- Synthesis, structure and hydrogenation catalytic activity of 3,η2-ampy)(μ,η1:η2-PhC=CHPh)(CO)6(PPh3)2> (Hampy = 2-amino-6-methylpyridine)
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The compound 3,η2-ampy)(μ,η1:η2-PhC=CHPh)(CO)6(PPh3)2> (1) (ampy = 2-amino-6-methylpyridinate) has been prepared by reaction of 3,η2-ampy)(μ,η1:η2-PhC=CHPh)(CO)7(PPh3)> with triphenylphosphine at room temperature.However, the reaction of 3,η2-ampy)(CO)7(PPh3)2> with diphenylacetylene requires a higher temperature (110 deg C) and does not give complex 1 but the phenyl derivative 3,η2-ampy)(μ,η1:η2-PhC=CHPh)(μ-PPh2)(Ph)(CO)5(PPh3)> (2).The thermolysis of complex 1 (110 deg C) also gives complex 2 quantitatively.Both 1 and 2 have been characterized by X-ray diffraction methods.Complex 1 is a catalyst precursor for the homogeneous hydrogenation of diphenylacetylene to a mixture of cis- and trans-stilbene under mild conditions (80 deg C, 1 atm. of H2), although progressive deactivation of the catalytic species is observed.The dihydride 3,η2-ampy)(μ,η1:η2-PhC=CHPh)(CO)5(PPh3)2> (3), which has been characterized spectroscopically, is an intermediate in the catalytic hydrogenation reaction. Key words: Ruthenium; X-ray diffraction; Hydrogenation; Homogenous catalysis; Clusters; Phosphine
- Cabeza, Javier A.,Llamazares, Angela,Riera, Victor,Briard, Pierrette,Ouahab, Lahcene
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- Controllable synthesis of palladium nanoparticles and their catalytic abilities in Heck and Suzuki reactions
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The monodisperse palladium nanoparticles with the size of about 5.0 nm were prepared by the thermal decomposition of palladium acetylacetonate in the presence of oleylamine and borane tributylamine complex. The palladium nanoparticles were loaded on the a
- Li, Yong,Dai, Yu,Yang, Zhengyin,Li, Tianrong
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- Investigation of the Wittig reaction with electrogenerated bases: Influence of experimental conditions on the yield and stereochemistry
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The influence of experimental parameters on the yields and stereochemistry of the Wittig reaction was studied using the synthesis of stilbene initiated by different electrogenerated bases as a model reaction. Electrolyses were carried out in batch cells under different conditions, including constant potential or constant current with different electrode materials and using solvents of different polarity. It is shown that proper selection of experimental conditions in Wittig reactions allows a choice of stereoselectivity in the reactions and the optimization of yields.
- Bettencourt, Ana Paula,Freitas, Ana Maria,Montenegro, M. Irene
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- Influence of the Support on the Catalytic Characteristics of the Deposited Palladium in the Liquid-Phase Hydrogenation of Diphenylacetylene
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Palladium catalysts on various types of supports were studied in the liquid-phase hydrogenation of diphenylacetylene. Samples of Pd/SiO2–Al2O3, Pd/MgAl2O4, Pd/Al2O3, and Pd/TiO2 were characterized by the chemisorption of the CO and IR spectroscopy of adsorbed CO. The use of n-hexane as the solvent increases the reaction rate, which can be explained by the better solubility of hydrogen in the liquid phase. It is established that the acid–base properties of the support do not affect the activity and selectivity of the catalysts in the reaction under study. However, they alter the electronic state of palladium. According to the catalytic tests, Pd/TiO2 has the highest activity (turnover frequency) and selectivity to alkene. The comparison of the obtained catalytic data and the results of IR spectroscopy made it possible to conclude that this is due to the electron density redistribution between the palladium and TiOx particles, which is caused by the strong metal–support interaction.
- Bragina,Smirnova,Krivoruchenko,Markov,Baeva,Stakheev, A. Yu.
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- Synthesis and catalytic application of palladium nanoparticles supported on kaolinite-based nanohybrid materials
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Palladium nanoparticles (PdNPs) were deposited on the surface of the modified clay mineral, kaolinite. To improve compatibility, abundance and control of the size of the nanoparticles, kaolinite was modified by the grafting of an amino alcohol (triethanol
- Ngnie, Gaelle,Dedzo, Gustave K.,Detellier, Christian
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- THE PETERSON REACTION, PART I, THE EFFECT OF REACTION CONDITIONS AND STERIC CROWDING
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The diastereoisomeric ratio of stilbenes formed in the Peterson reaction of PhCHSiR3(-) with PhCHO is shown to be insensitive to medium effects and temperature, but varies significantly as the bulk of SiR3 increases.
- Bassindale, Alan R.,Ellis, Richard J.,Taylor, Peter G.
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- From 4-nitrotoluene and 4,4′-dinitrobibenzyl to: E -4,4′-dinitrostilbene: An electrochemical approach
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The dianions formed by the electroreduction of Z-O2NC6H4CHCHC6H4NO2, E-O2NC6H4CHCHC6H4NO2, O2NC6H4CH2-CH2C6H4NO2 or O2NC6H4CMeH-CMeHC6H4NO2, as well as the anion radical arising from 4-nitrotoluene, are stable, in the time scale of cyclic voltammetry (DMF + 0.10 M NBu4BF4). However, in the electrolysis time scale (from minutes to hours), only the dianion O2NC6H4CMeH-CMeHC6H4NO22- remains stable, since the reduced species, Z-O2NC6H4CHCHC6H4NO22-, O2NC6H4CH2-CH2C6H4NO22- or O2NC6H4Me-, evolve to form the E-O2NC6H4CHCHC6H4NO22- dianion. This intermediate is recovered as the neutral species E-O2NC6H4CHCHC6H4NO2 with concomitant water reduction after the work-up with water, as demonstrated by combined electrolysis, cyclic voltammetry experiments, UV-spectroelectrochochemistry and theoretical calculations. Bulk electrolysis under optimized conditions (ACN + 0.10 M NBu4BF4) provides 40% and 67% isolated yields of E-4,4′-dinitrostilbene from 4-nitrotoluene and 4,4′-dinitrobibenzyl, respectively.
- Gallardo, Iluminada,Gómez, Ana Belén,Guirado, Gonzalo,Lari?o, Adrián,Moreno, Miquel,Ortigosa, Manuel,Soler, Sergio
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- Addition of Diazoalkanes to Enynes Promoted by a Ruthenium Catalyst: Simple Synthesis of Alkenyl Bicyclo[3.1.0]hexane Derivatives
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[C*pRuCl(cod)] (C*p=C5Me 5, cod=cyclooctadiene) promotes the reaction of 1,6-enynes with an excess of diazoalkane in dioxane in one step to afford selectively 1-alkenyl bicyclo[3.1.0]hexane derivatives (see scheme, X=O, NTs; Y=CO2Et; R1=H, Me; R2=H; Ts=p-toluenesulfonyl). This novel reaction involves the stereoselective formation of three C-C bonds and a cyclopropanation step.
- Monnier, Florian,Castillo, Dante,Derien, Sylvie,Toupet, Loic,Dixneuf, Pierre H.
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- Isolated, well-defined organovanadium(III) on silica: Single-site catalyst for hydrogenation of alkenes and alkynes
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A well-defined, isolated, single-site organovanadium(iii) catalyst on SiO2 [(SiO2)V(Mes)(THF)] was synthesized via surface organometallic chemistry, and fully characterized using a combination of analytical and spectroscopic techniques (EA, ICP, 1H NMR, TGA-MS, EPR, XPS, DR-UV/Vis, UV-Raman, DRIFTS, XAS). The catalyst exhibits unprecedented reactivity in liquid-and gas-phase alkene/alkyne hydrogenation. Kinetic poisoning experiments revealed that 100% of the V sites are active for hydrogenation.
- Sohn,Camacho-Bunquin,Langeslay,Ignacio-De Leon,Niklas,Poluektov,Liu,Connell,Yang,Kropf,Kim,Stair,Ferrandon,Delferro
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- Catalytic investigations of carbon-carbon bond-forming reactions by a hydroxyapatite-bound palladium complex
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A new type of hydroxyapatite-bound palladium complex (PdHAP-1) was synthesized by treatment of a nonstoichiometric Ca-deficient hydroxyapatite, Ca9(HPO4)(PO4)5(OH), with PdCl 2(PhCN)2 in ac
- Mori, Kohsuke,Hara, Takayoshi,Oshiba, Michitaka,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
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- Stable functionalized phosphorenes with photocatalytic HER activity
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Phosphorene, a mono-elemental 2D material of phosphorus, can catalyze the hydrogen evolution reaction (HER) owing to the suitable position of its conduction band minimum but the ambient instability of phosphorene is the major challenge for its application. We have functionalized phosphorene with indium(iii) chloride, tris(pentafluorophenyl) borane and a benzyl group. The functionalized phosphorenes show stability under ambient conditions as well as good dispersibility in water and exhibit hydrogen yields as high as 6597 μmol h-1 g-1. The HER activity of the functionalized phosphorenes is much superior compared to pristine phosphorene and black phosphorus-based catalysts reported earlier.
- Vishnoi, Pratap,Gupta, Uttam,Pandey, Richa,Rao
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- Mesoporous soot-supported palladium as a heterogeneous catalyst for the Heck reaction in ionic liquids
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The Heck reaction between bromobenzene and styrene in the ionic liquid catalyzed by ultrafine particles of palladium metal supported onto hydrophylized mesoporous soot follows a true heterogeneous mechanism.
- Aslanov, Leonid A.,Kabachii, Yury A.,Kochev, Sergey Yu.,Romanovsky, Boris V.,Valetsky, Petr M.,Volkov, Vladimir V.,Yatsenko, Alexander V.,Zakharov, Valery N.
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- Adsorption-Induced Segregation as a Method for the Target-Oriented Modification of the Surface of a Bimetallic Pd–Ag Catalyst
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The effect of palladium segregation was studied which resulted from the effect of CO and O2 on the surface structure and catalytic characteristics of the Pd–Ag2/Al2O3 catalyst. The IR-spectroscopic study of adsorbed CO showed that Pd1 centers isolated from each other by silver atoms predominated on the surface of reduced Pd–Ag2/Al2O3, as evidenced by the almost complete absence of absorption bands typical for the multicentred CO adsorption. In the course of catalyst treatment with CO and O2, the intensity of absorption bands characteristic of the multicenter CO adsorption considerably increased due to the transformation of a portion of monatomic Pd1 centers into multiatomic Pdn ones as a result of the surface segregation of Pd. In this case, a substantial increase in the catalyst activity in the liquid-phase hydrogenation of diphenylacetylene was observed. It was established that, after treatment with CO, the catalyst selectivity for the formation of a target olefin (stilbene) remained almost constant, whereas the treatment with O2 led to a decrease in the selectivity because of more considerable surface modification.
- Stakheev, A. Yu.,Smirnova,Markov,Baeva,Bragina,Rassolov,Mashkovsky
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- PdZn/α-Al2O3 catalyst for liquid-phase alkyne hydrogenation: effect of the solid-state alloy transformation into intermetallics
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The complex characterization of a PdZn /Al2O3 catalyst by XPS, XRD, TEM and H2-TPD techniques revealed the route of solid-state alloy → intermetallics transformation. The influence of this transformation on the performance of PdZn /Al2O3 in the liquid-phase hydrogenation of diphenylacetylene was estimated.
- Mashkovsky, Igor S.,Markov, Pavel V.,Bragina, Galina O.,Baeva, Galina N.,Rassolov, Aleksandr V.,Bukhtiyarov, Andrey V.,Prosvirin, Igor P.,Bukhtiyarov, Valery I.,Stakheev, Aleksandr Yu.
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- Thorough examination of a Wittig-Horner reaction using reaction calorimetry (RC-1), LabMax, and ReactIR
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The kinetics and thermodynamics of a Wittig-Horner reaction was investigated, together with side reactions such as the hydrolysis of benzyi phosphonate. It was found that the water content in the reaction mass has a crucial effect on the rates both of the unwanted hydrolysis of the phosphonate and of the main reaction. The reaction was found to be fourth-order. That means that the reaction is very fast at the start but tails off towards the end. On the basis of the kinetic and thermodynamic parameters, a simulation of the whole process was made, including the expected concentrations of the product under the required conditions (temperature, reactor characteristics, etc.). The experimental values of the concentrations were obtained from spectra collected via a rapid reaction mode in the ReactIR (a spectrum was collected every ~3 s). Exact agreement between experimental and theoretical values confirms the correctness of the mathematical model and enables right planning of the industrial process.
- Grabarnick, Michael,Zamir, Sharona
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- Liquid-Phase Hydrogenation of Internal and Terminal Alkynes on Pd–Ag/Al2O3 Catalyst
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Abstract: The structure and catalytic properties of a bimetallic Pd–Ag/α-Al2O3 catalyst are studied in the liquid-phase hydrogenation of substituted internal and terminal alkynes using diphenylacetylene, phenylacetylene, 1-phenyl-1-propyne, and 1-phenyl-1-butyne as sample alkynes. IR spectroscopy of adsorbed CO, X?ray diffraction (XRD), and electron microscopy were used to show that the active sites on the Pd–Ag nanoparticle surface are Pd1 sites. The synthesized Pd–Ag/α-Al2O3 catalyst shows a much higher selectivity in the hydrogenation of internal symmetric and asymmetric alkynes compared to the monometallic Pd/α?Al2O3 sample. Also, it was found in the hydrogenation of diphenylacetylene and 1-phenyl-1-propyne on Pd–Ag/α-Al2O3 that the rate of the stage of desired olefin hydrogenation substantially decreases, which favors the kinetic control of the process.
- Rassolov,Bragina,Baeva,Smirnova,Kazakov,Mashkovsky,Stakheev, A. Yu.
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- Cobalt-Catalyzed Redox-Neutral Sulfonylative Coupling from (Hetero)aryl Boronic Acids, Ammonium Salts and Potassium Metabisulfite
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An efficient cobalt-catalyzed redox-neutral sulfonylative coupling to afford (hetero)aryl alkyl sulfones from boronic acids, ammonium salts and potassium metabisulfite has been realized. Commercially available and air-stable CoCl2, in combination with phenanthroline ligand, is sufficient to achieve rapid and high-yielding conversion of the reactants into the corresponding sulfones. This practical transformation proceeds smoothly through C?N bond cleavage under redox-neutral catalytic conditions and shows broad functional-group tolerance. Other carbon based electrophiles, including diaryliodonium salts, heteroaryl halides, and carbonates were compatible. Further transformation of aryl alkyl sulfones then allows conversion into olefins, alkenyl sulfones and halogenated sulfones, respectively, in a one-pot process.
- Zhang, Yingying,Zhu, Haibo,Fan, Qiangwen,Yang, Liu,Xie, Zongbo,Le, Zhang-Gao
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- Kinetics of liquid-phase diphenylacetylene hydrogenation on “single-atom alloy” Pd-Ag catalyst: Experimental study and kinetic analysis
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Catalytic performance of Pd1Ag3/Al2O3 single-atom alloy (SAA) catalyst was studied in liquid-phase hydrogenation of diphenylacetylene (DPA) and compared with the performance of the reference monometallic Pd/Al2O3. Formation of SAA structure in Pd1Ag3/Al2O3 was confirmed by FTIR CO technique. It was found that Pd1Ag3/Al2O3 single-atom alloy catalyst exhibits excellent selectivity in diphenylethene (stilbene) (ca. 98 %), which remains constant over a wide range of DPA conversions (0–95%), while over Pd/Al2O3 selectivity decreases steadily with the increase in DPA conversion. It is remarkable that the selectivity of Pd1Ag3/Al2O3 depends neither on hydrogen pressure (5–15 bar), nor on DPA concentration (0.0262 – 0.159 mol/l). In contrast, over the reference Pd/Al2O3 selectivity tends to decrease with increasing P(H2) and decreasing DPA concentration. The proposed reaction network comprises hydrogenation of DPA in a parallel formation of cis and trans-stilbene with following hydrogenation to bibenzyl and direct formation of the latter from the initial DPA. The calculations clearly shows the capability of the kinetic model to describe the experimental dependencies for Pd1Ag3 single-atom catalyst in an excellent way with the degree of explanation equal to ca. 99 %.
- Rassolov, Alexander V.,Mashkovsky, Igor S.,Bragina, Galina O.,Baeva, Galina N.,Markov, Pavel V.,Smirnova, Nadezhda S.,W?rn?, Johan,Stakheev, Alexander Yu.,Murzin, Dmitry Yu.
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- Heterometallic Mg?Ba Hydride Clusters in Hydrogenation Catalysis
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Reaction of a MgN“2/BaN”2 mixture (N“=N(SiMe3)2) with PhSiH3 gave three unique heterometallic Mg/Ba hydride clusters: Mg5Ba4H11N”7 ? (benzene)2 (1), Mg4Ba7H13N“9 ? (toluene)2 (2) and Mg7Ba12H26N”12 (3). Product formation is controlled by the Mg/Ba ratio and temperature. Crystal structures are described. While 3 is fully insoluble, clusters 1 and 2 retain their structures in aromatic solvents. DFT calculations and AIM analyses indicate highly ionic bonding with Mg?H and Ba?H bond paths. Also unusual H????H? bond paths are observed. Catalytic hydrogenation with MgN“2, BaN”2 and the mixture MgN“2/BaN”2 has been studied. Whereas MgN“2 is only active in imine hydrogenation, alkene and alkyne hydrogenation needs the presence of Ba. The catalytic activity of the MgN”2/BaN“2 mixture lies in general between that of its individual components and strong cooperative effects are not evident.
- Wiesinger, Michael,Knüpfer, Christian,Elsen, Holger,Mai, Jonathan,Langer, Jens,Harder, Sjoerd
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p. 4567 - 4577
(2021/09/09)
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- Pd?Zn Alloy Nanoparticles Encapsulated into Mesoporous Silica with Confinement Effect for Highly Selective Semi-Hydrogenation of Phenylacetylene
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In the process of hydrogenation of phenylacetylene to styrene, it is a crucial step to improve the reaction selectivity of the target product styrene. Herein, we have designed the Pd?Zn alloy nanoparticles encapsulated into mesoporous silica with confinement effect (Pd?Zn@MS) for highly selective semi-hydrogenation of phenylacetylene via annealing the Pd NPs@ZIF-8 in reducing atmosphere. The as-obtained Pd?Zn@MS achieved up to the 95 % of conversion rate and 92 % of selectivity, because the mesoporous silica exhibits a steric hindrance effect for the reactant molecular size, and the Pd?Zn alloy nanoparticles shows the high selectivity for the target product styrene. DFT calculations demonstrates that the PdZn alloy nanoparticles can reduce significantly the desorption energy barrier of styrene from 1.72 eV to 0.95 eV, compared with the Pd nanoparticles. Meanwhile the mesoporous silica in the outer layer greatly guarantees the stability of the catalytic performance of the catalyst, and the catalytic performance did not drop after the five-cycle test. This work provides a new idea for the selective hydrogenation of phenylacetylene and the process of limited-area catalysis.
- Li, Zhenxing,Hu, Mingliang,Liu, Bowen,Liu, Jiahao,Wang, Ping,Yao, Jiasai,Zhang, Xin,He, Miao,Song, Weiyu
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p. 868 - 873
(2020/10/23)
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- Highly selective semi-hydrogenation of alkynes with a Pd nanocatalyst modified with sulfide-based solid-phase ligands
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Soluble small molecular/polymeric ligands are often used in Pd-catalyzed semi-hydrogenation of alkynes as an efficient strategy to improve the selectivity of targeted alkene products. The use of soluble ligands requires their thorough removal from the reaction products, which adds significant extra costs. In the paper, commercially available, inexpensive, metallic sulfide-based solid-phase ligands (SPL8-4 and SPL8-6) are demonstrated as simple yet high-performance insoluble ligands for a heterogeneous Pd nanocatalyst (Pd@CaCO3) toward the semi-hydrogenation of alkynes. Based on the reactions with a range of terminal and internal alkyne substrates, the use of the solid-phase ligands has been shown to markedly enhance the selectivity of the desired alkene products by efficiently suppressing over-hydrogenation and isomerization side reactions, even during the long extension of the reactions following full substrate conversion. A proper increase in the dosage or a reduction in the average size of the solid-phase ligands enhances such effects. With their insoluble nature, the solid-phase ligands have the distinct advantage in their simple, convenient recycling and reuse while without contaminating the products. A ten-cycle reusability test with the SPL8-4/Pd@CaCO3 catalyst system confirms its well-maintained activity and selectivity over repeated uses. A mechanistic study with x-ray photoelectron spectroscopy indicates that the solid-phase ligands have electronic interactions with Pd in the supported catalyst, contributing to inhibit the binding and further reaction of the alkene products. This is the first demonstration of solid-phase ligands for highly selective semi-hydrogenation of alkynes, which show strong promise for commercial applications.
- Huang, Lingqi,Hu, Kecheng,Ye, Ganggang,Ye, Zhibin
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- A Bifunctional Copper Catalyst Enables Ester Reduction with H2: Expanding the Reactivity Space of Nucleophilic Copper Hydrides
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Employing a bifunctional catalyst based on a copper(I)/NHC complex and a guanidine organocatalyst, catalytic ester reductions to alcohols with H2 as terminal reducing agent are facilitated. The approach taken here enables the simultaneous activation of esters through hydrogen bonding and formation of nucleophilic copper(I) hydrides from H2, resulting in a catalytic hydride transfer to esters. The reduction step is further facilitated by a proton shuttle mediated by the guanidinium subunit. This bifunctional approach to ester reductions for the first time shifts the reactivity of generally considered "soft"copper(I) hydrides to previously unreactive "hard"ester electrophiles and paves the way for a replacement of stoichiometric reducing agents by a catalyst and H2.
- Kaicharla, Trinadh,Ngoc, Trung Tran,Teichert, Johannes F.,Tzaras, Dimitrios-Ioannis,Zimmermann, Birte M.
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supporting information
p. 16865 - 16873
(2021/10/20)
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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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- Synthesis, crystal structure, and catalytic activity of bridged-bis(N-heterocyclic carbene) palladium(II) complexes in selective Mizoroki-Heck cross-coupling reactions
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A series of three 1,3-propanediyl bridged bis(N-heterocyclic carbene)palladium(II) complexes (Pd-BNH1, Pd-BNH2, and Pd-BNH3), with + I effect order of the N-substituents of the ligand (isopropyl > benzyl > methoxyphenyl), was the subject of a spectroscopic, structural, computational and catalytic investigation. The bis(NHC)PdBr2 complexes were evaluated in Mizoroki-Heck coupling reactions of aryl bromides with styrene or acrylate derivatives and showed high catalytic efficiency to produce diarylethenes and cinnamic acid derivatives. The X-ray structure of the most active palladium complex Pd-BNH3 shows that the Pd(II) center is bonded to the two carbon atoms of the bis(N-heterocyclic carbene) and two bromide ligands in cis position, resulting in a distorted square planar geometry. The NMR data of Pd-BNH3 are consistent with a single chair-boat rigid conformer in solution with no dynamic behavior of the 8-membered ring palladacycle in the temperature range 25–120 °C. The catalytic activities of three Pd-bridged bis(NHC) complexes in the Mizoroki-Heck cross-coupling reactions were not found to have a direct correlation with +I effect order of the N-substituents of the ligand. However, a direct correlation was found between the DFT calculated absolute softness of the three complexes with their respective catalytic activity. The highest calculated softness, in the case of Pd-BNH3, is expected to favor the coordination steps of both the soft aryl bromides and alkenes in the Heck catalytic cycle.
- El Ali, Bassam,Fettouhi, Mohammed,Iali, Wissam,Mansour, Waseem,Suleiman, Rami
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- Synthesis of N-Heterocyclic Carbine Silver(I) and Palladium(II) Complexes with Acylated Piperazine Linker and Catalytic Activity in Three Types of C—C Coupling Reactions
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Two bis-imidazolium salts LH2·Cl2 and LH2·(PF6)2 with acylated piperazine linker and two N-heterocyclic carbene (NHC) silver(I) and palladium(II) complexes [L2Ag2](PF6)2 (1) and [L2Pd2Cl4] (2) were prepared. The crystal structures of LH2·Cl2 and 1 were confirmed by X-ray analysis. In 1, one 26-membered macrometallocycle was generated through two silver(I) ions and two bidentate ligands L. The catalytic activity of 2 was investigated in Sonogashira, Heck-Mizoroki and Suzuki-Miyaura reactions. The results displayed that these C—C coupling reactions can be smoothly carried out under the catalysis of 2.
- Liu, Qingxiang,Zhang, Xiantao,Zhao, Zhixiang,Li, Xinying,Zhang, Wei
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supporting information
p. 605 - 613
(2021/02/01)
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- Green and sustainable palladium nanomagnetic catalyst stabilized by glucosamine-functionalized Fe3O4@SiO2 nanoparticles for Suzuki and Heck reactions
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A novel magnetic and heterogeneous palladium-based catalyst stabilized by glucosamine-functionalized magnetic Fe3O4@SiO2 nanoparticle was synthesized. The strategy relies on the covalently bonding of glucosamine to cyanuric chloride-functionalized magnetic nanoparticles followed by complexation with palladium. The structure of magnetic nanocatalyst was fully determined by FT-IR, XRD, DLS, FE-SEM, TEM, ICP, UV-Vis, TGA, VSM, and EDX. The obtained results confirmed that the palladium nanoparticles stabilized by glucosamine immobilized onto the magnetic support exhibited high activity in cross-coupling reactions of Suzuki-Miyaura and Mizoroki-Heck. Various aryl halides were coupled with arylboronic acid (Suzuki cross-coupling reaction) and olefins (Heck reactions) under the green conditions to provide corresponding products in high to excellent yields. Interestingly, the catalyst can be easily isolated from the reaction media by magnetic decantation and can subsequently be applied for consecutive reaction cycles (at least seven times) with no notable reduction in the catalytic activity.
- Eslahi, Hassan,Sardarian, Ali Reza,Esmaeilpour, Mohsen
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- 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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- Si-Gly-CD-PdNPs as a hybrid heterogeneous catalyst for environmentally friendly continuous flow Sonogashira cross-coupling
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We have reported a waste-minimized protocol for the Sonogashira cross-coupling exploiting the safe use of a CPME/water azeotropic mixture and the utilization of a heterogeneous hybrid palladium catalyst supported onto a silica/β-cyclodextrin matrix in con
- Cravotto, Giancarlo,Ferlin, Francesco,Martina, Katia,Menzio, Janet,Sciosci, Daniele,Vaccaro, Luigi,Valentini, Federica
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supporting information
p. 7210 - 7218
(2021/09/28)
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- A New Nitrogen Pd(II) Complex Immobilized on Magnetic Mesoporous Silica: A Retrievable Catalyst for C–C Bond Formation
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Abstract: A new nitrogen ligand, i.e. 1,3-di-(o-aminophenoxy)-2-propyl propargyl ether (DPPE), has been synthesized and characterized. Magnetic mesoporous silica composite (MNP@SiO2-SBA) was obtained via embedding magnetite nano-particles (MNPs) between SBA-15 channels. DPPE palladium dichloride (MNP@SiO2-SBA-DPPE-Pd(II)) was then prepared via click chemistry and fully characterized. The activity and recyclability of supported magnetic Pd(II) catalyst were evaluated in Heck coupling reaction after optimizing the optimal reaction conditions including solvent, amount of catalyst, base and temperature. Aryl iodides and aryl bromides showed enhanced activity compared to those of aryl chlorides in the Heck reaction. The catalyst was easily separated magnetically, reused in five runs sequentially, and no significant loss of activity was observed. Graphic Abstract: [Figure not available: see fulltext.]
- Mousavi, Samira,Mansoori, Yagoub,Nuri, Ayat,Koohi-Zargar, Behzad
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p. 1923 - 1936
(2020/11/30)
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- Pd salen complex@CPGO as a convenient, effective heterogeneous catalyst for Suzuki–Miyaura and Heck–Mizoroki cross-coupling reactions
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A Pd(II) Schiff base complex supported on graphene oxide nanosheets (Pd(II) salen@CPGO) has been synthesized and characterized by FT-IR, ICP-AES, XRD, SEM/EDX and TEM. The synthesized nanocatalyst has been found to be an efficient heterogeneous catalyst for Suzuki–Miyaura and Heck–Mizoroki coupling reactions. Pd(II) salen@CPGO could be separated and recovered easily from the reaction mixture and recycled several times without a discernible decrease in its catalytic activity. The construction of a solid sheet-supported Pd catalyst would be expected to be a promising system to perform heterogeneous catalytic reactions.
- Ghabdian, Mahdieh,Nasseri, Mohammad Ali,Allahresani, Ali,Motavallizadehkakhky, Alireza
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p. 1713 - 1728
(2018/05/25)
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- Introduction of a Recyclable Basic Ionic Solvent with Bis-(NHC) Ligand Property and The Possibility of Immobilization on Magnetite for Ligand- and Base-Free Pd-Catalyzed Heck, Suzuki and Sonogashira Cross-Coupling Reactions in Water
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A new versatile and recyclable NHC ligand precursor has been developed with ligand, base, and solvent functionalities for the efficient Pd-catalyzed Heck, Suzuki and Sonogashira cross-coupling reactions under mild conditions. Furthermore, NHC ligand precursor was immobilized on magnetite and its catalytic activity was also evaluated towards the coupling reactions as a heterogeneous catalyst. The NHC ligand precursor was prepared with imidazolium functionalization of TCT followed by a simple ion exchange by hydroxide ions. However, the results revealed an excellent catalytic activity for the both homogeneous and heterogeneous catalytic systems. 1.52?g.cm?3 and 1194 cP was obtained for the density and viscosity of the NHC ligand precursor respectively. On the other hand, the heterogeneous type could be readily recovered from the reaction mixture and reused for several times while preserving its properties. Heterogeneous nature of the magnetic catalyst was studied by hot filtration, mercury poisoning, and three-phase tests. High to excellent yields were obtained for all entries for the both homogeneous and heterogeneous catalysts, which reflects the high consistency of the catalyst. Graphic Abstract: [Figure not available: see fulltext.]
- Min, Qingwang,Miao, Penghua,Chu, Deyu,Liu, Jinghan,Qi, Meijuan,Kazemnejadi, Milad
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p. 3030 - 3047
(2021/02/16)
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- Bis(NHC)-Pd-catalyzed one-pot competitive C-C*C-C, C-C*C-O, C-C*C-N, and C-O*C-N cross-coupling reactions on an aryl di-halide catalyzed by a homogenous basic ionic liquid (TAIm[OH]) under base-free, ligand-free, and solvent-free conditions
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Bis(NHC)-Pd-catalyzed competitive asymmetrical C-C*C-C, C-C*C-O, C-C*C-N, and O-C*C-N cross-coupling reactions were performedviathe one-pot strategy in the presence of a new ionic liquid, which played the roles of solvent, base, and ligand simultaneously. The ionic liquid was prepared based on a methyl imidazolium moiety with hydroxyl counter anionsviaa Hofmann elimination on a 1,3,5-triazine framework (TAIm[OH]). Pd ions could be efficiently coordinated through the bis(NHC)-ligand moiety in the ionic liquid. Based on differences in the competitive kinetics of C-C cross-coupling reactions (Heck, Suzuki, and Sonogashira) with C-N and C-O cross-coupling reactions, and also differences in the kinetics of aryl halides, the coupling reactions could be selectively performed with a low amount of by-products. The competitive cross-coupling reactions were thus performed with high selectivity under mild reaction conditions.
- Zhu, Yanfang,Xu, Guiyang,Kazemnejadi, Milad
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p. 11662 - 11671
(2021/07/11)
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- A new Pd(II)-supported catalyst on magnetic SBA-15 for C-C bond formation via the Heck and Hiyama cross-coupling reactions
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Magnetic mesoporous silica composite (MNP@SiO2-SBA) was obtained via embedding magnetite nanoparticles between SBA-15 channels. It was silylated with N-(3-(trimethoxysilyl)propyl)picolinamide (TMS-PCA) and then complexed with Pd(II). The obtained supported Pd(II) catalyst (MNP@SiO2-SBA-PCA) was characterized by conventional methods. The prepared magnetic catalyst showed high activity in the Heck and Hiyama reactions under optimal reaction conditions, including solvent, amount of catalyst, base, and temperature. Aryl bromides and iodides showed better results than aryl chlorides, and the catalyst exhibited noticeable stability and reused several times.
- Rahimi, Leila,Mansoori, Yagoub,Nuri, Ayat,Koohi-Zargar, Behzad,Esquivel, Dolores
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- Catalytic investigation of Pd(II) complexes over Heck–Mizoroki reaction: Tailored synthesis, characterization and density functional theory
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Tailored reaction of Schiff base ligands with palladium(II) chloride and imidazole afford three complexes of formula [Pd(II)(L)(imdz)2]Cl, which are L = 2-((E)-(p-lylimino)methyl)-6-methoxyphenol (complex 1), 2-methoxy-6-((E)-(phenylimine)methyl)phenol (complex 2) and 2-((E)-(4-chlorophenyl-imino)methyl)-6-methoxyphenol (complex 3). Compounds were characterized with elemental analysis, molar conductance, electronic spectroscopy, ESI-MS, FT-IR, TGA, 1H-NMR and 13C-NMR. Molecular structure and different quantum chemical parameters were calculated using the B3LYP basis set of density functional theory with the standard 6-311+G (d, 2p) level. The catalytic potential of 1-3 was examined over Heck-Mizoroki reaction and found in order of 1 > 2 > 3.
- Shukla, Satyendra N.,Gaur, Pratiksha,Bagri, Sanjay S.,Mehrotra, Ripul,Chaurasia, Bhaskar
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p. 269 - 282
(2021/05/06)
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- Pd Nanoparticles Stabilized on the Cross-Linked Melamine-Based SBA-15 as a Catalyst for the Mizoroki–Heck Reaction
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Mesoporous SBA-15 silicate with a high surface area was prepared by a hydrothermal method, successively modified by organic melamine ligands and then used for deposition of Pd nanoparticles onto it. The synthesized materials were characterized with infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), nitrogen physisorption, scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), nuclear magnetic resonance (NMR) and inductively coupled plasma (ICP-OES). The catalyst was effectively used in the Mizoroki–Heck coupling reaction of various reactants in the presence of an organic base giving the desired products in a short reaction time and with small catalysts loadings. The reaction parameters such as the base type, amounts of catalyst, solvents, and the temperature were optimized. The catalyst was easily recovered and reused at least seven times without significant activity losses. Graphic Abstract: [Figure not available: see fulltext.]
- Amiri, Mandana,Bezaatpour, Abolfazl,Mikkola, Jyri-Pekka,Murzin, Dmitry Yu.,Nuri, Ayat,Vucetic, Nemanja
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- Nickel/Cobalt-Catalyzed Reductive Hydrocyanation of Alkynes with Formamide as the Cyano Source, Dehydrant, Reductant, and Solvent
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A Ni/Co co-catalyzed reductive hydrocyanation of various alkynes was developed for the production of saturated nitriles. Hydrocyanic acid is generated in situ from safe and readily available formamide. Formamide played multiple roles as a cyano source, dehydrant, and reductant for the NiII pre-catalyst and vinyl nitriles, along with acting as the co-solvent in this reaction. Detailed mechanistic investigation supported a pathway via hydrocyanation of C≡C bond and the subsequent reduction of C=C bond. Wide substrate scope, the employment of a cheap and stable nickel salt as pre-catalyst, a safe cyano source and convenient experimental operation render this hydrocyanation practical for the laboratory synthesis of saturated nitriles. (Figure presented.).
- Zhang, Jin,Luo, Cui-Ping,Yang, Luo
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p. 283 - 288
(2020/12/01)
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- Ruthenium-Catalyzed Dehydrogenation Through an Intermolecular Hydrogen Atom Transfer Mechanism
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The direct dehydrogenation of alkanes is among the most efficient ways to access valuable alkene products. Although several catalysts have been designed to promote this transformation, they have unfortunately found limited applications in fine chemical synthesis. Here, we report a conceptually novel strategy for the catalytic, intermolecular dehydrogenation of alkanes using a ruthenium catalyst. The combination of a redox-active ligand and a sterically hindered aryl radical intermediate has unleashed this novel strategy. Importantly, mechanistic investigations have been performed to provide a conceptual framework for the further development of this new catalytic dehydrogenation system.
- Huang, Lin,Bismuto, Alessandro,Rath, Simon A.,Trapp, Nils,Morandi, Bill
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supporting information
p. 7290 - 7296
(2021/03/01)
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- Ruthenium-Catalyzed E-Selective Partial Hydrogenation of Alkynes under Transfer-Hydrogenation Conditions using Paraformaldehyde as Hydrogen Source
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E-alkenes were synthesized with up to 100 % E/Z selectivity via ruthenium-catalyzed partial hydrogenation of different aliphatic and aromatic alkynes under transfer-hydrogenation conditions. Paraformaldehyde as a safe, cheap and easily available solid hydrogen carrier was used for the first time as hydrogen source in the presence of water for transfer-hydrogenation of alkynes. Optimization reactions showed the best results for the commercially available binuclear [Ru(p-cymene)Cl2]2 complex as pre-catalyst in combination with 2,2-bis(diphenylphosphino)-1,1-binaphthyl (BINAP) as ligand (1 : 1 ratio per Ru monomer to ligand). Mechanistic investigations showed that the origin of E-selectivity in this reaction is the fast Z to E isomerization of the formed alkenes. Mild reaction conditions plus the use of cheap, easily available and safe materials as well as simple setup and inexpensive catalyst turn this protocol into a feasible and promising stereo complementary procedure to the well-known Z-selective Lindlar reduction in late-stage syntheses. This procedure can also be used for the production of deuterated alkenes simply using d2-paraformaldehyde and D2O mixtures.
- Fetzer, Marcus N. A.,Tavakoli, Ghazal,Klein, Axel,Prechtl, Martin H. G.
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p. 1317 - 1325
(2021/02/11)
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- Recyclable and reusable PdCl2(PPh3)2/PEG-400/H2O system for the hydrophenylation of alkynes with sodium tetraphenylborate
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A stable and efficient PdCl2(PPh3)2/PEG-400/H2O catalytic system for the hydrophenylation reaction of alkynes has been developed. In the presence of 3 mol% PdCl2(PPh3)2 and 2 equiv. of HOAc, the hydrophenylation of both terminal and internal alkynes with sodium tetraphenylborate proceeded smoothly in a mixture of PEG-400 and water at room temperature or 50 °C to afford a variety of phenyl-substituted alkenes in moderate to high yields. The isolation of the products was easily performed by extraction with petroleum ether, and the PdCl2(PPh3)2/PEG-400/H2O system could be readily recycled and reused six times without apparent loss of catalytic activity.
- Liu, Rong,Zhang, Tingli,Huang, Bin,Cai, Mingzhong
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p. 172 - 178
(2020/07/04)
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- Rhodium-Catalyzed Regioselective Hydroformylation of Alkynes to α,β-Unsaturated Aldehydes Using Formic Acid
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A rhodium-catalyzed hydroformylation of alkynes with formic acid was developed. The method provides α,β-unsaturated aldehydes in high yield and E-selectivity without the need to handle toxic CO gas.
- Fan, Chao,Hou, Jing,Chen, Yu-Jia,Ding, Kui-Ling,Zhou, Qi-Lin
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supporting information
p. 2074 - 2077
(2021/04/05)
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- Conjugate addition of acetal-derived benzyl radicals generated from low-valent titanium-mediated CO bond cleavage
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A new method for the generation of benzyl radicals from acetals via low-valent titanium-mediated homolytic CO bond cleavage is presented. The low cost and availability of the developed titanium reagent enable efficient access to α-alkoxy carbon radical species via the developed reaction.
- Suga, Takuya,Nakamura, Masaharu,Takada, Ryusei,Ukaji, Yutaka
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supporting information
p. 1258 - 1260
(2021/05/17)
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- A simple and efficientin situgenerated copper nanocatalyst for stereoselective semihydrogenation of alkynes
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Development of a simple, effective, and practical method for (Z)-selective semihydrogenation of alkynes has been considered necessary for easy-to-access applications at organic laboratory scales. Herein, (Z)-selective semihydrogenation of alkynes was achieved using a copper nanocatalyst which was generatedin situsimply by adding ammonia borane to an ethanol solution of copper sulfate. Different types of alkynes including aryl-aryl, aryl-alkyl, and aliphatic alkynes were selectively reduced to (Z)-alkenes affording up to 99% isolated yield. The semihydrogenation of terminal alkynes to alkenes and gram-scale applications were also reported. In addition to eliminating catalyst preparation, the proposed approach is simple and practical and serves as a suitable alternative method to the conventional Lindlar catalyst.
- Park, Byoung Yong,Lim, Taeho,Han, Min Su
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p. 6891 - 6894
(2021/07/19)
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- Cascade Reductive Friedel-Crafts Alkylation Catalyzed by Robust Iridium(III) Hydride Complexes Containing a Protic Triazolylidene Ligand
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The synthesis of complex molecules like active pharmaceutical ingredients typically requires multiple single-step reactions, in series or in a modular fashion, with laborious purification and potentially unstable intermediates. Cascade processes offer attractive synthetic remediation as they reduce time, energy, and waste associated with multistep syntheses. For example, triarylmethanes are traditionally prepared via several synthetic steps, and only a handful of cascade routes are known with limitations due to high catalyst loadings. Here, we present an expedient catalytic cascade process to produce triarylmethanes. For this purpose, we have developed a bifunctional iridium system as the efficient catalyst to build heterotriaryl synthons via reductive Friedel-Crafts alkylation from ketones, arenes, and hydrogen. The catalytically active species were generated in situ from a robust triazolyl iridium(III) hydride complex and acid and is composed of a metal-bound hydride and a proximal ligand-bound proton for reversible dihydrogen release. These complexes catalyze the direct hydrogenation of ketones at slow rates followed by dehydration. Appropriate adjustment of the conditions successfully intercepts this dehydration and leads instead to efficient C-C coupling and Friedel-Crafts alkylation. The scope of this cascade process includes a variety of carbonyl substrates such as aldehydes, (alkyl)(aryl)ketones, and diaryl ketones as precursor electrophiles with arenes and heteroarenes for Friedel-Crafts coupling. The reported method has been validated in a swift one-step synthesis of the core structure of a potent antibacterial agent. Excellent yields and exquisite selectivities were achieved for this cascade process with unprecedentedly low iridium loadings (0.02 mol %). Moreover, the catalytic activity of the protic system is significantly higher than that of an N-methylated analogue, confirming the benefit of the Ir-H/N-H hydride-proton system for high catalytic performance.
- Albrecht, Martin,Alshakova, Iryna D.
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p. 8999 - 9007
(2021/07/31)
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- N-Methylphenothiazine S-Oxide Enabled Oxidative C(sp2)–C(sp2) Coupling of Boronic Acids with Organolithiums via Phenothiaziniums
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Herein, we report the development of a transition-metal-free oxidative C(sp2)–C(sp2) coupling of readily available boronic acids and organolithiums via phenothiazinium ions. Various biaryl, styrene, and diene derivatives were obtained using this reaction system. The key to this process is N-methylphenothiazine S-oxide (PTZSO), which allows efficient conversion of boronic acids to phenothiazinium ions. The mechanism of phenothiazinium formation using PTZSO was investigated using theoretical calculations and experiments, which provided insight into the unique reactivity of PTZSO.
- Yoshida, Tatsuki,Honda, Yuki,Morofuji, Tatsuya,Kano, Naokazu
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p. 9664 - 9668
(2021/12/17)
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- Quaternary Phosphonium Carboxylates: Structure, Dynamics and Intriguing Olefination Mechanism
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We have earlier shown how the Wittig chemistry can be done using novel Eigenbase phosphonium carboxylate reagents. Here we discuss the phenomenon of ion pairing, their solution tautomerism, solid-state structure, and mechanistic aspects of olefination. The results point to a complex process involving unfamiliar H-bond-driven ion-pair equilibria followed by standard Wittig reaction steps.
- Müller-Bunz, Helge,Muldoon, Jimmy,Nikitin, Kirill,Vetter, Anna C.
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supporting information
(2022/01/12)
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- Amido PNP complexes of iridium: Synthesis and catalytic olefin and alkyne hydrogenation
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In situ lithiation of HN(o-C6H4PPh2)2 (H[1a]) or HN(o-C6H4PiPr2)2 (H[1b]) with nBuLi in THF at ?35°C followed by addition of [Ir(μ-Cl)(COD)]2 (COD = 1,5-cyclooctadiene) in toluene at ?35°C generates 5-coordinate [1a]Ir(η4-COD) (2a) or 4-coordinate [1b]Ir(η2-COD) (2b), respectively. Oxidative addition of N-H in H[1b] to [Ir(μ-Cl)(COD)]2 affords square pyramidal [1b]Ir(H)(Cl) (3b). Metathetical reaction of 3b with LiBHEt3 in the presence of 1 atm of H2 in toluene produces [1b]Ir(H)2 (4b). Both 2a and 4b are active for catalytic hydrogenation of olefins and alkynes under extremely mild conditions.
- Huang, Mei-Hui,Zou, Xue-Ru,Liang, Lan-Chang
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p. 353 - 360
(2019/12/24)
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- Catalytic Activity of a Zr MOF Containing POCOP-Pd Pincer Complexes
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A metal-organic framework assembled from POCOP-Pd pincer complex metallolinkers (1-PdBF4, Zr6O4(OH)4(L-PdMeCN)3(BF4)3, L = (2,6-(OPAr2)2C6H3, Ar = p-C6H4CO2-) has been generated via postsynthetic oxidative I-/BF4- ligand exchange with NOBF4. 1-PdBF4 catalyzes a range of organic transformations, including transfer hydrogenation of unsaturated organic substrates, terminal alkyne hydration, and intramolecular hydroarylation of alkynes. The homogeneous analogue, tBu4POCOP-PdBF4, shows poor catalytic activity for transfer hydrogenation and alkyne hydration and decomposes under the catalytic reaction conditions. Solubility limitations and catalyst deactivation pathways observed for the homogeneous pincer complex propound the advantages of using porous solid supports to immobilize organometallic species.
- Kassie, Abebu A.,Wade, Casey R.
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p. 2214 - 2221
(2020/07/06)
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- Alumina-Supported Palladium–Silver Bimetallic Catalysts with Single-Atom Pd1 Sites in the Liquid-Phase Hydrogenation of Substituted Alkynes
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Abstract: The catalytic characteristics of Pd–Ag/Al2O3 bimetallic catalysts with an Ag/Pd atomic ratio of 0.03–3.0 have been studied in the selective liquid-phase hydrogenation of diphenylacetylene and 1-phenyl-1-propyne. It has been found that an increase in the Ag/Pd ratio leads to a significant increase in selectivity, which, however, is accompanied by a decrease in the catalyst activity. Comparison with data of an earlier structural study suggests that an increase in selectivity observed with an increase in the Ag/Pd ratio to 0.5–1.0 is attributed to the following two factors: (1) the suppression of the formation of palladium hydride and (2) an increase in the fraction of “single-atom” Pd1 sites isolated from each other by Ag atoms on the surface of the Pd–Ag nanoparticles. An increase in the Ag/Pd value to 2.0–3.0 leads to a further increase in the selectivity, which exceeds the selectivity of a commercial Lindlar catalyst (Pd–Pb/CaCO3). In this case, the most probable cause of the high selectivity is the formation of the single-atom Pd1 sites on the surface of the Pd–Ag alloy and an increase in the stability of the structure.
- Rassolov,Bragina,Baeva,Mashkovsky,Stakheev, A. Yu.
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p. 869 - 878
(2020/12/31)
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- Method for preparing alkene compound from alkyne compound
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The invention belongs to the technical field of organic synthesis, and particularly relates to a method for preparing an alkene compound from an alkyne compound. The method comprises the following step: reacting an alkyne compound in the presence of a photocatalyst and alkali under illumination to obtain an alkene compound. A sacrificial agent used in the invention can be used as a reaction solvent. The preparation method provided by the invention can inhibit the over-reduction of the alkyne compound to obtain an alkene compound. The method has the advantages of mild reaction conditions and simple operation, and can efficiently and greenly synthesize an alkene compound.
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-
Paragraph 0061-0062
(2020/07/03)
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- Ruthenium-Catalyzed E-Selective Alkyne Semihydrogenation with Alcohols as Hydrogen Donors
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Selective direct ruthenium-catalyzed semihydrogenation of diaryl alkynes to the corresponding E-alkenes has been achieved using alcohols as the hydrogen source. The method employs a simple ruthenium catalyst, does not require external ligands, and affords the desired products in > 99% NMR yield in most cases (up to 93% isolated yield). Best results were obtained using benzyl alcohol as the hydrogen donor, although biorenewable alcohols such as furfuryl alcohol could also be applied. In addition, tandem semihydrogenation-alkylation reactions were demonstrated, with potential applications in the synthesis of resveratrol derivatives.
- Ekebergh, Andreas,Begon, Romain,Kann, Nina
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p. 2966 - 2975
(2020/03/04)
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- Accelerating Chemo- And Regioselective Hydrogenation of Alkynes over Bimetallic Nanoparticles in a Metal-Organic Framework
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Selective semihydrogenation of alkynes has been a long-term and significant target, yet it remains a great challenge. Herein, bimetallic nanoparticles in a metal-organic framework (MOF), i.e., CuPd&at;ZIF-8 composite, featuring a cubic CuPd core and a porous ZIF-8 shell, have been rationally fabricated for this end. Given the unique physicochemical properties, the Cu nanocubes can not only convert solar energy into heat to accelerate the reaction but also serve as the seed for in situ formation of Pd nanoparticles (NPs) on their external surface to regulate the chemoselectivity of Pd active sites. The additional growth of the MOF shell is helpful to stabilize the CuPd core and offer regioselectivity via the steric hindrance effect. Ammonia borane provides active hydrogen species to significantly boost the hydrogenation and ensure the high selectivity. As a result, the CuPd&at;MOF exhibits high efficiency, featuring a turnover frequency (TOF, 6799 min-1) of 5-105 times higher than that in previous reports, and high chemo- and regioselectivity toward the semihydrogenation of alkynes, in the presence of NH3BH3 as a hydrogen source, under visible-light irradiation at ambient temperature.
- Guan, Qiaoqiao,Jiang, Hai-Long,Li, Luyan,Lu, Junling,Yang, Qihao,Yang, Weijie,Yu, Shu-Hong
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p. 7753 - 7762
(2020/08/21)
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- Graphdiyne-based Pd single-Atom catalyst for semihydrogenation of alkynes to alkenes with high selectivity and conversion under mild conditions
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The development of efficient heterogeneous catalysts for alkyne hydrogenation with high activity and selectivity is highly desirable and yet remains a great challenge. Herein, a Pd single-Atom catalyst (Pds-GDY) is prepared using graphdiyne as support, and used in the semihydrogenation of alkynes. As a proof of concept, the Pds-GDY exhibits a high activity for the semihydrogenation of phenylacetylene under mild reaction conditions, with a TOF of 6290 h-1, and a selectivity of 99.3% at 100% conversion, both much higher than those of the counterparts comprising Pd nanoparticles (NPs), namely, PdNP1-GDY (with 2 nm Pd NPs) and PdNP2-GDY (with 12 nm Pd NPs). In addition, after the full conversion of phenylacetylene, Pds-GDY could still maintain a selectivity as high as 98.9% towards styrene, with almost no phenylethane produced even with a prolonged reaction time; in contrast, for PdNP1-GDY and PdNP2-GDY, within the same reaction time, the selectivity decreases dramatically to 66.6% and 8.5%, respectively. Infrared spectroscopy reveals that Pds-GDY features the weakest adsorption to styrene, which is responsible for its high performance. This work provides an effective strategy to rationally design Pd catalysts for semihydrogenation of alkynes to alkenes with desirable activity and selectivity. This journal is
- Lu, Tong-Bu,Lu, Xiu-Li,Si, Rui,Tang, Shang-Feng,Wang, Hong-Juan,Yin, Xue-Peng,Zhang, Chao
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supporting information
p. 20925 - 20930
(2020/11/02)
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- Stereoselective Rhodium-Catalyzed Isomerization of Stereoisomeric Mixtures of Arylalkenes
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A new efficient method for the synthesis of a high ratio of E -alkenes from E / Z mixtures of alkenes with B 2pin 2in the presence of a rhodium catalyst is described. This reaction features mild reaction conditions, broad functional group tolerance, and highly great application potential.
- Yang, Hongxuan,Dong, Wenke,Wang, Wencan,Li, Tao,Zhao, Wanxiang
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supporting information
p. 2833 - 2840
(2020/10/06)
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- Synthesis of a Cellulosic Pd(salen)-Type Catalytic Complex as a Green and Recyclable Catalyst for Cross-Coupling Reactions
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Abstract: A green recyclable cellulose-supported Pd(salen)-type catalyst was synthesized through sequential three steps: chlorination with thionyl chloride, modification by ethylenediamine, and the formation of Schiff base with salicylaldehyde to immobilize palladium chloride through multiple binding sites. This novel heterogeneous cellulosic Pd(salen)-type catalytic complex was fully characterized by FT-IR, SEM, TEM, XPS, ICP-AES and TG. The traditional cross-coupling chemistry, such as Suzuki, Heck, Sonogashira, Buchwald–Hartwig amination and etherification, was then investigated in the presence of the above cellulose-palladium nanoparticle. Studies have shown that the synthesized catalyst shows high activity and efficiency for all types of transformations, providing the corresponding carbon–carbon or carbon–heteroatom coupling products in a general and mild manner. Furthermore, the catalyst demonstrates high to excellent yields and is easily recycled by simple filtration for up to twelve cycles without any significant loss of catalytic activity. Graphic Abstract: [Figure not available: see fulltext.]
- Sun, Peng,Yang, Jiaojiao,Chen, Chunxia,Xie, Kaijun,Peng, Jinsong
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p. 2900 - 2910
(2020/03/31)
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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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- Design, Synthesis, Characterization and Application of BNPs@SiO2(CH2)3NH-CC-AMP-Pd (0) as a New Reusable Nano-Catalyst for Suzuki and Heck Cross-Coupling Reactions
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Abstract: A simple and effective method was used for the successful preparation of the Boehmite@(CH2)3NH-CC-AMP-Pd (0) NPs as an environmentally friendly heterogeneous nano-catalyst. The synthesized nano-catalyst was well identified by different techniques like FT-IR, XRD, XPS, TEM, SEM, EDX, TGA, mapping, and ICP analysis. The BNPs@SiO2(CH2)3NH-CC-AMP-Pd was used as a recoverable nano-catalyst for Suzuki‐Miyaura and Mizoroki‐Heck coupling reactions under mild, green and sustainable conditions with excellent yields (H2O, EtOH as solvent for Suzuki reaction and solvent-free conditions for Heck reaction). Also, the distribution of palladium on the catalyst surface is uniform and the average palladium size is between 20 and 30?nm. Compared to similar works, this protocol has some of the important aspects such as: thermal and mechanical stability of the catalyst, low palladium leaching (9.7%), the simplicity of the preparation, the availability of raw materials, not expensive, no need for neutral atmosphere, appropriate times, green conditions, use low amount of catalyst (1.42?mol%) and reused catalyst for several consecutive times (at least seven times). Graphic Abstract: [Figure not available: see fulltext.]
- Khodamorady, Minoo,Bahrami, Kiumars
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p. 1571 - 1590
(2019/12/11)
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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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- Fe3O4-Lignin@Pd-NPs: A highly efficient, magnetically recoverable and recyclable catalyst for Mizoroki-Heck reaction under solvent-free conditions
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Palladium nanoparticles (Pd-NPs) were synthesized under green conditions in water by chemical reduction of PdCl2 with NaOH and supported by Fe3O4-Lignin. Fe3O4-Lignin is an organic–inorganic hybrid core-shell was synthesized by sonication of a mixture of Fe3O4-NPs (20 nm) and alkali lignin. The new materials Fe3O4-Lignin and Fe3O4-Lignin@Pd-NPs were characterized by PXRD, SEM and FT-IR spectroscopy. The Fe3O4-Lignin@Pd-NPs was further confirmed by UV–Visible spectroscopy, TEM, EDX, HRICP-AES and TGA/DTA. The average size of Pd-NPs determined from PXRD was 5–10 nm. The amount of palladium loaded on Fe3O4-Lignin obtained from EDX analysis was 26.63percent by mass. The amount of Fe and Pd present in the catalyst obtained from HRICP-AES was 11.88 (wt. percent) and 10.90 (wt. percent) respectively per gram of lignin. The catalytic potential of Fe3O4-Lignin@Pd-NPs was evaluated in Mizoroki-Heck C-C coupling reaction. During the optimization studies of reaction between iodobenzene and n-butyl acrylate in various solvents and under solvent-free but aerobic conditions using various inorganic and organic bases, the product n-butyl 3-phenylprop-2-enoate (1a) obtained was as high as 95percent in highly polar solvents as short as in 10 min and 99percent under solvent-free conditions in 3 min at 140 °C using n-Pr3N as base. The scope of the above catalyst was investigated in the Mizoroki-Heck reaction of various aryl/heterocyclic halides and n-butyl acrylate/styrene under optimized solvent-less conditions. The corresponding products were obtained in high yields (73–99percent). The catalyst recovered by magnetic decantation was reused for five times in the C-C coupling reaction between iodobenzene and n-butyl acrylate which yielded 90–95percent of the desired product, 1a.
- Madrahalli Bharamanagowda, Marulasiddeshwara,Panchangam, Raghavendra Kumar
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- Promising new catalytic properties of a Co (II)-carboxamide complex and its derived Co3O4 nanoparticles for the Mizoroki-Heck and the Epoxidation reactions
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The new Co(II) - carboxamide complex (1) and Co3O4 nanoparticles (2), by way of thermal decomposition of (1) have been efficiently synthesised in the environment-friendly. X-ray diffraction reveals a slightly distorted octahedral coordination of cobalt (four nitrogens and two oxygens) in (1) and regular octahedral or tetrahedral ones (oxygens only) in (2). The investigation of (1) and (2) in the Mizoroki-Heck and epoxidation of alkens reactions showed them both to be powerful, green and inexpensive catalysts.
- Kiani, Mahsa,Bagherzadeh, Mojtaba,Meghdadi, Soraia,Fadaei-Tirani, Farzaneh,Babaie, Maryam,Schenk-Jo?, Kurt
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- Magnetically recoverable nanostructured Pd complex of dendrimeric type ligand on the MCM-41: Preparation, characterization and catalytic activity in the Heck reaction
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A palladium complex of a dendrimer type ligand of aminoethylacrylamide immobilized onto the mesoporous channels of MCM-41 with magnetic core was prepared and characterized using various techniques such as XRD, TEM, BET, FT-IR, TGA, and VSM. The prepared nanostructured material was found as a magnetically recoverable catalyst for Heck reaction of aryl halides and vinylic C-H. The catalyst is easily recoverable with an external magnet and is reusable with different leaching amounts depending to loading of Pd. A hot filtration test was also performed and gave evidence that Palladium in heterogeneous samples can dissolve and then redeposit on the surface of the support material.
- Abdollahi-Alibeik, Mohammad,Gharibpour, Najmeh,Ramazani, Zahra
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p. 184 - 199
(2020/11/19)
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- A new approach to large scale production of dimethyl sulfone: A promising and strong recyclable solvent for ligand-free Cu-catalyzed C-C cross-coupling reactions
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Dimethyl sulfone (DMSN) was easily prepared through efficient oxidation of dimethyl sulfoxide (DMSO) and used as a strong and green solvent for organic reactions. A mixture of HNO3/NaOCl was used as an oxidizing agent for efficient oxidation of DMSO to DMSN. The effect of DMSN was evaluated for copper-catalyzed coupling reactions. It is worth noting that DMSN could play the role of a ligand for copper ions. A general survey was accomplished for various types of C-C cross-coupling reactions catalyzed by CuI in DMSN in the absence of any ligand. Moderate to good yields were achieved for Sonogashira, Heck, and Suzuki cross-coupling reactions. Finally, DMSN was recovered and reused for several consecutive runs without any loss of its activity.
- Cheng, Shen,Wei, Wei,Zhang, Xingyu,Yu, Hewei,Huang, Mingming,Kazemnejadi, Milad
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p. 2069 - 2076
(2020/04/07)
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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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- 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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- Electrochemical oxidative decarboxylation and 1,2-aryl migration towards the synthesis of 1,2-diaryl ethers
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Carboxylic acid compounds are important chemicals and are widely present in various natural products. They are not only nucleophiles, but also radical precursors. Classic transition-metal-catalyzed and photochemical decarboxylation have shown their excellent site selectivity in radical chemistry. However, electrochemical decarboxylation with a long history hasn't got enough attention in recent years. In this work, the electrochemical oxidative decarboxylation and 1,2-aryl migration of 3,3-diarylpropionic acids have been introduced to construct C-O bonds with alcohols. Remarkably, this transformation can proceed smoothly without metal catalysts and external oxidants.
- Bu, Faxiang,Hu, Xia,Lei, Aiwen,Lu, Lijun,Wang, Shengchun,Zhang, Heng
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p. 10000 - 10004
(2020/10/06)
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- Influence of the N→Ru Coordinate Bond Length on the Activity of New Types of Hoveyda-Grubbs Olefin Metathesis Catalysts Containing a Six-Membered Chelate Ring Possessing a Ruthenium-Nitrogen Bond
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An efficient approach to the synthesis of new types of Hoveyda-Grubbs catalysts containing an N→Ru bond in a six-membered chelate ring is proposed. The synthesis of the organometallic compounds is based on the interaction of ready accessible 2-vinylbenzylamines and 1,3-bis(2,4,6-trimethylphenyl)-2-trichloromethylimidazolidine ligands with dichloro(3-phenyl-1H-inden-1-ylidene)bis(tricyclohexylphosphane)ruthenate, and it afforded the target ruthenium complexes in 70-80% yields. Areas of practical utility and potential applications of the obtained chelates were highlighted by tests of the catalysts in different olefin cross-metathesis (CM) and ring-closing-metathesis (RCM) reactions. These experiments revealed a high catalytic performance (up to 10-2 mol %) of all the synthesized structures in a broad temperature range. The structural peculiarities of the resultant ruthenium catalysts were thoroughly investigated by X-ray crystallography, which allowed making a reliable correlation between the structure of the metallo-complexes and their catalytic properties. It was proved that the bond length between ruthenium and nitrogen in the six-membered chelate ring has the greatest effect on the stability and efficiency of the catalyst. As a rule, the shorter and stronger the N→Ru bond, the higher the stability of the complex and the worse its catalytic characteristics. In turn, the coordination N→Ru bond length can be finely tuned and varied over a wide range of values by changing the steric volume of the cyclic substituents at the nitrogen atom, which will make it possible, as appropriate, to obtain in the future metal complexes with predictable stability and the required catalytic activity. Also, it was found that complexes in which the nitrogen atom is included in the morpholine or isoquinoline rings are the most efficient catalysts in this series. An attempt to establish a correlation between the N→Ru bond length and the 1H and 13C chemical shifts in the Ru═CH fragment has been made.
- Alekseeva, Kseniia A.,Antonova, Alexandra S.,Grigoriev, Mikhail S.,Kumandin, Pavel A.,Nikitina, Eugeniya V.,Novikov, Roman A.,Polyanskii, Kirill B.,Sinelshchikova, Anna A.,Vasilyev, Kirill A.,Zubkov, Fedor I.
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supporting information
p. 4599 - 4607
(2020/12/22)
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- Novel resveratrol derivatives have diverse effects on the survival, proliferation and senescence of primary human fibroblasts
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Resveratrol alters the cytokinetics of mammalian cell populations in a dose dependent manner. Concentrations above 25–50 μM typically trigger growth arrest, senescence and/or apoptosis in multiple different cell types. In contrast, concentrations below 10 μM enhance the growth of log phase cell cultures and can rescue senescence in multiple strains of human fibroblasts. To better understand the structural features that regulate these effects, a panel of 24 structurally-related resveralogues were synthesised and evaluated for their capacity to activate SIRT1, as determined by an ex-vivo SIRT1 assay, their toxicity, as measured by lactate dehydrogenase release, and their effects on replicative senescence in MRC5 human fibroblasts as measured by their effects on Ki67 immunoreactivity and senescence-associated β galactosidase activity. Minor modifications to the parent stilbene, resveratrol, significantly alter the biological activities of the molecules. Replacement of the 3,5-dihydroxy substituents with 3,5-dimethoxy groups significantly enhances SIRT1 activity, and reduces toxicity. Minimising other strong conjugative effects also reduces toxicity, but negatively impacts SIRT1 activation. At 100 μM many of the compounds, including resveratrol, induce senescence in primary MRC5 cells in culture. Modifications that reduce or remove this effect match those that reduce toxicity leading to a correlation between reduction in labelling index and increase in LDH release. At 10 μM, the majority of our compounds significantly enhance the growth fraction of log phase cultures of MRC5 cells, consistent with the rescue of a subpopulation of cells within the culture from senescence. SIRT1 activation is not required for rescue to occur but enhances the size of the effect.
- Birar, Vishal C.,Faragher, Richard G. A.,Ostler, Elizabeth L.,Sheerin, Angela N.
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p. 817 - 826
(2020/08/17)
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