- Heterogeneous Hydrogenation of Quinoline Derivatives Effected by a Granular Cobalt Catalyst
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We communicate a convenient method for the pressure hydrogenation of quinolines in aqueous solution by using a particulate cobalt-based catalyst that is prepared in situ from simple Co(OAc)2 4H2O through reduction with abundant zinc powder. This catalytic protocol permits a brisk and atom-efficient access to a variety of 1,2,3,4-tetrahydroquinolines thereby relying solely on easy-to-handle reagents that are all readily obtained from commercial sources. Both the reaction setup assembly and the autoclave charging procedure are conducted on the bench outside an inert-gas-operated containment system, thus rendering the overall synthesis time-saving and operationally very simple.
- Timelthaler, Daniel,Topf, Christoph
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p. 629 - 642
(2021/11/22)
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- Utilization of renewable formic acid from lignocellulosic biomass for the selective hydrogenation and/or N-methylation
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Lignocellulosic biomass is one of the most abundant renewable sources in nature. Herein, we have developed the utilization of renewable formic acid from lignocellulosic biomass as a hydrogen source and a carbon source for the selective hydrogenation and further N-methylation of various quinolines and the derivatives, various indoles under mild conditions in high efficiencies. N-methylation of various anilines is also developed. Mechanistic studies indicate that the hydrogenation occurs via a transfer hydrogenation pathway.
- Zhou, Chao-Zheng,Zhao, Yu-Rou,Tan, Fang-Fang,Guo, Yan-Jun,Li, Yang
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p. 4724 - 4728
(2021/09/06)
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- Homogeneous pressure hydrogenation of quinolines effected by a bench-stable tungsten-based pre-catalyst
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We report on an operationally simple catalytic method for the tungsten-catalyzed hydrogenation of quinolines through the use of the easily handled and self-contained precursor [WCl(η5-Cp)(CO)3]. This half sandwich complex is indefinitely storable on the bench in simple screw-capped bottles or stoppered flasks and can, if required, be prepared on a multi-gram scale while the actual catalytic transformations were performed in the presence of a Lewis acid in order to achieve both decent substrate conversions and product yields. The described method represents a facile and atom-efficient access to a variety of 1,2,3,4-tetrahydroquinolines that circumvents the use of cost-intensive and oxygen-sensitive phosphine ligands as well as auxiliary hydride reagents.
- Heizinger, Christian,Topf, Christoph,Vielhaber, Thomas
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p. 451 - 461
(2021/11/11)
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- Covalent Organic Frameworks toward Diverse Photocatalytic Aerobic Oxidations
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Photoactive two-dimensional covalent organic frameworks (2D-COFs) have become promising heterogenous photocatalysts in visible-light-driven organic transformations. Herein, a visible-light-driven selective aerobic oxidation of various small organic molecules by using 2D-COFs as the photocatalyst was developed. In this protocol, due to the remarkable photocatalytic capability of hydrazone-based 2D-COF-1 on molecular oxygen activation, a wide range of amides, quinolones, heterocyclic compounds, and sulfoxides were obtained with high efficiency and excellent functional group tolerance under very mild reaction conditions. Furthermore, benefiting from the inherent advantage of heterogenous photocatalysis, prominent sustainability and easy photocatalyst recyclability, a drug molecule (modafinil) and an oxidized mustard gas simulant (2-chloroethyl ethyl sulfoxide) were selectively and easily obtained in scale-up reactions. Mechanistic investigations were conducted using radical quenching experiments and in situ ESR spectroscopy, all corroborating the proposed role of 2D-COF-1 in photocatalytic cycle.
- Liu, Shuyang,Tian, Miao,Bu, Xiubin,Tian, Hua,Yang, Xiaobo
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supporting information
p. 7738 - 7744
(2021/05/07)
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- Cu-Catalyzed Chemoselective Reduction of N-Heteroaromatics with NH3·BH3 in Aqueous Solution
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An efficient catalytic system was successfully developed on reduction of N-heteroaromatics with H3N?BH3 as hydrogen source in CuSO4 solution, featuring excellent chemoselectivity as well as very broad functional group tolerance. Various challenging substrates, such as OH-, NH2-, Cl-, Br-, etc., contained quinolines, quinoxalines, 1,5-naphthyridines and quinazolines were all reduced smoothly. Mechanistic studies suggested that [Cu-H] intermediate might be generated from NH3?BH3, which was believed to form with H3N?BH3 in CuSO4 solution.
- Gao, Chao,Xuan, Qingqing,Song, Qiuling
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supporting information
p. 2504 - 2508
(2021/07/31)
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- Convenient synthesis of cobalt nanoparticles for the hydrogenation of quinolines in water
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Easily accessible cobalt nanoparticles are prepared by hydrolysis of NaBH4 in the presence of inexpensive Co(ii) salts. The resulting material is an efficient catalyst for the hydrogenation of quinoline derivatives in water. The activity and chemoselectivity of this catalyst are comparable to other cobalt-based heterogeneous catalysts.
- Beller, Matthias,Dorcet, Vincent,Fischmeister, Cedric,Hervochon, Julien,Junge, Kathrin
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p. 4820 - 4826
(2020/08/14)
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- Homogeneous Hydrogenation with a Cobalt/Tetraphosphine Catalyst: A Superior Hydride Donor for Polar Double Bonds and N-Heteroarenes
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The development of catalysts based on earth abundant metals in place of noble metals is becoming a central topic of catalysis. We herein report a cobalt/tetraphosphine complex-catalyzed homogeneous hydrogenation of polar unsaturated compounds using an air- and moisture-stable and scalable precatalyst. By activation with potassium hydroxide, this cobalt system shows both high efficiency (up to 24 000 TON and 12 000 h-1 TOF) and excellent chemoselectivities with various aldehydes, ketones, imines, and even N-heteroarenes. The preference for 1,2-reduction over 1,4-reduction makes this method an efficient way to prepare allylic alcohols and amines. Meanwhile, efficient hydrogenation of the challenging N-heteroarenes is also furnished with excellent functional group tolerance. Mechanistic studies and control experiments demonstrated that a CoIH complex functions as a strong hydride donor in the catalytic cycle. Each cobalt intermediate on the catalytic cycle was characterized, and a plausible outer-sphere mechanism was proposed. Noteworthy, external inorganic base plays multiple roles in this reaction and functions in almost every step of the catalytic cycle.
- Duan, Ya-Nan,Du, Xiaoyong,Cui, Zhikai,Zeng, Yiqun,Liu, Yufeng,Yang, Tilong,Wen, Jialin,Zhang, Xumu
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supporting information
p. 20424 - 20433
(2019/12/27)
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- General and Chemoselective Copper Oxide Catalysts for Hydrogenation Reactions
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Copper oxide catalysts have been prepared by pyrolysis of copper acetate on aluminum oxide. The material resulting from pyrolysis at 800 °C allows for catalytic hydrogenations at low temperature of a variety of unsaturated compounds such as quinolines, alkynes, ketones, imines, and polycyclic aromatic hydrocarbons as well as nitroarenes with good activity and selectivity.
- Li, Wu,Cui, Xinjiang,Junge, Kathrin,Surkus, Annette-Enrica,Kreyenschulte, Carsten,Bartling, Stephan,Beller, Matthias
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p. 4302 - 4307
(2019/05/08)
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- Iodine catalyzed reduction of quinolines under mild reaction conditions
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A reduction of quinolines to synthetically versatile tetrahydroquinoline molecules with I2 and HBpin is described. In the presence of iodine (20 mol%) as a catalyst, reduction of quinolines and other N-heteroarenes proceeded readily with hydroboranes as the reducing reagents. The broad functional-group tolerance, good yields and mild reaction conditions imply high practical utility.
- Yang, Chun-Hua,Chen, Xixi,Li, Huimin,Wei, Wenbo,Yang, Zhantao,Chang, Junbiao
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supporting information
p. 8622 - 8625
(2018/08/06)
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- Synthesis method of 1, 2, 3, 4-tetrahydroquinoline compound
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Belonging to the technical field of organic chemical synthesis, the invention discloses a synthesis method of a 1, 2, 3, 4-tetrahydroquinoline compound. The method adopts elemental iodine as the catalyst, uses borane as the reductant, and subjects a quinoline compound to catalytic reduction reaction, thus obtaining the product. Compared with the existing synthesis methods, the method has the greatest characteristics of use of cheap I2 as the catalyst, no need for metal to participate in reaction, mild reaction conditions, rapidity and high efficiency, high catalytic efficiency, simple operation, good selectivity, high product conversion rate up to 80% or more, is of great popularization and application value, and is beneficial to industrial production.
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Paragraph 0039; 0040; 0041; 0042
(2018/11/27)
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- Gold Particles Supported on Amino-Functionalized Silica Catalyze Transfer Hydrogenation of N-Heterocyclic Compounds
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In this work we demonstrate that exceptionally small gold particles (d=0.6±0.2 nm) supported on amino-functionalized mesoporous silicate SBA-15 are highly active in transfer hydrogenation of structurally diverse unsaturated N-heterocyclic compounds. The heterocyclic ring is reduced selectively. The gold particles aggregate to a diameter of 4–5 nm in the presence of formic acid/triethylamine (hydrogen donor) during the first catalytic run. In subsequent cycles the nanoparticles maintain their size, yielding a very stable catalytic system that was recycled more than five times. In contrast, analogous SBA catalysts featuring larger (~5–35 nm) gold particles are not active. Excess formic acid also leads to the formation of formamide derivatives of the products of hydrogenation, which can be deformylated quantitatively. Fifteen structurally different substrates, including the scaffolds of quinoline, isoquinoline, quinoxaline, acridine, phenanthroline, quinazoline, and phenanthridine are hydrogenated and deformylated to give the amine products in >90% overall yield. Deuterium labeling experiments indicate that 1,2-addition with subsequent disproportionation of the formed intermediate is the preferred reaction path over the 1,4-addition one, suggesting the participation of a gold hydride species. (Figure presented.).
- Vilhanová, Beáta,van Bokhoven, Jeroen A.,Ranocchiari, Marco
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supporting information
p. 677 - 686
(2017/02/23)
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- A General and Highly Selective Cobalt-Catalyzed Hydrogenation of N-Heteroarenes under Mild Reaction Conditions
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Herein, a general and efficient method for the homogeneous cobalt-catalyzed hydrogenation of N-heterocycles, under mild reaction conditions, is reported. Key to success is the use of the tetradentate ligand tris(2-(diphenylphosphino)phenyl)phosphine). This non-noble metal catalyst system allows the selective hydrogenation of heteroarenes in the presence of a broad range of other sensitive reducible groups.
- Adam, Rosa,Cabrero-Antonino, Jose R.,Spannenberg, Anke,Junge, Kathrin,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 3216 - 3220
(2017/03/17)
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- Cobalt-catalysed transfer hydrogenation of quinolines and related heterocycles using formic acid under mild conditions
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Herein, we report the first example of homogeneous non-noble metal-catalyzed transfer hydrogenation of N-heteroarenes. The combination of Co(BF4)2·6H2O with tris(2-(diphenylphosphino)phenyl)phosphine L1 is able to selectively reduce quinolines in the presence of other sensitive functional groups, under mild conditions, using formic acid as a hydrogen source.
- Cabrero-Antonino, Jose R.,Adam, Rosa,Junge, Kathrin,Jackstell, Ralf,Beller, Matthias
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p. 1981 - 1985
(2017/07/15)
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- Reduction method of nitrogen-containing heterocyclic compound
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The invention discloses a reduction method of a nitrogen-containing heterocyclic compound. The reduction method comprises the following steps: firstly, adding bis(pinacolato)diboron, palladium acetate and cesium carbonate into a pressure-resisting sealing reaction vessel; filling with nitrogen, adding water and quinoline compounds, performing stirring reaction at room temperature, and tracking by using TLC and GC in a reaction process so as to decide specific reaction time; secondly, after the reaction is ended, taking out a reaction product in the first step from the pressure-resisting sealing reaction vessel, cooling to room temperature, then adding ethyl acetate for fully mixing, and subsequently performing filtering and washing of ethyl acetate to obtain an organic phase; thirdly, performing spin drying on a solvent in the organic phase obtained in the second step, purifying by using a silica gel column, and then leaching with an eluant to obtain a product. The eluant is a mixed solution of petroleum ether and the ethyl acetate. The reduction method disclosed by the invention accords with the idea of green chemistry, and is better in economy and simple in operation.
- -
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Paragraph 0020; 0021; 0022; 0024
(2017/02/09)
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- Diboron-assisted palladium-catalyzed transfer hydrogenation of N-heteroaromatics with water as hydrogen donor and solvent
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A Pd-catalyzed transfer hydrogenation of various N-heteroaromatic compounds with B2pin2 as a mediator and environmentally benign water as both solvent and hydrogen donor has been disclosed. This reaction proceeded under ambient temperature with a broad range of N-heteroaromatic compounds among which imidazo[1,2-a]pyridine derivatives were for the first time selectively reduced to 5,6,7,8-tetrahydroimidazo[1,2-a]pyridines, which are the core structural motifs of an inhibitor of human O-GlcNAcase. Mechanistic studies suggested that the new protons in products are from water and Pd-H might be the key intermediate with B2pin2 as the H2O activator.
- Xuan, Qingqing,Song, Qiuling
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supporting information
p. 4250 - 4253
(2016/09/09)
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- COMPOUND HAVING 11 ?-HSD1 INHIBITORY ACTIVITY
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The present invention provides compounds having excellent 11β-HSD1 inhibitory activity. A compound represented by the following formula (I): [wherein X1 represents an oxygen atom, or the formula -(CR11R12)p-, etc., Y1 represents a hydrogen atom, a hydroxyl group, etc., Z1 represents an oxygen atom or the formula -(NR14)-, R1 represents a hydrogen atom, a halogen atom, a cyano group, a C1-4 alkyl group, a C1-4 alkyl group substituted with 1 to 3 halogen atoms, a C1-4 alkoxy group, a C1-4 alkoxycarbonyl group, a carboxyl group, a carbamoyl group, or an amino group, and m represents an integer of 1 or 2, and R2 represents a hydrogen atom or a C1-4 alkyl group, and n represents an integer of 1 or 2].
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Page/Page column 10-11
(2010/04/25)
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- RENIN INHIBITORS
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The present invention relates to novel renin inhibitors of general formula (1), novel intermediates involved in their synthesis, their pharmaceutically acceptable salts and pharmaceutical compositions containing them. The present invention also relates to a process of preparing compounds of general formula (1), their tautomeric forms, their pharmaceutically acceptable salts, pharmaceutical compositions containing them, and novel intermediates involved in their synthesis.
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Page/Page column 25
(2009/09/04)
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- Through-Space Transmission of 19F-13C Coupling via an Intermediate Bond. An Experimental and Theoretical Study
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In order to obtain a deeper insight into the title effect, several compounds with an F atom very close to a C-H of a nearby functional group were synthesized and the relevant couplings measured.The most conspicuous case was that of 8-fluoro-2-hydroxynaphthalene-1-carbaldehyde where a close proximity between the F and H atoms is the result of fluorine-oxygen repulsion and the formation of an intramolecular hydrogen bond between the hydroxyl and carbonyl groups.The experimental four-bond J(F,CHO) coupling is 26.2 Hz.A compound very similar to this one, but without the OH group, was chosen on which to perform a polarization propagator analysis of the through-space (TS) coupling pathways, at the RPA-INDO level.The expression for the TS coupling in terms of the projected polarization propagator and perturbators was numerically analysed.It is found that this coupling is completely dominated by a TS component of the Fermi contact (FC) term, the main features of which are: (i) It decays exponentially with the F-H distance; (ii) Its main contribution comes from an electron excitation involving the F lone-pair, the C-H bond of the CHO moiety and its corresponding antibonding orbital; (iii) The ?-type lone-pair does not contribute to the TS coupling pathway of the FC term.
- Rae, Ian D.,Staffa, Alfred,Diz, Agustin C.,Giribet, Claudia G.,Azua, Martin C. Ruiz de,Contreras, Ruben H.
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p. 1923 - 1940
(2007/10/02)
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- Selectivity in the Hydrogenation of 6- and 8-Substituted-quinolines
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Quinoline (1) and the 6- or 8-substituted-quinolines (2)-(14) (R = Me, Pri, But, Ph, OMe, OH, CF3, or F) were hydrogenated catalytically on platinum under either weakly basic (solvent MeOH) or strongly acidic (solvent CF3CO2H) conditions.In methanol the only product was the corresponding 1,2,3,4-tetrahydro-compound.In trifluoroacetic acid, compounds hydrogenated in the benzene ring were isolated as major products; both electron-withdrawing and electron-donating substituents at C-6 or C-8 cause (sometimes drastic) reduction in yield.The products were characterized by their 1H and 13C n.m.r. spectra.
- Hoenel, Michael,Vierhapper, Friedrich W.
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p. 1933 - 1939
(2007/10/02)
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