- A soluble polyethyleneglycol-anchored phosphine as a highly active, reusable ligand for Pd-catalyzed couplings of aryl chlorides: comparison with cross and non-cross-linked polystyrene and silica supports
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The so-called SPhos phosphine, an extremely active ligand in the amination and Suzuki coupling of sterically-hindered aryl chlorides, has been anchored on different supports such as non-soluble (cross-linked polystyrene) and soluble (non-cross-linked polystyrene and polyethyleneglycol) polymers, as well as high surface silica. SPhos anchored on polyethyleneglycol (PEG-SPhos) showed the best activity for both amination and Suzuki couplings. The PEG-SPhos ligand can be quantitatively recovered from the reaction mixture through precipitation with diethyl ether and recycled in four consecutive runs without loosing activity. 31P NMR spectra of the reused anchored ligand showed that deactivation of the PEG-SPhos ligand comes from the progressive oxidation of the phosphine-to-phosphine oxide.
- Leyva, Antonio,García, Hermenegildo,Corma, Avelino
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Read Online
- Aminoferrocene lithiation by boron trifluoride activation
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(Figure Presented) Lithiation of BF3-complexed dimethylaminoferrocene occurs exclusively ortho to the dimethylamino group in the cyclopentadienyl ring providing structurally diverse products in 76-94% yield after electrophile quench. This method represents the first direct C2-lithiation of a monosubstituted aminoferrocene, offering rapid and complementary access to this class of compounds over procedures that utilize carbon- and sulfur-based directing groups and may serve as a prelude to an asymmetric process.
- Metallinos, Costa,Zaifman, Josh,Dodge, Laura
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Read Online
- Amination of Aryl Halides Mediated by Electrogenerated Nickel from Sacrificial Anode
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Electrochemical C(sp2)?N couplings mediated by nickel salts generated from the sacrificial anode has been described for the first time. In this approach, the sacrificial nickel anode is employed as the sole source of nickel and the process, operationally simple to set up, enables the preparation of functionalized arylamine derivatives with moderate to good yields, under mild reaction conditions and without additional ligand. A cooperative process between the two electrodes is involved in the proposed mechanism.
- Daili, Farah,Sengmany, Stéphane,Léonel, Eric
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p. 2462 - 2469
(2021/06/28)
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- Synthesis and antimicrobial evaluation of new 2-pyridinone and 2-iminochromene derivatives containing morpholine moiety
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As trail to overcome on the antimicrobial drug-resistance problems, new functionalized 2-pyridinone and 2-iminochromene derivatives bearing morpholine moiety were designed and synthesized. The 2-pyridinone derivatives were obtained through the cyclization of cyanoacetohydrazone of 4-morpholinylacetophenone with 1,3-dicarbonyl compounds, α,β-unsaturated nitriles or 2-(arylidene)malononitriles. The 2-iminochromene derivatives were synthesized through the ring closure of cyanoacetohydrazonewith salicylaldehyde derivatives. The antibacterial and antifungal activities for the synthesized 2-pyridinone and 2-iminochromene derivatives were investigated. Most of the tested compounds showed moderate activity against P. vulgaris. Compounds 4a,b and 5a,b showed moderate activity against G ?ve bacteria. All iminochromene derivatives showed moderate activity against C. albicans. Compound 8c was the most active compound.
- Salem, Mohamed A.,Abbas, Samir Y.,Helal, Mohamed H.,Alzahrani, Abdullah Y.
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p. 2117 - 2123
(2021/07/09)
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- Cobalt-Catalyzed C-H Activation and [3 + 2] Annulation with Allenes: Diastereoselective Synthesis of Indane Derivatives
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An unprecedented bidentate directing-group-assisted cobalt-catalyzed oxidative C-H activation of aryl hydrazones followed by asyn-diastereoselective [3 + 2] annulation reaction has been achieved, employing allenes as the annulation partners. The selective 2,3-migratory insertion of allenes with arylcobalt(III) species and the subsequent intramolecular diastereoselective nucleophilic addition ofη1-allylcobalt onto the imine resulted in [3 + 2] annulation over the alternative [4 + 2] annulation. Furthermore, the oxidative annulation obviates the need for stoichiometric metal oxidants and proceeds under aerobic conditions.
- Dey, Arnab,Volla, Chandra M. R.
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supporting information
p. 5018 - 5023
(2021/07/19)
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- COMPOUNDS AND METHODS OF THEIR USE
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Provided are agents capable of binding the KIX domain of CBP or MED15 to inhibit the binding between SREBP1 and the KIX domain of MED15 or CBP. Also provided are compositions containing the agents and methods of their use.
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Page/Page column 86
(2020/05/19)
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- Aryl-Diadamantyl Phosphine Ligands in Palladium-Catalyzed Cross-Coupling Reactions: Synthesis, Structural Analysis, and Application
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Synthesis, temperature-dependent NMR structure investigation and utilization of a new, stable and easily accessible aryl-diadamantylphosphine ligand family is reported. The bulky and electron-rich phosphorus center of the ligand enhances the catalytic activity of palladium in cross-coupling reactions of sterically demanding ortho-substituted aryl halides. In our study, we demonstrated the synthetic applicability of the new phosphine ligands in Buchwald-Hartwig and tosyl hydrazone coupling reactions.
- Sinai, ádám,Simkó, Dániel Cs.,Szabó, Fruzsina,Paczal, Attila,Gáti, Tamás,Bényei, Attila,Novák, Zoltán,Kotschy, András
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supporting information
p. 1122 - 1128
(2020/03/03)
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- Design, Synthesis and Antitubercular Activity of Novel Isoniazid?Cyclic?Amine?Azachalcones Hybrids
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In this work, it is described the design of twenty-four heterocyclic amine-azachalcones compounds through molecular hybridization of chalcone scaffold and fragments of isoniazid, fluoroquinolones, and linezolid with antituberculosis potential. The new compounds were synthesized via Claisen-Schmidt condensation, providing yields of 36-95%. Fifteen compounds showed antituberculosis activity against Mycobacterium tuberculosis H37Rv strain. Two amine-azachalcones 15 and 17 showed relevant biological activity with minimum inhibitory concentration (MIC) values of 6.62 and 4.85 μM, respectively. Compound 12 showed the best profile of antitubercular activity with MIC = 9.54 μM and selectivity index (SI) = 9.33. It was found that morpholine group is important to increase potency of antimycobacterial activity but also to add some toxicity to the chalcone molecular framework. The results described herein would be a guide in the designing of novel and optimized antitubercular derivatives based on the chalcone scaffold.
- Barbosa, Sandro L.,Baroni, Adriano C. M.,Croda, Júlio,Gomes, Giovana B.,Guerrero, Palimécio G.,Moreira, Flora M. F.,Oliveira, Jefferson R. S.,Perdomo, Renata T.,Shiguemoto, Cristiane Y. K.,das Neves, Amarith R.
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p. 1284 - 1295
(2020/10/14)
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- BIOREDUCIBLE N-OXIDE-BASED PROBES FOR IMAGING OF HYPOXIA
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Hypoxia occurs when limited oxygen supply impairs physiological functions and is a pathological hallmark of many diseases including cancer and ischemia. Thus, detection of hypoxia can guide treatment planning and serve as a predictor of patient prognosis. Current methods suffer from invasiveness, poor resolution and low specificity. To address these limitations, various hypoxia-responsive probes (HyPs) for photoacoustic imaging are disclosed. The emerging modality converts safe, non-ionizing light to ultrasound waves, enabling acquisition of high-resolution 3D images in deep tissue. The HyPs feature an N-oxide trigger that is reduced in the absence of oxygen by haem proteins such as CYP450 enzymes. Reduction of HyPs produce a spectrally distinct product, facilitating identification via photoacoustic imaging. HyPs exhibit selectivity for hypoxic activation in vitro, in living cells and in multiple disease models in vivo. HyPs are also compatible with NIR fluorescence imaging, establishing its versatility as a multimodal imaging agent.
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Paragraph 0220
(2020/03/09)
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- Organic semiconductor photocatalyst can bifunctionalize arenes and heteroarenes
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Photoexcited electron-hole pairs on a semiconductor surface can engage in redox reactions with two different substrates. Similar to conventional electrosynthesis, the primary redox intermediates afford only separate oxidized and reduced products or, more rarely, combine to one addition product. Here, we report that a stable organic semiconductor material, mesoporous graphitic carbon nitride (mpg-CN), can act as a visible-light photoredox catalyst to orchestrate oxidative and reductive interfacial electron transfers to two different substrates in a two- or three-component system for direct twofold carbon–hydrogen functionalization of arenes and heteroarenes. The mpg-CN catalyst tolerates reactive radicals and strong nucleophiles, is straightforwardly recoverable by simple centrifugation of reaction mixtures, and is reusable for at least four catalytic transformations with conserved activity.
- Ghosh, Indrajit,Khamrai, Jagadish,Savateev, Aleksandr,Shlapakov, Nikita,Antonietti, Markus,K?nig, Burkhard
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p. 360 - 366
(2019/08/15)
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- A group of diphosphine-thiosemicarbazone complexes of palladium: Efficient precursors for catalytic C–C and C–N coupling reactions
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Reaction of 4-R-benzaldehyde thiosemicarbazone (denoted in general as HL-R; where H stands for the dissociable acidic proton and R (R = OCH3, CH3, H, Cl and NO2) for the substituent) with [Pd(dppe)(EtOH)2]2+, generated in situ via interaction of [Pd(dppe)Cl2] (dppe = 1,2-bis(diphenylphosphino)ethane) with AgNO3 in hot ethanol, in the presence of triethylamine affords a group of orange complexes of the type [Pd(dppe)(L-R)]NO3. Structures of [Pd(dppe)Cl2] and [Pd(dppe)(L-OCH3)]NO3 have been determined by X-ray crystallography. In the [Pd(dppe)(L-R)]NO3 complexes, the thiosemicarbazone ligands are coordinated to the metal center as monoanionic bidentate N,S-donors forming five-membered chelate rings. The [Pd(dppe)(L-R)]NO3 complexes show intense absorptions in the visible and ultraviolet regions, which have been analyzed by TDDFT calculations. All the [Pd(dppe)(L-R)]NO3 complexes are found to efficiently catalyze Suzuki-type C–C and Buchwald-type C–N coupling reactions.
- Thapa, Kiran,Paul, Piyali,Bhattacharya, Samaresh
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p. 232 - 239
(2018/11/06)
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- Nickel-Catalyzed Decarboxylation of Aryl Carbamates for Converting Phenols into Aromatic Amines
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Herein, we describe a new catalytic approach to accessing aromatic amines from an abundant feedstock, namely phenols. The most reliable catalytic method for converting phenols to aromatic amines uses an activating group, such as a trifluoromethane sulfonyl group. However, this activating group is eliminated as a leaving group during the amination process, resulting in significant waste. Our nickel-catalyzed decarboxylation reaction of aryl carbamates forms aromatic amines with carbon dioxide as the only byproduct. As this amination proceeds in the absence of free amines, a range of functionalities, including a formyl group, are compatible. A bisphosphine ligand immobilized on a polystyrene support (PS-DPPBz) is key to the success of this reaction, generating a catalytic species that is significantly more active than simple nonsupported variants.
- Nishizawa, Akihiro,Takahira, Tsuyoshi,Yasui, Kosuke,Fujimoto, Hayato,Iwai, Tomohiro,Sawamura, Masaya,Chatani, Naoto,Tobisu, Mamoru
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supporting information
p. 7261 - 7265
(2019/05/16)
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- METHODS FOR FORMING ARYL CARBON-NITROGEN BONDS USING LIGHT AND PHOTOREACTORS USEFUL FOR CONDUCTING SUCH REACTIONS
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The disclosure relates to a method for forming aryl carbon-nitrogen bonds and to photoreactors useful in these and other light-driven reactions. The method comprises contacting an aryl halide with an amine in the presence of a Ni salt catalyst solution and an optional base, thereby forming a reaction mixture; exposing the reaction mixture to light under reaction condition sufficient to produce the aryl carbon-nitrogen bonds. In certain embodiments, the amine may be present in a molar excess to the aryl halide. In certain embodiments, the Ni salt catalyst solution includes a Ni(II) salt and a polar solvent, wherein the Ni(II) salt is dissolved in the polar solvent. In certain embodiments, the reactions conditions include holding the reaction mixture at between about room temperature and about 80° C. for between about 1 hour and about 20 hours such that at least about 50% yield is obtained.
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Paragraph 0097-0098; 0176-0177
(2019/11/22)
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- Chalcone compound containing morpholine ring and preparation and application of compound
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The invention provides a chalcone compound containing a morpholine ring. Fluoroacetophenone and morpholine are mixed in an organic solvent, heated and stirred, the mixture and aromatic aldehyde are mixed in the solvent to be added to an alkaline reaction, and the target compound is prepared after post-treatment of reaction liquid. Preparation conditions are mild, the operation is convenient, the cost is low, and industrial application prospects are wide. The chalcone compound containing the morpholine ring has good anti-breast cancer activity, lays a foundation for screening and developing newdrugs, has important practical value and can be applied to preparation of drugs for treating breast cancer. The structural general formula is shown in the description.
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Paragraph 0020-0023
(2019/07/04)
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- Synthesis and biological evaluation of some novel thiobenzimidazole derivatives as anti-renal cancer agents through inhibition of c-MET kinase
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Benzimidazole is an interesting scaffold constituting a main core in many anticancer agents against variable cell lines as Carbendazim (I) and Nocodazole (II). Accordingly, eighteen compounds of 2-((1H-benzoimidazol-2-yl)thio)-1-(aryl/heteroaryl)ethan-1-ones, in their sulfate salt and free forms, were designed and investigated as anticancer agents. In vitro preliminary screening of selected compounds by the National Cancer Institute (NCI) on a panel of 60 cell lines revealed renal cancer cell line (A498) as the most vulnerable cell line; accordingly, IC50 values against A498 cell line were determined for compounds with the best results. The best inhibitory activity was for compound 4a with (IC50 = 6.97 μM) compared to sunitinib as a reference drug (IC50 = 6.99 μM). Compound 4a was further subjected to cell cycle analysis that indicated the decrease in cell population in the G2/M phase when compared to the untreated control cells. In addition, it showed significant increase in the late apoptosis in Annexin-V FTIC study compared to the control cells. An enzymatic inhibitory study on compound 4a against c-Met and MAP kinases revealed its better activity against c-Met kinase with (IC50 = 0.27 μM) compared to sunitinib (IC50 = 0.18 μM). Molecular docking study was conducted to reveal the interactions of compound 4a in the active site of c-Met kinase. Computational ADME study was performed to insure that compound 4a has proper pharmacokinetic and drug-likeness properties.
- Ibrahim, Hany S.,Albakri, Mohamed E.,Mahmoud, Walaa R.,Allam, Heba Abdelrasheed,Reda, Ahmed M.,Abdel-Aziz, Hatem A.
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p. 337 - 348
(2019/01/18)
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- Application of hydrazino and hydrazido linkers to connect benzenesulfonamides with hydrophilic/phobic tails for targeting the middle region of human carbonic anhydrases active site: Selective inhibitors of hCA IX
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Herein we report the design and synthesis of three different sets of novel benzenesulfonamides (5a-e, 7a-e and 10a-d) incorporating hydrophilic/hydrophobic tails by hydrazido or hydrazino linkers. The newly synthesized benzenesulfonamides were examined in vitro for their inhibitory activity towards four human (h) carbonic anhydrase (hCA, EC 4.2.1.1) isoforms, hCA I, II, IX and XII using a stopped-flow CO2 hydrase assay. All these isoforms were inhibited by the sulfonamides (5a-e, 7a-e and 10a-d) with variable degrees in the following KI ranges: 76.8–357.4 nM for hCA I, 8.2–94.6 nM for hCA II, 2.0–46.3 nM for hCA XI, and 8.3–88.3 nM for hCA XII. The sulfonamide 7d exhibited potent anti-proliferative activity against breast MCF-7 cancer cell line under both normoxic and hypoxic conditions with IC50 values equal 3.32 ± 0.06 and 8.53 ± 0.32 μM, respectively, which are comparable to the reference drug doxorubicin (IC50 = 2.36 ± 0.04 and 8.39 ± 0.25 μM, respectively). Furthermore, 7d was screened for cell cycle disturbance and apoptosis induction in MCF-7 cells. It was found to persuade cell cycle arrest at G2-M stage as well as to alter the Sub-G1 phase, also, 7d resulted in a significant increase in the percent of annexinV-FITC positive apoptotic cells from 1.03 to 18.54%. Molecular docking study was carried out for 7d within the hCA IX and hCA XII active sites to rationalize the obtained inhibition results.
- Allam, Heba Abdelrasheed,Fahim, Samar H.,F.Abo-Ashour, Mahmoud,Nocentini, Alessio,Elbakry, Mohamed E.,Abdelrahman, Mohamed A.,Eldehna, Wagdy M.,Ibrahim, Hany S.,Supuran, Claudiu T.
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p. 547 - 556
(2019/07/04)
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- An Effective Heterogeneous Copper Catalyst System for C-N Coupling and Its Application in the Preparation of 2-Methyl-4-methoxydiphenylamine (MMDPA)
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A ligand-recyclable, environmentally benign heterogeneous catalyst system composed of CuI and polystyrene-supported N (-(4-(aminomethyl)naphthalen-1-yl)- N (-phenyl-1 H -pyrrole-2-carbohydrazide (PSAP) has been established for Ullmann type C-N coupling based on the homogeneous catalyst system N ′, N ′-diphenyl-1 H -pyrrole-2-carbohydrazide/CuI. This heterogeneous catalyst system maintained the catalytic effectiveness of the homogeneous catalyst. A variety of functionalized aryl bromides can be efficiently aminated with aryl amines and aliphatic amines with high selectivity for amines over alcohols. Moreover, a practical application of this catalyst system to promote the reaction of commercially available 4-methoxy-2-methylaniline and bromobenzene in 10 mmol scale, provided 2-methyl-4-methoxydiphenylamine (MMDPA) with 93% yield with the merit of the approach being simple operation for work-up and purification.
- Yi, Zhou,Huang, Manna,Wan, Yiqian,Zhu, Xinhai
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p. 3911 - 3920
(2018/09/29)
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- Buchwald-Hartwig amination reaction of aryl halides using heterogeneous catalyst based on Pd nanoparticles decorated on chitosan functionalized graphene oxide
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In this work, graphene oxide was functionalized with chitosan (GO-Chit) followed by a simple approach for immobilization of palladium nanoparticles onto a chitosan grafted graphene oxide surface. The Pd-nanocomposite (GO-Chit-Pd) was characterized using Transmission Electron Microscopy (TEM), Fourier transforms infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) measurements. The catalytic activity of the prepared heterogeneous graphene oxide functionalized chitosan-palladium (GO-Chit-Pd) was investigated in term of C-N coupling reaction (Buchwald-Hartwig amination reaction of aryl halides) yielding products of N-arylamines. The easy purification, convenient operation, and environmental friendliness, combined with a high yield, render this method viable for use in both laboratory research and larger industrial scales. Studying the reusability of the catalyst in this work showed that it could be reused for five times without obvious loss in catalytic activity.
- Sarvestani, Mosayeb,Azadi, Roya
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- C-N Cross-Coupling via Photoexcitation of Nickel-Amine Complexes
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C-N cross-coupling is an important class of reactions with far-reaching impacts across chemistry, materials science, biology, and medicine. Transition metal complexes can elegantly orchestrate diverse aminations but typically require demanding reaction conditions, precious metal catalysts, or oxygen-sensitive procedures. Here, we introduce a mild nickel-catalyzed C-N cross-coupling methodology that operates at room temperature using an inexpensive nickel source (NiBr2·3H2O), is oxygen tolerant, and proceeds through direct irradiation of the nickel-amine complex. This operationally robust process was employed for the synthesis of diverse C-N-coupled products (40 examples) by irradiating a solution containing an amine, an aryl halide, and a catalytic amount of NiBr2·3H2O with a commercially available 365 nm LED at room temperature without added photoredox catalyst and the amine substrate serving additional roles as the ligands and base. Density functional theory calculations and kinetic isotope effect experiments were performed to elucidate the observed C-N cross-coupling reactivity.
- Lim, Chern-Hooi,Kudisch, Max,Liu, Bin,Miyake, Garret M.
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supporting information
p. 7667 - 7673
(2018/05/31)
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- Silver-catalyzed intermolecular amination of fluoroarenes
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A novel highly selective Ag-catalyzed intermolecular amination of fluoroarenes has been developed. This transformation starts from readily available 4-carbonyl fluorobenzene and NaN3 or other nitrogen-source, via amination followed by C-F bond cleavage, thus affording the desired 4-carbonyl arylamine products under mild conditions. The reaction is accelerated using a small amount of water. This pathway is distinct from a previously reported radical amination reaction.
- Wang, Yu,Wei, Chenlong,Tang, Ruyun,Zhan, Haosheng,Lin, Jing,Liu, Zhenhua,Tao, Weihua,Fang, Zhongxue
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supporting information
p. 6191 - 6194
(2018/09/10)
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- Ni/Ti Dual Catalytic Cross-Coupling of Nitriles and Organobromides to Access Ketones
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Herein, we report the development of a dual catalytic approach for the cross-coupling of nitriles with aryl- and aliphatic-bromides. A titanium(III) catalyst is used to activate nitriles enabling their coupling with organobromides through a nickel catalyst. The Ni/Ti system efficiently prepared unsymmetrical ketones with good chemoselectivity and could selectively couple a bromide in the presence of other functionalizable handles.
- Chenniappan, Vinoth Kumar,Silwal, Sajan,Rahaim, Ronald J.
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p. 4539 - 4544
(2018/05/23)
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- Design, synthesis and biological evaluation of novel aryldiketo acids with enhanced antibacterial activity against multidrug resistant bacterial strains
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Antimicrobial resistance (AMR) is a major health problem worldwide, because of ability of bacteria, fungi and viruses to evade known therapeutic agents used in treatment of infections. Aryldiketo acids (ADK) have shown antimicrobial activity against several resistant strains including Gram-positive Staphylococcus aureus bacteria. Our previous studies revealed that ADK analogues having bulky alkyl group in ortho position on a phenyl ring have up to ten times better activity than norfloxacin against the same strains. Rational modifications of analogues by introduction of hydrophobic substituents on the aromatic ring has led to more than tenfold increase in antibacterial activity against multidrug resistant Gram positive strains. To elucidate a potential mechanism of action for this potentially novel class of antimicrobials, several bacterial enzymes were identified as putative targets according to literature data and pharmacophoric similarity searches for potent ADK analogues. Among the seven bacterial targets chosen, the strongest favorable binding interactions were observed between most active analogue and S. aureus dehydrosqualene synthase and DNA gyrase. Furthermore, the docking results in combination with literature data suggest that these novel molecules could also target several other bacterial enzymes, including prenyl-transferases and methionine aminopeptidase. These results and our statistically significant 3D QSAR model could be used to guide the further design of more potent derivatives as well as in virtual screening for novel antibacterial agents.
- Cvijeti?, Ilija N.,Verbi?, Tatjana ?.,Ernesto de Resende, Pedro,Stapleton, Paul,Gibbons, Simon,Jurani?, Ivan O.,Drakuli?, Branko J.,Zloh, Mire
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p. 1474 - 1488
(2017/11/17)
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- Exploring Tandem Ruthenium-Catalyzed Hydrogen Transfer and SNAr Chemistry
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A hydrogen-transfer strategy for the catalytic functionalization of benzylic alcohols via electronic arene activation, accessing a diverse range of bespoke diaryl ethers and aryl amines in excellent isolated yields (38 examples, 70% average yield), is reported. Taking advantage of the hydrogen-transfer approach, the oxidation level of the functionalized products can be selected by judicious choice of simple and inexpensive additives.
- Polidano, Kurt,Reed-Berendt, Benjamin G.,Basset, Ana?s,Watson, Andrew J. A.,Williams, Jonathan M. J.,Morrill, Louis C.
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p. 6716 - 6719
(2017/12/26)
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- Room-Temperature CuI-Catalyzed Amination of Aryl Iodides and Aryl Bromides
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A general and effective CuI/N′,N′-diaryl-1H-pyrrole-2-carbohydrazide catalyst system was developed for the amination of aryl iodides and bromides at room temperature with good chemoselectivity between -OH and -NH2 groups. Only 5 mol % of CuI and ligands was needed in this protocol to effect the amination of various aryl bromides and aryl iodides with a wide range of aliphatic and aryl amines (1.3 equiv).
- Ding, Xiaomei,Huang, Manna,Yi, Zhou,Du, Dongchen,Zhu, Xinhai,Wan, Yiqian
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p. 5416 - 5423
(2017/05/25)
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- Metal-free Synthesis of Aryl Amines: Beyond Nucleophilic Aromatic Substitution
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A mild and metal-free approach to C?N coupling is described that employs diaryliodonium salt electrophiles and secondary aliphatic amine nucleophiles. This reaction results in direct ipso-substitution of the iodonium moiety and unsymmetrical aryl(TMP)iodonium salts are primarily employed. Moreover, arene substituents and substitution patterns that currently pose a challenge to classical metal-free methods are accommodated and the alicyclic amine nucleophiles used here are unprecedented in other contemporary metal-free C?N coupling reactions.
- Sandtorv, Alexander H.,Stuart, David R.
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p. 15812 - 15815
(2016/12/16)
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- Ligand-free C-C and C-N cross-couplings with Pd/Nf-G nanocomposite
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Abstract The catalytic activity of electrochemical deposited Pd nanoparticles on nafion-graphene support was examined for Buchwald-Hartwig amination reaction and Heck coupling reaction. The developed protocol is very efficient and ecofriendly, providing excellent product yield. The Pd/Nf-G catalyst can be used up to four cycles with slight decrease in catalytic activity.
- Shelkar, Radheshyam S.,Shendage, Suresh S.,Nagarkar, Jayashree M.
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supporting information
p. 4463 - 4467
(2015/06/30)
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- Buchwald-Hartwig Amination of (Hetero)Aryl Tosylates Using a Well-Defined N-Heterocyclic Carbene/Palladium(II) Precatalyst
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The cross-coupling of aryl tosylates with amines and anilines was achieved by using for the first time a Pd-NHC system based on the popular Pd-PEPPSI precatalyst platform in which the anchoring imidazol-2-ylidene ligand IPr (NMe2)2 incorporates two dimethylamino groups as backbone substituents enhancing both the electronic and steric properties of the carbene. The system optimization and its application scope are disclosed.
- Zhang, Yin,Lavigne, Guy,César, Vincent
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p. 7666 - 7673
(2015/08/18)
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- Ligand-free N-arylation of heterocycles using metal-organic framework [Cu(INA)2] as an efficient heterogeneous catalyst
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A metal-organic framework [Cu(INA)2] was synthesized and used as a heterogeneous catalyst for arylation of a wide range of N-H heterocycles and aryl halides under ligand-free conditions. The N-arylation reaction involved the use of 5 mol% Cu-MOF catalyst with K3PO4 or tBuOLi as the base in dimethylacetamide (DMA) solvent at 100 °C in 6 h. [Cu(INA)2] exhibited higher catalytic activity for the N-arylation transformation than that of common homogeneous copper catalysts and other Cu-MOFs with unsaturated open metal sites such as Cu2(BDC)2(BPY), Cu3(BTC)2, and Cu2(BDC)2(DABCO). Interestingly, reaction conditions are compatible with a wide range of N-H heterocycles, functional groups, and aryl chlorides. A leaching test indicated no contribution of leached active species in the reaction filtrate. Furthermore, the [Cu(INA)2] catalyst could be facilely separated from the reaction mixture and recovered and reused several times without a significant degradation in catalytic activity.
- Truong, Thanh,Nguyen, Chi V.,Truong, Ngoc T.,Phan, Nam T. S.
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p. 107547 - 107556
(2016/01/09)
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- N-(2-acetyl-4-morpholinophenyl amide derivatives for inducing differentiation of mesenchymal stem cells to endothelial cells
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The present invention refers to mesenchymal stem cells the vascular endothelial cells inducing their differentiation to the rarity piperidinyl/molpholine for containing amide derivatives and provides use thereof in medicaments. Said amide derivatives the middle ply treated with a vascular endothelial mesenchymal stem cells specifically cells differentiation induction, and are by using an balloon expansion alcoholic beverage like damage for vascular endothelial cells, such as by a vascular event for the effective treatment is enabled.
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Paragraph 0146-0156
(2021/10/26)
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- Efficient and versatile buchwald-hartwig amination of (hetero)aryl chlorides using the Pd-PEPPSI-IPr(NMe2)2 precatalyst in the presence of carbonate base
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The precatalyst Pd-PEPPSI-IPr(NMe2)2, in which the IPr ligand was modified by attachment of two dimethylamino groups on to the 4- and 5-positions of the imidazolyl heterocycle, was found to show high catalytic efficiency in the Buchwald-Hartwig amination under mild conditions using Cs2CO3 as a weak base, using a low catalyst loading of 1 mol-%. The protocol is applicable to aryl chlorides bearing base-sensitive substituents, as exemplified by the coupling of 4-chloroacetophenone with aniline. It can also be used with an unprecedentedly wide range of amines, including strongly basic secondary alkylamines, primary arylamines, and primary alkylamines. The Palladium precatalyst Pd-PEPPSI-IPr(NMe2)2, whose supporting N-heterocyclic carbene ligand was decorated with two dimethylamino groups, was found to catalyse the Buchwald-Hartwig amination of aryl halides with a wide range of amines under mild conditions using cesium carbonate as base.
- Zhang, Yin,César, Vincent,Lavigne, Guy
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p. 2042 - 2050
(2015/03/18)
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- Asymmetric Reduction of Electron-Rich Ketones with Tethered Ru(II)/TsDPEN Catalysts Using Formic Acid/Triethylamine or Aqueous Sodium Formate
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The asymmetric transfer hydrogenation (ATH) of ketones under aqueous conditions using tethered Ru(II)/6-arene/diamine catalysts is described, as is the ATH of electron-rich substrates containing amine and methoxy groups on the aromatic rings. Although such substrates are traditionally challenging ones for ATH, the tethered catalysts work very efficiently. In the case of amino-substituted ketones, aqueous conditions give excellent results; however, for methoxy-substituted substrates, the more established formic acid/triethylamine system gives superior results.
- Soni, Rina,Hall, Thomas H.,Mitchell, Benjamin P.,Owen, Matthew R.,Wills, Martin
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p. 6784 - 6793
(2015/10/06)
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- Design, synthesis and anticancer activity of new 3-cyano-2 (1H)-pyridone and 3-cyanopyridine-2-(1H)-thione derivatives
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The main objective of the present research study is to synthesize some novel chalcone, cyanoacetohydrazone, enaminone, 3-cyano-2(1H)-pyridone and 3-cyanopyridine-2-(1H)-thione derivatives and evaluate them for their anticancer effect. The novel chalcones 2a-c were achieved by Claisen-Schmidt condensation of appropriate benzaldehydes with ethanone derivative 1. Treatment of cyanoacetic acid hydrazide with ethanone derivative 1 yielded the correspondinghydrazone derivative 3. Condensation of ethanone derivative 1 with DMF-DMA afforded (E)-3-(dimethylamino)-1-(4-morpholinophenyl)prop-2-en-1-one 4. Heterocyclization of chalcones 2a-c with cyanothioacetamide yielded 2-thioxo-1,2-dihydropyridine-3-carbonitriles 7ac. In a similar manner, cyclocondensation of chalcones 2a, b with cyanoacetamide afforded the corresponding 2-oxo-1,2-dihydropyridine-3-carbonitriles 8a, b. The Reaction of compound 2a with ethyl cyanoacetate furnished 2-oxo-1,2-dihydropyridine-3-carboxylate 12. The 2-oxo-4-phenyl-1,2-dihydro-pyridine-3,5-dicarbonitriles 14a, b were obtained by cyclization of cyanoacetohydrazone 3 with cinnamonitriles. The structures of the synthesized compounds were confirmed by elemental analysis, mass spectrometry, IR and 1H-NMR spectroscopy. The anticancer activity of the newly synthesized compounds was screened in vitro against Human lung carcinoma (A 549) cell line indicating that compounds 7b and 8a possess the most potent inhibitory effect against the human lung carcinoma cell line (A549).
- Motaal, E. A. Abdel,El-Gaby,Salem
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p. 875 - 884
(2015/10/28)
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- A catalyst system, copper/ N -methoxy-1 H -pyrrole-2-carboxamide, for the synthesis of phenothiazines in poly(ethylene glycol)
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A copper/N-methoxy-1H-pyrrole-2-carboxamide catalyst system has been established for the preparation of phenothiazines in good yields by two routes, starting from 2-iodoanilines and 2-bromobenzenethiol and from aryl ortho-dihalides and o-aminobenzenethiols, by conducting the reaction at 90 °C in poly(ethylene glycol)-100 (PEG-100). In addition, the catalyst system was useful for promoting direct arylation of various aryl amines, aliphatic amines, and aqueous ammonia. The simple experimental operation, low loading of catalyst system together with the use of green solvent, makes it attractive for the versatile syntheses of phenothiazines and various amines.
- Huang, Manna,Hou, Jianying,Yang, Ruiqiao,Zhang, Liting,Zhu, Xinhai,Wan, Yiqian
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supporting information
p. 3356 - 3364
(2015/02/02)
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- Synthesis and structural characterization of palladium(II) thiosemicarbazone complex: Application to the Buchwald-Hartwig amination reaction
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A simple route to synthesize mononuclear palladium(II) thiosemicarbazone complex has been described. Elemental analysis, spectral methods and single crystal X-ray diffraction analysis were used to confirm the composition of the complex. The new complex acts as an active homogeneous catalyst for the Buchwald-Hartwig amination reaction of a wide range of aryl and heteroaryl halides (bromides and chlorides), including activating, neutral and deactivating substrates, with various secondary amines under optimized conditions.
- Prabhu, Rupesh Narayana,Ramesh, Rengan
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p. 1120 - 1124
(2013/03/13)
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- Rapid and convenient synthesis of N-arylmorpholines under microwave irradiation
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A series of N-arylmorpholines 1a-1n was obtained by cyclocondensation of arylamines and diethylene glycol dimesylate under microwave irradiation in an aqueous potassium carbonate medium. The reaction is rapid and convenient, and a variety of functional groups are tolerated in the process.
- Li, Hong Bo,Liang, Wu,Ma, Chang Peng,Kai, Yong Mao,Li, Lei,Zhang, Yong Gang
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p. 995 - 998
(2013/08/23)
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- Ruthenium-catalyzed remote electronic activation of aromatic C-F bonds
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The tandem isomerization and nucleophilic aromatic substitution of allylic fluoro-substituted benzylic alcohols is described for the first time. In the presence of the ruthenium complex Ru(PPh3)3(CO)(H) 2, 1-(4-fluorophenyl)prop-2-en-1-ol is converted into the corresponding para-amino ketone or para-phenolic substituted ketone. Copyright
- Watson, Andrew J. A.,Atkinson, Benjamin N.,Maxwell, Aoife C.,Williams, Jonathan M. J.
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supporting information
p. 734 - 740
(2013/04/10)
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- Synthesis and biological evaluation of some novel thiazole compounds as potential anti-inflammatory agents
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In the present investigation, furo[2,3-d]thiazol-5(2H)-one 5 was obtained from reaction of thiosemicarbazone derivative 2 with diethyl acetylene dicarboxylate. A series of newly synthesized 2-(hydrazinyl)thiazol-4(5H)-one 6, 7 & 8 and 2-(4-(substituted)-thiazol-2-yl)hydrazono derivatives 9a, b & 10 were synthesized from treatment of thiosemicarbazone derivative 2 with appropriate α-halogenated compounds. Also, a one pot synthesis of thiazole derivatives 13 & 15 was achieved from three components reaction of hydrazone derivative 11 with phenyl isothiocyanate and α-halogenated compounds catalyzed by DMF/KOH. 4-(4-Morpholino phenyl) thiazol-2-amino 17 was obtained via the reaction of acetophenone derivative 1 with thiourea in presence of iodine. The reactivity of 2-aminothiazole 17 toward some electrophilic reagents was investigated. The structure of the newly compounds was confirmed on the basis of elemental analysis and spectral data. The antibacterial activity towards two Gram negative (Proteus mirabilis & Serratia marcesens) and two Gram positive (Staphylococcus aureus & Bacillus cereus) bacteria was investigated. The anti-inflammatory activity was also investigated and the inhibition of the carrageenin-induced oedema by these compounds was established.
- Helal,Salem,El-Gaby,Aljahdali
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p. 517 - 526
(2013/10/01)
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- Ruthenium-catalyzed transfer hydrogenation of amino- and amido-substituted acetophenones
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The ruthenium-catalyzed transfer hydrogenation of electron-rich amino-substituted acetophenones is reported. Variation of the reductant, ligands, base, and solvent allowed reaction optimization. A key discovery was the use of 1,4-butanediol as an irreversible reducing agent, which significantly improved the conversion. A range of amino- and amido-substituted aryl ketones were explored, and they all gave the corresponding alcohols in good yield, which demonstrates the wider applicability of this process. The ruthenium-catalyzed reduction of electron-rich amino-substituted acetophenones with 1,4-butanediol as an irreversible reducing agent is reported. Optimization of the conditions and variation of the amino substituent are explored as is the use of amido- and sulfonamidoacetophenones with varying results. Copyright
- Watson, Andrew J. A.,Fairbanks, Antony J.
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supporting information
p. 6784 - 6788
(2013/11/06)
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- A study of the Willgerodt-Kindler reaction to obtain thioamides and α-ketothioamides under solvent-less conditions
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In this paper, the results obtained in the synthesis of thioamides and α-ketothioamides by a modification of the Willgerodt-Kindler reaction, under solvent-free and noncatalyst conditions using IR energy as a source of activation, are presented. The use of IR energy in these reactions has been shown to lead to a mixture of thioamide and α-ketothioamide as the main products in most cases, with the latter predominating. The yields of α-ketothioamides from most of these reactions are better than those reported previously. To the best of our knowledge, this is the first time that IR energy has been applied to promote the Willgerodt-Kindler reaction.
- Valdez-Rojas, Jose Ernesto,Rios-Guerra, Hulme,Ramirez-Sanchez, Alma Leticia,Garcia-Gonzalez, Guadalupe,Alvarez-Toledano, Cecilio,Lopez-Cortes, Jose Guadalupe,Toscano, Ruben A.,Penieres-Carrillo, Jose Guillermo
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supporting information; experimental part
p. 567 - 573
(2012/08/08)
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- Amination of electron deficient aryl chlorides promoted by nano sized Mg(OH)2 under transition metals free condition
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This paper presents the amination reactions of electron deficient aryl chlorides promoted by Mg(OH)2 without transition metals. Only using stoichiometric amount of nano sized Mg(OH)2, good to moderate isolated yields could be achieved in N-methylpyrrolidone (NMP) after 24 h at 150 °C.
- Cui, Zhi Hao,Meng, Zi Hui,Mi, Yan Qing,Wang, Peng,Wang, Qi,Zhao, Lin Man,Cui, Ke Jian,Yu, Fang,Xu, Zhi Bin
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experimental part
p. 137 - 140
(2012/06/18)
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- Antimalarial Activity of Newly Synthesized Chalcone Derivatives In Vitro
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Twenty-seven novel chalcone derivatives were synthesized using Claisen-Schmidt condensation and their antimalarial activity against asexual blood stages of Plasmodium falciparum was determined. Antiplasmodial IC50 (half-maximal inhibitory concentration) activity of a compound against malaria parasites in vitro provides a good first screen for identifying the antimalarial potential of the compound. The most active compound was 1-(4-benzimidazol-1-yl-phenyl)-3-(2, 4-dimethoxy-phenyl)-propen-1-one with IC50 of 1.1μg/mL, while that of the natural phytochemical, licochalcone A is 1.43μg/mL. The presence of methoxy groups at position 2 and 4 in chalcone derivatives appeared to be favorable for antimalarial activity as compared to other methoxy-substituted chalcones. Furthermore, 3, 4, 5-trimethoxy groups on chalcone derivative probably cause steric hindrance in binding to the active site of cysteine protease enzyme, explaining the relative lower inhibitory activity.
- Yadav, Neesha,Dixit, Sandeep K.,Bhattacharya, Amit,Mishra, Lokesh C.,Sharma, Manish,Awasthi, Satish K.,Bhasin, Virendra K.
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experimental part
p. 340 - 347
(2012/08/29)
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- Rhodium(NHC)-catalyzed amination of aryl bromides
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(Figure Presented) A rhodium-catalyzed amination reaction of aryl halides with amines has been developed with the use of a N-heterocyclic carbene (NHC) ligand (I/Pr = 1,3-diisopropylimidazol-2-ylidene). The active metal species responsible for the reaction progress was identified. The developed procedure of the Rh-catalyzedW-arylation is convenient to carry out under mild reaction conditions displaying a wide range of substrate scope and high degree of functional group tolerance.
- Kim, Min,Chang, Sukbok
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supporting information; experimental part
p. 1640 - 1643
(2010/06/16)
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- Buchwald-Hartwig C-N cross coupling reactions catalyzed by a pseudo-pincer Pd(II) compound
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The reaction of the imino compound [C6H4-1-(OH)-3-(CH{double bond, long}NC6H2-2,4,6-Me3)] (1) with [Pd(COD)Cl2] affords in good yields the cyclometalated product {A figure is presented} (2), both species being unequivocally identified by single crystal X-ray structure analysis. Careful analysis of both structures in the solid state reveals the presence of important hydrogen bond interactions, leading in the case of the Pd(II) derivative to the formation of a pseudo-pincer/non-covalent pincer compound {A figure is presented} (2). The catalytic activity of this species was examined in Buchwald-Hartwig C-N cross coupling of morpholine with a series of p-substituted bromo-benzenes.
- Avila-Sorrosa, Alcives,Estudiante-Negrete, Fabiola,Hernández-Ortega, Simón,Toscano, Rubén A.,Morales-Morales, David
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experimental part
p. 1262 - 1268
(2010/07/05)
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- Synthesis, structure, and temperature-dependent dynamics of neutral palladium allyl complexes of annulated diaminocarbenes and their catalytic application for C-C and C-N bond formation reactions
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Imidazolinium salts 7,9-bis(2,4,6-trimethylphenyl)-6b,9a- dihydroacenaphtho[1,2-d]imidazolinium tetrafluoroborate and 7,9-bis(2,6- diisopropylphenyl)-6b,9a-dihydroacenaphtho[1,2-d]imidazolinium tetrafluoroborate, designated as [(BIAN-SIMes)(H)]BF4 (3a) and [(BIAN-SIPr)(H)]BF4 (3b), respectively, have been prepared and structurally characterized. The molecular structure of 3a shows the presence of a bifurcated hydrogen bond between the tetrafluoroborate anions and the central imidazolinium proton (-NCHN-). The palladium(II) complexes (η3- C3H5)Pd(BIAN-SIMes)Cl (5a) and (η3-C 3H5)Pd(BIAN-SIPr)Cl (5b) have been synthesized. The temperature-dependent NMR behavior of σ-bonded palladium(II) complex 5b was studied. The crystal structure of 5b shows a localized single and double bond between the allyl ligand. The catalytic activities of the palladium(II) complexes 5a and 5b have been evaluated for Suzuki-type C-C coupling and for room-temperature C-N bond formation using aryl halides.
- Dastgir, Sarim,Coleman, Karl S.,Cowley, Andrew R.,Green, Malcolm L. H.
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experimental part
p. 4858 - 4870
(2011/02/21)
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- Examination of the aromatic amination catalyzed by palladium on charcoal
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The Buchwald-Hartwig amination of aryl halides with secondary amines and functionalized aromatic amines catalyzed by solid-supported palladium is reported. The choices of ligand, base and solvent are crucial for the successful coupling. The ami-nation of aromatic iodides, bromides and chlorides can be easily achieved with palladium on charcoal in the presence of a biphenylphosphane-type ligand at 80-110 °C. In addition, the palladium on charcoal catalyst is easily separable after the reaction, and reusable several times with only small activity loss.
- Komaromi, Anna,Novak, Zoltan
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supporting information; experimental part
p. 1523 - 1532
(2010/08/19)
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- Ortho, ortho′-Substituted KITPHOS monophosphines: Highly efficient ligands for palladium-catalyzed C-C and C-N bond formation
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ortho, ortho′-Substitution of the phosphinoalkyne-derived aryl ring in KITPHOS (11-dicyclohexylphosphino-12-phenyl-9,10-ethenoanthracene) monophosphines enhances the performance of this class of ligand in palladium-catalyzed Suzuki-Miyaura cross-couplings and BuchwaldHartwig aminations, compared with their unsubstituted and mono-substituted counterparts. An alternative complementary synthesis of KITPHOS monophosphines has been developed and two new members of this family, 2,6-Me2-KITPHOS [11-dicyclohexylphosphino-12-(2,6-dimethylphenyl)-9,10-ethenoanthracene] and 2,6-(MeO)2-KITPHOS [11-dicyclohexylphosphino-12-(2,6-dimethoxyphenyl)-9,10-ethenoanthracene], have been prepared; palladium complexes of both are highly efficient catalysts for C - C and C - N bond formation with a range of electron-rich and electron-poor aromatic chlorides as well as heteroaryl chlorides.
- Doherty, Simon,Knight, Julian G.,McGrady, John P.,Ferguson, Alexandra M.,Ward, Nicholas A. B.,Harrington, Ross W.,Clegg, William
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supporting information; experimental part
p. 201 - 211
(2010/06/20)
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- METHOD FOR PREPARING ORTHO-SUBSTITUTED AMINOFERROCENES
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The present disclosure relates to a method for preparing an ortho-substituted aminoferrocene comprising reacting an aminoferrocene with a Lewis acid and a lithiating reagent in the presence of an electrophile to form the ortho-substituted aminoferrocene.
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Page/Page column 13
(2010/06/16)
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- Influence of biaryl phosphine structure on C-N and C-C bond formation
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In order to understand how electronic and other structural characteristics of biphenyl phosphine ligands affect Pd-catalyzed C-N and C-C bond-forming reactions, a new ligand, 2-(dicyclohexylphosphino)-4′-(N,N-dimethylamino)- 1,1′-biphenyl, was synthesized. This compound is isomeric with the commercially available 2-(dicyclohexylphosphino)-2′-(N,N-dimethylamino)-1, 1′-biphenyl that has been useful in C-N bondforming reactions of nucleosides. The new p-dimethylamino biphenyl ligand bears electronic similarities to the o-dimethylamino isomer, but it also possesses structural similarities to 2-(dicyclohexylphosphino)biphenyl, such as the unsubstituted ortho positions in the non-phosphine ring. Whereas 2-(dicyclohexylphosphino)- biphenyl can support catalysts for C-C bond formation, it was not effective in promoting aryl amination of a nucleoside substrate. However, the new ligand proved to be effective in promoting both aryl amination and C-C bond-forming reactions of nucleoside substrates, with some reactions even occurring at room temperature. Thus, the composite structural elements of this new ligand are thought to be criteria for reactivity of the catalytic system derived from it. We have probed the structures of the isomeric N,N-dimethylamino biphenyl ligands by X-ray crystallographic analysis. Interactions of the two ligands with Pd(OAc)2 have been investigated by 31P NMR, and they show substantial stoichiometry-dependent differences. These results have been compared to the interactions of Pd(OAc)2 with 2- (dicyclohexylphosphino)biphenyl as well as 2-(di-tert-butylphosphino)biphenyl, and they reveal marked differences as well. In this process, three cyclopalladated biaryl derivatives have been isolated and characterized by X-ray analysis.
- Pratap, Ramendra,Parrish, Damon,Gunda, Padmaja,Venkataraman,Lakshman, Mahesh K.
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scheme or table
p. 12240 - 12249
(2010/01/30)
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- Immobilization of NHC-bearing palladium catalysts on polyvinylpyridine; applications in Suzuki-Miyaura and Hartwig-Buchwald reactions under batch and continuous-flow conditions
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The facile coordinative immobilization of Organ's PEPPSI catalyst on a composite material composed of megaporous glass and polyvinylpyridine is described. The catalyst showed very good performance in Suzuki-Miyaura as well as Hartwig-Buchwald reactions of aryl chlorides under mild conditions and with low catalyst loadings. The modified PEPPSI catalyst was probed both under batch mode and continuous-flow applications. The flow setup was also utilized to shed light on the stability of the PEPPSI catalyst and the mobility of palladium.
- Mennecke, Klaas,Kirschning, Andreas
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experimental part
p. 3267 - 3272
(2009/05/30)
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- Study of the microwave-assisted hydrolysis of nitriles and esters and the implementation of this system in rapid microwave-assisted Pd-catalyzed amination
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Microwave-assisted hydrolysis of benzonitriles and methyl benzoates has been studied using a toluene/concd aq KOH two phase system in the presence and absence of phase transfer catalyst. Conditions to allow and avoid smooth hydrolysis could be identified. Based on the latter, the first microwave protocol which allows the rapid Pd-catalyzed amination of aliphatic amines with chlorobenzenes containing sensitive functional groups has been developed.
- Van Baelen, Gitte,Maes, Bert U.W.
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p. 5604 - 5619
(2008/09/21)
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- (t-Bu)2PN=P(i-BuNCH2CH2)3N: New efficient ligand for palladium-catalyzed C-N couplings of aryl and heteroaryl bromides and chlorides and for vinyl bromides at room temperature
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(Chemical Equation Presented) By employing Pd(OAc)2, Cs 2CO3, or NaOH, and the new ligand (t-Bu) 2PN=P(i-BuNCH2CH2)3N (3a), an electronically diverse array of aryl bromides and chlorides possessing base-sensitive substituents (nitro, ester, and keto) provide coupling products with bulky aryl amines in good to excellent yields. Aryl halides possessing other functional groups including cyano, amino, trifluoromethyl, and phenol, coupled with equal ease, producing highly functionalized amines in good to excellent yields. Moreover, an aryl chloro group can be preserved in the presence of a bromo substituent under our reaction conditions. BOC-protected amines also participated efficiently. Heterocyclic bromides and chlorides underwent clean couplings with amines in excellent yields. An important strength of our protocol is the use of lower palladium loadings than those reported earlier, without compromising yields. The air-stable palladium complex (η3-cinnamyl)PdCl·(3a) (5) was also employed successfully in C-N coupling reactions while the crotyl analogue was less efficacious. The 3a/Pd(OAc)2 catalyst system promotes, for the first time, efficient coupling of vinyl bromides with a variety of amines to produce imines and enamines at room temperature.
- Reddy, Ch. Venkat,Kingston, Jesudoss V.,Verkade, John G.
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p. 3047 - 3062
(2008/09/19)
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