- Resolution of the flumequine intermediate 6-fluoro-2-methyl-1,2,3,4-tetrahydroquinoline
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Racemic 6-fluoro-2-methyl-1,2,3,4-tetrahydroquinoline (FTHQ) was resolved by the N-phthaloyl derivative of the (R)-enantiomer. The enantiomeric mixture was very effectively enriched by recrystallisation from either the melt (working best for mixtures of relatively high starting enantiomeric purities) or from solution of its hydrochloride salt (giving good results when applied for mixtures of moderate to medium enantiomeric purities). Copyright (C) 2000 Elsevier Science Ltd.
- Balint, Jozsef,Egri, Gabriella,Vass, Gabor,Schindler, Jozsef,Gajary, Antal,Friesz, Antal,Fogassy, Elemer
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- Low-Temperature Nickel-Catalyzed C?N Cross-Coupling via Kinetic Resolution Enabled by a Bulky and Flexible Chiral N-Heterocyclic Carbene Ligand
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The transition-metal-catalyzed C?N cross-coupling has revolutionized the construction of amines. Despite the innovations of multiple generations of ligands to modulate the reactivity of the metal center, ligands for the low-temperature enantioselective amination of aryl halides remain a coveted target of catalyst engineering. Designs that promote one elementary reaction often create bottlenecks at other steps. We here report an unprecedented low-temperature (as low as ?50 °C), enantioselective Ni-catalyzed C?N cross-coupling of aryl chlorides with sterically hindered secondary amines via a kinetic resolution process (s factor up to >300). A bulky yet flexible chiral N-heterocyclic carbene (NHC) ligand is leveraged to drive both oxidative addition and reductive elimination with low barriers and control the enantioselectivity. Computational studies indicate that the rotations of multiple σ-bonds on the C2-symmetric chiral ligand adapt to the changing needs of catalytic processes. We expect this design would be widely applicable to diverse transition states to achieve other challenging metal-catalyzed asymmetric cross-coupling reactions.
- Hong, Xin,Shi, Shi-Liang,Wang, Zi-Chao,Xie, Pei-Pei,Xu, Youjun
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supporting information
p. 16077 - 16084
(2021/06/17)
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- Development of efficient solid chiral catalysts with designable linkage for asymmetric transfer hydrogenation of quinoline derivatives
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This vertically self-pillared (VSP) structure extends the application range of traditional porous materials with facile mass/ion transport and enhanced reaction kinetics. Here, we prepare a single crystal metal-organic framework (MOF), employing the ZIF-67 structure as a proof of concept, which is constructed by vertically self-pillared nanosheets (VSP-MOF). We further converted VSP-MOF into VSP-cobalt sulfide (VSP-CoS2) through a sulfidation process. Catalysis plays an important role in almost all battery technologies; for metallic batteries, lithium anodes exhibit a high theoretical specific capacity, low density, and low redox potential. However, during the half-cell reaction (Li++e=Li), uncontrolled dendritic Li penetrates the separator and solid electrolyte interphase layer. When employed as a composite scaffold for lithium metal deposition, there are many advantage to using this framework: 1) the VSP-CoS2 substrate provides a high specific surface area to dissipate the ion flux and mass transfer and acts as a pre-catalyst, 2) the catalytic Co center favors the charge transfer process and preferentially binds the Li+ with the enhanced electrical fields, and 3) the VSP structure guides the metallic propagation along the nanosheet 2D orientation without the protrusive dendrites. All these features enable the VSP structure in metallic batteries with encouraging performances.
- Ren, Yiqi,Tao, Lin,Li, Chunzhi,Jayakumar, Sanjeevi,Li, He,Yang, Qihua
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p. 1576 - 1585
(2021/05/10)
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- Identification of Human Toll-like Receptor 2-Agonistic Activity in Dihydropyridine-Quinolone Carboxamides
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Using a multiplexed, reporter gene-based, high-throughput screen, we identified 9-fluoro-7-hydroxy-3-methyl-5-oxo-N-(pyridin-3-ylmethyl)-2,3-dihydro-1H,5H-pyrido[3,2,1-ij]quinoline-6-carboxamide as a TLR2 agonist. Preliminary structure-activity relationship studies on the carboxamide moiety led to the identification of analogues that induce chemokines and cytokines in a TLR2-dependent manner. These results represent new leads for the development of vaccine adjuvants.
- Hu, Ziwei,Banothu, Janardhan,Beesu, Mallesh,Gustafson, Collin J.,Brush, Michael J. H.,Trautman, Kathryn L.,Salyer, Alex C. D.,Pathakumari, Balaji,David, Sunil A.
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supporting information
p. 132 - 136
(2019/01/15)
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- Deracemization of Phenyl-Substituted 2-Methyl-1,2,3,4-Tetrahydroquinolines by a Recombinant Monoamine Oxidase from Pseudomonas monteilii ZMU-T01
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A monoamine oxidase (MAO5) from Pseudomonas monteilii ZMU-T01 was first heterologously expressed in Escherichia coli BL21(DE3) and then used as a biocatalyst for the deracemization of racemic 2-methyl-1,2,3,4-tetrahdroquinoline derivatives to yield the unreacted R enantiomer with up to >99 % ee. Sequence alignment revealed that MAO5 shared 14.7 % identity toward the well-studied monoamine oxidase (MAO-N).
- Deng, Guozhong,Wan, Nanwei,Qin, Lei,Cui, Baodong,An, Miao,Han, Wenyong,Chen, Yongzheng
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p. 2374 - 2377
(2018/04/19)
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- Enantioselective hydrogenation of N-heteroaromatics catalyzed by chiral diphosphine modified binaphthyl palladium nanoparticles
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The first application of binaphthyl-stabilized palladium nanoparticles (Bin-PdNPs) with chiral modifiers in asymmetric hydrogenation of N-heteroaromatics is revealed. With an appropriate ratio of R-BINAP/Bin-PdNPs used, the pre-prepared chiral nanocatalyst achieves asymmetric hydrogenations of 2-substituted quinolines with good to excellent yields and moderate enantioselectivities, which showed superior catalytic properties to the R-BINAP/Pd complex. Moreover, this protocol is also applicable to 2-substituted indoles.
- Xia, Yun-Tao,Ma, Jing,Wang, Xiao-Dong,Yang, Lei,Wu, Lei
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p. 5515 - 5520
(2017/12/07)
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- Structure-Activity Relationship Studies with Tetrahydroquinoline Analogs as EPAC Inhibitors
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EPAC proteins are therapeutic targets for the potential treatment of cardiac hypertrophy and cancer metastasis. Several laboratories use a tetrahydroquinoline analog, CE3F4, to dissect the role of EPAC1 in various disease states. Here, we report SAR studies with tetrahydroquinoline analogs that explore various functional groups. The most potent EPAC inhibitor 12a exists as a mixture of inseparable E (major) and Z (minor) rotamers. The rotation about the N-formyl group indeed impacts the activity against EPAC.
- Sonawane, Yogesh A.,Zhu, Yingmin,Garrison, Jered C.,Ezell, Edward L.,Zahid, Muhammad,Cheng, Xiaodong,Natarajan, Amarnath
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supporting information
p. 1183 - 1187
(2017/11/15)
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- Acylative kinetic resolution of racemic heterocyclic amines with (R)-2-phenoxypropionyl chloride
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The acylative kinetic resolution of racemic heterocyclic amines such as 3,4-dihydro-3-methyl-2H-[1,4]benzoxazines, 3,4-dihydro-3-methyl-2H-[1,4]benzothiazine, 2-methyl-1,2,3,4-tetrahydro-quinolines and 2-methylindoline with enantiopure (R)-2-phenoxypropionyl chloride has been studied. It has been found that acylation of 3,4-dihydro-3-methyl-2H-[1,4]benzothiazine proceeds with the best stereoselectively when compared with other racemic amines. An efficient method for the preparation of (S)-3,4-dihydro-3-methyl-2H-[1,4]benzothiazine (99.4% ee) via a kinetic resolution protocol was developed. The possibility of recycling (R)-2-phenoxypropionic acid has been demonstrated.
- Vakarov, Sergey A.,Gruzdev, Dmitry A.,Chulakov, Evgeny N.,Sadretdinova, Liliya Sh.,Tumashov, Andrey A.,Pervova, Marina G.,Ezhikova, Marina A.,Kodess, Mikhail I.,Levit, Galina L.,Krasnov, Victor P.,Charushin, Valery N.
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supporting information
p. 1231 - 1237
(2016/11/23)
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- Model containing pyridine base crown ether chiral bis-phosphorus ligand and its in asymmetric catalytic application of the catalyst in the reaction (by machine translation)
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This invention relates to model containing pyridine base crown ether chiral bis-phosphorus ligand and its application of symmetrical catalytic reaction. Chiral bis-phosphorus ligand and intermediates containing pyridine base crown ether single phosphorus ligand the structural formula of (I) are respectively shown as the following formula, formula (I '). These chiral bis-phosphorus ligand of the transition metal complexes can be used as catalyst for asymmetric reactions, containing pyridine base crown ether of the invention the chiral bis-phosphorus ligand it is a kind of novel chiral ligand capable of regulating, by using different alkali metal ion, alkaline earth metal ion, rare-earth metal ion, ammonium salt or organic amine salt such as a crown ether, on the object with the ligand complex, the catalyst can be realized the space structure and electronic nature of the regulation and control. This kind of the alkali metal ion complexation assembled containing pyridine base crown ether chiral double-phosphorus ligand transition metal (Rh and Ir) complexes in catalytic hydrogenation reaction demonstrate excellent catalytic activity and good stereoselectivity. (by machine translation)
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Paragraph 0135; 0136; 0137
(2016/10/10)
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- A supramolecularly tunable chiral diphosphine ligand: Application to Rh and Ir-catalyzed enantioselective hydrogenation
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A supramolecularly tunable chiral bisphosphine ligand bearing two pyridyl-containing crown ethers, (-) or (+)-Xyl-P16C6-Phos, was fabricated and utilized in the Rh-catalyzed asymmetric hydrogenation of α-dehydroamino acid esters and Ir-catalyzed asymmetric hydrogenation of quinolines in high yields with excellent enantioselectivities (90-99% ee). Up to a 22% enhancement in enantioselectivity was achieved by the addition of certain amounts of alkali ions (Li+, Na+ or K+), which could be selectively recognized and effectively complexed by the crown ethers on the chiral Xyl-P16C6-Phos.
- Zhang, Xi-Chang,Hu, Yi-Hu,Chen, Chuan-Fu,Fang, Qiang,Yang, Li-Yao,Lu, Ying-Bo,Xie, Lin-Jie,Wu, Jing,Li, Shijun,Fang, Wenjun
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p. 4294 - 4299
(2016/07/06)
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- Solvent-Regulated Asymmetric Hydrogenation of Quinoline Derivatives in Oligo(Ethylene Glycol)s through Host–Guest Interactions
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The asymmetric hydrogenation of quinolines in oligo(ethylene glycol)s (OEGs) and poly(ethylene glycol)s (PEGs) with chiral cationic ruthenium diamine complexes has been investigated. Interestingly, in liquid PEGs or long-chain OEGs, the Ru catalysts lost their reactivity. Upon the addition of a little MeOH, the hydrogenation of quinoline was switched “ON”. Evidence from mass spectrometry and control experiments revealed that encapsulation of the quinolinium salt by PEG or long-chain OEG molecules through supramolecular interactions is possibly the main reason for such a switchable hydrogenation reaction. Moreover, the asymmetric hydrogenation of 2-substituted quinoline derivatives was achieved in triethylene glycol (3-OEG), thereby affording 1,2,3,4-tetrahydroquinolines with excellent reactivities and enantioselectivities (up to 99 % ee). Furthermore, the Ru catalyst could be readily recycled for both pure 3-OEG and biphasic 3-OEG/n-hexane systems without a clear loss of reactivity and enantioselectivity.
- Wang, Tianli,Chen, Ya,Ouyang, Guanghui,He, Yan-Mei,Li, Zhiyan,Fan, Qing-Hua
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p. 2773 - 2777
(2016/10/11)
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- Low Pressure Asymmetric Hydrogenation of Quinolines using an Annulated Planar Chiral N-Ferrocenyl NHC-Iridium Complex
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Annulated planar chiral N-ferrocenylimidazolones, obtained by acid-mediated cyclization of diphenylmethanol derivatives, may be reduced with diisobutylaluminium hydide (DIBAL-H) to afford a series of surprisingly stable and isolable hemiaminal ether aminals. Two of these derivatives can be oxidized with triphenylcarbenium tetrafluoroborate to imidazolinium salt precursors of N-heterocyclic carbenes (NHCs). Deprotonation of these salts in the presence of (cyclooctadiene)iridium chloride dimer {[Ir(COD)Cl]2} provides chiral coordination complexes bearing N-ferrocenyl NHCs with unique rigid tetracyclic frameworks. Cationic analogues of these complexes catalyze the asymmetric hydrogenation of 2-substituted quinolines under very mild conditions (1 mol% complex, 1 mol% PPh3, 1-5 atm H2, toluene, 25 C) in appreciable enantioselectivity (up to 90:10 er). The sensitivity of the hydrogenation process to changes in the phosphine additive suggests that an outer-sphere reaction mechanism may be involved, as proposed for a related achiral NHC-Ir complex reported by Crabtree and co-workers.
- John, Joshni,Wilson-Konderka, Cody,Metallinos, Costa
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p. 2071 - 2081
(2015/06/23)
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- Efficient enantioselective hydrogenation of quinolines catalyzed by conjugated microporous polymers with embedded chiral BINAP ligand
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Chiral Ir complexes were successfully used in the asymmetric hydrogenation of olefins, ketones, and quinolines. However, almost all the catalytic systems could not tolerate a high catalyst loading because of the formation of an irreversible iridium dimer and trimer during the reaction. It is expected that higher catalytic activity may be achieved if the Ir-complexes were isolated in space. The development of conjugated microporous polymers (CMPs) gives the opportunity for the spatial separation of the complexes. A series of chiral CMPs based on the chiral (R)-BINAP ligand (BINAP-CMPs) with different surface areas were synthesized. The BINAP ligands were separately distributed in the framework and were three times more active than the homogeneous catalyst (TOF 340 h-1 VS 100 h-1) for the asymmetric hydrogenation of quinolines.
- Wang, Xu,Li, Jun,Lu, Shengmei,Liu, Yan,Li, Can
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p. 1170 - 1174
(2015/09/01)
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- N-tosyl-(S)-prolyl chloride in kinetic resolution of racemic heterocyclic amines
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The kinetic resolution of racemic heterocyclic amines via acylation with N-tosyl-(S)-prolyl chloride was systematically investigated. It was established that racemic mixtures of aromatic amines could be resolved with high efficiency, while the acylation of 2- and 3-methylpiperidines occurred with low diastereoselectivity. A method for the preparation of enantiomerically pure (3R)-7,8-difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazine was developed.
- Gruzdev,Vakarov,Levit,Krasnov
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p. 1795 - 1807
(2014/05/06)
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- The use of phosphite-type ligands in the Ir-catalyzed asymmetric hydrogenation of heterocyclic compounds
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A series of chiral phosphite-type ligands was tested in asymmetric Ir-catalyzed hydrogenation of quinolines and 2,4,5,6-tetrahydro-1H-pyrazino(3,2, 1-j,k)carbazole. Hydrogenation of quinaldine hydrochloride provided superior enantioselectivity up to 65% ee compared to quinaldine free base. The ligands were tested for the first time in the asymmetric Ir-Ircatalyzed hydrogenation of 2,4,5,6-tetrahydro-1H-pyrazino(3,2,1-j,k)carbazole yielding the antidepressant drug, pirlindole. Chirality 26:56-60, 2013. 2013 Wiley Periodicals, Inc.
- Lyubimov, Sergey E.,Ozolin, Dmitry V.,Ivanov, Pavel Yu,Melman, Artem,Velezheva, Valeriya S.,Davankov, Vadim A.
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- A comparative study on the acylative kinetic resolution of racemic fluorinated and non-fluorinated 2-methyl-1,2,3,4-tetrahydroquinolines and 3,4-dihydro-3-methyl-2H-[1,4]benzoxazines
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The acylative kinetic resolution of racemic 6-fluoro-2-methyl-1,2,3,4- tetrahydroquinoline, 7,8-difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazine, and their non-fluorinated analogues with (S)-naproxen and N-phthaloyl-(S)-amino acyl chlorides has been carried out. It has been shown that the presence of fluorine atoms in the aromatic fragment of a heterocyclic amine results in the increasing stereoselectivity of acylation with (S)-naproxen acyl chloride and in a decrease in the efficiency of acylative kinetic resolution using N-phthaloyl-(S)-amino acyl chlorides. A method for the preparation of enantiopure (S)-6-fluoro-2-methyl-1,2,3,4-tetrahydroquinoline (ee >99%) was developed.
- Gruzdev, Dmitry A.,Chulakov, Evgeny N.,Levit, Galina L.,Ezhikova, Marina A.,Kodess, Mikhail I.,Krasnov, Victor P.
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p. 1240 - 1246
(2013/10/22)
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- Highly enantioselective synthesis of chiral tetrahydroquinolines and tetrahydroisoquinolines by ruthenium-catalyzed asymmetric hydrogenation in ionic liquid
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Asymmetric hydrogenation reactions of quinolines and 3,4- dihydroisoquinolines using the chiral cationic ruthenium complex Ru(TsDPEN) [TsDPEN=N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine] as catalyst in neat imidazolium ionic liquids have been investigated. The catalytic performance was influenced by the anion of the ionic liquids for both substrate classes. A range of 2-alkyl-substituted 1,2,3,4-tetrahydroquinolines and 1-alkyl-substituted 1,2,3,4-tetrahydroisoquinolines was obtained in high yields with up to >99% ee. Interestingly, the hydrogenation of quinoline derivatives bearing a carbonyl group was selective for the C-N (quinoline) over the C-O (ketone) bonds, while such a unique chemoselectivity was not observed in methanol. Furthermore, the ruthenium catalysts could be easily recycled at least 5 times in the asymmetric hydrogenation of 3,4-dihydroisoquinoline by solvent extraction. To further facilitate the recovery of catalyst and reduce the use of organic solvent, a thin film of ionic liquid containing Ru(TsDPEN) was supported on silica gels. This supported ionic liquid-phase catalyst was effective in the asymmetric hydrogenation of quinoline, and could be recycled at least 6 times by simple filtration. Copyright
- Ding, Zi-Yuan,Wang, Tianli,He, Yan-Mei,Chen, Fei,Zhou, Hai-Feng,Fan, Qing-Hua,Guo, Qingxiang,Chan, Albert S. C.
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supporting information
p. 3727 - 3735
(2014/01/06)
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- A new electronically deficient atropisomeric diphosphine ligand (S)-CF 3O-BiPhep and its application in asymmetric hydrogenation
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A new electronically deficient atropisomeric diphosphine ligand (S)-CF 3O-BiPhep was synthesized from 1-bromo-3-(trifluoromethoxy)benzene in high yield. The key steps included oxidative coupling with anhydrous ferric chloride and optical resolution by (+)-DMTA. The ligand afforded high performance for Ir-catalyzed asymmetric hydrogenation of quinolines with ee up to 92% and TON up to 25,000. It was also successfully applied to the Pd-catalyzed asymmetric hydrogenation of simple indoles with ee up to 87% and Rh-catalyzed asymmetric 1,4-addition of phenylboronic acid to 2-cyclohexenone with 97% ee.
- Zhang, De-Yang,Yu, Chang-Bin,Wang, Min-Can,Gao, Kai,Zhou, Yong-Gui
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supporting information; experimental part
p. 2556 - 2559
(2012/06/15)
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- Bronsted acid differentiated metal catalysis by kinetic discrimination
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A Bronsted acid differentiated metal catalyzed hydrogenation has been developed. A combinatorial variation of chiral triflylamides with achiral metal complexes results in a highly active catalyst for the asymmetric reduction.
- Rueping, Magnus,Koenigs, Rene M.
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supporting information; experimental part
p. 304 - 306
(2011/03/17)
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- Highly enantioselective hydrogenation of quinolines using phosphine-free chiral cationic Ruthenium catalysts: Scope, mechanism, and origin of enantioselectivity
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Asymmetric hydrogenation of quinolines catalyzed by chiral cationic η6-arene-N-tosylethylenediamine-Ru(II) complexes have been investigated. A wide range of quinoline derivatives, including 2-alkylquinolines, 2-arylquinolines, and 2-functionalized and 2,3-disubstituted quinoline derivatives, were efficiently hydrogenated to give 1,2,3,4-tetrahydroquinolines with up to >99% ee and full conversions. This catalytic protocol is applicable to the gram-scale synthesis of some biologically active tetrahydroquinolines, such as (-)-angustureine, and 6-fluoro-2-methyl-1,2,3,4-tetrahydroquinoline, a key intermediate for the preparation of the antibacterial agent (S)-flumequine. The catalytic pathway of this reaction has been investigated in detail using a combination of stoichiometric reaction, intermediate characterization, and isotope labeling patterns. The evidence obtained from these experiments revealed that quinoline is reduced via an ionic and cascade reaction pathway, including 1,4-hydride addition, isomerization, and 1,2-hydride addition, and hydrogen addition undergoes a stepwise H+/H- transfer process outside the coordination sphere rather than a concerted mechanism. In addition, DFT calculations indicate that the enantioselectivity originates from the CH/π attraction between the η6-arene ligand in the Ru-complex and the fused phenyl ring of dihydroquinoline via a 10-membered ring transition state with the participation of TfO- anion.
- Wang, Tianli,Zhuo, Lian-Gang,Li, Zhiwei,Chen, Fei,Ding, Ziyuan,He, Yanmei,Fan, Qing-Hua,Xiang, Junfeng,Yu, Zhi-Xiang,Chan, Albert S. C.
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supporting information; experimental part
p. 9878 - 9891
(2011/08/10)
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- Asymmetric metal-free synthesis of fluoroquinolones by organocatalytic hydrogenation
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A highly enantioselective organocatalytic transfer hydrogenation enabling the synthesis of both 6-fluoro-2-methyltetrahydroquinoline and 7,8-difluoro-3-methyl-benzoxazine has been developed. These key building blocks can for the first time be synthesized using the same methodology allowing fast and efficient, metal-free access to the antibiotic fluoroquinolones flumequine and levofloxacine.
- Rueping, Magnus,Stoeckel, Mirjam,Sugiono, Erli,Theissmann, Thomas
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experimental part
p. 6565 - 6568
(2010/10/19)
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- Asymmetrie hydrogenation with water/silane as the hydrogen source
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"Chamical Equation presentd" Water as a hydride source : A new pathway to form metal-hydride bonds has been developed through the reaction of easily available metal-silyl compounds with water. This method has been successfully applied to asymmetric hydrogenation of heteroaromatic compounds with up to 93 % ee under mild autoclave-free conditions (see scheme).
- Wang, Da-Wei,Wang, Duo-Sheng,Chen, Qing-An,Zhou, Yong-Gui
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supporting information; experimental part
p. 1133 - 1136
(2010/06/12)
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- Highly enantioselective hydrogenation of quinoline and pyridine derivatives with iridium-(P-Phos) catalyst
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The use of a chiral iridium catalyst gener-ated in situ from the (cyclooctadiene)iridium chlo-ride dimer, [Ir(COD)Cl]2, the P-Phos ligand [4, 4'-bis(diphenylphosphino)-2, 2', 6, 6'-tetramethoxy-3, 3'-bi-pyridine] and iodine (I2) for the asymmetric hydroge-nation of 2, 6-substituted quinolines and trisubstituted pyridines [2-substituted 7, 8-dihydroquinolin-5(6H)-one derivatives] is reported. The catalyst worked ef-ficiently to hydrogenate a series of quinoline deriva-tives to provide chiral 1, 2, 3, 4-tetrahydroquinolines in high yields and up to 96% ee. The hydrogenation was carried out at high S/C (substrate to catalyst) ratios of 2000-50000, reaching up to 4000 h-1 TOF (turnover frequency) and up to 43000 TON (turn-over number). The catalytic activity is found to be additive-controlled. At low catalyst loadings, de-creasing the amount of additive I2 was necessary to maintain the good conversion. The same catalyst system could also enantioselectively hydrogenate tri-substituted pyridines, affording the chiral hexahydro-quinolinone derivatives in nearly quantitative yields and up to 99% ee. Interestingly, increasing the amount of I2 favored high reactivity and enantiose-lectivity in this case. The high efficacy and enantiose-lectivity enable the present catalyst system of high practical potential.
- Tang, Wei-Jun,Tan, Jing,Xu, Li-Jin,Lam, Kim-Hung,Fan, Qing-Hua,Chan, Albert S. C.
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experimental part
p. 1055 - 1062
(2010/06/15)
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- Asymmetric hydrogenation of quinolines activated by Br?nsted acids
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Enantioselective hydrogenation of quinolines and quinoxalines catalyzed by iridium/diphosphine complex with catalytic amount of Br?nsted acid as activator was developed. In the presence of piperidine·TfOH as the activator, full conversions and up to 92% ee were obtained.
- Wang, Duo-Sheng,Zhou, Yong-Gui
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supporting information; experimental part
p. 3014 - 3017
(2010/07/10)
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- Inhibiting deactivation of iridium catalysts with bulky substituents on coordination atoms
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Introducing bulky groups on the coordination phosphorus atoms can effectively block the formation of inactive dimer species and improve the activity of the iridium catalysts. Results of ESI-MS analysis gave strong evidence. This strategy was successfully
- Wang, Duo-Sheng,Zhou, Juan,Wang, Da-Wei,Guo, Yin-Long,Zhou, Yong-Gui
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supporting information; experimental part
p. 525 - 528
(2010/09/20)
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- Highly efficient and enantioselective hydrogenation of quinolines and pyridines with Ir-Difluorphos catalyst
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The combination of the readily available chiral bisphosphine ligand Difluorphos with [Ir(COD)Cl]2 in THF resulted in a highly efficient catalyst system for asymmetric hydrogenation of quinolines at quite low catalyst loadings (0.05-0.002 mol%), affording the corresponding products with high enantioselectivities (up to 96%), excellent catalytic activities (TOF up to 3510 h-1) and productivities (TON up to 43000). The same catalyst was also successfully applied to the asymmetric hydrogenation of trisubstituted pyridines with nearly quantitative yields and up to 98% ee. In these two reactions, the addition of I2 additive is indispensable; but the amount of I2 has a different effect on catalytic performance. The Royal Society of Chemistry 2010.
- Tang, Weijun,Sun, Yawei,Lijin, Xu,Wang, Tianli,Qinghua Fan,Lam, Kim-Hung,Chan, Albert S.C.
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experimental part
p. 3464 - 3471
(2010/08/21)
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- Asymmetric hydrogenation of heteroaromatic compounds mediated by iridium-(P-OP) complexes
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A library of modular iridium complexes derived from P-OP ligands has been evaluated in iridium-mediated asymmetric hydrogenations of heteroaromatic compounds. The "lead" catalysts efficiently catalyzed the hydrogenation of several substituted quinolines and one quinoxaline (10 examples, up to 92% ee).
- Nunez-Rico, Jose L.,Fernandez-Perez, Hector,Benet-Buchholz,Vidal-Ferran, Anton
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scheme or table
p. 6627 - 6631
(2011/02/27)
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- Synthesis of tunable bisphosphine ligands and their application in asymmetric hydrogenation of quinolines
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(Chemical Equation Presented) A series of tunable axial chiral bisphosphine ligands have been synthesized from (S)-MeO-Biphep. The Ir complex of the MeO-PEG-supported ligand (S)-4k has been successfully applied in asymmetric hydrogenation of quinolines with up to 92% ee. The catalyst system is air-stable and recyclable.
- Wang, Xiao-Bing,Zhou, Yong-Gui
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p. 5640 - 5642
(2008/12/21)
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- Synthesis of sulfoximine-derived P,N ligands and their applications in asymmetric quinoline hydrogenations
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A series of naphthalene-bridged P,N-type sulfoximine ligands and their iridium complexes have been synthesized. They were applied in the enantioselective hydrogenation of quinoline derivatives, and enantioselectivities up to 92% ee have been achieved in the hydrogenation of 2-methylquinoline.
- Lu, Sheng-Mei,Bolm, Carsten
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supporting information; experimental part
p. 1101 - 1105
(2009/06/18)
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- Asymmetric hydrogenation of quinolines catalyzed by iridium complexes of monodentate BINOL-derived phosphoramidites
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The monodentate BINOL-derived phosphoramidite PipPhos is used as ligand for the iridium-catalyzed asymmetric hydrogenation of 2- and 2,6-substituted quinolines. If tri-ortho-tolylphosphine and/or chloride salts are used as additives enantioselectivities are strongly enhanced up to 89%. NMR indicates that no mixed complexes are formed upon addition of tri-ortho-tolylphosphine.
- Mrsic, Natasa,Lefort, Laurent,Boogers, Jeroen A. F.,Minnaard, Adriaan J.,Feringa, Ben L.,De Vries, Johannes G.
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scheme or table
p. 1081 - 1089
(2009/05/27)
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- Asymmetric hydrogenation of quinolines with high substrate/catalyst ratio
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The chiral diphosphinite ligand derived from (R)-1,1′-spirobiindane- 7,7′-diol has been found to be highly effective in the Ir-catalyzed asymmetric hydrogenation of quinolines with high substrate/catalyst ratio (up to 5000) and high enantioselectivity (up to 94% ee). The Royal Society of Chemistry.
- Tang, Wei-Jun,Zhu, Shou-Fei,Xu, Li-Jin,Zhou, Qi-Lin,Fan, Qing-Hua,Zhou, Hai-Feng,Lam, Kimhung,Chan, Albert S. C.
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p. 613 - 615
(2007/10/03)
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- Enantioselective hydrogenation of quinolines catalyzed by Ir(BINAP)-cored dendrimers: Dramatic enhancement of catalytic activity
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Figure presented The asymmetric hydrogenation of quinolines catalyzed by chiral dendritic catalysts derived from BINAP gave the corresponding products with high enantioselectivities (up to 93%), excellent catalytic activities (TOF up to 3450 h-1), and productivities (TON up to 43 000). In addition, the third-generation catalyst could be recovered by precipitation and filtration and reused at least six times with similar enantioselectivity.
- Wang, Zhi-Jian,Deng, Guo-Jun,Li, Yong,He, Yan-Mei,Tang, Wei-Jun,Fan, Qing-Hua
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p. 1243 - 1246
(2007/10/03)
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- Iridium-catalyzed asymmetric transfer hydrogenation of quinolines with Hantzsch esters
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The iridium-catalyzed enantioselective transfer hydrogenation of quinolines with Hantzsch esters was developed with up to 88% ee using [Ir(COD)Cl]2/(S)-SegPhos/I2 as a catalyst.
- Wang, Da-Wei,Zeng, Wei,Zhou, Yong-Gui
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p. 1103 - 1107
(2008/02/08)
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- Novel Ir-SYNPHOS and Ir-DIFLUORPHOS catalysts for asymmetric hydrogenation of quinolines
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Novel Ir-SYNPHOS and Ir-DIFLUORPHOS catalysts were synthesized and used for the synthesis of tetrahydroquinolines via asymmetric hydrogenation of the corresponding quinoline derivatives. Georg Thieme Verlag Stuttgart.
- Deport, Coralie,Buchotte, Marie,Abecassis, Keren,Tadaoka, Hiroshi,Ayad, Tahar,Ohshima, Takashi,Genet, Jean-Pierre,Mashima, Kazushi,Ratovelomanana-Vidal, Virginie
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p. 2743 - 2747
(2008/02/12)
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- Asymmetric hydrogenation of quinolines with recyclable and air-stable iridium catalyst systems
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The iridium complex-catalyzed asymmetric hydrogenation of quinolines in a DMPEG/hexane biphasic system was studied. Catalysts with C2-symmetric ligands such as Xyl-P-Phos, Cl-MeO-BIPHEP, SYNPHOS, and DifluorPhos are highly effective for this type of reaction. Most of the catalysts tested can be retained in DMPEG (Mn = 500), and the asymmetric hydrogenation of various quinoline substrates can be carried out in DMPEG/hexane biphasic system with up to 92% ee. The catalysts and the products can be separated via simple phase separation, and the reactivity/stereoselectivity of the catalysts can be retained for at least three reaction cycles.
- Chan, Sau Hing,Lam, Kim Hung,Li, Yue-Ming,Xu, Lijin,Tang, Weijun,Lam, Fuk Loi,Lo, Wai Hung,Yu, Wing Yiu,Fan, Qinghua,Chan, Albert S.C.
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p. 2625 - 2631
(2008/04/05)
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- A new class of versatile chiral-bridged atropisomeric diphosphine ligands: Remarkably efficient ligand syntheses and their applications in highly enantioselective hydrogenation reactions
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A series of chiral diphosphine ligands denoted as PQ-Phos was prepared by atropdiastereoselective Ullmann coupling and ring-closure reactions. The Ullmann coupling reaction of the biaryl diphosphine dioxides is featured by highly efficient central-to-axial chirality transfer with diastereomeric excess >99%. This substrate-directed diastereomeric biaryl coupling reaction is unprecedented for the preparation of chiral diphosphine dioxides, and our method precludes the tedious resolution procedures usually required for preparing enantiomerically pure diphosphine ligands. The effect of chiral recognition was also revealed in a relevant asymmetric ring-closure reaction. The chiral tether bridging the two aryl units creates a conformationally rigid scaffold essential for enantiofacial differentiation; fine-tuning of the ligand scaffold (e.g., dihedral angles) can be achieved by varying the chain length of the chiral tether. The enantiomerically pure Ru- and Ir-PQ-Phos complexes have been prepared and applied to the catalytic enantioselective hydrogenations of α- and β-ketoesters (C=O bond reduction), 2-(6′-methoxy- 2′-naphthyl)-propenoic acid, alkyl-substituted β-dehydroamino acids (C=C bond reduction), and N-heteroaromatic compounds (C=N bond reduction). An excellent level of enantioselection (up to 99.9% ee) has been attained for the catalytic reactions. In addition, the significant ligand dihedral angle effects on the Ir-catalyzed asymmetric hydrogenation of N-heteroaromatic compounds were also revealed.
- Qiu, Liqin,Kwong, Fuk Yee,Wu, Jing,Lam, Wai Har,Chan, Shusun,Yu, Wing-Yiu,Li, Yue-Ming,Guo, Rongwei,Zhou, Zhongyuan,Chan, Albert S. C.
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p. 5955 - 5965
(2007/10/03)
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- Asymmetric hydrogenation of quinolines catalyzed by iridium complexes of BINOL-derived diphosphonites
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A chiral diphosphonite, derived from BINOL and with an achiral diphenyl ether backbone, is an excellent ligand for the Ir-catalyzed asymmetric hydrogenation of quinolines; achiral P-ligands serving as possible additives (ee = 73-96%). The Royal Society of Chemistry 2006.
- Reetz, Manfred T.,Li, Xiaoguang
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p. 2159 - 2160
(2008/03/14)
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- Highly enantioselective iridium-catalyzed hydrogenation of quinoline derivatives using chiral phosphinite H8-BINAPO
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The chiral diphosphinite H8-BINAPO derived from H8-BINOL has been used in the Ir-catalyzed asymmetric hydrogenation of quinolines, and high enantioselectivity (up to 97% ee) was obtained. Immobilization of the iridium catalyst in poly(ethylene glycol) dimethyl ether (DMPEG) is also discussed. With DMPEG/hexane biphasic system, better enantioselectivities were obtained as compared to those observed in aprotic organic solvents.
- Kim, Hung Lam,Xu, Lijin,Feng, Lichun,Fan, Qing-Hua,Fuk, Loi Lam,Lo, Wai-Hung,Chan, Albert S. C.
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p. 1755 - 1758
(2007/10/03)
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- Air-stable Ir-(P-Phos) complex for highly enantioselective hydrogenation of quinolines and their immobilization in poly(ethylene glycol) dimethyl ether (DMPEG)
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An air-stable catalyst system Ir-(P-Phos) catalyst was found to be highly effective in the asymmetric hydrogenation of quinoline derivatives. The catalyst immobilized in DMPEG was efficiently recovered and reused eight times, retaining reactivity and enan
- Xu, Lijin,Lam, Kim Hung,Ji, Jianxin,Wu, Jing,Fan, Qing-Hua,Lo, Wai-Hung,Chan, Albert S. C.
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p. 1390 - 1392
(2007/10/03)
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- An efficient and practical chemoenzymatic preparation of optically active secondary amines
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(Chemical Equation Presented) An efficient and practical chemoenzymatic method was developed for the preparation of a variety of chiral secondary amines. Here, oxalamic esters were identified as unique derivatives amenable to the enzyme-catalyzed kinetic resolution of racemic secondary amines. Both enantiomers of the amines were produced in high optical purity and yields after the cleavage of the oxalamic groups.
- Hu, Shanghui,Tat, David,Martinez, Carlos A.,Yazbeck, Daniel R.,Tao, Junhua
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p. 4329 - 4331
(2007/10/03)
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- Asymmetric hydrogenation of quinolines catalyzed by iridium with chiral ferrocenyloxazoline derived N,P ligands
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Chiral ferrocenyloxazoline derived N,P ligands are used in the iridium-catalyzed asymmetric hydrogenation of quinolines, and up to 92% ee was obtained. The role of the planar chirality is also studied.
- Lu, Sheng-Mei,Han, Xiu-Wen,Zhou, Yong-Gui
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p. 909 - 912
(2007/10/03)
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- Highly enantioselective iridium-catalyzed hydrogenation of heteroaromatic compounds, quinolines
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The highly enantioselective hydrogenation of quinoline derivatives is developed using [Ir(COD)Cl]2/(R)-MeO-Biphep/I2 system, and this methodology has been applied to the asymmetric synthesis of three naturally occurring alkaloids angustureine, galipinine, and cuspareine. This method provided an efficient access to a variety of optically active tetrahydroquinolines with up to 96% ee. Copyright
- Wang, Wen-Bo,Lu, Sheng-Mei,Yang, Peng-Yu,Han, Xiu-Wen,Zhou, Yong-Gui
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p. 10536 - 10537
(2007/10/03)
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- Synthesis, absolute configuration and intermediates of 9-fluoro- 6,7- dihydro-5-methyl-1-oxo-1H,5H-benzo[i.j]quinolizine-2-carboxylic acid (flumequine)
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The antibacterial agent 9-fluoro-6,7-dihydro-5-methyl-1-oxo-1H,5H- benzo[i.j]quinolizine-2-carboxylic acid (flumequine) was synthesized in optically active form from 6-fluoro-2-methyl-1,2,3,4-tetrahydroquinoline (FTHQ). Racemic FTHQ was resolved with the enantiomers of 3-bromocamphor-8- sulfonic acid. The configurations were established by X-ray structures of the two diastereoisomeric salts. Enantiomeric excesses were determined by 1H NMR analysis.
- Balint, Jozsef,Egri, Gabriella,Fogassy, Elemer,Boecskei, Zsolt,Simon, Kalman,Gajary, Antal,Friesz, Antal
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p. 1079 - 1087
(2007/10/03)
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