- Metal Ion-Catalyzed Reduction of Substituted Nitrosobenzenes by 1-Benzyl-3,5-bis(1-pyrrolidinylcarbonyl)-1,4-dihydropyridine in Acetonitrile
-
Metal ion catalyzed reduction of substituted nitrosobenzenes by 1-benzyl-3,5-bis(1-pyrrolidinylcarbonyl)-1,4-dihydropyridine (BPDH) in acetonitrile has been studied for seven bivalent metal ions.The reduction of N-methylacridinium salt (MA) has also been examined.In the former cases, it was found that the metal ions catalyze the reduction by forming a 1 : 1 complex with BPDH according to a Michaelis-Menten type saturation kinetics which allowed to derive the association constants, KM, for the complexation and the second-order rate constants, k2, for the reduction.A linear relationship was found between log k2 and the ionization potentials of metal ions with a positive slope.A linear Hammett relationship was also observed between log k2 and the Hammett ? constants with a positive p value for three metal ions.These results suggest that a bivalent metal ion is sandwiched between the BPDH and the substrate and acts as a Lewis acid to stabilize the incipient N-oxide anion of the substrate which is formed by hydride transfer in the transition state.In the cases of MA, all metal ions inhibited the reduction.Repulsion between the positive charges of the metal ion-BPDH complex and the substrate salt appears to be prevailing.
- Awano, Hiroshi,Takemoto, Kazuo,Ohya, Hirohisa,Tomio, Minaki,Tamagaki, Seizo,Tagaki, Waichiro
-
-
Read Online
- ACID CATALYZED REDUCTION OF NITROSOBENZENE BY 3,5-DIPYRROLIDINOCARBAMOYL-N-BENZYL-1,4-DIHYDROPYRIDINE AS A NADH ANALOG
-
Acid catalyzed reduction of substituted nitrosobenzenes to the hydroxylamines by 3,5-dipyrrolidinocarbamoyl-N-benzyl-1,4-dihydropyridine has been studied in anhydrous acetonitrile.
- Awano, Hiroshi,Hirabayashi, Tetsuya,Tagaki, Waichiro
-
-
Read Online
- Rapid and convenient conversion of nitroarenes to anilines under microwave conditions using nonprecious metals in mildly acidic medium
-
Nitroarenes are reduced to the corresponding aniline derivatives using iron or zinc under mild conditions under microwave heating conditions. Mild acidity is provided by ammonium chloride in an aqueous methanol medium. The conditions are tolerant to other functional groups, with the exception of bromoalkyl derivatives, which yield complex reaction mixtures; otherwise, yields are generally quite high (80–99%).
- Keenan, Corey S.,Murphree, S. Shaun
-
-
Read Online
- Green synthesized silver nanoparticles decorated on reduced graphene oxide for enhanced electrochemical sensing of nitrobenzene in waste water samples
-
In the present work, an electrochemical sensor for nitrobenzene (NB) has been developed based on a green synthesized silver nanoparticles (AgNPs) decorated reduced graphene oxide (RGO) modified glassy carbon electrode (GCE). The AgNPs were synthesized using Justicia glauca leaf extract as a reducing and stabilizing agent. A RGO-AgNPs composite modified electrode was prepared by a simple electrochemical reduction of AgNPs dispersed GO solution. FESEM of RGO-AgNPs composite confirms that AgNPs are firmly attached on the RGO sheets and the average size of AgNPs is found to be 40 ± 5 nm. The modified electrode shows good efficiency with lower overpotential for electrocatalytic reduction of NB than that of other modified electrodes (AgNPs and RGO). The DPV response confirms that the reduction peak current of NB is linear over the concentrations from 0.5 to 900 μM. The sensitivity of the sensors is found to be 0.836 μA μM-1 cm-2 with the detection limit of 0.261 μM for NB. In addition, the RGO-AgNPs composite modified electrode shows good selectivity in the presence of potentially interfering similar compounds and good practicality in the waste water samples. This journal is
- Karuppiah, Chelladurai,Muthupandi,Chen, Shen-Ming,Ali, M. Ajmal,Palanisamy, Selvakumar,Rajan,Prakash,Al-Hemaid, Fahad M. A.,Lou, Bih-Show
-
-
Read Online
- Effect of substituents on the rate of oxidation of anilines with peroxomonosulfate monoanion (HOOSO3-) in aqueous acetonitrile: A mechanistic study
-
Mechanistic studies on the oxidation of 18 meta-, para-, and ortho-substituted anilines (Ans) by HOOSO3- in aqueous acetonitrile medium have been performed. The reaction can be characterized by the experimental rate equation, -d[HSO5-]/dt = k[An][HSO5-] The addition of p-toluenesulfonic acid (TsOH) retards the reaction. The increase in the reactivity of anilines as the medium is made more aqueous is interpreted. The reaction is enhanced by electron-donating groups on the amine in the series consistent with the rate-limiting nucleophilic attack of the amine on the persulfate oxygen. The proposed mechanism involves the conversion of phenylhydroxylamine to nitrosobenzene in a fast step. The ESR study reveals the absence of free radicals in the reaction. Various attempts have been made to analyze the experimental rate constants in terms of LFER plots. Improved correlations are obtained with σ- values and the σ- form of the Yukawa-Tsuno equation.
- Meenakshisundaram, Subbiah,Selvaraju,Made Gowda,Rangappa, Kanchugarakoppal S.
-
-
Read Online
- A study on the selective hydrogenation of nitroaromatics to N-arylhydroxylamines using a supported Pt nanoparticle catalyst
-
A supported Pt nanoparticle-based catalyst was used in the chemoselective hydrogenation of nitroarenes to N-arylhydroxylamines (N-AHA). Optimization of NB hydrogenation conditions showed that substantially higher N-PHA yields can be obtained at low temperature. Especially, the influence of an increased hydrogen pressure on selectivity is remarkable. Maximum yields increase from 55% N-PHA at 4 bar H2 to 80% at 23 bar H2 in ethanol. Further optimization led to the use of small amounts of amine additive, TMEDA, with 50 bar H2 raising the maximum yield to 97% N-PHA. The decreased N-PHA hydrogenation rate at high H2 pressure and the presence of TMEDA allow for selective transformation of a range of other nitroarenes containing electron-withdrawing and -donating (reducible) functional groups to their N-AHAs in excellent (more than 90%) yields.
- Boymans, Evert H.,Witte,Vogt
-
-
Read Online
- Supported bimetallic catalyst Pt-Pb/SiO2for selective conversion of nitrobenzene to p-aminophenol in pressurized CO2/H2O system
-
Various supported Pt-Pb bimetallic catalysts were prepared and applied for the catalytic conversion of nitrobenzene to p-aminophenol in the environmentally benign pressurized CO2/H2O system. Among the bimetallic catalysts prepared, Pt-Pb/SiO2is the best and nitrobenzene could be converted to p-aminophenol with a selectivity as high as 82% when the reaction was carried out using this catalyst at 110 °C under 5 MPa CO2and 0.2 MPa H2.
- Zhang, Ting-Ting,Jiang, Jing-Yang,Wang, Yan-Hua
-
-
Read Online
- The selective reduction of nitroarenes to N-arylhydroxylamines using Zn in a CO2/H2O system
-
Nitroarenes are reduced to the corresponding N-arylhydroxylamines with high selectivity using Zn dust in a CO2/H2O system under mild conditions. The yield of N-phenylhydroxylamine from nitrobenzene is 88% when the reaction is carried out at 25 °C for 1.5 hours with a Zn to nitrobenzene molar ratio equal to 3 under 0.1 MPa CO2. Other nitroarenes, which contain reducible functionality other than a nitro group, are also reduced to the corresponding N-arylhydroxylamines with yield from 88% to 99%. The process fully removes the need to use NH4Cl and is environmentally benign. The Royal Society of Chemistry 2009.
- Liu, Shijuan,Wang, Yanhua,Jiang, Jingyang,Jin, Zilin
-
-
Read Online
- Model molecules with oxygenated groups catalyze the reduction of nitrobenzene: Insight into carbocatalysis
-
The role of different oxygen functional groups on a carbon catalyst was studied in the reduction of nitrobenzene by using a series of model molecules. The carbonyl and hydroxyl groups played important roles, which may be ascribed to their ability to activate hydrazine. In comparison, the ester, ether, and lactone groups seemed to be inactive, whereas the carboxylic group had a negative effect. The reaction occurred most likely through a direct route, during which nitrosobenzene may be converted directly into aniline. Modeling carbon: Thanks to model molecules, the carbon-catalyzed reduction of nitrobenzene is mimicked. The role of different oxygen functional groups on a carbon catalyst is studied, and the carbonyl and hydroxyl groups seem to be the most important moieties, which may be ascribed to their ability to activate hydrazine. The reaction occurs more likely through a direct route, during which nitrosobenzene may also be converted directly into aniline.
- Wu, Shuchang,Wen, Guodong,Liu, Xiumei,Zhong, Bingwei,Su, Dang Sheng
-
-
Read Online
- SELECTIVE HYDROGENATION OF NITROBENZENE IN APROTIC MEDIA
-
The kinetics of hydrogenation of nitrobenzene in aprotic media was studied, and a scheme of the mechanism and a kinetic equation, corresponding to it, for the initial reaction rate are proposed.High selectivity with respect to N-phenylhydroxylamine is apparently due to the aprotic nature and donor properties of the solvent and also to the functioning of the catalyst as a unique "hydrogen electrode."
- Kushch, S. D.
-
-
Read Online
- Synthesis of N-arylhydroxylamines by antimony-catalyzed reduction of nitroarenes
-
Metallic antimony catalyzes the reduction of aromatic nitro compounds to the corresponding N-arylhydroxylamines in good yields with NaBH4 under mild conditions. The azoxybenzenes from autoxidation of N-arylhydroxylamines were also obtained in basic conditions.
- Ren, Pingda,Dong, Tingwei,Wu, Shihui
-
-
Read Online
- Synthesis, characterization, and biological studies of novel isoxazolidines: 1,3-Dipolar cycloaddition reactions
-
1,3-Dipolar cycloaddition reaction of nitrones to olefins is of synthetic interest. In the present work, isoxazolidines have been synthesized in high yield via intermolecular cycloaddition of N-arylnitrone with monosubstituted olefins and are employed for
- Vishu Kumar,Dhananjaya,Rangappa
-
-
Read Online
- Acid-catalysed Multi-electron Reduction of Nitrobenzene Derivatives by a Dihydronicotinamide Adenine Dinucleotide (NADH) Model Compound, 9,10-Dihydro-10-methylacridine
-
Acid-catalysed multi-electron reduction of nitrobenzene derivatives by a dihydronicotinamide adenine dinucleotide (NADH) model compound proceeds efficiently under mild conditions in the presence of perchloric acid in acetonitrile.
- Fukuzumi, Shunichi,Chiba, Makoto,Tanaka, Toshio
-
-
Read Online
- Acid-Catalyzed Hydrolysis of N-Hydroxyacetanilides: Amide Hydrolysis vs N-O Bond Heterolysis
-
Although it has been widely assumed that N-hydroxy-N-aryl amides decompose in acidic solution by acid-catalyzed N-O bond heterolysis, we have found that the N-hydroxyacetanilides 1a-e largely decompose by the alternative amide hydrolysis pathway.The immediate products of hydrolysis, the hydroxylamines 2a-e, can be detected by direct or indirect methods, but these materials also decompose via the Bamberger rearrangement under the reaction conditions.Only the p-EtO- and p-MeO-substituted N-hydroxyacetanilides (1a and 1b) exhibit any sign of N-O bond heterolysis, and only as a minor component (ca. 7percent) of the overall hydrolysis.No change in mechanism could be found for 1d in H2SO4 solutions as concentrated as 9 M.The lack of reactivity of 1a-e to N-O bond heterolysis is largely due to unfavorable protonation of the OH group.Protonation of the carbonyl oxygen is favored over the hydroxyl oxygen by ca. 7 orders of magnitude.
- Novak, Michael,Bonham, Gayl A.,Mohler, Linda K.,Peet, Kristine M.
-
-
Read Online
- Magnetically Recyclable Catalytic Carbon Nanoreactors
-
Multifunctional nanoreactors are assembled using hollow graphitized carbon nanofibers (GNFs) combined with nanocatalysts (Pd or Pt) and magnetic nanoparticles. The latter are introduced in the form of carbon-coated cobalt nanomagnets (Co@Cn) adsorbed on GNF, or formed directly on GNF from ferrocene yielding carbon-coated iron nanomagnets (Fe@Cn). High-resolution transmission electron microscopy demonstrates that Co@Cn and Fe@Cn are attached effectively to the GNFs, and the loading of nanomagnets required for separation of the nanoreactors from the solution with an external magnetic field is determined using UV–vis spectroscopy. Magnetically functionalized GNFs combined with palladium or platinum nanoparticles result in catalytically active magnetically separable nanoreactors. Applied to the reduction of nitrobenzene the multifunctional nanoreactors demonstrate high activity and excellent durability, while their magnetic recovery enables significant improvement in the reuse of the nanocatalyst over five reaction cycles (catalyst loss 0.5 wt%) as compared to the catalyst recovery by filtration (catalyst loss 10 wt%).
- Aygün, Mehtap,Chamberlain, Thomas W.,Gimenez-Lopez, Maria del Carmen,Khlobystov, Andrei N.
-
-
Read Online
- Nitrobenzene hydrogenation on Au/TiO2 and Au/SiO2 catalyst: Synthesis, characterization and catalytic activity
-
Recently, gold has been proposed as an active phase for the hydrogenation of nitro-arenes. This metal has been rarely used in hydrogenation reactions because gold does not possess hydrogen chemisorption capacity. However, small gold particles behave differently and they may be able to chemisorb hydrogen to same extent, leading to possible activity in hydrogenation reactions. This may provide an advantage because the reactions catalyzed by highly dispersed gold particles may be better controlled. In this work, TiO2 and SiO 2 supported Au catalysts were prepared by the deposition- precipitation method using urea and NaOH to precipitate the metallic component at different temperatures and hydrogen pressures. The metal loading for all the catalysts was 1 wt%. The catalysts were characterized by X-ray diffraction, high resolution transmission electron microscopy among others. The catalysts were then evaluated in the hydrogenation of nitrobenzene in a batch type reactor at 25 C. All the catalysts were active in the hydrogenation reaction and the major obtained product was aniline.
- Torres, Cecilia,Campos, Cristian,Fierro, Jose Luis Garcia,Oportus, Marcelo,Reyes, Patricio
-
-
Read Online
- Reduction of nitroarenes to N-arylhydroxylamines with KBH4/BiCl3 system
-
Aromatic nitro compounds could be selectively and rapidly reduced to the corresponding N-arylhydroxylamines in good yields with KBH4/BiCl3 system under mild conditions.
- Ren, Ping-Da,Pan, Xin-Wei,Jin, Qi-Hui,Yao, Zi-Peng
-
-
Read Online
- Colloid and nanosized catalysts in organic synthesis: IV. Reduction of nitroarenes with hydrazine hydrate catalyzed with metal nanoparticles
-
Reduction of a series of nitroarenes with hydrazine hydrate catalyzed with colloid iron, cobalt, nickel, and copper particles has been studied. High catalytic activity of nickel and iron nanoparticles has been demonstrated. Special features of nitrobenzene reduction in the presence of cobalt particles have been revealed.
- Mokhov, V. M.,Popov, Yu. V.,Nebykov, D. N.
-
-
Read Online
- Preparation of para -Aminophenol from Nitrobenzene through Bamberger Rearrangement Using a Mixture of Heterogeneous and Homogeneous Acid Catalysts
-
The direct preparation of para-aminophenol (PAP) from nitrobenzene (NB) through Bamberger rearrangement was studied in a biphasic medium using a mixture of NbOx/SiO2 and H2SO4 as an acid catalyst. After optimization of the reaction parameters, PAP was obtained with 85-88% selectivity that represents a 10% selectivity improvement compared to sulfuric acid alone. The optimized conditions were implemented in a scale-up reaction, and PAP was isolated in 84% yield (based on the recovered starting material) with 97% HPLC purity. Overall, this process requires less sulfuric acid than the traditional process, leading to a drastic reduction of the saline waste.
- Joncour, Roxan,Ferreira, Amadéo,Duguet, Nicolas,Lemaire, Marc
-
-
Read Online
- Selective synthesis of N-aryl hydroxylamines by the hydrogenation of nitroaromatics using supported platinum catalysts
-
Various substituted nitroaromatics were successfully hydrogenated to the corresponding N-aryl hydroxylamines in excellent yields (up to 99%) using supported platinum catalysts such as Pt/SiO2 under a hydrogen atmosphere (1 bar) at room temperature. The key to the fast and highly selective formation of hydroxylamines is the addition of small amounts of amines such as triethylamine and dimethyl sulfoxide; amines promote the conversion of nitroaromatics, while dimethyl sulfoxide inhibits further hydrogenation of hydroxylamines to anilines. The promotive effect depends on which type of amine and primary amine was most effective. The hydrogenation efficiently proceeded in common organic solvents, including isopropanol, diethyl ether, and acetone. This methodology should extend the application range of conventional solid catalysts to fine chemicals synthesis. The Royal Society of Chemistry 2009.
- Takenaka, Yasumasa,Kiyosu, Takahiro,Choi, Jun-Chul,Sakakura, Toshiyasu,Yasuda, Hiroyuki
-
-
Read Online
- Stabilizing a Platinum1Single-Atom Catalyst on Supported Phosphomolybdic Acid without Compromising Hydrogenation Activity
-
In coordination chemistry, catalytically active metal complexes in a zero- or low-valent state often adopt four-coordinate square-planar or tetrahedral geometry. By applying this principle, we have developed a stable Pt1single-atom catalyst with a high Pt loading (close to 1 wt %) on phosphomolybdic acid(PMA)-modified active carbon. This was achieved by anchoring Pt on the four-fold hollow sites on PMA. Each Pt atom is stabilized by four oxygen atoms in a distorted square-planar geometry, with Pt slightly protruding from the oxygen planar surface. Pt is positively charged, absorbs hydrogen easily, and exhibits excellent performance in the hydrogenation of nitrobenzene and cyclohexanone. It is likely that the system described here can be extended to a number of stable SACs with superior catalytic activities.
- Zhang, Bin,Asakura, Hiroyuki,Zhang, Jia,Zhang, Jiaguang,De, Sudipta,Yan, Ning
-
-
Read Online
- Environmentally friendly hydrogenation of nitrobenzene to p-aminophenol using heterogeneous catalysts
-
Nitrobenzene was converted to p-aminophenol at 353 K, using water as solvent and a bi-functional catalyst composed of a mechanical mixture of supported Pt catalyst with zirconium sulphate calcined at 773-923 K. The performance of this system is independent of the support used for Pt, and various supports, such as pure or sulphated zirconia and titania, carbon, MgLa mixed oxide, give similar results. At low Pt content, the reaction rate is first order relative to nitrobenzene, and the slow step is the partial hydrogenation of nitrobenzene to phenylhydroxylamine, which requires only minute amounts of Pt. At higher Pt loadings, the rate of hydrogenation of nitrobenzene to phenylhydroxylamine and consequently to aniline takes over that of the acid-catalysed Bamberger rearrangement of phenylhydroxylamine to p-aminophenol. The selectivity of this step depends critically on the solid acid: strong acids such as sulphated zirconia or zeolites give poor selectivities because they tend to decompose the hydroxylamine intermediate. This process does not require sulphuric acid or additives such as DMSO or alkylsulphides, thereby simplifying the downstream processing.
- Deshpande, Abhay,Figueras,Lakshmi Kantam,Jeeva Ratnam,Sudarshan Reddy,Sekhar
-
-
Read Online
- Nitroreductase from Salmonella typhimurium: Characterization and catalytic activity
-
The biocatalytic activity of nitroreductase from Salmonella typhimurium (NRSal) was investigated for the reduction of α,β-unsaturated carbonyl compounds, nitroalkenes, and nitroaromatics. The synthesized gene was subcloned into a pET28 overexpression system in E.coli BL21 strain, and the corresponding expressed protein was purified to homogeneity with 15% protein mass yield and 41% of total activity recovery. NRSal showed broad substrate acceptance for various nitro compounds such as 1-nitrocyclohexene and aliphatic nitroalkenes (alkene reductase activity), as well as nitrobenzene (nitroreductase activity), with substrate conversion efficiency of > 95%. However, the reduction of enones was generally low, proceeding albeit with high stereoselectivity. The efficient biocatalytic reduction of substituted nitroalkenes provides a route for the preparation of the corresponding nitroalkanes. NRSal also demonstrated the first single isolated enzyme-catalyzed reduction of nitrobenzene to aniline through the formation of nitrosobenzene and phenylhydroxylamine as intermediates. However, chemical condensation of the two intermediates to produce azoxybenzene currently limits the yield of aniline.
- Yanto, Yanto,Hall, Melanie,Bommarius, Andreas S.
-
-
Read Online
- Highly Selective and Solvent-Dependent Reduction of Nitrobenzene to N-Phenylhydroxylamine, Azoxybenzene, and Aniline Catalyzed by Phosphino-Modified Polymer Immobilized Ionic Liquid-Stabilized AuNPs
-
Gold nanoparticles stabilized by phosphine-decorated polymer immobilized ionic liquids (AuNP@PPh2-PIILP) is an extremely efficient multiproduct selective catalyst for the sodium borohydride-mediated reduction of nitrobenzene giving N-phenylhydroxylamine, azoxybenzene, or aniline as the sole product under mild conditions and a very low catalyst loading. The use of a single nanoparticle-based catalyst for the partial and complete reduction of nitroarenes to afford three different products with exceptionally high selectivities is unprecedented. Under optimum conditions, thermodynamically unfavorable N-phenylhydroxylamine can be obtained as the sole product in near quantitative yield in water, whereas a change in reaction solvent to ethanol results in a dramatic switch in selectivity to afford azoxybenzene. The key to obtaining such a high selectivity for N-phenylhydroxylamine is the use of a nitrogen atmosphere at room temperature as reactions conducted under an inert atmosphere occur via the direct pathway and are essentially irreversible, while reactions in air afford significant amounts of azoxy-based products by virtue of competing condensation due to reversible formation of N-phenylhydroxylamine. Ultimately, aniline can also be obtained quantitatively and selectively by adjusting the reaction temperature and time accordingly. Introduction of PEG onto the polyionic liquid resulted in a dramatic improvement in catalyst efficiency such that N-phenylhydroxylamine could be obtained with a turnover number (TON) of 100000 (turnover frequency (TOF) of 73000 h-1, with >99% selectivity), azoxybenzene with a TON of 55000 (TOF of 37000 h-1 with 100% selectivity), and aniline with a TON of 500000 (TOF of 62500 h-1, with 100% selectivity). As the combination of ionic liquid and phosphine is required to achieve high activity and selectivity, further studies are currently underway to explore whether interfacial electronic effects influence adsorption and thereby selectivity and whether channeling of the substrate by the electrostatic potential around the AuNPs is responsible for the high activity. This is the first report of a AuNP-based system that can selectively reduce nitroarenes to either of two synthetically important intermediates as well as aniline and, in this regard, is an exciting discovery that will form the basis to develop a continuous flow process enabling facile scale-up.
- Doherty, Simon,Knight, Julian G.,Backhouse, Tom,Summers, Ryan J.,Abood, Einas,Simpson, William,Paget, William,Bourne, Richard A.,Chamberlain, Thomas W.,Stones, Rebecca,Lovelock, Kevin R. J.,Seymour, Jake M.,Isaacs, Mark A.,Hardacre, Christopher,Daly, Helen,Rees, Nicholas H.
-
-
Read Online
- Selective reduction of nitroarenes to N-arylhydroxylamines by use of Zn in a CO2-H2O system, promoted by ultrasound
-
The promoting effect of ultrasound on the selective reduction of nitroarenes to N-arylhydroxylamines by use of Zn in an environmentally benign CO2-H2O system has been demonstrated. The yield of N-phenylhydroxylamine reaches 95% when the reaction is carried out with a Zn-to-nitrobenzene molar ratio of 2.2 under ultrasound (40 kHz) at 25 °C and normal pressure of CO2 for 60 min. Application of ultrasound to the reaction has the advantages of higher yield of N-arylhydroxylamines, shorter reaction time, and consumption of less Zn. Springer Science+Business Media B.V. 2012.
- Liu, Shijuan,Wang, Yanhua,Yang, Xun,Jiang, Jingyang
-
-
Read Online
- Dual catalysis with an IrIII-AuI heterodimetallic complex: Reduction of nitroarenes by transfer hydrogenation using primary alcohols
-
A triazolyl-di-ylidene ligand has been used for the preparation of a homodimetallic complex of gold, and a heterodimetallic compound of gold and iridium. Both complexes have been fully characterized and their molecular structures have been determined by means of X-ray diffraction. The catalytic properties of these two complexes have been evaluated in the reduction of nitroarenes by transfer hydrogenation using primary alcohols. The two complexes afford different reaction products; whereas the AuI-AuI catalyst yields a hydroxylamine, the IrIII-AuI complex facilitates the formation of an imine. Copyright
- Sabater, Sara,Mata, Jose A.,Peris, Eduardo
-
-
Read Online
- Polystyrene stabilized iridium nanoparticles catalyzed chemo- and regio-selective semi-hydrogenation of nitroarenes to N-arylhydroxylamines
-
Polystyrene stabilized Iridium (Ir@PS) nanoparticles (NPs) as a heterogeneous catalyst have been developed and characterized by IR, UV–Vis, SEM, TEM, EDX and XRD studies. The prepared Ir@PS catalyst showed excellent reactivity for chemo- and regio-selective controlled-hydrogenation of functionalized nitroarenes to corresponding N-arylhydroxylamine using hydrazine hydrate as reducing source and environmentally benign polyethylene glycol (PEG-400) as green solvent. The present methodology was applied for vast substrate scope and found to be compatible with wide range of reducible functional groups. The reaction performed at 85 °C or ambient temperature and completed within 5–80 minutes. The catalyst can easily be filtered out from reaction mixture and reusable.
- Bhattacherjee, Dhananjay,Das, Pralay,Kumar, Ajay,Shaifali,Zyryanov, Grigory V.
-
-
Read Online
- Nanocomposite-based inorganic-organocatalyst Cu(II) complex and SiO2- and Fe3O4 nanoparticles as low-cost and efficient catalysts for aniline and 2-aminopyridine oxidation
-
Bis-imino Cu(II) complex (CuLAn2), in which the imine ligand (HLAn) acts as a bidentate chelating ligand, was synthesized. The catalytic potential of the inorganic-organocatalyst was studied homogeneously and heterogeneously in the oxidation of aniline and 2-aminopyridine by H2O2 or tBuOOH. Two heterogeneous inorganic-organocatalysts, CuLAn2@Fe3O4 and CuLAn2@SiO2@Fe3O4, were synthesized by the successful immobilization of CuLAn2 on the Fe3O4 surface and the composited Fe3O4 with SiO2, respectively. The heterogeneous structure of those inorganic-organocatalysts was confirmed using Fourier-transform infrared, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscopy, and magnetic properties. The adsorption–desorption isotherms revealed respectable adsorption parameters (SBET, Vp, and rp). All catalysts exhibited high potential in the oxidation of aniline (with phenylhydroxylamine as the main product) and good potential in the oxidation of 2-aminopyridine, in the first attempt (with 2-nitropyridine-N-oxide and 2-nitrosopyridine-N-oxide as main products), at room temperature. Acetonitrile was found to be the best solvent compared to ethanol, dimethyl sulfoxide, chloroform, and water. The homogeneous catalyst exhibited reusability for three times. The heterogeneous catalysts, CuLAn2@Fe3O4 and CuLAn2@SiO2@Fe3O4, were active for five and seven times, respectively. A mechanism was proposed within electron and oxygen transfer processes.
- Adam, Mohamed Shaker S.,Al-Omair, Mohammed A.
-
-
Read Online
- Water Exclusion Reaction in Aqueous Media: Nitrone Formation and Cycloaddition in a Single Pot
-
(Equation Presented) The formation of nitrone (a water exclusion reaction) in aqueous media using surfactant and subsequent cycloaddition in the same pot, a new example of green chemistry, is reported. The control of regioselectivity favors the formation
- Chatterjee, Amrita,Maiti, Dilip Kumar,Bhattacharya, Pranab Kumar
-
-
Read Online
- Pt decorated hierarchical Sb2WO6microspheres as a surface functionalized photocatalyst for the visible-light-driven reduction of nitrobenzene to aniline
-
Optimizing the structure of semiconductor materials and introducing functional metal clusters have emerged as an effective strategy to improve the photocatalytic performances of catalysts through the synergistic effect between metals and supports. In this work, Pt nanocluster decorated hierarchical Sb2WO6microspheres which are assembled from ultra-thin nanosheets with only 3.3 nm thickness (Pt/SWO-NS) jointly achieve an efficient photocatalytic reduction of nitrobenzene to aniline and show 10 times higher activity than Pt decorated bulk Sb2WO6(Pt/SWO-bulk). More importantly, the respective roles of SWO-NS and Pt nanoclusters are deeply studied. SWO-NS with a unique 2D structure, abundant unsaturated surface sites and good visible light response would be favorable for stabilizing Pt nanoclusters, adsorbing and activating more nitrobenzene molecules and providing abundant photo-generated electrons. Meanwhile, Pt nanoclusters serve as electron enrichment centers to decompose HCOONH4to produce rich ·CO2?and active H for reducing the activated nitrobenzene molecules. In addition, on combining coordination chemistry, a possible synergistic mechanism for hierarchical Sb2WO6microspheres and Pt nanoclusters is proposed to elucidate the efficient reduction of nitrobenzene to aniline. We believe that this work would provide an effective strategy to optimize catalytic performance by the design of applicable nanocomposites with synergistic effects.
- Guo, Binbin,Shi, Yingzhang,Song, Yujie,Wang, Huan,Wang, Zhiwen,Wu, Ling,Wu, Taikang
-
-
Read Online
- Synthesis of N-Arylhydroxylamines by Tellurium-Catalyzed Reduction of Aromatic Nitro Compounds
-
p-Substituted nitrobenzenes were readily reduced with sodium borohydride and a catalytic amount of tellurium to give the corresponding hydroxylamines in good yields.
- Uchida, Shuji,Yanada, Kazuo,Yamaguchi, Hiromi,Meguri, Haruo
-
-
Read Online
- Unexpected selectivity in the oxidation of arylamines with ferrate-preliminary mechanistic considerations
-
Ferrate rapidly converts aromatic amines exclusively into either nitro- or azo-compounds under relatively mild conditions.
- Johnson, Michael D.,Hornstein, Brooks J.
-
-
Read Online
- Pulse Radiolysis of Nitrobenzene in Aqueous Solutions Containing Colloidal Platinum
-
The pulse radiolysis of nitrobenzene (NB) in aqueous solutions containing 2-propanol in the presence of colloidal Pt has been studied.The NB- anion decays away by a single first-order process.The rate of decay is also first order in colloidal platinum (Ptc).The rate depends on the pH of the solutions.At relatively high pHs, hydrogen reduces NB and this reaction is mediated by the Ptc.Irreversible redox processes which produce nitrosobenzene and phenylhydroxylamine also take place, competing effectively with hydrogen formation.
- Nahor, Gad S.,Rabani, Joseph
-
-
Read Online
- Exploring Opportunities for Platinum Nanoparticles Encapsulated in Porous Liquids as Hydrogenation Catalysts
-
The unusual combination of characteristics observed for porous liquids, which are typically associated with either porous solids or liquids, has led to considerable interest in this new class of materials. However, these porous liquids have so far only been investigated for their ability to separate and store gases. Herein, the catalytic capability of Pt nanoparticles encapsulated within a Type I porous liquid (Pt@HS-SiO2 PL) is explored for the hydrogenation of several alkenes and nitroarenes under mild conditions (T=40 °C, PH2=1 atm). The different intermediates in the porous liquid synthesis (i.e., the initial Pt@HS-SiO2, the organosilane-functionalized intermediate, and the final porous liquid) are employed as catalysts in order to understand the effect of each component of the porous liquid on the catalysis. For the hydrogenation of 1-decene, the Pt@HS-SiO2 PL catalyst in ethanol has the fastest reaction rate if normalized with respect to the concentration of Pt. The reaction rate slows if the reaction is completed in a “neat” porous liquid system, probably because of the high viscosity of the system. These systems may find application in cascade reactions, in particular, for those with mutually incompatible catalysts.
- Hemming, Ellen B.,Masters, Anthony F.,Maschmeyer, Thomas
-
-
Read Online
- Feasibility of room temperature reduction of aromatic carbonyl and nitro compounds by Zn/dil. HCl-Et2O system: An experimental and DFT study
-
This experimental study is about the feasibility of the room temperature reduction of the ether soluble aromatic carbonyl/nitro compounds by atomic hydrogen. The atomic hydrogen is produced by the novel Zn/dil. HCl-Et2O reducing system (wherein dil. HCl is slowly added to the ethereal solution of Zn and substrate).This study resulted in single or mixture of anticipated reduced products in different yields. The DFT study with B3LYP/6.311g ++ (d,p) basis set revealed that the stability of the first formed free radical (energy factor) and the homo nuclear nature of the carbonyl and nitro group (charge factor) decide the yield. It is also found that the presence of –M group at o- or p- position to the carbonyl/nitro group results in the favourable modification of above-mentioned factors. The above-mentioned factors also explain the preferential reduction of nitro group when it is present along with carbonyl group. The free radical mechanism was confirmed by the formation of pinacol coupled product in one instance. In one of the reduction reactions, an unreported compound viz. the dimer of o-amino benzaldehyde was obtained in good yield.
- Rajamathe,Selvaraj
-
-
Read Online
- A Modified System for the Synthesis of Enantioenriched N-Arylamines through Copper-Catalyzed Hydroamination
-
Despite significant recent progress in copper-catalyzed enantioselective hydroamination chemistry, the synthesis of chiral N-arylamines, which are frequently found in natural products and pharmaceuticals, has not been realized. Initial experiments with N-arylhydroxylamine ester electrophiles were unsuccessful and, instead, their reduction in the presence of copper hydride (CuH) catalysts was observed. Herein, we report key modifications to our previously reported hydroamination methods that lead to broadly applicable conditions for the enantioselective net addition of secondary anilines across the double bond of styrenes, 1,1-disubstituted olefins, and terminal alkenes. NMR studies suggest that suppression of the undesired reduction pathway is the basis for the dramatic improvements in yield under the reported method.
- Ichikawa, Saki,Zhu, Shaolin,Buchwald, Stephen L.
-
-
Read Online
- Catalytic reduction of nitroarenes to azoxybenzenes with sodium borohydride in the presence of bismuth
-
Aromatic nitro compounds have been found to be selectively reduced to axoxy compounds in good yields by NaBH4 in the presence of bismuth powder.
- Ren, Pingda,Pan, Shifeng,Dong, Tingwei,Wu, Shihui
-
-
Read Online
- Application of Al2O3/AlNbO4 in the oxidation of aniline to azoxybenzene
-
Al2O3/AlNbO4 powder was fabricated by a facile high-energy milling process. The precursor materials, Al2O3 and Nb2O5, are readily available and have very attractive properties. Moreover, the catalytic activity of the sample in the liquid phase oxidation of aniline (OA) in the presence of hydrogen peroxide as oxidant was evaluated. The catalyst was found to be highly efficient and selective in the oxidation of aniline to azoxybenzene under mild conditions. When mixed with 28% AlNbO4 the alumina-based catalyst achieved high conversion and selectivity and very similar to the pure Nb2O5.
- Batalha, Daniel C.,Luz, Sulusmon C.,Taylor, Jason G.,Fajardo, Humberto V.,Noremberg, Bruno S.,Cherubin, Igor J. S.,Silva, Ricardo M.,Gon?alves, Margarete R. F.,Bergmann, Carlos P.,Valentini, Antoninho,Carre?o, Neftalí L. V.
-
-
Read Online
- Structural Manipulation of Ruthenium(II) Polypyridine Nitrone Complexes to Generate Phosphorogenic Bioorthogonal Reagents for Selective Cellular Labeling
-
We report a new class of ruthenium(II) polypyridine complexes functionalized with a nitrone group as phosphorogenic bioorthogonal probes. These complexes were very weakly emissive owing to rapid C=N isomerization of the nitrone moiety, but exhibited signi
- Tang, Tommy Siu-Ming,Liu, Hua-Wei,Lo, Kenneth Kam-Wing
-
-
Read Online
- Selective conversion of nitroarenes using a carbon nanotube-ruthenium nanohybrid
-
Ruthenium nanoparticles were assembled on carbon nanotubes and the resulting nanohybrid was used in the hydrazine-mediated catalytic hydrogenation of various nitroarenes, at room temperature. Depending on the solvent, a selective transformation occurred, giving either access to the corresponding aniline or hydroxylamine derivative.
- Jawale, Dhanaji V.,Gravel, Edmond,Boudet, Caroline,Shah, Nimesh,Geertsen, Valérie,Li, Haiyan,Namboothiri, Irishi N. N.,Doris, Eric
-
-
Read Online
- Synthesis and characterization of adenosine adducts of arylamines
-
The synthesis of adducts of arylamines with adenosine are reported.
- Anil Kumar,Mantelingu,Rangappa
-
-
Read Online
- Solvent-free synthesis of nitrone-containing template as a chemosensor for selective detection of Cu(II) in water
-
A state-of-the-art method was developed for repurposing nitrone-containing compounds in the chemosensory field, the ability of the designed molecules to chelate metal cations was evaluated, and their unprecedented solubility in water was confirmed. A faci
- Angolini, Célio F. F.,Bartoloni, Fernando H.,Carneiro, Leonardo M.,Keppler, Artur F.
-
supporting information
(2021/10/30)
-
- Selective Reduction of Nitroarenes to Arylamines by the Cooperative Action of Methylhydrazine and a Tris(N-heterocyclic thioamidate) Cobalt(III) Complex
-
We report an efficient catalytic protocol that chemoselectively reduces nitroarenes to arylamines, by using methylhydrazine as a reducing agent in combination with the easily synthesized and robust catalyst tris(N-heterocyclic thioamidate) Co(III) complex [Co(κS,N-tfmp2S)3], tfmp2S = 4-(trifluoromethyl)-pyrimidine-2-thiolate. A series of arylamines and heterocyclic amines were formed in excellent yields and chemoselectivity. High conversion yields of nitroarenes into the corresponding amines were observed by using polar protic solvents, such as MeOH and iPrOH. Among several hydrogen donors that were examined, methylhydrazine demonstrated the best performance. Preliminary mechanistic investigations, supported by UV-vis and NMR spectroscopy, cyclic voltammetry, and high-resolution mass spectrometry, suggest a cooperative action of methylhydrazine and [Co(κS,N-tfmp2S)3] via a coordination activation pathway that leads to the formation of a reduced cobalt species, responsible for the catalytic transformation. In general, the corresponding N-arylhydroxylamines were identified as the sole intermediates. Nevertheless, the corresponding nitrosoarenes can also be formed as intermediates, which, however, are rapidly transformed into the desired arylamines in the presence of methylhydrazine through a noncatalytic path. On the basis of the observed high chemoselectivity and yields, and the fast and clean reaction processes, the present catalytic system [Co(κS,N-tfmp2S)3]/MeNHNH2 shows promise for the efficient synthesis of aromatic amines that could find various industrial applications.
- Ioannou, Dimitris I.,Gioftsidou, Dimitra K.,Tsina, Vasiliki E.,Kallitsakis, Michael G.,Hatzidimitriou, Antonios G.,Terzidis, Michael A.,Angaridis, Panagiotis A.,Lykakis, Ioannis N.
-
p. 2895 - 2906
(2021/02/27)
-
- Ultrasonic promoted synthesis of Ag nanoparticle decorated thiourea-functionalized magnetic hydroxyapatite: A robust inorganic-organic hybrid nanocatalyst for oxidation and reduction reactions
-
In this research, ultrasonic synthesis is applied for the fabrication of a novel catalyst, based on immobilization of silver nanoparticles (AgNPs) on thiourea functionalized magnetic hydroxyapatite. A recoverable Ag nano-catalyst is constructed by decoration of AgNPs on the surface of thiourea modified magnetic hydroxyapatite. Magnetic hydroxyapatite is used as an organic-inorganic hybrid support for the catalyst. The organic-inorganic hybrid support is prepared by co-precipitation, followed by its surface modification through covalent functionalization of 1-(3,5-bis(trifluoromethyl)phenyl)-3-propyl)thiourea. The fabricated catalyst has been characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD), nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller (BET) analysis. The nanoparticles are mostly tubular in shape and their particle sizes are smaller than 100 nm. This nanocatalyst shows efficient and robust catalytic activity in different reactions, including selective reduction of 4-nitrophenol (4NP) and oxidation of primary amines by applying NaBH4and urea hydrogen peroxide (UHP) as reagents, respectively. The catalyst shows good reusability in 10 sequential reaction runs.
- Bahadorikhalili, Saeed,Arshadi, Hosein,Afrouzandeh, Zahra,Ma'mani, Leila
-
p. 8840 - 8848
(2020/06/08)
-
- Selective Photoinduced Reduction of Nitroarenes to N-Arylhydroxylamines
-
We report the selective photoinduced reduction of nitroarenes to N-arylhydroxylamines. The present methodology facilitates this transformation in the absence of catalyst or additives and uses only light and methylhydrazine. This noncatalytic photoinduced transformation proceeds with a broad scope, excellent functional-group tolerance, and high yields. The potential of this protocol reflects on the selective and straightforward conversion of two general antibiotics, azomycin and chloramphenicol, to the bioactive hydroxylamine species.
- Kallitsakis, Michael G.,Ioannou, Dimitris I.,Terzidis, Michael A.,Kostakis, George E.,Lykakis, Ioannis N.
-
supporting information
p. 4339 - 4343
(2020/06/08)
-
- Optimized aqueous Kinugasa reactions for bioorthogonal chemistry applications
-
Kinugasa reactions hold potential for bioorthogonal chemistry in that the reagents can be biocompatible. Unlike other bioorthogonal reaction products, β-lactams are potentially reactive, which can be useful for synthesizing new biomaterials. A limiting factor for applications consists of slow reaction rates. Herein, we report an optimized aqueous copper(i)-catalyzed alkyne-nitrone cycloaddition involving rearrangement (CuANCR) with rate accelerations made possible by the use of surfactant micelles. We have investigated the factors that accelerate the aqueous CuANCR reaction and demonstrate enhanced modification of a model membrane-associated peptide. We discovered that lipids/surfactants and alkyne structure have a significant impact on the reaction rate, with biological lipids and electron-poor alkynes showing greater reactivity. These new findings have implications for the use of CuANCR for modifying integral membrane proteins as well as live cell labelling and other bioorthogonal applications.
- Bilodeau, Didier A.,Margison, Kaitlyn D.,Ahmed, Noreen,Strmiskova, Miroslava,Sherratt, Allison R.,Pezacki, John Paul
-
supporting information
p. 1988 - 1991
(2020/02/25)
-
- Bi(I)-Catalyzed Transfer-Hydrogenation with Ammonia-Borane
-
A catalytic transfer-hydrogenation utilizing a well-defined Bi(I) complex as catalyst and ammonia-borane as transfer agent has been developed. This transformation represents a unique example of low-valent pnictogen catalysis cycling between oxidation states I and III, and proved useful for the hydrogenation of azoarenes and the partial reduction of nitroarenes. Interestingly, the bismuthinidene catalyst performs well in the presence of low-valent transition-metal sensitive functional groups and presents orthogonal reactivity compared to analogous phosphorus-based catalysis. Mechanistic investigations suggest the intermediacy of an elusive bismuthine species, which is proposed to be responsible for the hydrogenation and the formation of hydrogen.
- Wang, Feng,Planas, Oriol,Cornella, Josep
-
supporting information
p. 4235 - 4240
(2019/04/17)
-
- LUMINOGENIC TRANSITION METAL-BASED PYRIDYL COMPLEX AND ITS USE
-
The present invention provides a luminogenic, in particular a phosphorogenic transition metal-based pyridyl complex containing a nitrone moiety, which nitrone moiety acts as a bioorthogonal functional group and an emission quencher, and can undergo cycloa
- -
-
Paragraph 0170; 0171
(2018/06/04)
-
- Low temperature liquid phase catalytic oxidation of aniline promoted by niobium pentoxide micro and nanoparticles
-
A microwave-assisted hydrothermal method was employed to synthesis Nb2O5 (niobium pentoxide) nanoparticles and the effects of synthesis conditions on the physical-chemical properties were evaluated. The catalytic activity of the prepared samples in the liquid phase oxidation of aniline with aqueous hydrogen peroxide as oxidizing agent was also studied. The nanoparticles showed hexagonal structure and rounded shape covered by nanoneedles. The results evidenced high catalytic activity with total conversion of aniline at ambient condition. Aniline conversion and product selectivities depended on the experimental parameters, particularly the oxidizing agent concentration, the nature of the solvent, type of the catalyst and reaction time.
- Ventura, Wellington M.,Batalha, Daniel C.,Fajardo, Humberto V.,Taylor, Jason G.,Marins, Natália H.,Noremberg, Bruno S.,Tański, Tomasz,Carre?o, Neftalí L.V.
-
p. 135 - 140
(2017/06/23)
-
- Synthesis of N-aryl and N-heteroaryl hydroxylamines via partial reduction of nitroarenes with soluble nanoparticle catalysts
-
Polystyrene-supported ruthenium nanoparticles enable the selective hydrazine-mediated reduction of nitroarenes to hydroxylamine products in high yield and selectivity. Key to obtaining the hydroxylamine product in good yield was the use of organic solvents capable of solubilizing the polystyrene-supported nanoparticle catalyst. N-aryl and N-heteroaryl hydroxylamines are generated under exceptionally mild conditions and in the presence of a various easily reduced functional groups.
- Tyler, Jefferson H.,Nazari, S. Hadi,Patterson, Robert H.,Udumula, Venkatareddy,Smith, Stacey J.,Michaelis, David J.
-
supporting information
p. 82 - 86
(2016/12/23)
-
- Concerted [1,3]-Rearrangement in Cationic Cobalt-Catalyzed Reaction of O-(Alkoxycarbonyl)-N-arylhydroxylamines
-
O-(Alkoxycarbonyl)-N-arylhydroxylamines were efficiently converted to 2-aminophenol derivatives by cationic cobalt catalysts at 30 °C. The results of 18O-labeling experiments suggested that rearrangement of the alkoxycarbonyl group from the aniline nitrogen to the ortho position proceeded in an unprecedented [1,3] manner.
- Nakamura, Itaru,Owada, Mao,Jo, Takeru,Terada, Masahiro
-
supporting information
p. 2194 - 2196
(2017/04/27)
-
- Cationic N-Heterocyclic Carbene Copper-Catalyzed [1,3]-Alkoxy Rearrangement of N-Alkoxyanilines
-
The [1,3]-alkoxy rearrangement reactions of N-alkoxyanilines were efficiently catalyzed by cationic N-heterocyclic carbene (NHC)-Cu catalysts in affording 2-alkoxyaniline derivatives in good to excellent yields with high functional group compatibility. For N-alkoxyanilines having an electron-withdrawing substituent at the meta-position, the alkoxy group selectively migrated to the more hindered ortho-position. In contrast, the alkoxy group migrated to the less hindered ortho-position for N-alkoxyanilines having an electron-donating substituent. Mechanistic studies suggest that the rearrangement reactions proceed via an intramolecular route.
- Nakamura, Itaru,Jo, Takeru,Ishida, Yasuhiro,Tashiro, Hiroki,Terada, Masahiro
-
supporting information
p. 3059 - 3062
(2017/06/23)
-
- TRIFLUOROMETHOXYLATION OF ARENES VIA INTRAMOLECULAR TRIFLUOROMETHOXY GROUP MIGRATION
-
The present invention provides a process of producing a trifluoromethoxylated aryl or trifluoromethoxylated heteroaryl having the structure: (I), wherein A is an aryl or heteroaryl, each with or without subsutitution; and R1 is -H, -(alkyl), -(alkenyl), -(alkynyl), -(aryl), -(heteroaryl), - (alkylaryl), - (alkylheteroaryl), -NH-(alkyl), -N(alkyl)2, -NH-(alkenyl), -NH-(alkynyl) -NH-(aryl), -NH-(heteroaryl), -O-(alkyl), -O-(alkenyl), -O-(alkynyl), -O-(aryl), -O-(heteroaryl), -S-(alkyl), -S- (alkenyl), -S-(alkynyl), -S-(aryl), or -S-(heteroaryl), comprising: (a) reacting a compound having the structure: (II), with a trifluoromethylating agent in the presence of a base in a first suitable solvent under conditions to produce a compound having the structure: (III); and (b) maintaining the compound produced in step (a) in a second suitable solvent under conditions sufficient to produce the trifluoromethoxylated aryl or trifluormethoxylated heteroaryl having the structure: (I).
- -
-
Page/Page column 56
(2016/05/02)
-
- Mechanistic studies on intramolecular C-H trifluoromethoxylation of (hetero)arenes via OCF3-migration
-
The one-pot two-step intramolecular aryl and heteroaryl C-H trifluoromethoxylation recently reported by our group has provided a general, scalable, and operationally simple approach to access a wide range of unprecedented and valuable OCF3-containing building blocks. Herein we describe our investigations to elucidate its reaction mechanism. Experimental data indicate that the O-trifluoromethylation of N-(hetero)aryl-N-hydroxylamine derivatives is a radical process, whereas the OCF3-migration step proceeds via a heterolytic cleavage of the N-OCF3 bond followed by rapid recombination of a short-lived ion pair. Computational studies further support the proposed ion pair reaction pathway for the OCF3-migration process. We hope that the current study would provide useful insights for the development of new transformations using versatile N-(hetero)aryl-N-hydroxylamine synthons.
- Lee, Katarzyna N.,Lei, Zhen,Morales-Rivera, Cristian A.,Liu, Peng,Ngai, Ming-Yu
-
supporting information
p. 5599 - 5605
(2016/07/06)
-
- An asymmetric pericyclic cascade approach to 3-alkyl-3-aryloxindoles: Generality, applications and mechanistic investigations
-
The reaction of L-serine derived N-arylnitrones with alkylarylketenes generates asymmetric 3-alkyl-3-aryloxindoles in good to excellent yields (up to 93%) and excellent enantioselectivity (up to 98% ee) via a pericyclic cascade process. The optimization, scope and applications of this transformation are reported, alongside further synthetic and computational investigations. The preparation of the enantiomer of a Roche anti-cancer agent (RO4999200) 1 (96% ee) in three steps demonstrates the potential utility of this methodology.
- Richmond, Edward,Ling, Kenneth B.,Duguet, Nicolas,Manton, Lois B.,elebi-?lcüm, Nihan,Lam, Yu-Hong,Alsancak, Sezen,Slawin, Alexandra M. Z.,Houk,Smith, Andrew D.
-
supporting information
p. 1807 - 1817
(2015/02/19)
-
- Controlled nitridation of tantalum (oxy)nitride nanoparticles towards optimized metal-support interactions with gold nanocatalysts
-
The electron regulation on supports can vary metal-support interactions with loaded metals in heterogeneous catalysis. In this paper, a facile Sr2+-mediated ionothermal route was introduced to control the nitridation degree in tantalum (oxy)nitrides, resulting in varied electronic properties and optimized interactions with gold nanocatalysts. A new mechanism was proposed that the formation of SrTa4O11 intermediates facilitated the replacement of O by N in controlled nitridation, and more importantly avoided undesired over-nitridation. As expected, the TaON support with defined nitridation promoted electronic metal-support interactions to generate Auδ- species, which was highly active for the thermal hydrogenation of nitrobenzene due to the moderated adsorption and effective activation on Auδ- in Au/TaON. This work elucidated the optimized metal-support interactions achieved on controllably nitridated supports, opening up new opportunities for the development of efficient nanocatalysts.
- Yang, Xiaoyun,He, Sina,Shu, Yijin,Shi, Zhangping,Guo, Yulin,Gao, Qingsheng,Tang, Yi
-
p. 89282 - 89289
(2015/11/09)
-
- Trifluoromethoxylation of arenes: Synthesis of ortho- Trifluoromethoxylated aniline derivatives by OCF3 migration
-
Aryl trifluoromethoxylation by a two-step sequence of O-trifluoromethylation of N-aryl-N-hydroxylamine derivatives and intramolecular OCF3 migration is presented. This protocol allows easy access to a wide range of synthetically useful ortho-OCF3 aniline derivatives. In addition, it utilizes bench-stable reagents, is operationally simple, shows high functional-group tolerance, and is amenable to gram-scale as well as one-pot synthesis.Areaction mechanism of a heterolytic cleavage of the N-OCF3 bond followed by recombination of the resulting nitrenium ion and trifluoromethoxide is proposed for the OCF3-migration reaction.
- Hojczyk, Katarzyna N.,Feng, Pengju,Zhan, Chengbo,Ngai, Ming-Yu
-
supporting information
p. 14559 - 14563
(2015/01/09)
-
- Copper-Catalyzed Oxidative Dimerizations of 3-N-Hydroxy-aminoprop-1-enes to form 1,4-Dihydroxy-2,3-diaminocyclohexanes with C2 Symmetry
-
This work describes the one-step construction of complex and important molecular frameworks through copper-catalyzed oxidations of cheap tertiary amines. Copper-catalyzed aerobic oxidations of N-hydroxyaminopropenes to form C2-symmetric N- and
- Ghorpade, Satish,Liu, Rai-Shung
-
supporting information
p. 12885 - 12888
(2016/02/18)
-
- Highly selective and controllable synthesis of arylhydroxylamines by the reduction of nitroarenes with an electron-withdrawing group using a new nitroreductase BaNTR1
-
A new bacterial nitroreductase has been identified and used as a biocatalyst for the controllable reduction of a variety of nitroarenes with an electron-withdrawing group to the corresponding N-arylhydroxylamines under mild reaction conditions with excellent selectivity (>99%). This method therefore represents a green and efficient method for the synthesis of arylhydroxylamines.
- Nguyen-Tran, Hieu-Huy,Zheng, Gao-Wei,Qian, Xu-Hong,Xu, Jian-He
-
supporting information
p. 2861 - 2864
(2014/03/21)
-
- POLYMER SUPPORTED REAGENTS AND METHODS OR REDUCING AROMATIC NITRO COMPOUNDS BY USING THE SAME
-
The present invention relates to a polymer supported reagent comprising a novel crosslinked mesoporous polymer, enabling a simple and easy production of an azoxy compound or an azo compound from an aromatic nitro compound, and a method of selectively reducing an aromatic nitro compound by using the same. The polymer supported reagent comprises a certain acrylamide mesoporous crosslinked polymer.
- -
-
Paragraph 0113; 0114
(2013/10/07)
-
- Solid supported platinum(0) nanoparticles catalyzed chemo-selective reduction of nitroarenes to N-arylhydroxylamines
-
Solid supported platinum(0) (SS-Pt) nanoparticles were developed as a heterogeneous catalyst following a reduction/deposition method and characterized by SEM, TEM, EDX and XRD analysis. The SS-Pt catalyst was applied in the chemo-selective reduction of nitroarenes to N-arylhydroxylamines using hydrazine hydrate as a hydrogen source. A wide variety of reducible functional groups such as halides, carboxylic acids, esters, amides, nitriles, keto, alkenes, alkynes and N-benzyl were well tolerated under the reaction conditions. This process was further successfully employed in 10 g scale reactions. N-Arylhydroxylamines were further applied for catalyst free synthesis of azoxybenzenes. Moreover, use of PEG-400 as cheap reaction medium, additive free methodology and the recyclability of SS-Pt catalyst up to ten times without significant loss of catalytic activity evidently follow the principles of green chemistry.
- Shil, Arun K.,Das, Pralay
-
supporting information
p. 3421 - 3428
(2013/12/04)
-
- Asymmetric pericyclic cascade approach to spirocyclic oxindoles
-
The reaction of chiral N-arylnitrones with carbocyclic alkylarylketenes generates spirocyclic oxindoles in good yields and with excellent levels of enantioselectivity (90-99% ee) via a pericyclic cascade process.
- Richmond, Edward,Duguet, Nicolas,Slawin, Alexandra M. Z.,Lebl, Tomas,Smith, Andrew D.
-
supporting information; experimental part
p. 2762 - 2765
(2012/07/14)
-
- Exploring α-chromonyl nitrones as 1,5-dipoles
-
N-Phenyl-C-chromonyl nitrones 1 and the allenoate zwitterion 2, generated by addition of phosphine to acetylenedicarboxylates, undergo a cascade reaction sequence involving an unprecedented [5+3] annulation followed by deoxygenative rearrangement leading to dihydropyridine-fused benzopyrones. Unusual electronic control by the N-substituents of 1 directs the annulation pathway, leading to two different ring-systems. Georg Thieme Verlag Stuttgart - New York.
- Wittstein, Kathrin,García, Ana B.,Schürmann, Markus,Kumar, Kamal
-
supporting information; experimental part
p. 227 - 232
(2012/03/10)
-
- 4-nitrobenzyloxycarbonyl derivatives of O 6-benzylguanine as hypoxia-activated prodrug inhibitors of O 6-alkylguanine-DNA alkyltransferase (AGT), which produces resistance to agents targeting the o -6 position of DNA guanine
-
A series of 4-nitrobenzyloxycarbonyl prodrug derivatives of O 6-benzylguanine (O6-BG), conceived as prodrugs of O 6-BG, an inhibitor of the resistance protein O6- alkylguanine-DNA alkyltransferase (AGT), were synthesized and evaluated for their ability to undergo bioreductive activation by reductase enzymes under oxygen deficiency. Three agents of this class, 4-nitrobenzyl (6-(benzyloxy)-9H-purin-2-yl)carbamate (1) and its monomethyl (2) and gem-dimethyl analogues (3), were tested for activation by reductase enzyme systems under oxygen deficient conditions. Compound 3, the most water-soluble of these agents, gave the highest yield of O6-BG following reduction of the nitro group trigger. Compound 3 was also evaluated for its ability to sensitize 1,2-bis(methylsulfonyl)-1-(2-chloroethyl)-2-[(methylamino)carbonyl] hydrazine (laromustine)-resistant DU145 human prostate carcinoma cells, which express high levels of AGT, to the cytotoxic effects of this agent under normoxic and oxygen deficient conditions. While 3 had little or no effect on laromustine cytotoxicity under aerobic conditions, significant enhancement occurred under oxygen deficiency, providing evidence for the preferential release of the AGT inhibitor O6-BG under hypoxia.
- Zhu, Rui,Liu, Mao-Chin,Luo, Mei-Zhen,Penketh, Philip G.,Baumann, Raymond P.,Shyam, Krishnamurthy,Sartorelli, Alan C.
-
experimental part
p. 7720 - 7728
(2012/01/13)
-
- Pericyclic cascade with chirality transfer: Reaction pathway and origin of enantioselectivity of the hetero-claisen approach to oxindoles
-
A new pericyclic cascade is proposed for the chiral auxiliary-controlled synthesis of 3,3-disubstituted oxindoles from nitrones and ketenes. The remarkable acyclic 1,6-stereochemical induction, hitherto unexplained, is rationalized by a stereoselective 3+
- Celebi-Oelcuem, Nihan,Lam, Yu-Hong,Richmond, Edward,Ling, Kenneth B.,Smith, Andrew D.,Houk, Kendall N.
-
supporting information; experimental part
p. 11478 - 11482
(2012/01/06)
-
- Synthesis of N-arylhydroxylamines by Pd-catalyzed coupling
-
Pd-catalyzed coupling of aryl halides with TeocNHOTBS, followed by treatment of the products with TBAF, provides effective access to a wide range of N-arylhydroxylamines by a route that produces stable doubly-protected intermediates and allows the protective groups to be removed under mild conditions that do not cause extensive degradation of the final product.
- Beaudoin, Daniel,Wuest, James D.
-
experimental part
p. 2221 - 2223
(2011/05/05)
-
- SINGLE-STEP CATALYTIC PREPARATION OF PARA-AMINOPHENOL
-
The method of using a bi-functional catalyst for the one-step preparation of para-aminophenol. The catalyst includes a mixture of a hydrogenation noble metal and a zirconium sulfate. Also, an improved single-step process for the preparation of para-aminophenol from nitrobenzene, in an aqueous medium, using the bi-functional catalyst.
- -
-
Page/Page column 8
(2011/05/03)
-
- METHOD FOR PRODUCING ARYLHYDROXYLAMINE
-
PROBLEM To provide a method for producing an arylhydroxylamine compound efficiently and safely under mild conditions. MEANS FOR SOLVING THE PROBLEM The present invention relates to a method for producing an arylhydroxylamine compound, which comprises contacting a nitroaryl compound with a hydrogen source in the coexistence of a platinum catalyst supported on amino group-coordinated silica and a poisoning agent.
- -
-
Page/Page column 23-24
(2010/03/04)
-
