- Substrate selectivity of human aldehyde oxidase 1 in reduction of nitroaromatic drugs
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Human aldehyde oxidase 1 (AOX1) catalyzes the oxidation of various drugs and endogenous compounds. Recently, we found that AOX1 catalyzed the reduction of drugs such as nitrazepam and dantrolene. In this study, we aimed to clarify the substrate selectivit
- Ogiso, Takuo,Fukami, Tatsuki,Mishiro, Kenji,Konishi, Keigo,Jones, Jeffrey P.,Nakajima, Miki
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- Intramolecular electron transfer in the photochemistry of some nitrophenyldihydropyridines
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4-Phenyl-1,4-dihydropyridine-3,5-dicarboxylates contain two π chromophores separated by an sp3 carbon. The lowest singlet is localized on the dihydropyridine moiety (1PyH2-Ph) and emits a blue fluorescence (with close to unitary efficiency in glass at 77 K). In 3-nitrophenyl derivatives (PyH2-PhNO2, some of which are photolabile drugs) the fluorescence is completely quenched. Reasonably, this is due to intramolecular electron transfer between the close-lying donor and acceptor moieties to give the charge-separated species (PyH2 .+-PhNO2.-). In EPA glass at 77 K, back-electron transfer gives the dihydropyridine-localized triplet ( 3PyH2-PhNO2), which emits a yellow phosphorescence. In solution, deprotonation from the radical cation on the dihydropyridine moiety initiates rearomatization, finally giving Py-PhNO 2 with low quantum yield (5 × 10-4 to 5 × 10-3, increasing up to 0.013 by irradiation at 254 nm, where direct excitation of the nitrophenyl chromophore contributes). In the presence of triethylamine, the reaction changes to neat reduction of the nitro group. When a tethered alkylamino group is present, oxidative degradation of that moiety occurs, again via an electron-transfer intramolecular process. This has been found with the drug nicardipine, where photodegration is more efficient (Φ 0.02 to 0.1). Donor-acceptor dyads of this type, easily available through the Hantzsch synthesis, may be useful for building new photoinduced electron-transfer systems.
- Fasani, Elisa,Fagnoni, Maurizio,Dondi, Daniele,Albini, Angelo
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- Simple RuCl3-catalyzed N-Methylation of Amines and Transfer Hydrogenation of Nitroarenes using Methanol
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Methanol is a potential hydrogen source and C1 synthon, which finds interesting applications in both chemical synthesis and energy technologies. The effective utilization of this simple alcohol in organic synthesis is of central importance and attracts scientific interest. Herein, we report a clean and cost-competitive method with the use of methanol as both C1 synthon and H2 source for selective N-methylation of amines by employing relatively cheap RuCl3.xH2O as a ligand-free catalyst. This readily available catalyst tolerates various amines comprising electron-deficient and electron-donating groups and allows them to transform into corresponding N-methylated products in moderate to excellent yields. In addition, few marketed pharmaceutical agents (e. g., venlafaxine and imipramine) were also successfully synthesized via late-stage functionalization from readily available feedstock chemicals, highlighting synthetic value of this advanced N-methylation reaction. Using this platform, we also attempted tandem reactions with selected nitroarenes to convert them into corresponding N-methylated amines using MeOH under H2-free conditions including transfer hydrogenation of nitroarenes-to-anilines and prepared drug molecules (e. g., benzocaine and butamben) as well as key pharmaceutical intermediates. We further enable one-shot selective and green syntheses of 1-methylbenzimidazole using ortho-phenylenediamine (OPDA) and methanol as coupling partners.
- Sarki, Naina,Goyal, Vishakha,Tyagi, Nitin Kumar,Puttaswamy,Narani, Anand,Ray, Anjan,Natte, Kishore
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p. 1722 - 1729
(2021/04/19)
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- Hydrogenation of Functionalized Nitroarenes Catalyzed by Single-Phase Pyrite FeS2 Nanoparticles on N,S-Codoped Porous Carbon
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Catalytic hydrogenation of nitroarenes is an industrially very important and environmentally friendly process for the production of anilines; however, highly chemoselective reduction of nitroarenes decorated with one or more reducible groups in a nitroarene molecule remains a challenge. Herein, a novel hybrid non-noble iron-based nanocatalyst (named as FeS2/NSC) was developed, which was prepared from biomass as C and N source together with inexpensive Fe(NO3)3 as Fe source through high-temperature pyrolysis in a straightforward and cost-effective procedure. Comprehensive characterization revealed that single-phase pyrite FeS2 nanoparticles with precisely defined composition and uniform size were homogeneously dispersed on N,S-codoped porous carbon with large specific surface area, hierarchical porous channels, and high pore volume. The resultant catalyst FeS2/NSC demonstrated good catalytic activity for hydrogenation of functionalized nitroarenes with good tolerance of various functional groups in water as a sustainable and green solvent. Compared with bulk pyrite FeS2 and other non-noble metal-based heterogeneous catalysts reported in the literature, a remarkably enhanced activity was observed under mild reaction conditions. More importantly, FeS2/NSC displayed exclusive chemoselectivity for the reduction of nitro groups for nitroarenes bearing varying readily reducible groups.
- Duan, Yanan,Dong, Xiaosu,Song, Tao,Wang, Zhaozhan,Xiao, Jianliang,Yuan, Youzhu,Yang, Yong
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- FE NANOPARTICLES WITH PPM CONTENTS OF PD, CU AND/OR NI, REACTIONS IN WATER CATALYZED BY THEM
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The present application discloses a nanoparticle composition prepared from a mixture comprising: a) a transition metal salt; b) an iron salt; and c) a reducing agent; and methods for the use of such compositions, including the reduction of an organic compound comprising a nitro group to form an organic compound comprising an amine group, the Cu-catalyzed cyclization of an azide and an alkyne (click chemistry) and cross coupling reactions, notably Suzuki-Miyaura reactions. The transition metal salts are in particular Pd, Cu and Ni salts, the content of these metals being typically in the ppm range based on the major constituent Fe in the final products.
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Paragraph 0069
(2017/07/14)
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- Safe and Selective Nitro Group Reductions Catalyzed by Sustainable and Recyclable Fe/ppm Pd Nanoparticles in Water at Room Temperature
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As a result of a unique synergy between ligand-free Fe/ppm Pd nanoparticles and PEG-containing designer surfactants, a facile and selective reduction of nitro-containing aromatics and heteroaromatics can be effected in water at room temperature in the presence of NaBH4. This new nanotechnology involves low catalyst loadings, is highly chemoselective, and tolerates a wide variety of functional groups. The process, which includes recycling of the entire aqueous medium, offers a general, environmentally responsible, and notably safe approach to highly valued reductions of nitro-containing compounds.
- Feng, Jie,Handa, Sachin,Gallou, Fabrice,Lipshutz, Bruce H.
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supporting information
p. 8979 - 8983
(2016/07/26)
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- Nanoscale Fe2O3-based catalysts for selective hydrogenation of nitroarenes to anilines
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Production of anilines - key intermediates for the fine chemical, agrochemical, and pharmaceutical industries - relies on precious metal catalysts that selectively hydrogenate aryl nitro groups in the presence of other easily reducible functionalities. Herein, we report convenient and stable iron oxide (Fe2O3) - based catalysts as a more earth-abundant alternative for this transformation. Pyrolysis of iron-phenanthroline complexes on carbon furnishes a unique structure in which the active Fe2O 3 particles are surrounded by a nitrogen-doped carbon layer. Highly selective hydrogenation of numerous structurally diverse nitroarenes (more than 80 examples) proceeded in good to excellent yield under industrially viable conditions.
- Jagadeesh, Rajenahally V.,Surkus, Annette-Enrica,Junge, Henrik,Pohl, Marga-Martina,Radnik, Joerg,Rabeah, Jabor,Huan, Heming,Schunemann, Volker,Brueckner, Angelika,Beller, Matthias
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p. 1073 - 1076
(2014/01/06)
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- Spectrofluorometric determination of nimodipine in dosage forms and human urine
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A simple sensitive and specific spectrofluorometric method was developed for the determination of nimodipine (NDP) in pharmaceutical preparations and human urine. The method is based on reduction of nimodipine with Zn/HCl and measuring the obtained fluore
- Belal,Al-Majed,Julkhuf,Khalil
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p. 874 - 876
(2007/10/03)
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- Syntheses, calcium channel antagonist and anticonvulsant activities of substituted 1,4-dihydro-3,5-pyridinedicarboxylates containing various 3-alkyl ester substituents
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A group of 3-alkyl-5-isopropyl 4-aryl-1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylates 10-20 containing an amine, quaternary ammonium, aryl(heteroaryl)alkenyl, 4-(4-fluorophenyl)-piperazin-1-yl or methoxy moiety in the C-3 alkyl ester R-substituent in combination with a C-4 phenyl ring bearing a 2,3-Cl2, 3-NO2, 3-NMe2, 4-NMe2 or 3,4,5-(OMe)3 X-substituent were prepared using the Hantzsch 1,4-dihydropyridine reaction. In vitro calcium channel antagonist activity (CCA) was determined using a guinea pig ileum longitudinal smooth muscle assay. In the C-4 3-nitrophenyl series of compounds, the C-3 ester R substituent was a determinant CCA activity where the relative potency order was -CH2CH2CH=C-(2-methylphenyl)2 ≤ -CH2CH2NMe2.HCl > -CH2CH2CH=C (3-methyl-2-thienyl)2 > -CH2CH2+NMe3I-. The position and nature of the C-4 phenyl X-substituent, were also determinants of CCA activity where the relative activity order was 3-NMe2>4-NMe2>3,4,5-(OMe)3. Anticonvulsant activities were determined in mice using the subcutaneous metrazol (scMet) and maximal electroshock (MES) screens. The compounds investigated were generally not effective for protecting against scMet induced seizures, except for 10 {X = 2,3-Cl2, R = 2-[4-(4-fluorophenyl)piperazin-1-yl]ethyl} and 14a (X = 3-NMe2.HCl, R = CH2CH2OMe), which exhibited modest activity. Compound 11a (X = 3-NO2, R = -CH2CH2NMe2.HCl) was the most effective agent in the MES screen. All of the compounds investigated, except for 11b (X = 3-NO2, R = -CH2CH2+NMe3 I-, Kp = 0.15) are lipophilic with n-octanol/aqueous phosphate buffer (pH = 7.4) partition coefficients (Kp) in the 121-424 range relative to the reference drug nimodipine (Kp = 187). The structure-activity relationship acquired reinforce the concept that calcium is only one of several factors that are involved in seizure generation.
- Yiu, Sai-Hay,Knaus, Edward E.
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- 4-heterocyclophenyl-substituted dihydropyridines
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4-Heterocyclophenyl-substituted dihydropyridines STR1 are prepared either by reacting suitable aldehydes with amino esters and β-keto esters, or preparing the heterocyclic substituents of the 4-phenyl by cyclization of corresponding amidines or hydrazides
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