- Zirconium-hydride-catalyzed site-selective hydroboration of amides for the synthesis of amines: Mechanism, scope, and application
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Developing mild and efficient catalytic methods for the selective synthesis of amines is a longstanding research objective. In this respect, catalytic deoxygenative amide reduction has proven to be promising but challenging, as this approach necessitates selective C–O bond cleavage. Herein, we report the selective hydroboration of primary, secondary, and tertiary amides at room temperature catalyzed by an earth-abundant-metal catalyst, Zr-H, for accessing diverse amines. Various readily reducible functional groups, such as esters, alkynes, and alkenes, were well tolerated. Furthermore, the methodology was extended to the synthesis of bio- and drug-derived amines. Detailed mechanistic studies revealed a reaction pathway entailing aldehyde and amido complex formation via an unusual C–N bond cleavage-reformation process, followed by C–O bond cleavage.
- Han, Bo,Jiao, Haijun,Wu, Lipeng,Zhang, Jiong
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p. 2059 - 2067
(2021/09/02)
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- Deoxygenative hydroboration of primary, secondary, and tertiary amides: Catalyst-free synthesis of various substituted amines
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Transformation of relatively less reactive functional groups under catalyst-free conditions is an interesting aspect and requires a typical protocol. Herein, we report the synthesis of various primary, secondary, and tertiary amines through hydroboration of amides using pinacolborane under catalyst-free and solvent-free conditions. The deoxygenative hydroboration of primary and secondary amides proceeded with excellent conversions. The comparatively less reactive tertiary amides were also converted to the corresponding N,N-diamines in moderate yields under catalyst-free conditions, although alcohols were obtained as a minor product.
- An, Duk Keun,Jaladi, Ashok Kumar,Kim, Hyun Tae,Yi, Jaeeun
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- Generation of Oxidoreductases with Dual Alcohol Dehydrogenase and Amine Dehydrogenase Activity
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The l-lysine-?-dehydrogenase (LysEDH) from Geobacillus stearothermophilus naturally catalyzes the oxidative deamination of the ?-amino group of l-lysine. We previously engineered this enzyme to create amine dehydrogenase (AmDH) variants that possess a new hydrophobic cavity in their active site such that aromatic ketones can bind and be converted into α-chiral amines with excellent enantioselectivity. We also recently observed that LysEDH was capable of reducing aromatic aldehydes into primary alcohols. Herein, we harnessed the promiscuous alcohol dehydrogenase (ADH) activity of LysEDH to create new variants that exhibited enhanced catalytic activity for the reduction of substituted benzaldehydes and arylaliphatic aldehydes to primary alcohols. Notably, these novel engineered dehydrogenases also catalyzed the reductive amination of a variety of aldehydes and ketones with excellent enantioselectivity, thus exhibiting a dual AmDH/ADH activity. We envisioned that the catalytic bi-functionality of these enzymes could be applied for the direct conversion of alcohols into amines. As a proof-of-principle, we performed an unprecedented one-pot “hydrogen-borrowing” cascade to convert benzyl alcohol to benzylamine using a single enzyme. Conducting the same biocatalytic cascade in the presence of cofactor recycling enzymes (i.e., NADH-oxidase and formate dehydrogenase) increased the reaction yields. In summary, this work provides the first examples of enzymes showing “alcohol aminase” activity.
- Tseliou, Vasilis,Schilder, Don,Masman, Marcelo F.,Knaus, Tanja,Mutti, Francesco G.
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supporting information
p. 3315 - 3325
(2020/12/11)
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- Self-regulated catalysis for the selective synthesis of primary amines from carbonyl compounds
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Most current processes for the general synthesis of primary amines by reductive amination are performed with enormously excessive amounts of hazardous ammonia. It remains unclear how catalysts should be designed to regulate amination reaction dynamics at a low ammonia-to-substrate ratio for the quantitative synthesis of primary amines from the corresponding carbonyl compounds. Herein we show a facile control of the reaction selectivity in the layered boron nitride supported ruthenium catalyzed reductive amination reaction. Specifically, locating ruthenium to the edge surface of layered boron nitride leads to an increased hydrogenation activity owing to the enhanced interfacial electronic effects between ruthenium and the edge surface of boron nitride. This enables self-accelerated reductive amination reactions which quantitatively synthesize structurally diverse primary amines by reductive amination of carbonyl compounds with twofold ammonia. This journal is
- Fan, Xiaomeng,Gao, Jin,Gao, Mingxia,Jia, Xiuquan,Ma, Jiping,Xu, Jie
-
supporting information
p. 7115 - 7121
(2021/09/28)
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- Selective Synthesis of Symmetrical Secondary Amines from Nitriles with a Pt?CuFe/Fe3O4 Catalyst and Ammonia Borane as Hydrogen Donor
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Hydrogenation of nitriles is an efficient and environmentally friendly route to synthesize symmetrical secondary amines, but it usually produces a mixture of amines, imines, and hydrogenolysis by-products. Herein we report a magnetic quaternary-component Pt?CuFe/Fe3O4 nanocatalyst system for the selective synthesis of symmetrical secondary amines with ammonia borane as hydrogen donor. The catalyst with a low Pt loading (0.456 wt%) is the source of the activity, and the d-band electron transfer from Cu to Fe enhances the selectivity. This synergistic effect results in the transformation of benzonitrile to dibenzylamine with excellent conversion (up to 99 %) and nearly quantitative selectivity (up to 96 %) under mild reaction conditions, nevertheless, the reaction TOF is as high as up to 1409.9 h?1. A variety of nitriles are suitable for the synthesis of symmetrical secondary amines. More importantly, unwanted hydrogenolysis byproducts, especially toluene, is not detected at all. In addition, the catalyst is magnetically recoverable, and it can be reused up to five times.
- Ai, Yongjian,Guo, Rongxiu,He, GuangQi,Hu, Ze-nan,Liang, Qionglin,Liu, Lei,Niu, Dun,Sun, Hong-bin,Tian, Haimeng,Zhang, Xinyue
-
p. 1783 - 1788
(2020/09/02)
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- A State-of-the-Art Heterogeneous Catalyst for Efficient and General Nitrile Hydrogenation
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Cobalt-doped hybrid materials consisting of metal oxides and carbon derived from chitin were prepared, characterized and tested for industrially relevant nitrile hydrogenations. The optimal catalyst supported onto MgO showed, after pyrolysis at 700 °C, magnesium oxide nanocubes decorated with carbon-enveloped Co nanoparticles. This special structure allows for the selective hydrogenation of diverse and demanding nitriles to the corresponding primary amines under mild conditions (e.g. 70 °C, 20 bar H2). The advantage of this novel catalytic material is showcased for industrially important substrates, including adipodinitrile, picolinonitrile, and fatty acid nitriles. Notably, the developed system outperformed all other tested commercial catalysts, for example, Raney Nickel and even noble-metal-based systems in these transformations.
- Formenti, Dario,Mocci, Rita,Atia, Hanan,Dastgir, Sarim,Anwar, Muhammad,Bachmann, Stephan,Scalone, Michelangelo,Junge, Kathrin,Beller, Matthias
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supporting information
p. 15589 - 15595
(2020/10/02)
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- Half-sandwiched ruthenium complex containing carborane schiff base ligand and preparation and application thereof
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The invention relates to a half-sandwiched ruthenium complex containing a carborane schiff base ligand and a preparation and an application thereof. The preparation method specifically comprises the following steps; i) dissolving o-carborane formaldehyde and aromatic amine in an organic solvent, carrying out reaction at 60-100 DEG C for 8-12h, cooling to room temperature after the reaction; ii) adding n-butyllithium, carrying out reaction at room temperature for 1.5-2.5h; ii) adding phellandrene ruthenium chloride dimer, carrying out reaction at room temperature for 3-6h, and obtaining the half-sandwiched ruthenium complex through separation. The half-sandwiched ruthenium complex is applied to catalyze transfer hydrogenation reaction of nitrile compounds. Compared with the prior art, the complex of the present invention is not sensitive to air and water, has stable properties, and shows high-efficiency catalytic activity in catalyzing the transfer hydrogenation reaction of nitrile compounds. The preparation method of the complex is simple and green, high in yield, mild in reaction conditions and good in universality.
- -
-
Paragraph 0067-0071
(2020/12/09)
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- Cobalt pincer complexes for catalytic reduction of nitriles to primary amines
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Various cobalt pincer type complexes 1-6 were applied for the catalytic hydrogenation of nitriles to amines. Among these, catalyst 4 is the most efficient, allowing the reduction of aromatic as well as aliphatic nitriles in moderate to excellent yields.
- Schneek?nig, Jacob,Tannert, Bianca,Hornke, Helen,Beller, Matthias,Junge, Kathrin
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p. 1779 - 1783
(2019/04/27)
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- Method for preparing primary amines through hydrogen transfer selective nitrile reduction
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The invention discloses a method for preparing primary amines through hydrogen transfer selective nitrile reduction. The method includes the step of adding low-price copper, iron and other metal saltsor low-price easy-to-obtain iodine elementary substances as additives with a nitrile compound as the raw material and oxazole borane as the hydrogen transfer agent under the mild conditions, therebypromoting the hydrogen transfer reaction and selectively synthesizing a series of corresponding primary amines under different conditions respectively. The high yield and high selectivity are achievedin the reaction. The oxazole borane is obtained through reaction of alkamine and a tetrahydrofuran complex of borane. In addition, the method is mild in reaction condition, easy to operate, free of high-pressure devices, environmentally friendly and high in raw material general applicability, the agents required for the reaction are all low in price and easy to obtain, the reduction product is only primary amines, and selectivity and repeatability are high. Thus, an effective scheme is provided for the industrial production of other high-additional-value compounds of similar structures in future.
- -
-
Paragraph 0042-0046
(2019/05/02)
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- Nitrogen-Doped Carbon-Supported Nickel Nanoparticles: A Robust Catalyst to Bridge the Hydrogenation of Nitriles and the Reductive Amination of Carbonyl Compounds for the Synthesis of Primary Amines
-
An efficient method was developed for the synthesis of primary amines either from the hydrogenation of nitriles or reductive amination of carbonyl compounds. The reactions were catalyzed by nitrogen-doped mesoporous carbon (MC)-supported nickel nanoparticles (abbreviated as MC/Ni). The MC/Ni catalyst demonstrated high catalytic activity for the hydrogenation of nitriles into primary amines in high yields (81.9–99 %) under mild reaction conditions (80 °C and 2.5 bar H2). The MC/Ni catalyst also promoted the reductive amination of carbonyl compounds for the synthesis of primary amines at 80 °C and 1 bar H2. The hydrogenation of nitriles and the reductive amination proceeded through the same intermediates for the generation of the primary amines. To the best of our knowledge, no other heterogeneous non-noble metal catalysts have been reported for the synthesis of primary amines under mild conditions, both from the hydrogenation of nitriles and reductive amination.
- Zhang, Yangmin,Yang, Hanmin,Chi, Quan,Zhang, Zehui
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p. 1246 - 1255
(2019/03/07)
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- Mild palladium-catalysed highly efficient hydrogenation of CN, C-NO2, and CO bonds using H2 of 1 atm in H2O
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Here we present the first example of a mild and high-efficiency protocol enabling a process in water using 1 atm of H2 for the efficient and selective hydrogenation of nitriles, nitro compounds, ketones, and aldehydes to yield primary amines and alcohols with satisfactory yields of up to >99%. Several palladium-based nanoparticle catalysts were prepared from K2PdCl4 and ligands, and one of them was found to be the best and most suitable for the hydrogenation of CN, C-NO2, and CO bonds. In addition, the catalyst Pd-NPs can be easily recycled and reused without losing their activity and selectivity. A plausible mechanism for the hydrogenation of a CN bond was also proposed, representing the first example that possesses great potential for sustainable industrial purposes.
- Liu, Yaxu,He, Shaopo,Quan, Ziyi,Cai, Huizhuo,Zhao, Yang,Wang, Bo
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supporting information
p. 830 - 838
(2019/02/27)
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- A ppm level Rh-based composite as an ecofriendly catalyst for transfer hydrogenation of nitriles: Triple guarantee of selectivity for primary amines
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Hydrogenation of nitriles to afford amines under mild conditions is a challenging task with an inexpensive heterogeneous catalyst, and it is even more difficult to obtain primary amines selectively because of the accompanying self-coupling side reactions. An efficient catalytic system was designed as Fe3O4@nSiO2-NH2-RhCu@mSiO2 to prepare primary amines through the transfer hydrogenation of nitrile compounds with economical HCOOH as the hydrogen donor. The loading of rhodium in the catalyst could be at the ppm level, and the TOF reaches 6803 h-1 for Rh. This catalytic system has a wide substrate range including some nitriles that could not proceed in the previous literature. The experimental results demonstrate that the excellent selectivity for primary amines is guaranteed by three tactics, which are the strong active site, the inhibition of side products by the hydrogen source and the special pore structure of the catalyst. In addition, the catalyst could be reused ten times without activity loss through convenient magnetic recovery.
- Liu, Lei,Li, Jifan,Ai, Yongjian,Liu, Yuhong,Xiong, Jialiang,Wang, Hongdong,Qiao, Yijun,Liu, Wenrui,Tan, Shanchao,Feng, Shaofei,Wang, Kunpeng,Sun, Hongbin,Liang, Qionglin
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p. 1390 - 1395
(2019/03/26)
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- Preparation of a magnetic mesoporous Fe3O4-Pd@TiO2 photocatalyst for the efficient selective reduction of aromatic cyanides
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Herein, a hierarchical magnetic mesoporous microsphere was successfully prepared as a photocatalyst via a simple and reproducible route. Typically, Pd nanoparticles (NPs) were evenly dispersed on the surface of a magnetic Fe3O4 microsphere and then coated with a porous anatase-TiO2 shell to form Fe3O4-Pd@TiO2. The core-shell structure could efficiently suppress the conglomeration of Pd NPs during the calcination process at high temperatures as well as the shedding of Pd during the catalytic reaction process in the liquid phase. The as-prepared photocatalyst was characterized by TEM, XRD, XPS, VSM, and N2 adsorption-desorption. Fe3O4-Pd@TiO2 exhibits high photocatalytic activity for the selective reduction of aromatic cyanides to aromatic primary amines in an acidic aqueous solution. Moreover, this magnetic photocatalyst could be easily recovered from the reaction mixture by an external magnet and reused five times without significant reduction in its activity. The superior photocatalytic efficiency of the proposed photocatalyst may be attributed to its high charge separation efficiency and charge transfer rate, which are caused by the Schottky junction and large interface area. The results indicate that the strategy of coating the active noble metal sites with a mesoporous semiconductor shell has a significant potential for application in metal-semiconductor-based photocatalytic reactions.
- Zhao, Ziming,Long, Yu,Luo, Sha,Wu, Wei,Ma, Jiantai
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p. 6294 - 6302
(2019/04/25)
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- Facile synthesis of supported Ru-Triphos catalysts for continuous flow application in selective nitrile reduction
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The selective catalytic hydrogenation of nitriles represents an important but challenging transformation for many homogeneous and heterogeneous catalysts. Herein, we report the efficient and modular solid-phase synthesis of immobilized Triphos-type ligands in very high yields, involving only minimal work-up procedures. The corresponding supported ruthenium-Triphos catalysts are tested in the hydrogenation of various nitriles. Under mild conditions and without the requirement of additives, the tunable supported catalyst library provides selective access to both primary amines and secondary imines. Moreover, the first application of a Triphos-type catalyst in a continuous flow process is presented demonstrating high catalyst life-time over at least 195 hours without significant activity loss.
- Konrath, Robert,Heutz, Frank J.L.,Steinfeldt, Norbert,Rockstroh, Nils,Kamer, Paul C.J.
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p. 8195 - 8201
(2019/09/19)
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- Reusable Nickel Nanoparticles-Catalyzed Reductive Amination for Selective Synthesis of Primary Amines
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The preparation of nickel nanoparticles as efficient reductive amination catalysts by pyrolysis of in situ generated Ni-tartaric acid complex on silica is presented. The resulting stable and reusable Ni-nanocatalyst enables the synthesis of functionalized and structurally diverse primary benzylic, heterocyclic and aliphatic amines starting from inexpensive and readily available carbonyl compounds and ammonia in presence of molecular hydrogen. Applying this Ni-based amination protocol, -NH2 moiety can be introduced in structurally complex compounds, for example, steroid derivatives and pharmaceuticals.
- Murugesan, Kathiravan,Beller, Matthias,Jagadeesh, Rajenahally V.
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supporting information
p. 5064 - 5068
(2019/03/19)
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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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- Chemoselective hydrogenation of nitriles to secondary or tertiary amines catalyzed by aqueous-phase catalysts supported on hexagonal mesoporous silica
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The first supported aqueous-phase catalyst for the hydrogenation of nitriles is revealed. The catalyst prepared from Pd(PhCN)2Cl2, water-soluble ligand 2,2′-biquinoline-4,4′-dicarboxylic acid dipotassium salt and mesoporous silica is a highly efficient catalyst for the selective formation of secondary or tertiary amines from aromatic or aliphatic nitriles. The catalytic system is stable and can be recycled and reused three times without loss of activity and selectivity. This environmentally friendly process is, in addition, an attractive alternative to many homogeneous and heterogeneous catalysts because of its easy preparation and the moderate operational conditions under which it is highly active.
- Nait Ajjou, Abdelaziz,Robichaud, André
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- Highly Stable COF-Supported Co/Co(OH)2 Nanoparticles Heterogeneous Catalyst for Reduction of Nitrile/Nitro Compounds under Mild Conditions
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Ordered nanoporosity in covalent organic framework (COF) offers excellent opportunity for property development. Loading nanoparticles (nPs) onto them is one approach to introducing tailor-made properties into a COF. Here, a COF–Co/Co(OH)2 composite containing about 16 wt% of 2 nPs is prepared on a N-rich COF support that catalyzes the release of theoretical equivalence of H2 from readily available, safe, and cheap NaBH4. Furthermore, the released H2 is utilized for the hydrogenation of nitrile and nitro compounds to amines under ambient conditions in a facile one-pot reaction. The COF “by choice” is built from “methoxy” functionalized dialdehydes which is crucial in enabling the complete retention of the COF structure under the conditions of the catalysis, where the regular Schiff bonds would have hydrolyzed. The N-rich binding pockets in the COF ensure strong nP–COF interactions, which provides stability and enables catalyst recycling. Modeling studies reveal the crucial role played by the COF in exposing the active facets and thereby in controlling the activation of the reducing agent. Additionally, via density functional theory, we provide a rational explanation for how these COFs can stabilize nanoparticles which grow beyond the limiting pore size of the COF and yet result in a truly stable heterogeneous catalyst – a ubiquitous observation. The study underscores the versatility of COF as a heterogeneous support for developing cheap and highly active nonnoble metal catalysts.
- Mullangi, Dinesh,Chakraborty, Debanjan,Pradeep, Anu,Koshti, Vijay,Vinod, Chathakudath P.,Panja, Soumendranath,Nair, Sunil,Vaidhyanathan, Ramanathan
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- Chemoselective hydrogenation of nitriles to primary amines catalyzed by water-soluble transition metal catalysts
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The water-soluble rhodium complex generated in situ from [Rh (COD)Cl]2 in aqueous ammonia has been revealed as a highly efficient catalyst for the hydrogenation of aromatic nitriles, to primary amines with excellent yields. The catalyst is also highly selective towards primary amines in the case of sterically hindered aliphatic nitriles. The catalytic system can also be recycled and re-used with no significant loss of activity.
- Nait Ajjou, Abdelaziz,Robichaud, André
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- Cobalt complex, preparation method thereof, and application thereof in selective catalysis of transfer hydrogenation reaction of cyano group
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The invention discloses a cobalt complex, a preparation method thereof, and an application thereof in the selective catalysis of a transfer hydrogenation reaction of a cyano group. The structural formula of the cobalt complex is represented by formula I. The cobalt complex is prepared through a reaction of a cobalt salt and an NNP ligand or a PNP ligand under the protection of an inert atmosphere;and the chemical formula of the cobalt salt is CoX12, wherein X1 represents halogen, a sulfate radical, a perchlorate radical, a hexafluorophosphate radical, a hexafluoroantimonate radical, a tetrafluoroborate radical, a trifluoromethanesulfonate radical or a tetra(pentafluorophenyl)borate radical. The cobalt complex can be used in the selective catalysis of the transfer hydrogenation reaction ofthe cyano group to obtain a primary amine compound, a secondary amine compound and a tertiary amine compound, the primary amine compound, the secondary amine compound and the tertiary amine compoundare important intermediates in a series of subsequent functionalizing reactions, and the cobalt complex has a very high catalysis activity, and has great research values and a great application prospect.
- -
-
Paragraph 0157-0160
(2018/05/07)
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- Direct Primary Amination of Alkylmetals with NH-Oxaziridine
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A method for the primary electrophilic amination of primary, secondary, and tertiary organometallic substrates from a bench-stable NH-oxaziridine reagent is described. This facile and highly chemoselective transformation occurs at ambient temperature and without transition metal catalysts or purification by column chromatography to provide alkylamine products in a single step. Density functional theory (DFT) calculations revealed that, despite the basicity of alkylmetals, the direct NH-transfer pathway is favored over proton and O-transfer.
- Behnke, Nicole Erin,Kielawa, Russell,Kwon, Doo-Hyun,Ess, Daniel H.,Kürti, László
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supporting information
p. 8064 - 8068
(2019/01/04)
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- Selective synthesis of mono- and di-methylated amines using methanol and sodium azide as C1 and N1 sources
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A Ru(ii) complex mediated synthesis of various N,N-dimethyl and N-monomethyl amines from organic azides using methanol as a methylating agent is reported. This methodology was successfully applied for a one-pot reaction of bromide derivatives and sodium azide in methanol. Notably, by controlling the reaction time several N-monomethylated and N,N-dimethylated amines were synthesized selectively. The practical applicability of this tandem process was revealed by preparative scale reactions with different organic azides and synthesis of an anti-vertigo drug betahistine. Several kinetic experiments and DFT studies were carried out to understand the mechanism of this transformation.
- Chakrabarti, Kaushik,Mishra, Anju,Panja, Dibyajyoti,Paul, Bhaskar,Kundu, Sabuj
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supporting information
p. 3339 - 3345
(2018/07/29)
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- Cobalt-Catalyzed and Lewis Acid-Assisted Nitrile Hydrogenation to Primary Amines: A Combined Effort
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The selective hydrogenation of nitriles to primary amines using a bench-stable cobalt precatalyst under 4 atm of H2 is reported herein. The catalyst precursor was reduced in situ using NaHBEt3, and the resulting Lewis acid formed, BEt3, was found to be integral to the observed catalysis. Mechanistic insights gleaned from para-hydrogen induced polarization (PHIP) transfer NMR studies revealed that the pairwise hydrogenation of nitriles proceeded through a Co(I/III) redox process.
- Tokmic, Kenan,Jackson, Bailey J.,Salazar, Andrea,Woods, Toby J.,Fout, Alison R.
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supporting information
p. 13554 - 13561
(2017/10/05)
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- Bifunctional N-Doped Co@C Catalysts for Base-Free Transfer Hydrogenations of Nitriles: Controllable Selectivity to Primary Amines vs Imines
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The transfer hydrogenation of nitriles is an important and alternative strategy to produce primary amines or imines, both of which play a crucial role in the synthesis of fine chemicals and pharmaceuticals. Nevertheless, developing highly active bifunctional catalyst system with controllable selectivity for these reactions still remains a huge challenge. In this study, we presented a bifunctional N-doped Co@C catalyst system (Co@NC) for the selective transfer hydrogenation of nitriles into either primary amines or imines. The Co@NC was prepared by the direct pyrolysis of an N-containing Co-MOF under an inert atmosphere, where the N-containing ligands could be transformed into highly graphitic N-doped carbon, endowing the catalysts with high-density special basic sites, while the Co2+ ions were reduced to uniform Co nanoparticles which were dispersed on or embedded in N-doped graphitic structures. Under base-free conditions with isopropyl alcohol as both proton donor and solvent, the optimized Co@NC-900 (obtained at 900 °C) catalyst could convert nitriles into primary amines or imines at will with surprising selectivities (mostly higher than 90%), depending on the solvent volume added to the reaction systems. Furthermore, a possible reaction mechanism was proposed. The N-derived basic sites on Co@NC could play a role similar to that of the base additives, which not only inhibit the formation of polyamine or prevent the products stacked on the surface of catalysts but also effectively promote the transfer hydrogenation of nitriles. The generated corresponding primary imines could controllably attack the primary imine intermediates to form imines by adjusting the concentration of Co@NC. It is clear that this strategy offers a high-performance catalyst system for base-free transfer hydrogenations of nitriles to selectively produce primary amines vs imines.
- Long, Jilan,Shen, Kui,Li, Yingwei
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p. 275 - 284
(2017/06/07)
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- Mild and Selective Cobalt-Catalyzed Chemodivergent Transfer Hydrogenation of Nitriles
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Herein, we describe a selective cobalt-catalyzed chemodivergent transfer hydrogenation of nitriles to synthesize primary, secondary, and tertiary amines. The solvent effect plays a key role for the selectivity control. The general applicability of this procedure was highlighted by the synthesis of more than 70 amine products bearing various functional groups in high chemoselectivity. Moreover, this mild system achieved >2000 TONs (turnover numbers) for the transfer hydrogenation of nitriles.
- Shao, Zhihui,Fu, Shaomin,Wei, Mufeng,Zhou, Shaolin,Liu, Qiang
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supporting information
p. 14653 - 14657
(2016/11/23)
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- Stereoelectronic effects in the reaction of aromatic substrates catalysed by: Halomonas elongata transaminase and its mutants
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A transaminase from Halomonas elongata and four mutants generated by an in silico-based design were recombinantly produced in E. coli, purified and applied to the amination of mono-substituted aromatic carbonyl-derivatives. While benzaldehyde derivatives were excellent substrates, only NO2-acetophenones were transformed into the (S)-amine with a high enantioselectivity. The different behaviour of wild-type and mutated transaminases was assessed by in silico substrate binding mode studies.
- Contente, Martina Letizia,Planchestainer, Matteo,Molinari, Francesco,Paradisi, Francesca
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p. 9306 - 9311
(2016/10/13)
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- Preparation and characterization of primary amines by potassium borohydride-copper chloride system from nitriles
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Nitriles undergo reduction to primary amines under optimized conditions at 50 °C using 0.25 equiv of copper chloride and 3.0 equiv of potassium borohydride in 80 % isopropanol. The aromatic and aralkyl nitriles could be effectively reduced in yield ranging from 60 to 90 %.
- Jiang, Han,Hu, Jialei,Xu, Xinliang,Zhou, Yifeng
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p. 3564 - 3566
(2015/12/30)
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- Transfer hydrogenation of unsaturated bonds in the absence of base additives catalyzed by a cobalt-based heterogeneous catalyst
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A novel non-noble Co@C-N catalytic system has been developed for catalytic transfer hydrogenation reactions. Co@C-N was found to be highly active and selective in the hydrogenation of a variety of unsaturated bonds with isopropanol in the absence of base additives.
- Long, Jilan,Zhou, Ying,Li, Yingwei
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supporting information
p. 2331 - 2334
(2015/02/05)
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- Two iron catalysts are better than one: A general and convenient reduction of aromatic and aliphatic primary amides
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It takes two: For the reduction of amides to amines iron catalysts were developed. A combination of two different iron catalysts made possible the challenging reduction of primary amides (see picture). Copyright
- Das, Shoubhik,Wendt, Bianca,Moeller, Konstanze,Junge, Kathrin,Beller, Matthias
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supporting information; experimental part
p. 1662 - 1666
(2012/05/05)
-
- Hydrogen transfer reduction of nitriles in DBU based ionic liquids
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Raney nickel catalyzed transfer hydrogenation of nitrile was proposed, with formats as hydrogen donor. Three ionic liquids, including [DBUH +][C2H5COO-], [DBUH +][C3H7COO-], and [DBUH +][C4H9COO-], were prepared as reaction medium, and [DBUH+][C4H9COO -] showed the best performance. Various nitriles were reduced with potassium formate as hydrogen donor, and considerable to excellent yields of amines were given. The ionic liquid can be used for 6 times at least, and the reaction process is clean. ARKAT-USA, Inc.
- Chen, Xinzhi,Zhou, Shaodong,Qian, Chao
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experimental part
p. 128 - 136
(2012/09/11)
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- Application of alkoxide in catalytic transfer hydrogenation of unsaturated nitrogen compounds
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Alcoholate was utilized in catalytic transfer hydrogenation of unsaturated nitrogen compounds. In the reduction of nitro compounds, oximes and imines, alkoxide was used as the promoter, with alcohol as the hydrogen source, while in the reduction of nitriles, alkoxide was used as the hydrogen source. Springer Science+Business Media B.V. 2012.
- Chen, Xinzhi,Zhou, Shaodong,Chen, Yuehan,Dong, Zehan,Gao, Yeyu,Qian, Chao,He, Chaohong
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p. 2255 - 2269
(2013/02/23)
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- A metal-free catalytic system for the oxidation of benzylic methylenes and primary amines under solvent-free conditions
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Iodine-pyridine-tert-butylhydroperoxide is developed as a green and efficient catalytic system for the oxidation of benzylic methylenes to ketones and primary amines to nitriles. The reaction conditions are quite mild and environmentally benign, no transition metals, organic solvents or hazard reagents being needed. The oxidation of benzylic methylenes gave the corresponding ketones in excellent yields with complete chemoselectivity, while the oxidation of primary amines was complete in several minutes, affording various nitriles in moderate to good yields.
- Zhang, Jintang,Wang, Zhentao,Wang, Ye,Wan, Changfeng,Zheng, Xiaoqi,Wang, Zhiyong
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supporting information; scheme or table
p. 1973 - 1978
(2010/06/15)
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- Facile cleavage of Si-C bonds during the sol-gel hydrolysis of aminomethyltrialkoxysilanes - A new method for the methylation of primary amines
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The reaction of chloromethyltriethoxysilane with (1R,2R)-bis(methylamino) cyclohexane (1) afforded the corresponding bis-silylated compound 2. The sol-gel hydrolysis of 2 did not give the expected bridged silsesquioxane owing to quantitative Si-C-bond cleavage. Instead, silica and (1R,2R)-bis(dimethylamino) cyclohexane (3) were obtained. This reaction was exploited to propose a new route for the methylation of amines. Such methylation reaction of amines could be extended to other amines and provides a new method for the selective monomethylation of primary amines. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Adima, Augustin,Bied, Catherine,Moreau, Joel J. E.,Man, Michel Wong Chi
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p. 2582 - 2588
(2007/10/03)
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- Rapid reduction of nitriles to primary amines with nickel boride at ambient temperature
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Reduction of a variety of nitriles to their corresponding primary amines can be achieved with nickel boride generated in situ in dry ethanol at ambient temperature. The reductions are very rapid and chemoselective.
- Khurana, Jitender M.,Kukreja, Gagan
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p. 1265 - 1269
(2007/10/03)
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- 2-aminopyridine derivatives and combinatorial libraries thereof
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The present invention relates to novel 2-aminopyridine derivative compounds of the following formula: wherein R1to R5have the meanings provided herein. The invention further relates to combinatorial libraries containing two or more such compounds, as well as methods of preparing 2-aminopyridine derivative compounds.
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- Synthesis of Primary Amines: First Homogeneously Catalyzed Reductive Amination with Ammonia
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(Matrix Presented) The synthesis of primary amines via reductive amination of the corresponding carbonyl compounds with aqueous ammonia is achieved for the first time with soluble transition metal complexes. Up to an 86% yield and a 97% selectivity for benzylamines were obtained in the case of various benzaldehydes by using a Rh-catalyst together with water-soluble phosphine and ammonium acetate. In the case of aliphatic aldehydes, a bimetallic catalyst based on Rh/Ir gave improved results.
- Gross, Thoralf,Seayad, Abdul Majeed,Ahmad, Moballigh,Beller, Matthias
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p. 2055 - 2058
(2007/10/03)
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- 5-HT2A receptor inverse agonists
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Disclosed herein is a new class of pyrazole compounds which act at the 5HT2A receptors.
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- Small molecule modulators of non-endogenous, constitutively activated human serotonin receptors
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Disclosed herein are non-endogenous, constitutively activated forms of the human 5-HT2A and human 5-HT2C receptors and uses of such receptors to screen candidate compounds. Further disclosed herein are candidate compounds identified by the screening method which act at the 5HT2A receptors. Yet further disclosed is a new class of compounds which act at the 5HT2A receptors.
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- Reduction of O-acyl oximes with sodium borohydride/iodine system
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O-acyl derivatives of aldoximes and ketoximes are reduced in good yields to the corresponding amines with sodium borohydride-iodine system.
- Barbry,Champagne
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p. 3503 - 3507
(2007/10/03)
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- Novel reduction of carboxylic acid, ester, amide and nitrile with samarium or ytteribium metal-hydrochloric acid system
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The reduction of organic functionalities with a samarium or ytteribium metal-hydrochloric acid system was investigated. Carboxylic acid, ester, amide and nitrile were rapidly reduced to the corresponding alcohol or primary amine with samarium or ytteribium metal in the presence of hydrochloric acid at room temperature under an argon atmosphere in good yields. Carboxylic acid was similarly reduced to alcohol with a magnesium or yttrium-hydrochloric acid system.
- Kamochi,Kudo
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p. 402 - 404
(2007/10/02)
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- Novel Reduction of Carboxylic Acids, Esters, Amides and Nitriles Using Samarium Diiodide in the Presence of Water
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Aromatic carboxylic acids, esters, amides, nitriles, chlorides, ketones and nitro compounds were rapidly reduced by the samarium diiodide-H2O system to the corresponding products at room temperature in good yields.
- Kamochi, Yasuko,Kudo, Tadahiro
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p. 1495 - 1498
(2007/10/02)
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- Reductions of carboxylic acids and their derivatives using samarium diiodide-acid system
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Carboxylic acid was converted to alcohol in a facile-rapid reduction using samarium diiodide in protic solvent under a basic or acidic medium at room temperature in high yield. A similar reaction of ester and anhydride reduced to the corresponding alcohol as the major products and nitrile afforded amine. Amide was rapidly reduced under a basic medium to afford alcohol, but the reduction with samarium diiodide-acid system of amide gave aldehyde in quantitative yield.
- Kamochi,Kudo
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p. 4301 - 4312
(2007/10/02)
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- Studies of Reduction with Dimethoxyborane-Transition Metal Salt Systems. I. Reduction of Nitriles, Aldehydes and Ketones with Dimethoxyborane-Transition Metal Salt Systems
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The reduction of a variety of functional groups with new dimethoxyborane-transition metal salt systems was investigated.The dimethoxyborane-cobaltous chloride system reduced nitriles and aldehydes under mild conditions in good yields, and the dimethoxyborane-nickelous chloride system similarly reduced nitriles, aldehydes, olefin and ketones.The other functional groups tested were unaffected by these systems.Keywords reduction; nitrile; aldehyde; ketone; dimethoxyborane; transition metal salt; dimethoxyborane-cobaltous chloride system; dimethoxyborane-nickelous chloride system
- Nose, Atsuko,Kudo, Tadahiro
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p. 808 - 810
(2007/10/02)
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- Selective Reductions. 29. A Simple Technique To Achieve an Enhanced Rate of Reduction of Representative Organic Compounds by Borane-Dimethyl Sulfide
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A dramatic increase in the rate of reduction of esters by borane-dimethyl sulfide (BMS) is observed when dimethyl sulfide is removed from the reaction mixture.On the basis of this observation, a new, improved procedure has been developed for the reduction by BMS of representative organic functional groups, such as esters, nitriles, and amides.The procedure involves addition of BMS to the substrate in refluxing tetrahydrofuran, allowing the liberated dimethyl sulfide to distill off during the reaction.Stoichiometric studies established the minimum amount of BMS required for the complete reduction of these functional groups.Thus, esters require 2 equiv of hydride (HBC=O to >CH2.Employing this stoichiometry, the reduction of aliphatic esters is quite rapid, complete in 0.5 h, while the reduction of aromatic esters is slower, requiring 4-16 h.The corresponding alcohols are produced in excellent yields.On the other hand, nitriles require 3 equiv of hydride (one borane unit/nitrile) and are reduced rapidly in 0.25 h to the corresponding borazine complex, readily hydrolyzed to the corresponding amines.On the other hand, amides require different equivalents of hydride, depending on the particular type of amide undergoing reduction.Thus, tertiary amides require 5 equiv of hydride and form the amine-borane adducts in 0.25 h.Secondary amides liberate hydrogen prior to forming the amine-borane complex, utilizing 6 equiv of hydride in 0.25-1.0 h.However, primary amides require only 4 equiv of hydride, 2 for hydrogen liberation and 2 for reduction, producing in 1.0-2.0 h the amine dibora derivatives, which are sufficiently weakly basic as not to complex with BMS.The ease of reduction of amides follows the order tertiarysecondary>primary.A simple procedure has been described for the reduction of tertiary and secondary amides using decreased amounts of BMS in the presence of boron trifluoride etherate.Unlike lithium aluminum hydride, super hydride, etc., the tendency for C-N bond cleavage to produce the alcohol is completely absent in these reductions of BMS.The reagent permits the presence of many common substituents, such as nitro, chloro, methoxy, etc.The reaction is not significantly susceptible to electronic and steric effects.Simple procedures have been developed for isolating the products.This study establishes a convenient synthetic route for the selective reduction of various organic functional groups with BMS where this transformation is desired in synthetic operations.
- Brown, Herbert C.,Moon Choi, Yong,Narasimhan, S.
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p. 3153 - 3163
(2007/10/02)
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- 4-Amino-3-quinolinecarboxylic acids and esters-antisecretory anti-ulcer compounds
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A method of reducing gastric acidity and treating peptic ulcers and pharmaceutical compositions therefor with certain 4-amino-3-quinolinecarboxylic acids and esters are disclosed. Illustrative of compounds useful in the method which relies on activity as antisecretory activity is the novel compound ethyl 8-methoxy-4-[(2-methylphenyl)amino]-3-quinolinecarboxylate which has the formula: STR1
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