- A study on applications of N-substituted main-chain NHC-palladium polymers as recyclable self-supported catalysts for the suzuki-miyaura coupling of aryl chlorides in water
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The preparation and characterization of a number of main-chain organometallic polymers (NHC-Pd MCOP) with different N-alkyl substituted groups such as benzyl (3a), n-hexyl (3b), and n-dodecyl (3c) are described. Among these polymers, 3c bearing the more lipophilic group n-dodecyl was found to be a more reactive and recoverable catalytic system in the Suzuki-Miyaura cross-coupling reaction of chloroarenes, including both deactivated and hindered aryl chlorides with different types of arylboronic acids under aqueous conditions. While the catalysts seem to be highly recyclable, on the contrary, we have provided much compelling evidence, such as kinetic monitoring, poisoning experiments, and average molecular weight determination before and after catalysis, that shows that the described organometallic polymers might be indeed the source of production of active soluble Pd species in the form of either Pd nanoparticles or fragmented NHC-Pd complexes. Our studies showed that in order to assess whether the catalysts are functioning in a heterogeneous pathway or they are simply a source of production of active Pd species, it is crucial to devise a suitable and highly efficient poison that could capture essentially soluble catalytic species. In this regard, we interestingly found that among a variety of well-known catalyst poisons such as Hg(0), SBA-15-PrSH, and cross-linked poly(4-vinylpyridine) (PVP), only PVP could efficiently quench catalysis, thus providing clear evidence of the formation soluble Pd species in our protocol. In addition, several experiments such as bright-field microscopy, dynamic light scattering (DLS) of the reaction mixture, and kinetic monitoring of the reaction at an early stage confirm not only that the described organometallic polymers could be a source of production of trace amounts of Pd nanoparticles but the capsular structures of these lipophilic polymers in water provides a means of entrapment of nanoclusters in a hydrophobic region, thus accelerating the reaction in pure water in the absence of any co-organic solvent.
- Karimi, Babak,Fadavi Akhavan, Pari
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- Palladium-Catalyzed Suzuki - Miyaura Cross-Couplings of Sulfonyl Chlorides and Boronic Acids
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(Equation presented) Arene-, arylmethane, and alk-2-ene-1-sulfonyl chlorides undergo Suzuki - Miyaura cross-coupling with arene-, heteroarene-, and alkeneboronic acids in THF at reflux. The reactivity order is Arl > ArSO2Cl > ArBr ? ArCl.
- Dubbaka, Srinivas Reddy,Vogel, Pierre
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- Pyridyl-supported pyrazolyl-N-heterocyclic carbene ligands and the catalytic activity of their palladium complexes in Suzuki-Miyaura reactions
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Palladium complexes of two new types of unsymmetrical pyridyl-supported pyrazolyl-N-heterocyclic carbene ligands were synthesized and structurally characterized. A strategy to release the steric strain of the ligand was realized by the introduction of methylene linkers to the ligand molecule. All the palladium complexes exhibited good to excellent catalytic activity in Suzuki-Miyaura reactions of phenyl or p-tolylboronic acid with aryl halides including iodobenzene, aryl bromides, and activated aryl chlorides under mild conditions, revealing that the new ligands are promising for the construction of highly active transition-metal catalysts.
- Zeng, Fanlong,Yu, Zhengkun
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- Amide-ligand-controlled highly para-selective arylation of monosubstituted simple arenes with arylboronic acids
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Pd-catalyzed highly para-selective arylations of monosubstituted simple arenes with arylboronic acids to widely existed biaryls have been developed. Inspired by requisite amide-directing groups in reported selective oxidative couplings, amide ligands, especially DMF, are designed and found to be critical for the selectivity control in current arylations.
- Luan, Yu-Xin,Zhang, Tao,Yao, Wei-Wei,Lu, Ke,Kong, Lu-Yao,Lin, Yu-Tong,Ye, Mengchun
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- Microwave-assisted organic acid-base-co-catalyzed tandem Meinwald rearrangement and annulation of styrylepoxides
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A novel organic acid-base-co-catalyzed conversion of styrylepoxides into [1,1′-biaryl]-3-carbaldehydes was realized under microwave irradiation. Styrylepoxides first underwent an acid-catalyzed Meinwald rearrangement followed by a tandem base-catalyzed Michael addition, aldol addition, and aromatization sequence to generate [1,1′-biaryl]-3-carbaldehydes.
- Shi, Yi,Li, Siqi,Lu, Yang,Zhao, Zizhen,Li, Pingfan,Xu, Jiaxi
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p. 2131 - 2134
(2020/02/27)
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- Base-Free Suzuki–Miyaura Coupling Reaction Using Palladium(II) Supported Catalyst in Water
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Abstract: The carbon–carbon bond formation via Suzuki–Miyaura reaction was performed in water as green solvent. Pd(OAc)2(PPh3)2 supported on magnesium hydroxide and cerium carbonate hydroxide composite was prepared and characterized by various techniques. The cross-coupling reaction of aryl halides carried out in water using mild conditions. The effects of temperature, solvents, the amount of catalyst and leaving groups were studied to find the optimization conditions for cross-coupling reaction. Various aryl halides were smoothly transformed into the biaryls in good yields. In addition, the catalyst also exhibited stability and catalytic performance in the cross-coupling of aryl halides. Graphical Abstract: [Figure not available: see fulltext.] A new approach is developed for carbon–carbon bond formation via Suzuki–Miyaura reaction.2 Pd(OAc)2(PPh3)2?supported on mixed magnesium hydroxide and cerium carbonate hydroxide were prepared and characterized by XRD, XPS, SEM–EDX techniques. The cross-coupling reaction of aryl halides can be carried out in water and under mild conditions (80 °C).
- Tomar, Ravi,Singh, Nidhi,Kumar, Neeraj,Tomar, Vartika,Chandra, Ramesh
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- Functionalised [(NHC)Pd(allyl)Cl] complexes: Synthesis, immobilisation and application in cross-coupling and dehalogenation reactions
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A novel NHC–palladium(II) (NHC?=?N-heterocyclic carbene) complex and its immobilised version have been prepared and fully characterised. Optimisation studies led to good catalytic activities in Suzuki-Miyaura cross coupling and chloroarene dehalogenation reactions. Furthermore, the unexpected palladium-mediated transfer hydrogenation of a carbonyl compound is reported.
- Collinson, John-Michael,Wilton-Ely, James D.E.T.,Díez-González, Silvia
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- Probing the Azaaurone Scaffold against the Hepatic and Erythrocytic Stages of Malaria Parasites
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The potential of azaaurones as dual-stage antimalarial agents was investigated by assessing the effect of a small library of azaaurones on the inhibition of liver and intraerythrocytic lifecycle stages of the malaria parasite. The whole series was screened against the blood stage of a chloroquine-resistant Plasmodium falciparum strain and the liver stage of P. berghei, yielding compounds with dual-stage activity and sub-micromolar potency against erythrocytic parasites. Studies with genetically modified parasites, using a phenotypic assay based on the P. falciparum Dd2-ScDHODH line, which expresses yeast dihydroorotate dehydrogenase (DHODH), showed that one of the azaaurone derivatives has the potential to inhibit the parasite mitochondrial electron-transport chain. The global urgency in finding new therapies for malaria, especially against the underexplored liver stage, associated with chemical tractability of azaaurones, warrants further development of this chemotype. Overall, these results emphasize the azaaurone chemotype as a promising scaffold for dual-stage antimalarials.
- Carrasco, Marta P.,Machado, Marta,Gon?alves, Lídia,Sharma, Moni,Gut, Jiri,Lukens, Amanda K.,Wirth, Dyann F.,André, Vania,Duarte, Maria Teresa,Guedes, Rita C.,dos Santos, Daniel J. V. A.,Rosenthal, Philip J.,Mazitschek, Ralph,Prudêncio, Miguel,Moreira, Rui
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supporting information
p. 2194 - 2204
(2016/10/19)
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- Design and synthesis of natural product derivatives with selective and improved cytotoxicity based on a sesquiterpene scaffold
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Brasilamide E (1) is a bisabolane sesquiterpenoid isolated from the solid-substrate fermentation cultures of a plant endophytic fungus Paraconiothyrium brasiliense. The compound specifically inhibited proliferation of the MCF-7 cells, but did not show cyt
- Zhang, Yang,Zhang, Zhuowei,Wang, Bo,Liu, Ling,Che, Yongsheng
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supporting information
p. 1885 - 1888
(2016/04/05)
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- Palladium Supported on Graphitic Carbon Nitride: An Efficient and Recyclable Heterogeneous Catalyst for Reduction of Nitroarenes and Suzuki Coupling Reaction
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In this study, a novel platelet-like nanocatalyst, Pd/g-C3N4 with easily approachable active sites, was developed. The mesoporous graphitic carbon nitride (g-C3N4) is a layered structure connected by planar amino groups, which can work as stabilizer and active support for noble metal nanoparticles. The palladium nanoparticles with an average particle size of 3.25 nm were evenly dispersed on the surface of g-C3N4 without aggregation. Detailed charaterizations reveal that there is no covalent-bond interaction between g-C3N4 and Pd NPs. The Pd/g-C3N4 catalyst showed excellent catalytic activity in the reduction of nitroarenes by NaBH4, and Suzuki coupling reaction of aryl halides with arylboronic acids under mild conditions. The reduction of 4-nitrophenol has a pseudo-first-order rate constant of 7.29 × 10-3 s-1, and an activity parameter of 1.37 s-1 mM-1, which is higher than those reported in the literature. Furthermore, the Suzuki coupling reactions processed smoothly with 97.0 % isolate yield in less than 30 min in water with PEG600 as the additive. The catalyst could be recycled for five times without significant loss of catalytic activity, which confirmed the good stability of the catalyst. Graphical Abstract: [Figure not available: see fulltext.]
- Zhao, Yukai,Tang, Ruiren,Huang, Rong
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p. 1961 - 1971
(2015/12/24)
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- Suzuki-miyaura cross-coupling under solvent-free conditions
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A solvent-free reaction protocol for Suzuki-Miyaura cross-couplings was developed. (Hetero)aryl bromides and chlorides are coupled with pinacol arylboronates in high yields. The reaction is catalyzed by conventional bis(triphenylphosphine)palladium(II) chloride [(PPh3) 2PdCl2] and/or palladium(II) acetate/SPhos [Pd(OAc) 2/SPhos] under air. Copyright
- Asachenko, Andrey F.,Sorochkina, Kristina R.,Dzhevakov, Pavel B.,Topchiy, Maxim A.,Nechaev, Mikhail S.
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p. 3553 - 3557
(2014/01/06)
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- "Click" magnetic nanoparticle-supported palladium catalyst: A phosphine-free, highly efficient and magnetically recoverable catalyst for Suzuki-Miyaura coupling reactions
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A novel magnetic nanoparticle-supported nano-palladium catalyst was successfully prepared via a "click" route. The as-prepared catalyst was well characterized and evaluated in Suzuki-Miyaura coupling in terms of activity and recyclability in aqueous ethanol. It was found to be highly efficient for the reactions of various aryl bromides with arylboronic acids under phosphine-free and low Pd loading (0.2 mol%) conditions. Moreover, the catalyst could be easily separated from the reaction system by an external magnet and reused several times without a remarkable loss of its activity. The Royal Society of Chemistry 2013.
- Zhang, Qiang,Su, Hong,Luo, Jun,Wei, Yunyang
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p. 235 - 243
(2013/03/29)
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- Ordered mesoporous organosilica with ionic-liquid framework: Au efficient and reusable support for the palladium-catalyzed suzuki-miyaura coupling reaction in water
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The preparation of a novel palladium-supported periodic mesoporous organosilica based on alkylimidazolium ionic liquid (Pd@PMO-IL) in which imidazoilium ionic liquid is uniformly distributed in the silica mesoporous framework is described. Both Pd@PMO-IL and the parent PMO-IL were characterized by N2-adsorptiondesorption, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), TEM, and solid-state NMR spectroscopy. We have demonstrated that Pd@PMO-IL is an efficient and reusable catalyst for the Suzuki-Miyaura coupling reaction of various types of iodo-, bromo-, and even deactivated aryl chlorides in water. It was also found that although the PMO-IL nanostructure acts as reservoir for soluble Pd species, it can also operate as a nanoscaffold to recapture the Pd nanoparticles into the mesochannels thus preventing extensive agglomeration of Pd. This observation might be attributed to the isolated ionic liquid units that effectively control the reaction mechanism by preventing Pd agglomeration and releasing and recapturing Pd nanoparticles during the reaction process. The catalyst can be recovered and reused for at least four reaction cycles without significant loss of activity.
- Karimi, Babak,Elhamifar, Dawood,Clark, James H.,Hunt, Andrew J.
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supporting information; experimental part
p. 8047 - 8053
(2010/09/07)
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- Main-chain NHC-palladium polymer as a recyclable self-supported catalyst in the Suzuki-Miyaura coupling of aryl chlorides in water
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We have demonstrated an efficient and reusable NHC-palladium polymer self-supported catalyst for the Suzuki-Miyaura coupling reaction, which even works for deactivated aryl chlorides and aryl fluorides in water.
- Karimi, Babak,Akhavan, Pari Fadavi
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supporting information; experimental part
p. 3750 - 3752
(2009/12/01)
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- Non-thiol farnesyltransferase inhibitors: Utilization of the far aryl binding site by arylthienylacryloyl-aminobenzophenones
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We recently described two novel aryl binding sites of farnesyltransferase. The 4- and 5-arylsubstituted thienylacryloyl moieties turned out as appropriate substituents for our benzophenone-based AAX-peptidomimetic capable for occupying the far aryl binding site.
- Mitsch, Andreas,Altenkaemper, Mirko,Sattler, Isabel,Schlitzer, Martin
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- Structure-activity relationships of novel anti-malarial agents part 8. Effect of different central aryls in biarylacryloylaminobenzophenones on antimalarial activity
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Replacement of the 2,5-disubstituted furyl residue present in the known antimalarial agents 8 by other aryl residues resulted in a more or less reduced antimalarial activity in most cases. The only exemption was the 2,4-thienylene compound 11a displaying activity with an IC50 value of 120 nM. In conclusion, the 2,5-furylene compound 8e remains to represent the most active antimalarial agent in this series of farnesyltransferase inhibitors.
- Wiesner,Mitsch,Altenkaemper,Ortmann,Jomaa,Schlitzer, Martin
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p. 854 - 856
(2007/10/03)
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- Carbon-carbon and carbon-nitrogen coupling reactions catalyzed by palladium nanoparticles derived from a palladium substituted Keggin-type polyoxometalate
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(matrix presented) Palladium 15-20 nm particles stabilized by a Keggin-type polyoxometalate were prepared by reduction of K5PPdW11O39 with H2. The nanoparticles were shown to be effective catalysts for Suzuki-, Heck-, and Stille-type carbon-carbon coupling and carbon-nitrogen coupling reactions of bromoarenes in aqueous media. Chloroarenes were also reactive in reaction media without solvent.
- Kogan, Vladimir,Aizenshtat, Zeev,Popovitz-Biro, Ronit,Neumann, Ronny
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p. 3529 - 3532
(2007/10/03)
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- Vilsmeier Reaction on Some 1-Alkyl-1-arylallyl Alcohols: Benzannulation Leading to Biphenyl-mono- and Dicarboxaldehydes
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1,1-Disubstituted alkylarylallyl alcohols (2a-d) have been prepared from alkyl aryl ketones (1a-d) by Grignard reaction with vinylmagnesium bromide and subjected to the action of phosphoryl chloride in dimethylformamide under Vilsmeier reaction conditions.The biphenyl-mono- (3a-d) and dicarboxaldehydes (4a-d) formed have been readily separated and fully characterized.
- Rao, M. Suresh Chander,Rao, G. S. Krishna
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p. 213 - 216
(2007/10/02)
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