- Selective Reduction of Nitroarenes to Arylamines by the Cooperative Action of Methylhydrazine and a Tris(N-heterocyclic thioamidate) Cobalt(III) Complex
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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.
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p. 2895 - 2906
(2021/02/27)
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- Synthesis and antileishmanial evaluation of thiazole orange analogs
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Cyanine compounds have previously shown excellent in vitro and promising in vivo antileishmanial efficacy, but the potential toxicity of these agents is a concern. A series of 22 analogs of thiazole orange ((Z)-1-methyl-4-((3-methylbenzo[d]thiazol-2(3H)-ylidene)methyl)quinolin-1-ium salt), a commercial cyanine dye with antileishmanial activity, were synthesized in an effort to increase the selectivity of such compounds while maintaining efficacy. Cyanines possessing substitutions on the quinolinium ring system displayed potency against Leishmania donovani axenic amastigotes that differed little from the parent compound (IC50 12–42 nM), while ring disjunction analogs were both less potent and less toxic. Changes in DNA melting temperature were modest when synthetic oligonucleotides were incubated with selected analogs (ΔTm ≤ 5 °C), with ring disjunction analogs showing the least effect on this parameter. Despite the high antileishmanial potency of the target compounds, their toxicity and relatively flat SAR suggests that further information regarding the target(s) of these molecules is needed to aid their development as antileishmanials.
- Abdelhameed, Ahmed,Liao, Xiaoping,McElroy, Craig A.,Joice, April C.,Rakotondraibe, Liva,Li, Junan,Slebodnick, Carla,Guo, Pu,Wilson, W. David,Werbovetz, Karl A.
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supporting information
(2019/11/28)
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- Radiosynthesis of (R,S)-[18F]GE387: A Potential PET Radiotracer for Imaging Translocator Protein 18 kDa (TSPO) with Low Binding Sensitivity to the Human Gene Polymorphism rs6971
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Translocator protein (TSPO) is a biomarker of neuroinflammation, which is a hallmark of many neurodegenerative diseases and has been exploited as a positron emission tomography (PET) target. Carbon-11-labelled PK11195 remains the most applied agent for imaging TSPO, despite its short-lived isotope and low brain permeability. Second-generation radiotracers show variance in affinity amongst subjects (low-, mixed-, and high-affinity binders) caused by the genetic polymorphism (rs6971) of the TSPO gene. To overcome these limitations, a new structural scaffold was explored based on the TSPO pharmacophore, and the analogue with a low-affinity binder/high-affinity binder (LAB/HAB) ratio similar (1.2 vs. 1.3) to that of (R)-[11C]PK11195 was investigated. The synthesis of the reference compound was accomplished in six steps and 9 % overall yield, and the precursor was prepared in eight steps and 8 % overall yield. The chiral separation of the reference and precursor compounds was performed using supercritical fluid chromatography with >95 % ee. The absolute configuration was determined by circular dichroism. Optimisation of reaction conditions for manual radiolabelling revealed acetonitrile as a preferred solvent at 100 °C. Automation of this radiolabelling method provided R and S enantiomers in respective 21.3±16.7 and 25.6±7.1 % decay-corrected yields and molar activities of 55.8±35.6 and 63.5±39.5 GBq μmol?1 (n=3). Injection of the racemic analogue into a healthy rat confirmed passage through the blood–brain barrier.
- Qiao, Luxi,Fisher, Emily,McMurray, Lindsay,Milicevic Sephton, Selena,Hird, Matthew,Kuzhuppilly-Ramakrishnan, Nisha,Williamson, David J.,Zhou, Xiouyun,Werry, Eryn,Kassiou, Michael,Luthra, Saijinder,Trigg, William,Aigbirhio, Franklin I.
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p. 982 - 993
(2019/04/17)
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- Ultra-low-loading palladium nanoparticles stabilized on nanocrystalline Polyaniline (Pd@PANI): A efficient, green, and recyclable catalyst for the reduction of nitroarenes
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Ultra-low-loading Pd@PANI nanocomposites (0.048 w.t% Pd) were synthesized via a method that combined interfacial polymerization and in situ composite with camphor sulfonic acid ((+)-CSA) as a dopant. Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, and X-ray photoelectron spectroscopy (XPS) were performed to characterize the structures. It can be used as an efficient catalyst for the reduction of nitroarenes in aqueous solution by using a smaller amount of NaBH4 (2.5 equiv.) at room temperature with high activity (TON?=?3.4?×?103), good stability (cycled eight times), as well as wide applicability (27 substrates). The catalyst also showed a marvelous activity in the gram-level reaction (yield?=?92%). UV–Visible spectrophotometry was used to investigate the reaction kinetics for the reduction of 4-nitrophenol to 4-aminophenol, and the results reconfirmed the excellent performance of the catalyst. The unique properties and superior performance of the prepared ultra-low-loading Pd@PANI nanocomposites lead it be an attractive alternative catalyst for conventional organic catalytic applications.
- Wang, Gang,Yuan, Shuo,Wu, Zhiqiang,Liu, Wanyi,Zhan, Haijuan,Liang, Yanping,Chen, Xiaoyan,Ma, Baojun,Bi, Shuxian
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- Induction of Axial Chirality in 8-Arylquinolines through Halogenation Reactions Using Bifunctional Organocatalysts
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The enantioselective syntheses of axially chiral heterobiaryls were accomplished through the aromatic electrophilic halogenation of 3-(quinolin-8-yl)phenols with bifunctional organocatalysts that control the molecular conformations during successive halogenations. Axially chiral quinoline derivatives, which have rarely been synthesized in an enantioselective catalytic manner, were afforded in moderate-to-good enantioselectivities through bromination, and an analogous protocol also enabled enantioselective iodination. In addition, this catalytic reaction, which allows enantioselective control through the use of mono-ortho-substituted substrates, allowed the asymmetric synthesis of 8-arylquinoline derivatives bearing two different halogen groups in high enantioselectivities.
- Miyaji, Ryota,Asano, Keisuke,Matsubara, Seijiro
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p. 9996 - 10000
(2017/08/01)
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- Controllable Synthesis of Mesoporous Iron Oxide Nanoparticle Assemblies for Chemoselective Catalytic Reduction of Nitroarenes
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Iron(III) oxide is a low-cost material with applications ranging from electronics to magnetism, and catalysis. Recent efforts have targeted new nanostructured forms of Fe2O3 with high surface area-to-volume ratio and large pore volume. Herein, the synthesis of 3D mesoporous networks consisting of 4-5 nm γ-Fe2O3 nanoparticles by a polymer-assisted aggregating self-assembly method is reported. Iron oxide assemblies obtained from the hybrid networks after heat treatment have an open-pore structure with high surface area (up to 167 m2 g-1) and uniform pores (ca. 6.3 nm). The constituent iron oxide nanocrystals can undergo controllable phase transition from γ-Fe2O3 to α-Fe2O3 and to Fe3O4 under different annealing conditions while maintaining the 3D structure and open porosity. These new ensemble structures exhibit high catalytic activity and stability for the selective reduction of aryl and alkyl nitro compounds to the corresponding aryl amines and oximes, even in large-scale synthesis.
- Papadas, Ioannis T.,Fountoulaki, Stella,Lykakis, Ioannis N.,Armatas, Gerasimos S.
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p. 4600 - 4607
(2016/03/22)
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- TETRAHYDRO-AZEPINOQUINOLINES AS AGONISTS OF THE 5-HT2C RECEPTOR
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Certain tetrahydro-azepinoquinolines of structural formula (I) are agonists of the mammalian 5-HT2c receptor, and, in particular, are selective agonists of the mammalian 5-HT2c receptor. The compounds of the present invention are therefore useful for the treatment, control, or prevention of duseases, conditions, or disorders responsive to stimulation of the 5-HT2c receptor, such as obesity, obesity-related condtions, and certain CNS-related disorders, including schizophrenia and depression. They are also useful as aids for tobacco smoking cessation. Formula (I).
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Page/Page column 47; 48
(2016/03/22)
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- Controllable Effect of Structural Modification of Sulfonylurea Herbicides on Soil Degradation
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The study of soil degradation behaviors of sulfonylurea herbicides in relation to their different structural attributes is utmost important for us to comprehend the development of new eco-friendly herbicides. It is postulated that the structural modification of the chemical structures could influence their degradation rates in soil. Nine devised structures were synthesized to study their herbicidal activity as well as their soil degradation behaviors respectively. The novel compounds I-3–I-7 were characterized by UV,1H NMR and13C NMR, MS and EA. Bioassays indicated that most of target compounds displayed superior herbicidal activities in comparison with Chlorsulfuron. Soil degradation results further confirmed our previous assumption that the introduction of electron-donating substituents at 5thposition of the benzene ring distinctly increased their degradation rates, among which dimethylamino and diethylamino groups can adjust the degradation rate to a more favorable status.
- Hua, Xuewen,Zhou, Shaa,Chen, Minggui,Wei, Wei,Liu, Ming,Lei, Kang,Zhou, Sha,Li, Yonghong,Wang, Baolei,Li, Zhengming
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p. 1135 - 1142
(2016/11/25)
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- Iridium-catalyzed transfer hydrogenation of nitroarenes to anilines
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A simple and general homogeneous catalyst system composed of commercially available [Ir(cod)Cl]2 and 1,10-phenanthroline has been developed for the selective transfer hydrogenation of nitroarenes to anilines. It utilized the readily accessible 2-propanol as a hydrogen donor and had wide substrate scope. A careful mechanistic investigation through real-time detection and a series of controlled experiments with possible intermediates was also carried out, which showed that the transformation proceeds via both phenylhydroxylamine and azobenzene intermediates and the reduction of hydrazobenzene leading to aniline might be the rate-determining step.
- Chen, Shujie,Lu, Guoping,Cai, Chun
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p. 5360 - 5365
(2015/07/07)
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- Mechanistic studies of the reduction of nitroarenes by NaBH4 or hydrosilanes catalyzed by supported gold nanoparticles
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Herein, we show that mesoporous titania-supported gold nanoparticle assemblies (Au/MTA) catalyze the activation of NaBH4 and 1,1,3,3-tetramethyl disiloxane (TMDS) compounds, which act as transfer hydrogenation agents for the reduction of nitroarenes to the corresponding anilines in moderate to high yields. On the other hand, nitroalkanes are reduced to the corresponding diazo and hydrazo compounds under the studied conditions. The substantial measured primary kinetic isotope effects found here suggested that B-H bond cleavage occurs in a rate-determining step and [Au]-H active hybrids are formed, which are responsible for the reduction of nitroarenes to the corresponding amines. Formal Hammett-type kinetic analysis of a range of para-X-substituted nitroarenes lends support to this hypothesis. Nitro compounds substituted with electron-withdrawing groups were reduced faster than the corresponding compounds with electron-donating groups. The presence of water enhanced the catalytic activity of Au/MTA in aprotic solvents. Nuclear magnetic resonance studies support the formation of the corresponding hydroxylamines as the only intermediate products. On the basis of the high observed chemoselectivities and the fast and clean reaction processes, these catalytic systems, i.e., Au/MTA-NaBH4 and Au/MTA-TMDS, show promise for the efficient synthesis of aromatic amines at industrial levels.
- Fountoulaki, Stella,Daikopoulou, Vassiliki,Gkizis, Petros L.,Tamiolakis, Ioannis,Armatas, Gerasimos S.,Lykakis, Ioannis N.
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p. 3504 - 3511
(2015/02/19)
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- Catalytic activation of hydrazine hydrate by gold nanoparticles: Chemoselective reduction of nitro compounds into amines
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Supported gold nanoparticles (2NH2 as a transfer hydrogenation agent. Aryl and alkyl nitro compounds are cleanly and selectively reduced into the corresponding amines in the presence of 4 equivalents of hydrazine. The reaction tolerates other potentially reducible functionalities such as carboxylate, carbonyl, cyano or halides which remain intact.
- Gkizis, Petros L.,Stratakis, Manolis,Lykakis, Ioannis N.
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- Identification and development of an efficient route to SB-649915
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The discovery and development of an efficient manufacturing route to the SSRI-5-HT1A receptor antagonist 6-[(1-{2-[(2-methyl-5-quinolinyl)oxy]ethyl}-4- piperidinyl)methyl]-2H-1,4-benzoxazin-3(4H)-one (SB-649915) 1 is described. The existing route to 1 involved coupling quinoline 6 with piperidine 5 and was considered lengthy as a consequence of the nine synthetic steps required to prepare 5. Two new routes to the key piperidine intermediate 5 are identified which deliver this compound in five and two steps respectively, from readily available materials using novel lithiation and Friedel-Crafts methodology respectively. The latter of these two routes was successfully demonstrated at 5 L scale to deliver 700 g of 5. Development to the methanesulfonate 34, an alternative to quinoline 6, is also described as is the final alkylation of piperidine 5 with this methanesulfonate 34 to deliver SB-649915 1.
- Armitage, Mark,Bret, Guillaume,Choudary, Bernie M.,Kingswood, Mike,Loft, Mike,Moore, Steve,Smith, Steve,Urquhart, Michael W. J.
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p. 1626 - 1634
(2013/02/22)
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- A new class of heterogeneous platinum catalysts for the chemoselective hydrogenation of nitroarenes
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A new series of nanostructured platinum catalysts able to catalyze the selective reduction of nitroarenes has been developed. The materials, made of organosilica physically doped with nanostructured platinum(0), are stable and efficient. Reactions in general proceed with high yield and often go to completion, while the catalysts can be reused in further reaction runs. This establishes a new class of relevant solid catalysts for synthetic organic chemistry named SiliaCat Platinum-Hydrogel.
- Pandarus, Valerica,Ciriminna, Rosaria,Beland, Francois,Pagliaro, Mario
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scheme or table
p. 1306 - 1316
(2011/06/25)
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- Copper-catalyzed synthesis of azaspirocyclohexadienones from ∝-azido- N -arylamides under an oxygen atmosphere
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A copper-catalyzed reaction of ∝-azido-N-arylamides was found to proceed under an oxygen atmosphere to afford azaspirocyclohexadienones. The present transformation is carried out by a sequence of denitrogenative formation of iminyl copper species from ∝-azido-N-arylamides and their imino-cupration with an intramolecular benzene ring on the amido nitrogen followed by consecutive formation of C-O bonds. The preliminary investigation revealed that molecular oxygen is a prerequisite for achieving the present catalytic cyclization and that one of the oxygen atoms of O2 was found to be incorporated into the cyclohexadienone moiety.
- Chiba, Shunsuke,Zhang, Line,Lee, Jian-Yuan
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supporting information; experimental part
p. 7266 - 7267
(2010/08/05)
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- SUBSTITUTED QUINAZOLINE DERIVATIVES AND THEIR USE AS INHIBITORS
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The use of a compound of formula (I) 1 or a salt, ester or amide thereof; where X is O, or S, S(O) or S(O)2, or NR6 where R6 is hydrogen or C1-6 alkyl,; R5 is an optionally substituted 5-membered heteroaromatic ring, R1, R2 ,R3, R4 are independently selected from various specified moieties, in the preparation of a medicament for use in the inhibition of aurora 2 kinase. Certain compounds are novel and these, together with pharmaceutical compositions containing them are also described and claimed
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- Furan Derivatives. Part 13. Synthesis of Thiopyranobenzofuran
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Thiopyranobenzofuran 9 possessing benzofuran and methylenethiopyran structures in the molecule was synthesized starting from 1-chloro-4-methoxy-2-nitrobenzene 11.Some reactions (formylation, protonation and catalytic hydrogenation) on 9 were examined.The 2-position of 9 was highly reactive toward electrophilic reagents and the furan ring was readily reduced by catalytic hydrogenation with palladium-charcoal.Thiopyranobenzofuran 9 has both properties of methylenethiopyran and benzofuran.
- Horaguchi, Takaaki,Hasegawa, Kohei,Hasegawa, Eietsu,Shimizu, Takahachi,Tanemura, Kiyoshi,Suzuki, Tsuneo
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p. 503 - 509
(2007/10/02)
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