkyl)(amino)carbene having bicyclo[2.2.2] octane skeleton (BICAAC) was synthesized and characterized. The enhanced σ-donating and π-accepting ability of this carbene lend a hand to form a robust Pd-carbene bond, which allowed us to probe its reactivity as a precatalyst in Heck-Mizoroki and Suzuki-Miyaura cross-coupling reactions with low catalyst loading in open-air conditions. The diverse range of substrates was explored for both the cross-coupling reactions. To get a better understanding of the catalytic reactions, several analytical techniques such as field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and powder X-ray diffraction were employed in a conclusive manner.
- Chakrabortty, Soumyadeep,Kaur, Mandeep,Adhikari, Manu,Manar, Krishna K.,Singh, Sanjay
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supporting information
p. 6209 - 6217
(2021/05/06)
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- Design, synthesis, and biological evaluation of pyrimidine analogs as SecA inhibitors
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SecA, a key component of the bacterial Sec-dependent secretion pathway, is an attractive target for the development of new antimicrobial agents. We have previously reported pyrimidine analogs as SecA inhibitors. Herein, we report an extension of the earlier work in the synthesis and evaluation of a series of 15 5-cyanothiouracil derivatives as SecA inhibitors. All the compounds have been evaluated for their inhibition of SecA ATPase (EcSecAN68) and for their antimicrobial activity against Escherichia coli NR698 (a leaky mutant) and Bacillus anthracis Sterne. Twelve compounds showed IC50 of less than 6.3 μM when tested against EcSecAN68. In antimicrobial studies against E. coli NR698, six compounds showed MIC of 12.5 μM with three being less than 6.3 μM. Against B. anthracis Sterne, three compounds showed MIC of 6.3 μM.
- Bamba, Fante,Jin, Jinshan,Chaudhary, Arpana S.,Tai, Phang C.,Wang, Binghe
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p. 1334 - 1340
(2021/03/19)
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- Palladium Nanoparticles Anchored on Magnesium Organosilicate: An Effective and Selective Catalyst for the Heck Reaction
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A new and effective palladium catalyst supported on a magnesium organosilicate for application in the Heck reaction is presented. A group of compounds comprising 22 examples were synthesized in moderate to high yields (up to 99%) within a short time. The palladium supported on magnesium organosilicate catalyst was characterized as an amorphous solid by SEM, containing around 33% of palladium inside the solid, and even with this low quantity of palladium, the catalyst was very efficient in the Heck reaction. Besides, based on the Scherrer equation, the crystallite size of the synthesized palladium nanoparticles was ultrasmall (around 1.3 nm). This strategy is a simple and efficient route for the formation of C-C bonds via the Heck cross-coupling reaction.
- Dos Santos, Beatriz F.,Da Silva, Beatriz A. L.,De Oliveira, Aline R.,Sarragiotto, Maria H.,Rinaldi, Andrelson W.,Domingues, Nelson Luís C.
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supporting information
p. 1301 - 1306
(2020/11/04)
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- Discovery of highly potent and selective influenza virus neuraminidase inhibitors targeting 150-cavity
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Encouraged by our earlier discovery of N1-selective inhibitors, the 150-cavity of influenza virus neuraminidases (NAs) could be further exploited to yield more potent oseltamivir derivatives. Herein, we report the design, synthesis and biological evaluation of a series of novel oseltamivir derivatives via the structural modifications at C5–NH2 of oseltamivir targeting 150-cavity. Among them, compound 5c bearing 4-(3-methoxybenzyloxy)benzyl group exhibited the most potent activity, which was lower or modestly improved activities than oseltamivir carboxylate (OSC) against N1 (H1N1), N1 (H5N1) and N1 (H5N1–H274Y). Specifically, there was 30-fold loss of activity against the wild-type strain H1N1. However, 5c displayed 4.85-fold more potent activity than OSC against H5N1–H274Y NA. Also, 5c demonstrated low cytotoxicity in vitro and no acute toxicity in mice. Molecular docking studies provided insights into the high potency of 5c against N1 and N1–H274Y mutant NAs. Besides, the in silico prediction of physicochemical properties and CYP enzymatic inhibitory ability of representative compounds were conducted to evaluate their drug-like properties.
- Jia, Ruifang,Zhang, Jian,Bertagnin, Chiara,Cherukupalli, Srinivasulu,Ai, Wei,Ding, Xiao,Li, Zhuo,Zhang, Jiwei,Ju, Han,Ma, Xiuli,Loregian, Arianna,Huang, Bing,Zhan, Peng,Liu, Xinyong
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- Synthesis of Pd@graphene oxide framework nanocatalyst with enhanced activity in Heck-Mizoroki cross-coupling reaction
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A new method was developed for producing a catalyst involving a Pd nanoparticle (NP) embedded in a graphene oxide framework (Pd@GOF) with ordered macro- and mesoporous structures. First, 5,5′-diamino-2,2′-bipyridine was selected as cross-linking for covalent modification of GO nanosheets to prepare a three-dimensional (3D) framework with interlayer spaces in which well-dispersed and ultra-small Pd NPs in situ grew and embedded the framework. The synthesized nanopores 3D Pd@GOF can act as nanoreactors to help the reaction substrates thoroughly come into contact with the surface of Pd NPs, thereby exhibiting high activity toward the Heck reaction, rarely reported concerning Pd NPs supported on one-side functionalized graphene. The Pd@GOF catalyst can be used 10 times without any significant loss in the catalytic activity, confirming the long-term stability of this catalyst. Therefore, the covalently assembled GOF was proposed as a universal platform for hosting noble metal NPs to construct the desired metal@GOF nanocatalyst with improved activity and stability that can be used in a broad range of practical applications.
- Shekarizadeh, Arezoo,Azadi, Roya
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- Hydrogel supported vinylimidazole based PEPPSI-Pd-NHC catalysts: The catalytic activities in Heck and Suzuki-Miyaura coupling reactions
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Increasing environmental awareness and limited raw material resources have increased the importance of catalysts by leading to green technology. For this purpose, there is a need for efficient, new, selective, reusable, environmentally friendly catalysts
- Boztepe, Cihangir,Künkül, As?m,Gürbüz, Nevin
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- A new PEPPSI type N-heterocyclic carbene palladium(II) complex and its efficiency as a catalyst for Mizoroki-Heck cross-coupling reactions in water
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Abstract: A new air and moisture stable PEPPSI (PEPPSI: pyridine-enhanced pre-catalyst preparation, stabilisation, and initiation) themed palladium N-heterocyclic carbene (NHC) complex [Pd(L)Br2(Py)] (1) [L: 2-flurobenzyl)-1-(4-methoxyphenyl)-1H-imidazolline-2-ylidene] was synthesized and characterized. The structure of complex 1 was determined by X-ray single-crystal analysis. The palladium center in 1 adopted a square planar geometry with carbene and pyridine ligands occupying the mutual trans position. The complex 1 was employed to catalyze the Mizoroki-Heck cross-coupling reactions of aryl bromides/iodides with styrene in water. To the best of our knowledge, this is the first report where a Pd-PEPPSI catalyst was successfully employed in aqueous-phase Mizoroki-Heck reaction. Good to excellent yields of cross-coupling products were obtained with a range of representative aryl bromides/iodides under relatively mild conditions (100 °C, 1 mol% of 1). Graphic abstract: A new palladium PEPPSI complex was synthesized, characterized and evaluated as catalyst for the Mizoroki-Heck reaction in aqueous medium. Both electron-donating and electron-withdrawing aryl halides (bromides and iodides) reacted with styrene to give corresponding coupling products in moderate to excellent yields.[Figure not available: see fulltext.].
- Borah, Dhrubajit,Das, Pankaj,Saha, Biswajit,Sarma, Bipul
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- Immobilized Pd on Eggshell Membrane: A powerful and recyclable catalyst for Suzuki and Heck cross-coupling reactions in water
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A stable heterogeneous palladium catalysts, the waste eggshell membrane (ESM) anchored Pd complex, was synthesized by a simple and green technique. The catalyst obtained can display an outstanding catalytic activity for Suzuki and Heck coupling reactions in water media. The reactions of various aryl halides with aryl boronic acids and terminal alkenes provided the corresponding products in moderate to excellent yields. More importantly, this novel and efficient catalyst with high stability can be easily reused for at least twelve times with no decrease of the catalytic activity, performing an endurable and wide tolerance of the substrates. Facile synthesis, high catalytic activity, and recyclability make these catalysts interesting for further studies.
- Wu, Shang,Jiang, Hongyan,Zhang, Hong,Zhao, Lianbiao,Yuan, Peilin,Zhang, Ying,Su, Qiong,Wang, Yanbin,Wu, Lan,Yang, Quanlu
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- Catalytic activity of Pd dithiolate complexes with large-bite-angle diphosphines in Heck coupling reactions
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Palladium(II) complexes of aryl dithiolates and wide-bite-angle diphosphines Xantphos and dppf have been developed as efficient catalysts in Suzuki and Suzuki carbonylation reactions. The catalytic activity of these highly stable, discrete and charged complexes was investigated in Heck coupling reactions of styrene and a variety of aryl bromides. Under optimized reaction conditions these palladium complexes showed excellent activity with high turnover number (6 × 106) and high turnover frequency (4 × 105 h?1). The effect of bite angle of diphosphines on the catalytic activity of the complexes [Pd2(P∩P)2(SC12H8S)]2(OTf)4 followed the trend P∩P = Xantphos > dppf > dppe as the order of their bite angles. The catalyst could be reused, and after three cycles the formation of significant amount of Pd nanoparticles was noticed, which were characterized using powder X-ray diffraction, energy-dispersive X-ray analysis and transmission electron microscopy. The high catalytic activity has been attributed to the Pd nanoparticles.
- Mane, Pravin A.,Neogy, Suman,Dey, Sandip
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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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- Synthesis and characterization of Pd(II) complexes bearing NS, CS, SNS and SCS ligands. Evaluation of their microwave assisted catalytic activity in C–C coupling reactions
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A series of coordination (Pd-NS, Pd-SNS, Pd-SNS-O) and organometallic (Pd-C and Pd-SCS) Pd(II) complexes supported by bidentate and tridentate ligands featuring sulphur moieties have been prepared. All ligands and their palladium complexes were fully char
- Aguilar-Castillo, Bethsy A.,Gabriel Flores-Rojas, G.,González-Sebastián, Lucero,Hernández-Ortega, Simón,Morales-Morales, David,Reyes-Martínez, Reyna
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- Multidentate N-Heterocyclic Carbene Complexes of Nickel and Palladium: Structural Analysis and Catalytic Application in Mizoroki–Heck Coupling Reaction
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Two series of electron-rich metal (Ni and Pd) complexes, namely a pyridine-coordinated tridentate NHC/amidate/phenoxy metal complex and a tetradentate complex bearing an extra pyridyl group, were synthesized. Two carbene moieties, imidazole-based and benzimidazole-based NHCs, were also incorporated into the ligand backbones. Seven of the new complexes were structurally characterized and comparative structural analysis revealed that the tetradentate complex with a flanking pyridyl side-arm was less distorted, leading to chelation-assisted stronger NHC coordination and hence a shorter metal–carbene bond. The catalytic activities of the two sets of palladium complexes for the Mizoroki–Heck coupling reaction were investigated. The comparative data showed that despite the higher thermal stability and the presence of the flanking hemilabile pyridyl side-arm which provided unsaturation to the metal center, the catalytic performance was slightly inferior to that of the tridentate palladium complex with a “throw-away” pyridine ligand. The tridentate palladium complex with the benzimidazole-based NHC moiety was the most effective catalyst, allowing the utilization of a range of aryl chlorides including deactivated substrates with a low 0.2 mol-% Pd loading in molten n-tetrabutylammonium bromide.
- Liu, Li-Cheng,Tzeng, Yan-Hsiang,Hung, Cheng-Hau,Lee, Hon Man
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p. 3601 - 3611
(2020/09/01)
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- Sulphonic acid functionalized porphyrin anchored with a: Meso -substituted triazolium ionic liquid moiety: A heterogeneous photo-catalyst for metal/base free C-C cross-coupling and C-N/C-H activation using aryl chloride under visible light irradiation
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We report an easy process to synthesize sulphonic acid functionalized porphyrin, anchored with a meso-substituted triazolium ionic liquid moiety (SAFPTILM) for metal/base free C-C cross-coupling and C-N/C-H activation using aryl chloride under visible light irradiation. The acid strength has been measured based on the Hammett indicator. The SAFPTILM photocatalyst comprising 18 π-conjugated electronic systems with the chromophore substituents in the meso-position can provide rapid electronic conducting channels during photocatalysis under the irradiation of visible light. It was found that SAFPTILM is an efficient photocatalyst for the Heck, Sonogashira, Buchwald, Ullmann/Fittig coupling and C-H activation of phenols with different aryl chlorides in the absence of a base/noble metal, using 5 W LED (yellow) light under ambient conditions. The photocatalyst with low band gap (1.55 eV) comprising conjugation, favors coupling reaction of unactivated aryl chlorides, by easy excitation of electrons and transfer to the conjugated benzimidazolium based phenylenediamine support delaying the recombination of photoinduced electron-hole pairs.
- Bhansali, Karan,Raut, Subodh,Barange, Shital,Bhagat, Pundlik
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p. 19690 - 19712
(2020/12/04)
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- An Annelated Mesoionic Carbene (MIC) Based Ru(II) Catalyst for Chemo- And Stereoselective Semihydrogenation of Internal and Terminal Alkynes
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The catalytic utility of [RuL1(CO)2I2] (1), containing an annelated π-conjugated imidazo-naphthyridine-based mesoionic carbene (MIC) ligand (L1), is evaluated for E-selective alkyne semihydrogenation. The precatalyst 1, in combination with 2 equiv of AgBArF, semihydrogenates a broad range of internal alkynes with molecular hydrogen (5 bar) in water. (E)-Alkenes are accessed in high yields, and a number of reducible functional groups are tolerated. A chelate MIC ligand and two cis carbonyls provide a well-defined platform at the Ru center for hydrogenation and isomerization. The loss of two iodides and the presence of two carbonyls render the Ru center electron deficient and thus the formation of metal vinylidenes with terminal alkynes is avoided. This is leveraged for the semihydrogenation of terminal alkynes by the same catalytic system in isopropyl alcohol. Reaction profile, isomerization, kinetic, and DFT studies reveal initial alkyne hydrogenation to a (Z)-alkene, which further isomerizes to an (E)-alkene via metal-catalyzed Z → E isomerization.
- Bera, Jitendra K.,Choudhury, Joyanta,Das, Shubhajit,Dutta, Indranil,Pati, Swapan K.,Saha, Sayantani,Yadav, Suman
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p. 3212 - 3223
(2020/10/02)
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- A Simple Nickel Catalyst Enabling an E-Selective Alkyne Semihydrogenation
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Stereoselective alkyne semihydrogenations are attractive approaches to alkenes, which are key building blocks for synthesis. With regards to the most atom-economic reducing agent dihydrogen (H2), only few catalysts for the challenging E-selective alkyne semihydrogenation have been disclosed, each with a unique substrate scope profile. Here, we show that a commercially available nickel catalyst facilitates the E-selective alkyne semihydrogenation of a wide variety of substituted internal alkynes. This results in a simple and broadly applicable overall protocol to stereoselectively access E-alkenes employing H2, which could serve as a general method for synthesis.
- Thiel, Niklas O.,Kaewmee, Benyapa,Tran Ngoc, Trung,Teichert, Johannes F.
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p. 1597 - 1603
(2020/02/05)
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- Tetranuclear Palladium Complexes of Abnormal N-Heterocyclic Carbene Ligands and their Catalytic Activities in Mizoroki-Heck Coupling Reaction of Electron-Rich Aryl Chlorides
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Based on the ligand scaffold of an imidazolyl/benziimidazolyl moiety and a N-CH2C(=O)NHPh substituent, two series of ligand precursors with ortho hydroxy groups incorporated on the N-phenyl rings were prepared. The structural fine tuning of the ligand scaffold allowed the synthesis of tetranuclear palladium complexes with abnormal N-heterocyclic carbene (aNHC) ligands. For precursors with C2-methyl blocking groups, pyridine-assisted C?H bond activation led to the formation of mononuclear tridentate palladium aNHC complexes or tetranuclear complexes with tridentate CNO donors. Representative mononuclear and tetranuclearpalladium aNHC complexes were structurally characterized by X-ray diffraction studies, revealing very short Pd?C bond distances. The tetranuclear palladium aNHC complexes were very effective in catalyzing Mizoroki-Heck coupling reaction, and were capable of employing a range of aryl chlorides including deactivated substrates with low palladium loading of 0.2 mol%. (Figure presented.).
- Lee, Jhen-Yi,Su, Yong-Siang,Wang, Yu-Shan,Lee, Hon Man
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p. 4714 - 4726
(2019/09/03)
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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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- Magnetically thiamine palladium complex nanocomposites as an effective recyclable catalyst for facile sonochemical cross coupling reaction
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The carbon–carbon cross coupling reactions through transition-metal-catalyzed processes has been significantly developed for their important synthetic applications. In this research, we have shown that NiFe2O4@TASDA-Pd(0) is a highly active, novel and reusable catalyst with excellent performance for the Mizoroki–Heck coupling reaction of several types of iodo, bromo, and even aryl chlorides in DMF under ultrasound irradiation. The novel palladium catalyst prepared and characterized by using FT-IR spectrum, X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), thermo gravimetric analysis (TGA) and vibrating sample magnetometer (VSM). The catalyst can be recovered and recycled several times without marked loss of activity.
- Naeimi, Hossein,Kiani, Fatemeh
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- Facile construction & modeling of a highly active thiacalixphenyl[4]arene-protected nano-palladium catalyst for various C-C cross-coupling reactions
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The design and creation of thiacalixphenyl[4]arene tetraacetohydrazide (TPTAH) has been utilized for the construction of palladium nanoparticles (PdNps). The molecular modelling studies give an insight into the surface properties of TPTAH capped PdNps. The plausible reduction mechanism of Pd(ii) to Pd(0) is due to the presence of hydrazide group on the periphery. The charge transfer for this reduction was initiated by the carbonyl group and N-atom. TPTAH behaves as a reducing and stabilizing agent for the formation of catalytically active TPTAH-PdNps that were characterized by UV-Vis spectroscopy, selected area electron diffraction (SAED), transmission electron microscopy (TEM), and powder X-ray diffraction. The TPTAH-PdNps with size 4 ± 2 nm were found to be catalytically active for C-C cross-coupling reactions such as the Suzuki-Miyaura, Heck, and Stille reactions. TPTAH-PdNps are superior to the conventional Pd catalyst in terms of yield, catalyst loading, reaction time, and recyclability.
- Modi, Krunal,Patel, Chirag,Panchal, Urvi,Liska, Alan,Kongor, Anita,Jiri, Ludvik,Jain
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p. 5611 - 5622
(2019/04/04)
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- Mesoporous Hierarchically Hollow Flower-Like CoAl-LDH@N,S-doped Graphene@Pd Nanoarchitectures for Heck Couplings
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Abstract: A smart strategy for the synthesis of hierarchical CoAl-LDH hollow spheres assembled with nitrogen and sulfur co-doped graphene for high holding of palladium nanoparticles (CoAl-LDH@N,S-G@Pd) is reported. This architecture exhibited excellent activity in Heck reactions with TOF as high as 1633?h?1 due to a strong metal–support interaction, good electron transfers and high surface area. Graphic Abstract: [Figure not available: see fulltext.].
- Rohani, Sahar,Mohammadi Ziarani, Ghodsi,Badiei, Alireza,Ziarati, Abolfazl,Luque, Rafael
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p. 2984 - 2993
(2019/07/05)
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- Synthesis of new Pro-PYE ligands as co-catalysts toward Pd-catalyzed Heck-Mizoroki cross coupling reactions
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The present research work describes the synthesis of five new ligands containing pyridinium amine, [H2L1][OTf]2-[H2L5][I]2 from two new precursors, [P3Et][I] and [P2Me][CF3SO3]. The structure elucidations of the compounds were confirmed by multinuclear NMR (1H, 13C), FT-IR and by single crystal XRD techniques. Theoretical DFT studies were carried out to get better insight into the electronic levels and structural features of all the molecules. These synthesized new Pro-PYE ligands [H2L1][OTf]2-[H2L5][I]2 were found to be significantly active as co-catalysts for Pd(CH3CO2)2 toward Heck-Mizoroki coupling reactions with wide substrate scope in the order of [H2L1][OTf]2 ? [H2L2][OTf]2 > [H2L3][OTf]2 > [H2L4][OTf]2 > [H2L5][I]2.
- Munir, Naima,Masood, Sara,Liaqat, Faroha,Tahir, Muhammad Nawaz,Yousuf, Sammer,Kalsoom, Saima,Mughal, Ehsan Ullah,Sumrra, Sajjad Hussain,Maalik, Aneela,Zafar, Muhammad Naveed
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p. 37986 - 38000
(2019/12/03)
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- Synthesis, structure, computational and catalytic activities of palladium complexes containing hydrazide based amino-phosphine ligands
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Two new N, N-bis(diphenylphosphino)-amine ligands [where amine = N-Aminophthalimide (in L1) and Hydrazine dihydrochloride (in L2)] and their Pd(II) complexes, C1 and C2 have been synthesized and characterized by IR and NMR spectroscopies. Single crystal X-ray diffraction techniques have been used to determine the crystal structures of the complexes. Moreover, the catalytic activities of mentioned complexes in Heck coupling reactions have been assessed. The NBO analysis has been used to investigate the nature of the metal-ligand interactions. In the case of L2, preparation route could have produced two different products (Pro.1 and Pro.2), but only one structure has been gained which has been prepared in high purity. To address the reason for this manner, kinetics and thermodynamics of two different pathways that could have led to possible products have been investigated theoretically.
- Gholivand, Khodayar,Kahnouji, Mohammad,Maghsoud, Yazdan,Hosseini, Mahdieh,Mark Roe, Stephen
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p. 281 - 292
(2018/11/26)
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- Dipalladium(I) complexes of ortho- and para-functionalized 1,3-bis(aryl)triazenide ligands: Synthesis, structure and catalytic activity
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The synthesis and characterization of a series dipalladium(I) complexes of formulae [Pd{1-[2′-(methoxycarbonyl)phenyl]-3-[4′-X-phenyl]triazenide}]2 [X = F (4), Cl (5), Br (6)] are reported. The crystal structure of complex 4 was determined by X-ray diffraction studies. The previously reported dipalladium(I) 1–3 as well as the new complexes 4–6 were used as catalysts in the Heck and Suzuki couplings of different p-substituted bromobenzenes.
- Correa-Ayala, Erick,Campos-Alvarado, Carlos,Chávez, Daniel,Hernández-Ortega, Simón,Morales-Morales, David,Miranda-Soto, Valentín,Parra-Hake, Miguel
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p. 130 - 138
(2019/03/12)
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- A polymer-supported salen-palladium complex as a heterogeneous catalyst for the Mizoroki-Heck cross-coupling reaction
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In this work, the catalytic performance of a polymer-supported Pd(II)-salen complex (PS-Pd-salen) as an effective and environmentally friendly catalyst for the Mizoroki-Heck C[sbnd]C cross-coupling reaction is presented. The PS-Pd-salen complex was employed as a catalyst for Mizoroki-Heck reactions of an aryl halide with various terminal alkenes (Styrene, Methyl acrylate, Ethyl acrylate, n-butyl acrylate, tert-Butyl acrylate) under phosphine free conditions. Moreover, a range of Mizoroki-Heck reactions using different polar solvents, co-solvents, and bases has been investigated. Aryl iodides and bromides with terminal alkene are well activated in C[sbnd]C coupling reactions. All products were isolated by column chromatography as liquids/white to off-white crystalline solids and confirmed by 1H and 13C NMR spectroscopy. The catalyst could be easily separated by filtrations and reusability of catalyst was also assessed under optimized conditions. The hot filtration test revealed that the catalyst was truly heterogeneous, very active and stable under the reaction conditions and could be reused up to fifth cycles with analogous activities to that of the fresh catalyst. High catalytic activity at a low concentration (30 mg) and flexibility under mild reaction conditions, simple product work-up towards Mizoroki-Heck reactions indicated that PS-Pd-salen was an efficient catalyst for C[sbnd]C coupling reactions.
- Balinge, Kamlesh Rudreshwar,Bhagat, Pundlik Rambhau
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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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- 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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- Different properties of P,C-donor Pd(II) and Pt(II); spectroscopic and X-ray analysis, catalytic potential and anti-proliferative potency
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This account describes our recent studies on pallada-and platinaphosphacycle complexes with an unsymmetrical phosphonium ylide, Ph2PC(CH2)PPh2 = C(H)C(O)C6H4-p-NO2 (Y), derived from 1,1-bis(diphenylphosphino)ethylene (dppee). These complexes have been prepared through reactions between (Y) and [MCl2(cod)] (M = Pd (C1) or Pt (C2); cod = 1,5-cyclooctadiene) in equimolar ratio in the hope of finding new compounds that may be useful in stereoselective catalysis and find use as antitumor metallodrugs. Characterization of these compounds was performed by elemental analysis, IR, 1H, 13C, and 31P NMR spectroscopic methods. The structures of the Pd and Pt complexes were determined by single crystal x-ray structural analyses, showing that both complexes consist of five-membered rings formed by coordination of the phosphorus ylide (Y) through the phosphine group and the ylidic carbon atom to the metal center. The catalytic activity of the complexes, using the Mizoroki–Heck and Suzuki-Miyaura cross-coupling reactions, have been evaluated and compared. Moreover, both compounds have been found to have antitumor activity against AGS (gastric carcinoma), MCF-7 (breast carcinoma) and A549 (non-small lung carcinoma) cells with the average of IC50 values from 61.19 to 290.17 μM. Generally, C2 reveals high anticancer activity than C1.
- Yousefi, Abed,Sabounchei, Seyyed Javad,Moazzami Farida, Seyed Hamed,Karamian, Roya,Rahmani, Nosrat,Gable, Robert W.
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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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- Synthesis and Characterization of C, C -Type Palladacycles and Their Catalytic Application in Mizoroki-Heck Coupling Reaction
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Two series of ligand precursors, based on imidazo[1,2-a]pyridine and C2-phenyl substituted imidazole moieties, were developed and synthesized in high yields, featuring an N-CH2(C=O)Ar substituent on the imidazole ring. Upon reacting with palladium acetate, both series of ligands underwent double C-H bond activations at the methylene and o-aryl carbon sites on the N-CH2(C=O)Ar substituent, yielding C,C-type palladacycles bearing five-membered chelate rings. A dimeric palladium complex with bridging bromides was obtained from the ligand precursor with the bromide anion, whereas an ionic palladium complex with two "throw away" pyridine ligands was formed with the precursor of the tetrafluoroborate anion. All complexes are air-stable and were characterized by 1H and 13C NMR spectroscopy and elemental analysis. The structures of three of the new complexes were further established by single-crystal X-ray diffraction studies. These complexes have been screened for catalyzing Mizoroki-Heck coupling reaction using ionic salt as solvent. The complex based on imidazo[1,2-a]pyridine, which has an electron-donating 4-methoxyphenyl ring on the ligand scaffold, was the most efficient catalyst, capable of using activated aryl chloride and sterically hindered aryl bromide as substrates. It was also successfully applied in the green process of one-pot Mizoroki-Heck coupling/trans-esterification reaction in molten ionic salt.
- Lo, Chi Hou,Lee, Hon Man
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p. 1150 - 1159
(2018/04/17)
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- Pd(OAc)2 immobilized on imine-functionalized microporous covalent triazine polymer as efficient heterogeneous catalyst for Mizoroki–Heck cross-coupling reaction
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A template consisting of Pd(OAc)2 immobilized on imine-functionalized microporous covalent triazine polymer network (Pd/TATAE) was synthesized and found to be an efficient and recyclable heterogeneous solid catalyst for Mizoroki–Heck C–C coupling of styrene with substituted aryl halides under mild reaction conditions and without addition of any ligand or additives. Furthermore, Pd/TATAE could be recycled for nine consecutive cycles with minor loss of catalytic activity. Finally, the Pd/TATAE catalyst showed good catalytic activity with excellent yield of 96?% and high turnover number of 3349.
- Sadhasivam, Velu,Mathappan, Mariyappan,Harikrishnan, Muniyasamy,Chithiraikumar, Chinnadurai,Murugesan, Sepperumal,Siva, Ayyanar
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p. 2853 - 2866
(2018/02/16)
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- An efficient class of bis-NHC salts: Applications in Pd-catalyzed reactions under mild reaction conditions
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This study describes an efficient class of bis-N-heterocyclic carbene (bis-NHC) salts that can be easily made from commercially available and inexpensive starting materials. The application of these salts to Pd-catalyzed reactions is described. The palladium (Pd) catalyst generated in situ was highly effective under mild reaction conditions.
- Chiu, Chien-Cheng,Chiu, Hui-Tzu,Lee, Dong-Sheng,Lu, Ta-Jung
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p. 26407 - 26415
(2018/08/04)
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- Collaboration of Ni, polyoxometalates and layered double hydroxides: synthesis, characterization, electrochemical and mechanism investigations as nano-catalyst in the Heck coupling reaction
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Nickel (Ni) nanoparticles were immobilized on the surface of magnetic MgAl layered double hydroxide intercalated 10-molybdo-2-vanadophosphate (Fe–MgAl/Mo10V2–Ni) for the first time. The presence of Ni nanoparticles onthe high-surface area Fe–MgAl LDH structure in the presence of Mo10V2 makes this catalyst an ideal option in terms of efficiency and selectivity for Heck coupling reaction. Synergic effects of Mo10V2 and Ni were investigated by an electrochemical technique. Increasing of the ECSA of the catalyst compared to Fe–Mg–Al–Ni leads to enhancement of the catalytic activity and proves the synergic effect. A new catalytic mechanism was introduced for this kind of reaction. The resulting structure and its catalytic behavior were characterized by FT-IR, XRD, ICP-AES, TEM, SEM, EDX, EBSD, XPS, BET, VSM, CV, LSV and zeta potential analyses. More importantly, Fe–MgAl/Mo10V2–Ni can easily be separated from the reaction mixture using an external magnet and reused for at least four successive runs without any substantial reduction in its catalytic activity.
- Rafiee, Ezzat,Kahrizi, Masoud
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p. 7289 - 7309
(2018/09/21)
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- One-pot synthesis of new N-(1-methylpyridin-4(1H)-ylidene)amine ligands for palladium-catalyzed heck coupling reaction
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A series of new derivatives of N -(1-methylpyridin-4(1 H) -ylidene)amines, [L1 ]–[L 5 ], were synthesized and characterized by FTIR, NMR, MS, and XRD analysis. These targeted compounds were synthesized by the melt reaction between N -methylated-4-chloropyridinium triflate and corresponding amines (1-naphthyl amine, o-ansidine, 2-nitroaniline, p-ansidine, and cyclohexyl amine) followed by the addition of sodium hydride in dichloromethane in the same pot. These highly electron-donating N -(1-methylpyridin-4(1 H) -ylidene)amine ligands considerably improve the catalytic activity of palladium acetate towards Heck–Mizoroki carbon–carbon cross-coupling reactions.
- Zafar, Muhammad,Zahra, Sabeen,Tahir, Muhammad,Mughal, Ehsan,Nazar, Muhammad,Rafique, Hummera
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- Efficient Mizoroki–Heck coupling reactions using phosphine-modified Pd(II)–picolinate complex
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Efficient Mizoroki–Heck couplings were obtained using a very easily synthesizable palladium(II) complex of hemilabile N–O ligand (picolinate), with high turnover frequencies up to >10,000 h?1, in just 15 min, with high selectivity of >99% to the desired products. Wide applicability of the simple-looking palladium complex catalyst was established with differently functionalized substrates. Catalyst screening studies revealed intricate details of dependence of catalyst performance on different reaction parameters and conditions and arriving at the optimized facile methodology.
- Sharma, Sonam,Sarkar, Bibhas R.
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supporting information
p. 906 - 914
(2018/03/21)
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- Kryptofix 5 as an inexpensive and efficient ligand for the palladium-catalyzed Mizoroki-Heck reaction
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A novel complex of PdCl2 with a multidentate cryptand ligand, Kryptofix 5, has been prepared and characterized by various techniques including 1H- and 13C NMR spectroscopy, Fourier transform infrared (FT-IR), Raman, ultraviolet and visible (UV-VIS) spectroscopy, inductively coupled plasma (ICP), CHN elemental and energy dispersive X-ray analysis (EDX). This heat- and air-stable complex was utilized as a highly active catalyst for the Mizoroki-Heck reaction of aryl halides with various olefins. Interestingly, it was found that aryl bromides as well as aryl iodides were efficiently cross-coupled with terminal alkenes at 130?°C in 10?min. Furthermore, the least reactive aryl chlorides reacted with styrene to obtain the desired products in acceptable yields.
- Movassagh, Barahman,Ranjbari, Shabnam
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- Monodentate phosphorus-coordinated palladium(II) complexes as new catalyst for Mizoroki-Heck reaction of aryl halides with electron-deficient olefins
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Four novel palladium(II) complexes coordinated by phosphorus atoms from both 3,5-disubstituted-1H-1,2,4-diazaphospholes in monodentate fashion were developed as efficient catalyst for the Mizoroki-Heck reaction of aryl halides with electron-deficient olefins. The coupling reaction of aryl halide bearig different functional groups with olefin derivatives took place and the corresponding products were isolated in good to excellent yields under optimal conditions. The procedure exhibits good functional group tolerance and wide substrate scope. This Mizoroki-Heck reaction was further achieved using Pd(OAc)2 and 3,5-di-isopropyl-1H-1,2,4-diazaphospholes as combined catalyst, which provide the convenient and alternative method in organic synthesis
- Zhao, Fang,Xin, Li,Zhang, Yingying,Jia, Xuefeng
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supporting information
p. 493 - 496
(2017/09/06)
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- Dehydrative Cross-Coupling of 1-Phenylethanol Catalysed by Palladium Nanoparticles Formed in situ under Acidic Conditions
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A dehydrative cross-coupling of 1-phenylethanol catalysed by sugar derived, in situ formed palladium(0) nanoparticles under acidic conditions is realised. The acidic conditions allow for use of alcohols as a feedstock in metal-mediated coupling reactions via their in situ dehydration and subsequent cross-coupling. Extensive analysis of the size and morphology of the palladium nanoparticles formed in situ showed that the zero-valent metal was surrounded by hydrophilic hydroxyl groups. EDX-TEM imaging studies using a prototype silicon drift detector provided insight into the problematic role of molecular oxygen in the system. This increased understanding of the catalyst deactivation allowed for the development of the cross-coupling methodology. A 250-12,000 fold increase in molar efficiency was observed when compared to related two-step protocols that use alternative feedstocks for the palladium-mediated synthesis of stilbenes. This work opens up a new research area in which the active catalyst is formed, stabilised and regenerated by a renewable sugar.
- Camp, Jason E.,Bousfield, Thomas W.,Dunsford, Jay J.,Adams, James,Britton, Joshua,Fay, Michael W.,Angelis-Dimakis, Athanasios
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supporting information
p. 3862 - 3874
(2018/09/29)
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- Facile synthesis of magnetic recyclable palladium-gold alloy nanoclusters catalysts PdAur/Fe3O4@LDH and its catalytic applications in Heck reaction
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A series of novel magnetic recyclable Pd–Au nanoclusters (NCs) catalysts x-PdAur/Fe3O4@LDH (x: Pd loading in wt%, r: Au/Pd molar ratio, LDH: layered double hydroxide, here refers the typical MgAl-LDH) were synthesized by a facile polyol reduction followed sol immobilization of PdAur–PVP on core@shell support Fe3O4@LDH. Systematic characterizations reveal that the obtained catalysts possess the honeycomb-like core@shell, and the ultrafine PdAu alloy nanoclusters with the size in 1.70–2.55 nm highly dispersed on the LDH nanoplates shell. The obtained catalysts 1.0-PdAur/Fe3O4@LDH (r: 0.11, 0.16 and 0.48) show higher Heck activity of iodobenzene with styrene than monomentallic ones, especially 1.0-PdAu0.16/Fe3O4@LDH displays the highest Heck activity under the optimal condition. Moreover, the catalysts can be applied for the Heck reaction of a variety of aryl halides with alkenes, and can be conveniently separated by an external magnet and reused ten runs without significant loss of activity.
- Li, Jin,Wang, Yajuan,Jiang, Shunwang,Zhang, Hui
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- Transition-Metal-Free Highly Chemoselective and Stereoselective Reduction with Se/DMF/H2O System
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A novel metal-free reduction system, in which H2Se (or HSe-) produced in situ from Se/DMF/H2O acts as the active reducing species, has been developed. By using water as an inexpensive, safe, and environmentally friendly surrogate as the hydrogen donor, this new reduction system incorporating Se/DMF/H2O displayed high selectivity and good activity in the reduction of α,β-unsaturated ketones and alkynes. Therefore, this reduction system has great potential to be a general and practical reduction methodology in organic transformation.
- Li, Hong-Chen,An, Cui,Wu, Ge,Li, Guo-Xing,Huang, Xiao-Bo,Gao, Wen-Xia,Ding, Jin-Chang,Zhou, Yun-Bing,Liu, Miao-Chang,Wu, Hua-Yue
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p. 5573 - 5577
(2018/09/12)
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- Towards environmentally friendlier Suzuki-Miyaura reactions with precursors of Pd-NHC (NHC = N-heterocyclic carbene) complexes
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The preparation of [NHC·H][Pd(η3-R-allyl)Cl2] complexes is disclosed and represents a facile, atom-economical, environmentally friendly and rapid synthesis. These palladates are immediate synthetic precursors to the well-known [Pd(NHC)(η3-R-allyl)Cl] complexes. Their activation leading to catalytically relevant species has been studied in the Suzuki-Miyaura reaction. The need for an activation step prior to the catalysis was examined. The reaction scope showcases its ease and breadth in terms of functional group tolerance. Electron-donating and electron-withdrawing aryl chlorides and bromides were coupled effectively as well as heteroatom-containing and sterically hindered aryl halides. The catalytic reaction was conducted in ethanol with a weak and inexpensive inorganic base.
- Zinser, Caroline M.,Warren, Katie G.,Meadows, Rebecca E.,Nahra, Fady,Al-Majid, Abdullah M.,Barakat, Assem,Islam, Mohammad S.,Nolan, Steven P.,Cazin, Catherine S. J.
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supporting information
p. 3246 - 3252
(2018/07/29)
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- Palladium-Catalyzed Reductive Coupling Reaction of Terminal Alkynes with Aryl Iodides Utilizing Hafnocene Difluoride as a Hafnium Hydride Precursor Leading to trans-Alkenes
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Herein, we describe a reductive cross-coupling of alkynes and aryl iodides by using a novel catalytic system composed of a catalytic amount of palladium dichloride and a promoter precursor, hafnocene difluoride (Cp2HfF2, Cp=cyclopentadienyl anion), in the presence of a mild reducing reagent, a hydrosilane, leading to a one-pot preparation of trans-alkenes. In this process, a series of coupling reactions efficiently proceeds through the following three steps: (i) an initial formation of hafnocene hydride from hafnocene difluoride and the hydrosilane, (ii) a subsequent hydrohafnation toward alkynes, and (iii) a final transmetalation of the alkenyl hafnium species to a palladium complex. This reductive coupling could be chemoselectively applied to the preparation of trans-alkenes with various functional groups, such as an alkyl group, a halogen, an ester, a nitro group, a heterocycle, a boronic ester, and an internal alkyne.
- Takahashi, Keita,Ogiwara, Yohei,Sakai, Norio
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supporting information
p. 809 - 814
(2018/03/13)
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