- Redox-Neutral Imination of Alcohol with Azide: A Sustainable Alternative to the Staudinger/Aza-Wittig Reaction
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The traditional Staudinger/aza-Wittig reaction represents one of the most powerful tools for imine formation. However, for this multistep procedure, the sacrificial phosphine has to be used, resulting in difficulties in the purification process and waste disposal at the same time. Here, we report a redox-neutral azide-alcohol imination methodology enabled by a base-metal nickel PN3 pincer catalyst. The one-step, waste-free, and high atom-economical features highlight its advantages further. Moreover, mechanistic insight suggests a non-metal-ligand cooperation pathway based on the observation of an intermediate and density functional theory calculations.
- Li, Huaifeng,Lupp, Daniel,Das, Pradip K.,Yang, Li,Gon?alves, Théo P.,Huang, Mei-Hui,El Hajoui, Marwa,Liang, Lan-Chang,Huang, Kuo-Wei
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p. 4071 - 4076
(2021/04/12)
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- Nickel Complexes Bearing N,N,O-Tridentate Salicylaldiminato Ligand: Efficient Catalysts for Imines Formation via Dehydrogenative Coupling of Primary Alcohols with Amines
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Treatment of salicylaldiminato ligand L1H-L2H (L1H = 2,4-di-tert-butyl-6-((quinolin-8-ylimino)methyl)phenol; L2H = 2,4-di-tert-butyl-6-(((2-(diethylamino)ethyl)imino)methyl)phenol) with Ni(OAc)2·4H2O in refluxing ethanol afforded nickel complexes [(L1)Ni(OAc)] (1) and [(L2)Ni(OAc)] (2), respectively. Reaction of L3H (L3H = (2,4-di-tert-butyl-6-(((2-(pyridin-2-yl)ethyl)imino)methyl)phenol)) with Ni(OAc)2·4H2O in the presence of excess triethylanmine gave the dual ligands coordinated nickel complex [(L2)2Ni] (3). Complexes 1-3 were well characterized by high-resolution mass spectrometry, infrared spectroscopy, elemental analysis, and X-ray diffraction analysis. All the three Ni(II) complexes exhibited efficient activity and good selectivity in the acceptorless dehydrogenative coupling of alcohols and amines to produce imines and diimines. The present protocol provides an atom-economical and sustainable route for the synthesis of various imine derivatives by employing an earth-abundant nickel salt and easily prepared salicylaldiminato ligands.
- Han, Zhangang,Hao, Zhiqiang,Lin, Jin,Lu, Guo-Liang,Zhang, Junhua,Zhang, Xiaoying
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p. 3843 - 3853
(2021/11/18)
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- Half-Sandwich Ruthenium Complexes Bearing Hemilabile κ2-(C,S)?Thioether-Functionalized NHC Ligands: Application to Amide Synthesis from Alcohol and Amine
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Amide synthesis is one of the most crucial transformations in chemistry and biology. Among various catalytic systems, N-heterocyclic carbene (NHC)-based ruthenium (Ru) catalyst systems have been proven to be active for direct synthesis of amides by sustainable acceptorless dehydrogenative Coupling of primary alcohols with amines. Most often, these catalytic systems usually use monodentate NHC and thus require an additional ligand to obtain high reactivity and selectivity. In this work, a series of cationic Ru(II)(η6-p-cymene) complexes with thioether-functionalized N-heterocyclic carbene ligands (imidazole and benzimidazole-based) have been prepared and fully characterized. These complexes have then been used in the amidation reaction and the most promising one (i. e. 3 c) has been applied on a large range of substrates. High conversions albeit with moderate yields have generally been obtained.
- Achard, Thierry,Bellemin-Laponnaz, Stéphane,Chen, Weighang,Egly, Julien,Maisse-Fran?ois, Aline
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supporting information
(2022/01/20)
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- FeCl2-PPh3 as an efficient catalytic system for the acceptorless dehydrogenation of amines into imines
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In this work, a novel and simple catalytic system including FeCl2, PPh3 and potassium tert-butoxide has been employed for the synthesis of imines from amines. In order to prove the catalytic acceptorless dehydrogenation pathway for this transformation, the liberated H2 gas is detected by NMR spectroscopy. By utilizing this protocol, a variety of arylamines were used successfully for the preparation of corresponding imines in good to excellent yields (on a 1?mmol scale, 73–91% yield for homocoupling, 71 and 91% for heterocoupling).
- Nazarahari, Maryam,Azizian, Javad
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p. 5705 - 5710
(2021/07/06)
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- Cyclometalated Half-Sandwich Iridium(III) Complexes: Synthesis, Structure, and Diverse Catalytic Activity in Imine Synthesis Using Air as the Oxidant
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Four air-stable cyclometalated half-sandwich iridium complexes 1-4 with C,N-donor Schiff base ligands were prepared through C-H activation in moderate-to-good yields. These complexes have been well characterized, and their exact structure was elaborated on by single-crystal X-ray analysis. The iridium(III) complexes 1-4 showed good catalytic activity in the imine synthesis under open-flask conditions (air as the oxidant) from primary amine oxidative homocoupling, secondary amine dehydrogenation, and the cross-coupling reaction of amine and alcohol. Substituents bonded on the ligands of the iridium complexes displayed little effect on the catalytic efficiency. The stability and good catalytic efficiency of the iridium catalysts, mild reaction conditions, and substrate universality showed their potential application in industrial production.
- Li, Rong-Jian,Ling, Chun,Lv, Wen-Rui,Deng, Wei,Yao, Zi-Jian
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p. 5153 - 5162
(2021/05/04)
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- Cobalt-Catalyzed α-Arylation of Substituted α-Bromo α-Fluoro β-Lactams with Diaryl Zinc Reagents: Generalization to Functionalized Bromo Derivatives
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A cobalt-catalyzed cross-coupling of α-bromo α-fluoro β-lactams with diarylzinc or diallylzinc reagents is herein disclosed. The protocol proved to be general, chemoselective and operationally simple allowing the C4 functionalization of β-lactams. The substrate scope was expanded to α-bromo lactams and amides, α-bromo lactones and esters as well as N- and O-containing heterocycles.
- Br?se, Stefan,Chen, Hi-Yung,Cossy, Janine,Koch, Vanessa,Lei, Aiwen,Lorion, Mélanie M.,Nieger, Martin
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supporting information
p. 13163 - 13169
(2020/09/23)
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- Efficient Co-Catalyzed Double Hydroboration of Nitriles: Application to One-Pot Conversion of Nitriles to Aldimines
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The commercially available and bench-stable Co(acac)2/dpephos system is employed as a precatalyst for selective and efficient room temperature hydroboration of organic nitriles with HBPin to produce a series of N,N-diborylamines [RN(BPin)2], which react in situ with aldehydes to give aldimines. Formation of aldimines from N,N-diborylamines does not require a dehydrating agent, is applicable to a wide range of N,N-diborylamine and aldehyde substrates and is highly chemoselective, being unaffected by various common functional groups, such as alkenes, alkynes, secondary amines, ketones, esters, amides, carboxylic acids, pyridines, nitriles, and nitro compounds. The overall transformation represents a synthetically valuable approach to aldimines from nitriles and can be performed in a sequential one-pot manner, tolerating ester, lactone, carboxamide and unactivated alkene functionalities.
- Gudun, Kristina A.,Slamova, Ainur,Hayrapetyan, Davit,Khalimon, Andrey Y.
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supporting information
p. 4963 - 4968
(2020/04/17)
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- Highly efficient microwave assisted synthesis of magnetically separable GO-CoFe2O4 nanocomposite for visible light induced oxidative coupling of benzyl amines
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The present paper describes an efficient microwave-assisted synthesis of magnetic CoFe2O4 and its nanocomposite with graphene oxide (GO-CoFe2O4) for photocatalytic oxidative coupling of benzylamines to the corresponding imines using molecular oxygen. The surface morphologies and structures of both CoFe2O4 and GO-CoFe2O4 nanocomposites were investigated by various spectroscopic techniques including powder X-ray diffraction (XRD), Transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption–desorption isotherms, X-ray photoelectron spectroscopy (XPS) and Raman Spectroscopy. Photocatalytic oxidative coupling experiments demonstrated that GO-CoFe2O4 exhibited significantly higher efficiency than CoFe2O4 nanoparticles, suggesting that GO played an important role in the reaction. Moreover, the magnetic nature of the synthesized nanocomposite provided facile recovery of the material by the influence of an external magnet.
- Jain, Suman L.,Khatri, Praveen K.,Sadanandan, Aathira M.
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- Air-Stable Half-Sandwich Iridium Complexes as Aerobic Oxidation Catalysts for Imine Synthesis
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Several N,O-coordinate half-sandwich iridium complexes, 1-5, containing constrained bulky β-enaminoketonato ligands were prepared and clearly characterized. Single-crystal X-ray diffraction characterization of these complexes indicates that the iridium center adopts a distorted octahedral geometry. Complexes 1-5 showed good catalytic efficiency in the oxidative homocoupling of primary amines, dehydrogenation of secondary amines, and the oxidative cross-coupling of amines and alcohols, which furnished various types of imines in good yields and high selectivities using O2 as an oxidant under mild conditions. No distinctive substituent effects of the iridium catalysts were observed in these reactions. The diverse catalytic activity, broad substrate scope, mild reaction conditions, and high yields of the products made this catalytic system attractive in industrial processes.
- Deng, Wei,Fan, Xiao-Nan,Ou, Hui-Dan,Yao, Zi-Jian
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supporting information
(2020/04/02)
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- Visible-light-induced regioselective cross-dehydrogenative coupling of 2 H-indazoles with ethers
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A visible-light-promoted regioselective C(sp2)-H/C(sp3)-H cross-dehydrogenative coupling between 2H-indazoles and ethers has been achieved using a catalytic amount of rose bengal as an organophotoredox-catalyst and tert-butyl hydroperoxide (TBHP) as an oxidant at ambient temperature under aerobic conditions. A variety of C-3 oxyalkylated 2H-indazoles have been synthesized in moderate to good yields. Mechanistic studies suggest a radical pathway of the present reaction.
- Singsardar, Mukta,Laru, Sudip,Mondal, Susmita,Hajra, Alakananda
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p. 4543 - 4550
(2019/04/30)
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- Cobalt-Catalyzed α-Arylation of Substituted α-Halogeno β-Lactams
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The treatment of 3-bromo β-lactams by an aryl Grignard, in the presence of CoCl2 (2 mol %) and TMEDA (2 mol %) in THF, produces 3-aryl β-lactams in good yields and excellent diastereoselectivity.
- Koch, Vanessa,Lorion, Mélanie M.,Barde, Etienne,Br?se, Stefan,Cossy, Janine
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supporting information
p. 6241 - 6244
(2019/08/26)
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- Synthesis of Secondary Aldimines from the Hydrogenative Cross-Coupling of Nitriles and Amines over Al2O3-Supported Ni Catalysts
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A heterogeneous Ni catalyst was discovered to be active in the synthesis of secondary cross-imines via hydrogenative coupling of nitriles and amines. The mesoporous Al2O3-supported Ni nanoparticles (abbreviated as Ni/m-Al2O3-600, where 600 represents the reduction temperature) were active in hydrogenative coupling of nitriles and amines reaction at 80 °C and 1 bar H2, affording corresponding cross-imines with yields in the range 64.1-98.1%. Density functional theory calculations reveal the hydrogenation of benzonitrile (PhCN) to benzylamine (PhCH2NH2) has higher activation energy than that for hydrogenative cross-coupling of PhCN and RNH2 on the Ni/m-Al2O3-600 catalyst, suggesting the latter reaction is more favorable. The theoretical calculations are in good agreement with our experimental results.
- Zhou, Peng,Jiang, Liang,Wang, Shuguo,Hu, Xun,Wang, Hongming,Yuan, Ziliang,Zhang, Zehui
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p. 8413 - 8423
(2019/09/07)
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- Hydrogenated Cu2OAu@CeO2 Z-scheme catalyst for photocatalytic oxidation of amines to imines
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The design and fabrication of highly active visible light photocatalysts for organic synthesis reactions are particularly challenging for solar energy utilization and conversion. Herein, hydrogenated Z-scheme yolk-shell Cu2OAu@CeO2 (H-Cu2OAu@CeO2) photocatalysts were synthesized using cubic Cu2O as the starting core material via surface Au deposition and oxidation etching process, followed by hydrogenation treatment. When compared with CeO2, Cu2O@CeO2, and Cu2O@CeO2Au nanocomposites, optimized H-Cu2OAu@CeO2 showed remarkably higher visible light oxidation activity for the synthesis of imines from amines at ambient pressure and room temperature. The remarkably enhanced photoactivity of the H-Cu2OAu@CeO2 composite mainly derives from the enhanced photoinduced charge separation efficiency, porous yolk-shell structure, proper surface defects, and well-maintained strong oxidation/reduction capabilities. The Z-scheme charge transfer process and photocatalytic reaction mechanism of the H-Cu2OAu@CeO2 composites were also provided through spectral and photoelectrochemical analyses together with the investigation of structure and photocatalytic oxidation reactions. This study provides a probable approach for designing unique Z-scheme catalysts.
- Liu, Yingying,Chen, Yajie,Zhou, Wei,Jiang, Baojiang,Zhang, Xin,Tian, Guohui
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p. 5535 - 5543
(2018/11/20)
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- Mesoporous cobalt/manganese oxide: A highly selective bifunctional catalyst for amine-imine transformations
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Herein, we discuss a heterogeneous catalytic protocol using cobalt doped mesoporous manganese oxide for amine-alcohol cross-coupling to selectively produce symmetric or asymmetric imines. Thorough investigations on the surface chemistry and physical properties of the material revealed its outstanding oxidation-reduction properties and reaction mechanism which was supported by quantum mechanical calculations done by using density functional theory (DFT).
- Dutta, Biswanath,March, Seth,Achola, Laura,Sahoo, Sanjubala,He, Junkai,Shirazi Amin, Alireza,Wu, Yang,Poges, Shannon,Pamir Alpay,Suib, Steven L.
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p. 3180 - 3185
(2018/07/29)
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- A Metal-Free Approach to 1,2-Diamines via Visible Light-Driven Reductive Coupling of Imines with Perylene as a Photoredox Catalyst
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A simple, metal-free, and versatile approach to 1,2-diamines has been developed based on reductive coupling reactions of various imines, where perylene, an aromatic hydrocarbon, was used as a photoredox catalyst under visible light irradiation using a white light-emitting diode. The use of 1 mol % perylene enabled almost complete conversion of the imines, leading to the formation of their corresponding 1,2-diamines, which were isolated in good yields. The ratios between dl and meso diamines ranged from 31:69 to 82:18 depending on the substituents of the imines.
- Okamoto, Shusuke,Ariki, Risako,Tsujioka, Hiroki,Sudo, Atsushi
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p. 9731 - 9736
(2017/09/23)
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- Asymmetric Petasis Borono-Mannich Allylation Reactions Catalyzed by Chiral Biphenols
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Chiral biphenols catalyze the asymmetric Petasis borono-Mannich allylation of aldehydes and amines through the use of a bench-stable allyldioxaborolane. The reaction proceeds via a two-step, one-pot process and requires 2–8 mole % of 3,3′-Ph2-BINOL as the optimal catalyst. Under microwave heating the reaction affords chiral homoallylic amines in excellent yields (up to 99 %) and high enantioselectivies (er up to 99:1). The catalytic reaction is a true multicomponent condensation reaction whereas both the aldehyde and the amine can possess a wide range of structural and electronic properties. Use of crotyldioxaborolane in the reaction results in stereodivergent products with anti- and syn-diastereomers both in good diastereoselectivities and enantioselectivities from the corresponding E- and Z-borolane stereoisomers.
- Jiang, Yao,Schaus, Scott E.
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supporting information
p. 1544 - 1548
(2017/02/05)
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- Method for synthesizing imine through cross-coupling of hydroxylation phenanthroline copper complex/O2 catalytic oxidation alcohol and amine
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The invention discloses a method for synthesizing imine through cross-coupling of hydroxylation phenanthroline copper complex/O2 catalytic oxidation alcohol and amine. According to the method, an economical and cheap hydroxylation phenanthroline copper complex is selected as a catalyst, green O2 is selected as an oxidizing agent, cross-coupling of alcohol and amine is realized under the condition of normal temperature, alkali and an expensive free radical of nitroxide is prevented from being used, and a series of imine compounds are successfully prepared. The method provided by the invention is high in reaction selectivity and relatively wide in a substrate application range, and has a great industrial application potential.
- -
-
Paragraph 0017; 0040; 0041
(2017/12/02)
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- MANGANESE BASED COMPLEXES AND USES THEREOF FOR HOMOGENEOUS CATALYSIS
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The present invention relates to novel manganese complexes and their use, inter alia, for homogeneous catalysis in (1) the preparation of imine by dehydrogenative coupling of an alcohol and amine; (2) C-C coupling in Michael addition reaction using nitriles as Michael donors; (3) dehydrogenative coupling of alcohols to give esters and hydrogen gas (4) hydrogenation of esters to form alcohols (including hydrogenation of cyclic esters (lactones) or cyclic di-esters (di- lactones), or polyesters); (5) hydrogenation of amides (including cyclic dipeptides, lactams, diamide, polypeptides and polyamides) to alcohols and amines (or diamine); (6) hydrogenation of organic carbonates (including polycarbonates) to alcohols or hydrogenation of carbamates (including polycarbamates) or urea derivatives to alcohols and amines; (7) dehydrogenation of secondary alcohols to ketones; (8) amidation of esters (i.e., synthesis of amides from esters and amines); (9) acylation of alcohols using esters; (10) coupling of alcohols with water and a base to form carboxylic acids; and (11) preparation of amino acids or their salts by coupling of amino alcohols with water and a base. (12) preparation of amides (including formamides, cyclic dipeptides, diamide, lactams, polypeptides and polyamides) by dehydrogenative coupling of alcohols and amines; (13) preparation of imides from diols.
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-
Paragraph 00277-00278
(2017/09/05)
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- Formation of 2-Azaallyl Cobalt(I) Complexes by Csp3-H Bond Activation
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Three novel unsymmetrical η3-2-azaallyl cobalt(I) complexes, [(2-PPh2)C6H4]CHN[CHC6H4(4-R)]Co(PMe3)2 (4-6) (R = H (4); Cl (5); and OMe (6)), were synthesized by the r
- Xing, Junyang,Sun, Hongjian,Xue, Benjing,Li, Xiaoyan,Fuhr, Olaf,Fenske, Dieter
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supporting information
p. 975 - 980
(2017/04/21)
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- Homologation of α-aryl amino acids through quinone-catalyzed decarboxylation/Mukaiyama-Mannich addition
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A new method for amino acid homologation by way of formal C-C bond functionalization is reported. This method utilizes a 2-step/1-pot protocol to convert α-amino acids to their corresponding N-protected β-amino esters through quinone-catalyzed oxidative decarboxylation/in situ Mukaiyama-Mannich addition. The scope and limitations of this chemistry are presented. This methodology provides an alternative to the classical Arndt-Eistert homologation for accessing β-amino acid derivatives. The resulting N-protected amine products can be easily deprotected to afford the corresponding free amines.
- Haugeberg, Benjamin J.,Phan, Johnny H.,Liu, Xinyun,O'Connor, Thomas J.,Clift, Michael D.
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supporting information
p. 3062 - 3065
(2017/03/17)
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- Iron-Catalyzed Mild and Selective Hydrogenative Cross-Coupling of Nitriles and Amines To Form Secondary Aldimines
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The first example of a base-metal-catalyzed homogeneous hydrogenative coupling of nitriles and amines to selectively form secondary cross-imines is reported. The reaction is catalyzed under mild conditions by a well-defined (iPr-PNP)Fe(H)Br(CO) pincer pre-catalyst and catalytic tBuOK.
- Chakraborty, Subrata,Leitus, Gregory,Milstein, David
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supporting information
p. 2074 - 2078
(2017/02/15)
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- Transition-Metal-Controlled Inorganic Ligand-Supported Non-Precious Metal Catalysts for the Aerobic Oxidation of Amines to Imines
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Most state-of-art transition-metal catalysts usually require organic ligands, which are essential for controlling the reactivity and selectivity of reactions catalyzed by transition metals. However, organic ligands often suffer from severe problems including cost, toxicity, air/moisture sensitivity, and being commercially unavailable. Herein, we show a simple, mild, and efficient aerobic oxidation procedure of amines using inorganic ligand-supported non-precious metal catalysts 1, (NH4)n[MMo6O18(OH)6] (M=Cu2+; Fe3+; Co3+; Ni2+; Zn2+, n=3 or 4), synthesized by a simple one-step method in water at 100 °C, demonstrating that the catalytic activity and selectivity can be significantly improved by changing the central metal atom. In the presence of these catalysts, the catalytic oxidation of primary and secondary amines, as well as the coupling of alcohols and amines, can smoothly proceed to afford various imines with O2 (1 atm) as the sole oxidant. In particular, the catalysts 1 have transition-metal ion core, and the planar arrangement of the six MoVI centers at their highest oxidation states around the central heterometal can greatly enhance the Lewis acidity of catalytically active sites, and also enable the electrons in the center to delocalize onto the six edge-sharing MO6 units, in the same way as ligands in traditional organometallic complexes. The versatility of this methodology maybe opens a path to catalytic oxidation through inorganic ligand-coordinated metal catalysis.
- Yu, Han,Zhai, Yongyan,Dai, Guoyong,Ru, Shi,Han, Sheng,Wei, Yongge
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supporting information
p. 13883 - 13887
(2017/10/13)
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- Dual Heterogeneous Catalyst Pd-Au@Mn(II)-MOF for One-Pot Tandem Synthesis of Imines from Alcohols and Amines
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A new Mn(II) metal-organic framework (MOF) 1 was synthesized by the combination of 4,4,4-trifluoro-1-(4-(pyridin-4-yl)phenyl)butane-1,3-dione (L) and Mn(OAc)2 in solution. 1 features a threefold-interpenetrating NbO net containing honeycomb-like channels, in which the opposite Mn(II)···Mn(II) distance is 23.5075(10) ?. Furthermore, 1 can be an ideal platform to support Pd-Au bimetallic alloy nanoparticles to generate a composite catalytic system of Pd-Au@Mn(II)-MOF (2). 2 can be a highly active bifunctional heterogeneous catalyst for the one-pot tandem synthesis of imines from benzyl alcohols and anilines and from benzyl alcohols and benzylamines.
- Chen, Gong-Jun,Ma, Hui-Chao,Xin, Wen-Ling,Li, Xiao-Bo,Jin, Fa-Zheng,Wang, Jing-Si,Liu, Ming-Yang,Dong, Yu-Bin
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supporting information
p. 654 - 660
(2017/01/13)
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- A one-pot synthesis of highly substituted tetrahydropyridines from N-benzylidenemethanamines, dialkyl acetylenedicarboxylates and benzylidenemalononitriles
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A simple and efficient synthesis of highly substituted tetrahydropyridines has been develope using a one-pot, two step reactions. The synthesis of a series of N-benzylidenemethanamine from benzylamines and benzaldehydes in the presence of acetic acid, followed by cyclizatio with dialkyl acetylenedicarboxylates and benzylidenemalononitriles, gave the correspondin tetrahydropyridines in good yields.
- Mehrabi, Hossein,Mohebbi, Ahmad
-
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- Load manganese oxidizing catalytic chipboard spreading method for one-step synthesis of imines
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The invention belongs to the technical fields of chemistry and chemical engineering, and concretely relates to a method for one step synthesis of imine through catalyzing alcohol and amine by supported manganese oxide. A reaction of alcohol and amine is carried out in a solvent or solvent-free state at 60-90DEG C for 6-48h with the supported manganese oxide as a catalyst and molecular oxygen or air as an antioxidant to realize one step synthesis of a corresponding imine compound. The valence of manganese in the catalyst is +2, +3 or +4, the general formula of the catalyst is MnOx, and a carrier is hydroxyapatite (Ca10(PO4)6(OH)2). The catalyst still has very good activity and selectivity after the catalyst is reused at least 9 times. The catalyst used in the method has the characteristics of simple preparation, cheapness, high reaction selectivity and environmental protection.
- -
-
Paragraph 0074; 0075
(2017/02/02)
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- Manganese-Catalyzed Environmentally Benign Dehydrogenative Coupling of Alcohols and Amines to Form Aldimines and H2: A Catalytic and Mechanistic Study
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The catalytic dehydrogenative coupling of alcohols and amines to form aldimines represents an environmentally benign methodology in organic chemistry. This has been accomplished in recent years mainly with precious-metal-based catalysts. We present the dehydrogenative coupling of alcohols and amines to form imines and H2 that is catalyzed, for the first time, by a complex of the earth-abundant Mn. Detailed mechanistic study was carried out with the aid of NMR spectroscopy, intermediate isolation, and X-ray analysis.
- Mukherjee, Arup,Nerush, Alexander,Leitus, Gregory,Shimon, Linda J. W.,Ben David, Yehoshoa,Espinosa Jalapa, Noel Angel,Milstein, David
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supporting information
p. 4298 - 4301
(2016/05/09)
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- Factors influencing the regioselectivity of the oxidation of asymmetric secondary amines with singlet oxygen
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Aerobic amine oxidation is an attractive and elegant process for the α functionalization of amines. However, there are still several mechanistic uncertainties, particularly the factors governing the regioselectivity of the oxidation of asymmetric secondary amines and the oxidation rates of mixed primary amines. Herein, it is reported that singlet-oxygen-mediated oxidation of 1° and 2° amines is sensitive to the strength of the α-C-H bond and steric factors. Estimation of the relative bond dissociation energy by natural bond order analysis or by means of one-bond C-H coupling constants allowed the regioselectivity of secondary amine oxidations to be explained and predicted. In addition, the findings were utilized to synthesize highly regioselective substrates and perform selective amine cross-couplings to produce imines.
- Ushakov, Dmitry B.,Plutschack, Matthew B.,Gilmore, Kerry,Seeberger, Peter H.
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supporting information
p. 6528 - 6534
(2015/04/22)
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- Aerobic oxidation of amines to imines by cesium-promoted mesoporous manganese oxide
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Selective oxidation of amines to imines is one of the most studied reactions in the field of heterogeneous catalysis. Cs ion-promoted mesoporous manganese oxide (meso Cs/MnOx) was synthesized using an inverse surfactant micelle as a soft template. The chemical and structural properties of the mesoporous manganese oxide material were characterized by powder X-ray diffraction, nitrogen sorption, electron microscopy, and X-ray photoelectron spectra. The meso-Cs/MnOx material presented an aggregated nanocrystalline nature with monomodal mesoporous size distributions. The catalyst was found to be effective in the oxidation of amines to imines under aerobic conditions. The meso Cs/MnOx exhibited oxidation of primary, secondary, cyclic, aromatic, and aliphatic amines to imines, and the conversions reached as high as >99%. The catalyst was also effective in oxidative cross-condensation of two different amines to produce asymmetrically substituted imines. Surface-active Mn3+ species along with labile lattice oxygen were found to play an important role in the catalytic activity. Mild reaction conditions (air atmosphere and absence of any oxidative or basic promoters), ease of product separation by simple filtration, and significant reusability make this mesoporous manganese oxide material an economical and ecofriendly catalyst for the syntheses of versatile imine derivatives.
- Biswas, Sourav,Dutta, Biswanath,Mullick, Kankana,Kuo, Chung-Hao,Poyraz, Altug S.,Suib, Steven L.
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p. 4394 - 4403
(2015/11/11)
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- The Cu(OTf)2 catalysed microwave assisted synthesis of a new scaffold, 7-aryl-7,8-dihydropyrido[4,3-c]pyridazin-5(6H )-one
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The synthesis of novel 7-aryl-7,8-dihydropyrido[4,3-c]pyridazin-5(6 H)-ones is described including a one-step Mannich-type reaction followed by intramolecular ring closure of ethyl 3-methylpyridazine-4-carboxylate and aldimines, catalysed by the Lewis aci
- Muylaert, Koen,Mangelinckx, Sven,Jatczak, Martyna,De Coen, Laurens M.,Van Hecke, Kristof,Stevens, Christian V.
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p. 139 - 155
(2015/02/19)
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- Asymmetric synthesis of tetrahydropyridines via an organocatalytic one-pot multicomponent Michael/aza-Henry/cyclization triple domino reaction
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A low loading of a quinine-derived squaramide efficiently catalyzes the triple-domino Michael/aza-Henry/cyclization reaction between 1,3-dicarbonyl compounds, β-nitroolefins, and aldimines to provide tetrahydropyridines bearing three contiguous stereogeni
- Blümel, Marcus,Chauhan, Pankaj,Hahn, Robert,Raabe, Gerhard,Enders, Dieter
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supporting information
p. 6012 - 6015
(2015/01/08)
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- Regio- and stereoselective lipase-catalysed acylation of methyl α-D-glycopyranosides with fluorinated β-lactams
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Burkholderia cepacia lipase (lipase PS-D) catalysed acylation with 3,3-difluoro-4-phenyl-, -thiophen-3-yl- and -4-pyridylazetidin-2-ones was examined for the formation of N-Boc-protected 6-O-acylated sugar-β-amino acid conjugates from methyl α-D-galacto-, -gluco- and mannopyranosides and Boc2O. The 6-O-acylated glycopyranoside-β-amino acid conjugates were isolated and characterized. The low solubility of the gluco- and mannopyranosides and the high reactivity of the pyridylazetidinone restricted product formation. Activation of the β-lactam ring by the presence of fluorine substituents was shown to be necessary for the enzymatic acylation reaction. The (S)-enantiomers of the racemic β-lactam substrates reacted with the sugars. The lipase-catalysed diastereoselective ring-opening of aromatic and hetero-aromatic β-lactams was explored for the formation of β-amino acid conjugates of methyl α-D-glycopyranosides. Potential hydrolytic side-reactions were minimized by a suitable choice of solvent, lipase preparation and the use of molecular sieves.
- Sundell, Riku,Siirola, Elina,Kanerva, Liisa T.
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supporting information
p. 6753 - 6760
(2016/02/18)
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- Catalytic activity of MCM-41 and Al grafted MCM-41 for oxidative self and cross coupling of amines
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The catalytic activity of MCM-41 mesoporous silica (MS) and Al grafted MCM-41 (Al-MS) with varied amount of Al were studied for oxidative self and cross coupling of benzyl amines to imines. The role of Al, its amount, acidity of the catalyst, effect of reaction conditions (especially presence of solvent and excess air) and amines nature on the oxidative coupling reactions were investigated. Surface OH groups play an effective role in amine activation by hydrogen bonding, whereas the acid sites generated by incorporation of optimum amount of Al further improve the activity. The Al in optimum amount (Si/Al: 20) showed good catalytic activity in self coupling of benzyl amine as compared to MS and Al-MS with high Al loading. A suitable polar solvent and presence of excess air significantly promote the activity of MS and Al-MS for amine coupling reactions. The MS without Al was also found to be efficient catalyst for oxidative self and cross coupling of amines. The presence of Al in Al-MS (in optimum amount, i.e., Si/Al: 20) made the self coupling of benzyl amine faster than MS, whereas the cross coupling reactions with Al-MS were observed to be slightly slower than MS, which is probably due to competitive adsorption of amine substrate and amine nucleophile over acidic sites. The activity of MS and Al-MS catalysts for self and cross coupling reactions was also dependent of the amines nature (basicity and nucleophilicity).
- Tayade, Kamlesh N.,Mishra, Manish
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p. 114 - 125
(2014/01/06)
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- Direct imine formation by oxidative coupling of alcohols and amines using supported manganese oxides under an air atmosphere
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Manganese oxides loaded on various supports have been prepared and studied for the direct imine formation by oxidative coupling of alcohols and amines. Among the catalysts, hydroxyapatite supported manganese oxides (MnO x/HAP) show the best activity and selectivity for this reaction in the absence of an additional base using air as the environmentally benign terminal oxidant. NH3-/CO2-TPD results show that the amphoteric properties of MnOx/HAP are crucial for this reaction to obtain a satisfactory yield. Various aromatic alcohols and amines are smoothly transformed into the corresponding imines in good to excellent yields. The catalyst is reusable and gives 98% yield of the product in all 9 reuse tests. Compared with the fresh catalyst, the XRD and SEM of the reactivated MnO x/HAP after nine reactions do not show any obvious change. This journal is the Partner Organisations 2014.
- Chen, Bo,Li, Jun,Dai, Wen,Wang, Lianyue,Gao, Shuang
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p. 3328 - 3334
(2014/06/10)
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- Synthesis and pharmacological characterization of benzenesulfonamides as dual species inhibitors of human and murine mPGES-1
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The microsomal prostaglandin E2 synthase 1 (mPGES-1) became a desirable target in recent years for the research of new anti-inflammatory drugs. Even though many potent inhibitors of human mPGES-1, tested in vitro assay systems, have been synthe
- Hanke, Thomas,R?rsch, Florian,Thieme, Theresa M.,Ferreiros, Nerea,Schneider, Gisbert,Geisslinger, Gerd,Proschak, Ewgenij,Gr?sch, Sabine,Schubert-Zsilavecz, Manfred
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p. 7874 - 7883
(2014/01/06)
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- Visible-light-induced selective photocatalytic aerobic oxidation of amines into imines on TiO2
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Imines are important intermediates for the synthesis of fine chemicals, pharmaceuticals, and agricultural chemicals. Selective oxidation of amines into their corresponding imines with dioxygen is one of the most-fundamental chemical transformations. Herein, we report the oxidation of a series of benzylic amines into their corresponding imines with atmospheric dioxygen as the oxidant on a surface of anatase TiO2 under visible-light irradiation (λ>420 nm). The visible-light response of this system was caused by the formation of a surface complex through the adsorption of a benzylic amine onto the surface of TiO2. From the analysis of products of specially designed benzylic amines, we demonstrated that a highly selective oxygenation reaction proceeds via an oxygen-transfer mechanism to afford the corresponding carbonyl compound, whose further condensation with an amine would generate the final imine product. We found that when primary benzylic amines (13 examples), were chosen as the substrates, moderate to excellent selectivities for the imine products were achieved (ca. 38-94%) in moderate to excellent conversion rates (ca. 44-95%). When secondary benzylic amines (15 examples) were chosen as the substrates, both the corresponding imines and aldehydes were detected as the main products with moderate to high conversion rates (ca. 18-100%) and lower selectivities for the imine products (ca. 14-69%). When tribenzylamine was chosen as the substrate, imine (27%), dibenzylamine (24%), and benzaldehyde products (39%) were obtained in a conversion of 50%. This report can be viewed as a prototypical system for the activation of C-H bonds adjacent to heteroatoms such as N, O, and S atoms, and oxofuctionalization with air or dioxygen as the terminal oxidant under visible-light irradiation using TiO2 as the photocatalyst. Go green! Visible-light irradiation of a surface complex of benzylic amines adsorbed onto a TiO2 surface induces charge-transfer; an oxygen-transfer mechanism affords the corresponding carbonyl compounds and condensation with an amine generates the imine product. Copyright
- Lang, Xianjun,Ma, Wanhong,Zhao, Yubao,Chen, Chuncheng,Ji, Hongwei,Zhao, Jincai
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experimental part
p. 2624 - 2631
(2012/03/27)
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- Palladium-catalyzed aryl iodide carbonylation as a route to imidazoline synthesis: Design of a five-component coupling reaction
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Take five: A new method employing aryl halide carbonylation to directly access heterocycles has been described (see scheme). In a single palladium-catalyzed reaction the catalyst mediates two consecutive carbonylation steps, thereby converting five components (aryl iodide, two units imine, and two units CO) into an imidazoline ring.
- Bontemps, Sebastien,Quesnel, Jeffrey S.,Worrall, Kraig,Arndtsen, Bruce A.
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supporting information; body text
p. 8948 - 8951
(2011/10/19)
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- Efficient Iridium-thioether-dithiolate catalyst for β-alkylation of alcohols and selective imine formation via N-alkylation reactions
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An Ir-thioether-dithiolate complex, [Cp*Ir(η3-tpdt)] (Cp* = η5-C5Me5, tpdt = S(CH 2CH2S-)2), is evaluated for its catalytic potential in the β-alkylation of secondary alcohols and the N-alkylation of amines with alcohols. The β-alkylation reaction proceeded efficiently under low catalyst loading and in the absence of any sacrificial hydrogen additive with only water being formed as the coproduct. The same complex also proved to be efficient in the synthesis of imines via the N-alkylation reaction. The predominant formation of imines, rather than amines, in this reaction is a deviation from the product selectivity usually observed in similar N-alkylation reactions involving organometallic catalysts.
- Xu, Chang,Goh, Lai Yoong,Pullarkat, Sumod A.
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experimental part
p. 6499 - 6502
(2012/02/06)
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- Metal-free aerobic oxidative coupling of amines to imines
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Oxidative coupling of primary amines to imines is achieved with high to moderate yields by refluxing suspensions of amines and water under one atmosphere dioxygen without any additives. Tandem acid-free aza Diels-Alder reactions for synthesis of N-alkyl-4-pyridones are also accomplished. The Royal Society of Chemistry 2011.
- Liu, Lianghui,Zhang, Siyu,Fu, Xuefeng,Yan, Chun-Hua
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p. 10148 - 10150
(2011/11/04)
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- Selective formation of imines by aerobic photocatalytic oxidation of amines on TiO2
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An oxygenation pathway: The title transformation involves a two-step process: a selective oxygenation step to generate aldehyde intermediates and a subsequent condensation step to afford the imine products (see scheme).
- Lang, Xianjun,Ji, Hongwei,Chen, Chuncheng,Ma, Wanhong,Zhao, Jincai
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supporting information; experimental part
p. 3934 - 3937
(2011/05/15)
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- Simple, chemoselective, and diastereoselective Reformatsky-type synthesis of α-bromo-α-fluoro-β-lactams
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The chemoselective and diastereoselective synthesis of syn-α-bromo-α-fluoro-β-lactams was achieved using the diethylzinc-mediated Reformatsky-type reaction of ethyl dibromofluoroacetate with imines. The reaction led to diastereomerically pure β-lactams in good to moderate yields (up to 78% yield) with only small amounts of aziridine derivatives. Noncyclized 3-amino-2-bromo-2-fluoro carboxylic esters, usual Reformatsky adducts, were not formed. In contrast, reactions carried out under typical Reformatsky conditions using zinc metal were poorly chemoselective, leading to mixtures of β-lactams and aziridine derivatives.
- Tarui, Atsushi,Kawashima, Naoto,Sato, Kazuyuki,Omote, Masaaki,Miwa, Yoshihisa,Minami, Hideki,Ando, Akira
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supporting information; experimental part
p. 2000 - 2003
(2010/06/21)
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- Structural-activity relationship study of highly-functionalized imidazolines as potent inhibitors of nuclear transcription factor-κB mediated IL-6 production
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We herein describe the synthesis and anti-inflammatory properties of a small library of imidazoline-based NF-κB inhibitors. The structure-activity relationship of various substituents on an imidazoline core structure was evaluated for the ability to inhibit NF-κB mediated IL-6 production. Optimization of the scaffolds was pursued by correlating luciferase-based NF-κB reporter assays with inhibition of IL-6 production in IL-1β stimulated human blood. Several derivatives were found to inhibit NF-κB mediated IL-6 production in the nanomolar range in IL-1β stimulated human blood.
- Kahlon, Daljinder K.,Lansdell, Theresa A.,Fisk, Jason S.,Tepe, Jetze J.
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experimental part
p. 3093 - 3103
(2009/10/02)
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- Highly efficient oxidation of amines to imines by singlet oxygen and its application in ugi-type reactions
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A variety of secondary benzylic amines were oxidized to imines in 90% to >99% yields by singlet oxygen generated from oxygen and a porphyrin photosensitizer. On the basis of these reactions, a protocol was developed for oxidative Ugi-type reactions with singlet oxygen as the oxidant. This protocol has been used to synthesize C1- and N-functionalized benzylic amines in up to 96% yields.
- Jiang, Gaoxl,Chen, Jian,Huang, Jie-Sheng,Che, Chi-Ming
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scheme or table
p. 4568 - 4571
(2009/12/07)
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- Synthesis of α,α-difluoro-β-amino esters or gem-difluoro-β-lactams as potential metallocarboxypeptidase inhibitors
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The synthesis of gem-difluorinated β-lactams and gem-difluorinated β-amino acids, each possessing a potential basic functional group, from ethyl bromodifluoroacetate and either imines (for β-lactams) or N-(α-aminoalkyl)benzotriazoles (for β-amino esters) was investigated. A series of these compounds were used for the design of novel metallocarboxypeptidase inhibitors. N-Alkylation and N-acylation of these two versatile scaffolds were carried out, leading to the expected targets in moderate to good yields. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Boyer, Nicolas,Gloanec, Philippe,De Nanteuil, Guillaume,Jubault, Philippe,Quirion, Jean-Charles
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scheme or table
p. 4277 - 4295
(2009/04/10)
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- Cycloaddition reactions of imines with 3-thiosuccinic anhydrides: Synthesis of the tricyclic core of martinellic acid
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Arylthio-substituted succinic anhydrides undergo cycloaddition reactions with imines to produce γ-lactams in high yield and with high diastereoselectivity. The origin of the selectivity is proposed to result from anion-π repulsion in the transition state. The utility of this technique is demonstrated in a synthesis of the carbon framework common to the alkaloids martinellic acid and martinelline in five steps.
- Ng, Pui Yee,Masse, Craig E.,Shaw, Jared T.
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p. 3999 - 4002
(2007/10/03)
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- Versatile, fragrant, convertible isonitriles
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The metalation of oxazoles leads to ring opening to the isocyanoenolate that can be O-acylated to give the unsaturated isonitriles. These substances undergo conventional multicomponent reactions. The products of their reactions are readily converted to acyl substitution products by treatment with acid and a nucleophile. These unsaturated isonitriles are notable by their simple preparations and, unusually, their nonoffensive odors. Copyright
- Pirrung, Michael C.,Ghorai, Subir
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p. 11772 - 11773
(2007/10/03)
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- Base induced carbon-nitrogen (C=N) double bond migration in Schiff bases
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Various Schiff bases have been prepared to study base induced carbon-nitrogen double bond migrations. Schiff bases derived from aliphatic aldehydes display highest selectivity. Hydrolysis of the resulting rearranged Schiff base provides an entry to make amines from aldehydes. The reaction has possible practical application.
- Gangadasu,Narender,China Raju,Jayathirtha Rao
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p. 2598 - 2600
(2007/10/03)
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- New reactions of IBX: Oxidation of nitrogen- and sulfur-containing substrates to afford useful synthetic intermediates
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New reactions for the synthetic toolbox: 2-lodoxybenzoic acid (IBX) was employed to access a diverse array of useful synthetic intermediates. Among other transformations, the developed chemistry converts amines into imines, dithianes into carbonyl groups, N-heterocycles into N-heteroaromatic compounds, and hydroxylamines into oximes in high yields.
- Nicolaou,Mathison, Casey J. N.,Montagnon, Tamsyn
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p. 4077 - 4082
(2007/10/03)
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- Chemoselective debenzylation of N-benzyl tertiary amines with ceric ammonium nitrate
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Treatment of a range of N-benzyl tertiary amines with aqueous eerie ammonium nitrate results in N-debenzylation to afford the corresponding secondary amine. Chemoselective mono-W-debenzylation of N-benzyl tertiary amines is shown to occur in the presence of N-benzyl amides, O-benzyl ethers, O-benzyl esters, O-benzyl phenolates and 5-benzyl ethers. The Royal Society of Chemistry 2000.
- Bull, Steven D.,Davies, Stephen G.,Fenton, Carry,Mulvaney, Andrew W.,Shyam Prasad,Smith, Andrew D.
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p. 3765 - 3774
(2007/10/03)
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- Mechanistic and synthetic aspects of amine oxidations promoted by 3-methyl-5-ethyllumiflavinium perchlorate
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Preparative and kinetic aspects of the chemistry of 3-methyl-5-ethyllumiflavinium perchlorate (1) with primary and secondary amines have been investigated. Reactions of! with primary and secondary amines leads to rapid production of modestly stable C4a-adducts. The rates of these processes, determined by stopped-flow kinetic methods, parallel amine nucleophilicities. The C4a-adducts undergo benzylamine promoted elimination reactions to produce N-benzylaldimine products with rates that parallel reactivity profiles expected for E2-elimination processes. Finally, flavinium salt 1 serves as a catalyst for oxidations of primary and secondary amines under aerobic conditions.
- Hoegy, Susan E.,Mariano, Patrick S.
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p. 5027 - 5046
(2007/10/03)
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