- Phosphonium-stibonium and bis-stibonium cations as pnictogen-bonding catalysts for the transfer hydrogenation of quinolines
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Bifunctional Lewis acidic group 15 compounds have emerged as appealing platforms for anion sensing and organocatalysis. As part of our interest in the chemistry of these compounds, we have now compared the catalytic properties of [o-(MePPh2)Cs
- Yang, Mengxi,Hirai, Masato,Gabba?, Fran?ois P.
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- Cobalt catalyzed sp3 C-H amination utilizing aryl azides
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A dinuclear Co(ii) complex supported by a modular, tunable redox-active ligand system is capable of selective C-H amination to form indolines from aryl azides in good yields at low (1 mol%) catalyst loading. The reaction is tolerant of medicinally relevant heterocycles, such as pyridine and indole, and can be used to form 5-, 6-, and 7-membered rings. The synthetic versatility obtained using low loadings of an earth abundant transition metal complex represents a significant advance in catalytic C-H amination technology.
- Villanueva, Omar,Weldy, Nina MacE,Blakey, Simon B.,MacBeth, Cora E.
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- Deciphering a Reaction Network for the Switchable Production of Tetrahydroquinoline or Quinoline with MOF-Supported Pd Tandem Catalysts
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A mechanistic study of heterogeneous tandem catalytic systems is crucial for understanding and improving catalyst activity and selectivity but remains challenging. Here, we demonstrate that a thorough mechanistic study of a multistep reaction can guide us to the controllable selective synthesis of phenyltetrahydroquinoline or phenylquinoline with easily accessible precursors. The one-pot production can be achieved, catalyzed by a well-defined, bifunctional metal-organic framework-supported Pd nanoparticles, with only water as the side product. Our mechanistic study identifies six transient intermediates and ten transformation steps from the operando magic angle spinning nuclear magnetic resonance study under 27.6 bar H2. In particular, reactive intermediate 2-phenyl-3,4-dihydroquinoline cannot be observed with conventional chromatographic techniques but is found to reach the maximal concentration of 0.11 mol L-1 under the operando condition. The most probable reaction network is further deduced based on the kinetic information of reaction species, obtained from both operando and ex situ reaction studies. This deep understanding of the complex reaction network enables the kinetic control of the conversions of key intermediate, 2-phenyl-3,4-dihydroquinoline, with the addition of a homogeneous co-catalyst, allowing the selective production of tetrahydroquinoline or quinoline on demand. The demonstrated methods in this work open up new avenues toward efficient modulation of reactions with a complex network to achieve desired selectivities.
- Bao, Zongbi,Chen, Jingwen,Huang, Wenyu,Kobayashi, Takeshi,Nie, Renfeng,Qi, Long,Qi, Zhiyuan,Ren, Qilong,Sun, Qi,Yang, Qiwei,Zhang, Biying,Zhang, Zhiguo
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- Thiophostone-derived Bronsted acids in the organocatalyzed transfer hydrogenation of quinolines: Influence of the P-stereogenicity
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A new approach to Bronsted acid organocatalysis is described and is based on the use of thiophosphonic acids possessing both a chiral backbone and a chiral phosphorus function. The influence of the phosphorus stereochemistry on the enantioselectivity prov
- Ferry, Angelique,Stemper, Jeremy,Marinetti, Angela,Voituriez, Arnaud,Guinchard, Xavier
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- Liberating N-CNTs Confined Highly Dispersed Co?Nx Sites for Selective Hydrogenation of Quinolines
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Selective hydrogenation of quinoline and its derivatives is an important means to produce corresponding 1,2,3,4-tetrahydroquinolines for a wide spectrum of applications. A facile and efficient “laser irradiation in liquid” technique to liberate the inaccessible highly dispersed Co?Nx active sites confined inside N-doped carbon nanotubes is demonstrated. The liberated Co?Nx sites possess generic catalytic activities toward selective hydrogenation of quinoline and its hydroxyl, methyl, and halogen substituted derivatives into corresponding 1,2,3,4-tetrahydroquinolines with almost 100% conversion efficiency and selectivity. This laser irradiation treatment approach should be widely applicable to unlock the catalytic powers of inaccessible catalytic active sites confined by other materials.
- Gong, Wanbing,Yuan, Qinglin,Chen, Chun,Lv, Yang,Lin, Yue,Liang, Changhao,Wang, Guozhong,Zhang, Haimin,Zhao, Huijun
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- Chiral chalcogen bond donors based on the 4,4'-bipyridine scaffold
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Organocatalysis through chalcogen bonding (ChB) is in its infancy, as its proof-of-principle was only reported in 2016. Herein, we report the design and synthesis of new chiral ChB donors, as well as the catalytic activity evaluation of the 5,50-dibromo-2
- Weiss, Robin,Aubert, Emmanuel,Peluso, Paola,Cossu, Sergio,Pale, Patrick,Mamane, Victor
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- Tuning porosity and activity of microporous polymer network organocatalysts by co-polymerisation
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Microporous polymer networks based on binaphthyl phosphoric acids are suitable heterogeneous asymmetric organocatalysts. Herein we show that the porous characteristics of such networks can be fine-tuned by co-polymerisation. This enables us to investigate the influence of the surface area and porosity in microporous networks on their catalytic performance. In this case, the activity of the polymers in an asymmetric hydrogenation reaction is increased by the use of polymers with higher surface areas. The Royal Society of Chemistry 2014.
- Schmidt, Johannes,Kundu, Dipti Sankar,Blechert, Siegfried,Thomas, Arne
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- Catalysis with Chalcogen Bonds
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Herein, we introduce catalysts that operate with chalcogen bonds. Compared to conventional hydrogen bonds, chalcogen bonds are similar in strength but more directional and hydrophobic, thus ideal for precision catalysis in apolar solvents. For the transfer hydrogenation of quinolines and imines, rate enhancements well beyond a factor of 1000 are obtained with chalcogen bonds. Better activities with deeper σ holes and wider bite angles, chloride inhibition and correlation with computed anion binding energies are consistent with operational chalcogen bonds. Comparable to classics, such as 2,2′-bipyrroles or 2,2′-bipyridines, dithieno[3,2-b;2′,3′-d]thiophenes (DTTs), particularly their diimides, but also wide-angle cyclopentadithiazole-4-ones are identified as privileged motifs to stabilize transition states in the focal point of the σ holes on their two co-facial endocyclic sulfur atoms.
- Benz, Sebastian,López-Andarias, Javier,Mareda, Jiri,Sakai, Naomi,Matile, Stefan
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- Asymmetric Synthesis of Hydroquinolines with α,α-Disubstitution through Organocatalyzed Kinetic Resolution
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The first kinetic resolution of hydroquinoline derivatives with α,α-disubstitution has been achieved through asymmetric remote aminations with azodicarboxylates enabled by chiral phosphoric acid catalysis. Mechanistic studies suggest a monomeric catalyst pathway proceeding through rate- and enantio-determining electrophilic attack promoted by a network of attractive non-covalent interactions between the substrate and catalyst. Facile subsequent removal and transformations of the newly introduced hydrazine moiety enable these protocols to serve as powerful tools for asymmetric synthesis of N-heterocycles with α,α-disubstitution.
- Chen, Yunrong,Zhu, Chaofan,Guo, Zheng,Liu, Wei,Yang, Xiaoyu
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p. 5268 - 5272
(2021/02/05)
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- Method for selective catalytic hydrogenation of aromatic heterocyclic compounds in non-hydrogen participation manner
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The invention discloses a method for selective catalytic hydrogenation of aromatic heterocyclic compounds in a non-hydrogen participation manner. The method comprises the following steps: by taking 1, 5-cyclooctadiene iridium chloride dimer as a catalyst and phenylsilane as a hydrogen source, carrying out stirring reaction under mild conditions without adding a ligand, namely catalytically hydrogenating the aromatic heterocyclic compounds to obtain hydrogenated products of the aromatic heterocyclic compounds. The method has the advantages of low cost, mild reaction conditions, high selectivity and the like, and special equipment such as a high-pressure kettle and the like and high-temperature conditions which are required when hydrogen is used are avoided.
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Paragraph 0025-0029; 0080-0084
(2021/08/19)
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- PREPARATION METHOD OF 2-SUBSTITUTED 1,2,3,4-TETRAHYDROQUINOLINE COMPOUND
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2 -substituted quinoline compounds are disclosed. The present invention relates to a 2 -substituted 2 -tetrahydroquinoline compound by hydroconversion of 1, 2, 3, 4 -substituted quinoline compounds using a catalyst composition comprising an isothiuronium salt and a Handoesr. In accordance with the present invention, 2 -substituted 1, 2, 3, 4 -tetrahydroquinoline compounds can be produced in high yield with improved reaction efficiency and reaction rate.
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Paragraph 0111-0121
(2021/08/05)
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- S-Benzyl-N,N'-diphenyl substituted isothiouronium iodide as a highly efficient organocatalyst for transfer hydrogenation of 2-substituted quinolines
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An isothiouronium organocatalyst prepared from thiourea was first employed to catalyze the transfer hydrogenation of various 2-alkyl and arylquinolines with Hantzsch ester as the hydrogen source. This metal-free catalyzed reduction of 2-substituted quinoline efficiently rendered good to excellent yields of tetrahydroquinolines under mild conditions with a small amount of catalyst (5 mol%).
- Kang, Sungmin,Kim, Taek Hyeon
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supporting information
(2021/10/14)
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- Synthesis of Fused Heterocyclic Systems Derived from 2-Aryl-1,2,3,4-tetrahydroquinolines
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Abstract: A convenient method of synthesis of fused heterocyclic systems, involving cyclization of the reaction products of 2-aryl-1,2,3,4-tetrahydroquinolines with triphosgene, chloroacetyl chloride, and oxalyl chloride in the presence of anhydrous AlCl
- Baimuratov, M. R.,Golovko, Yu. A.,Gruzd, Yu. A.,Klimochkin, Yu. N.,Kulemina, S. V.,Zemtsova, M. N.
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p. 793 - 800
(2021/06/12)
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- Pd/c catalyzed decarboxylation-transfer hydrogenation of quinoline carboxylic acids
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Pd/C catalyzed decarboxylation-transfer hydrogenation of quinoline carboxylic acids and transfer hydrogenation of quinolines had been developed for the synthesis of 1,2,3,4-tetrahydroquinolines. These two processes were implemented smoothly using Pd/C (0.9 mol%) as a catalyst with ammonium formate as a hydrogen source in ethanol at 80oC. The reaction system can also be applied to transfer hydrogenation of benzo[h]quinoline and 2,9-dimethyl-1,10-phenanthroline with good to excellent yields. And the gram scale and recycling of catalyst had been tested with good results. Furthermore, the mechanism of Pd/C catalyzed reduction of quino-line carboxylic acids and quinolines had been proposed.
- Chen, Xia,Zhou, Xiao-Yu
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p. 625 - 633
(2021/09/30)
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- Tuning the Catalytic Performance of Cobalt Nanoparticles by Tungsten Doping for Efficient and Selective Hydrogenation of Quinolines under Mild Conditions
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Non-noble bimetallic CoW nanoparticles (NPs) partially embedded in a carbon matrix (CoW@C) have been prepared by a facile hydrothermal carbon-coating methodology followed by pyrolysis under an inert atmosphere. The bimetallic NPs, constituted by a multishell core-shell structure with a metallic Co core, a W-enriched shell involving Co7W6 alloyed structures, and small WO3 patches partially covering the surface of these NPs, have been established as excellent catalysts for the selective hydrogenation of quinolines to their corresponding 1,2,3,4-tetrahydroquinolines under mild conditions of pressure and temperature. It has been found that this bimetallic catalyst displays superior catalytic performance toward the formation of the target products than the monometallic Co@C, which can be attributed to the presence of the CoW alloyed structures.
- Concepción, Patricia,Corma, Avelino,Liu, Lichen,Puche, Marta,Sorribes, Iván
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p. 8197 - 8210
(2021/07/13)
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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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- 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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- Chiral ferrocene-indole diphosphine ligand as well as preparation method and application thereof
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The invention relates to a chiral ferrocene-indole diphosphine ligand as well as a preparation method and application thereof. The specific preparation method comprises the following steps: dissolving an indole compound and a chiral ferrocene phosphine ac
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Paragraph 0083-0084
(2021/05/22)
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- Lewis Acidic Telluronium Cations: Enhanced Chalcogen-Bond Donor Properties and Application to Transfer Hydrogenation Catalysis
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We describe the synthesis and structures of o-C6F4(TeMes)2 (1) and o-C6F4(TeArF)2 (2, ArF = 3,5-(CF3)2C6H3)), two new bifunctional tellurides featuring an electron-withdrawing backbone. While 2 resisted methylation, 1 reacted with Me3O·BF4 in CH2Cl2 to afford o-C6F4(TeMes)(TeMeMes) ([3]+), a mixed-valent telluride/telluronium cation isolated as a tetrafluoroborate salt. Although attempts to methylate the second telluride have been unsuccessful, [3]+ readily catalyzes the hydrogenation of 2-phenyl-quinoline with Hantzsch ester. Comparison with simple telluronium cations including [ArF2TeMe]+ and [MesArFTeMe]+ confirms that the catalytic activity of these compounds originates from the presence of a tetravalent, cationic tellurium center.
- Gabba?, Fran?ois P.,Zhou, Benyu
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supporting information
p. 2371 - 2374
(2021/07/26)
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- Tandem synthesis of tetrahydroquinolines and identification of the reaction network byoperandoNMR
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The study of the reaction mechanism and complex network for heterogeneously catalyzed tandem reactions is challenging but can guide reaction design and optimization. Here, we describe a case study using bifunctional metal-organic framework supported Pd nanoparticles (Pd/UiO-66(HCl)) for the one-pot tandem synthesis of substituted tetrahydroquinolinesviathe Claisen-Schmidt condensation and reductive intramolecular cyclization. The directly observed evolution of intermediates and products, including reactive species containing hydroxylamine group and unstable intermediate 2-phenyl-3,4-dihydroquinoline, was enabled byoperandomagic angle spinning nuclear magnetic resonance studies under 50 bar H2. The reaction network of the tandem reaction is deduced based on reaction kinetic information obtained from theoperandostudy. The optimized procedure was applied to various acetophenone and nitrobenzaldehyde derivatives carrying different functional groups, and eight valuable substituted tetrahydroquinolines were obtained in moderate to good yields. This work provides a molecular-level understanding of the catalytic system and brings up new opportunities for efficient and sustainable synthesis of medicinally relevant building blocks.
- Chen, Jingwen,Qi, Long,Zhang, Biying,Chen, Minda,Kobayashi, Takeshi,Bao, Zongbi,Yang, Qiwei,Ren, Qilong,Huang, Wenyu,Zhang, Zhiguo
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p. 4332 - 4341
(2021/07/12)
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- A Novel Approach to N-Tf 2-Aryl-2,3-Dihydroquinolin- 4(1H)-ones via a Ligand-Free Pd(II)-Catalyzed Oxidative Aza-Michael Cyclization
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2-Aryl-2,3-dihydroquinolin-4(1H)-ones have recently been identified as important structures with potent biological activities such as antitumor and antidiabetic effect. Herein, a total of 25 novel N-Tf 2-aryl-2,3-dihydroquinolin-4(1H)-ones were expediently synthesized via the oxidative aza-Michael cyclization of N-Tf-2′-aminodihydrochalcones by ligand-free palladium(II) catalysis. This study presents a new synthetic approach to yield N-Tf 2-aryl-2,3-dihydroquinolin-4(1H)-ones, which can be easily transformed into pharmacologically interesting aza-flavanones and other N-heterocycles, such as quinolines and tetrahydroquinolines, in yields up to 84 %. This methodology has various advantages, which includes short reaction times under mild conditions and suitable functional group tolerance. Furthermore, a plausible mechanism was proposed and demonstrated by kinetic analysis.
- Kim, Young Min,Yoo, Hyung-Seok,Son, Seung Hwan,Kim, Ga Yeong,Jang, Hyu Jeong,Kim, Dong Hwan,Kim, Soo Dong,Park, Boyoung Y.,Kim, Nam-Jung
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p. 618 - 622
(2020/12/15)
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- The Alkylation and Reduction of Heteroarenes with Alcohols Using Photoredox Catalyzed Hydrogen Atom Transfer via Chlorine Atom Generation
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Radical additions to heteroaromatic bases are frequently employed for the rapid synthesis of complex products using C–H functionalization strategies. The conditions that are commonly employed are typically harsh, routinely requiring stoichiometric oxidants and other additives. In search for milder reaction environments allowing late-stage functionalization, we present the alkylation of N-heteroarenes using primary alcohols and ethers as radical precursors, where the corresponding alkyl radical is formed via hydrogen atom transfer process with a photoredox catalyzed chlorine atom generation as HAT agent. Furthermore, we explore the reduction of the heteroarenes in moderate to high yields when using secondary alcohols.
- Zidan, Montserrat,Morris, Avery O.,McCallum, Terry,Barriault, Louis
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supporting information
p. 1453 - 1458
(2019/08/01)
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- Continuous Flow Synthesis of Quinolines via a Scalable Tandem Photoisomerization-Cyclization Process
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A continuous photochemical process is presented that renders a series of quinoline products via an alkene isomerization and cyclocondensation cascade. It is demonstrated that a high-power LED lamp generates the desired targets with higher productivity and efficiency than a medium-pressure Hg-lamp. The scope of this tandem process is established and allows for the generation of various substituted quinolines in high yields and with throughputs of greater than one gram per hour. Finally, this effective flow process is coupled with a telescoped hydrogenation reaction to render a series of tetrahydroquinolines including the antimalarial natural product galipinine.
- Di Filippo, Mara,Baumann, Marcus
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p. 6199 - 6211
(2020/08/26)
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- Design and synthesis of a chiral halogen-bond donor with a sp3-hybridized carbon-iodine moiety in a chiral fluorobissulfonyl scaffold
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The first example of a chiral halogen-bond donor with a sp3-hybridized carbon-iodine moiety in a fluorobissulfonyl scaffold is described. The binaphthyl backbone was designed as a chiral source and the chiral halogen-bond donor (R)-1 was synthesized from
- Matsuzaki, Kohei,Shibata, Norio,Shiro, Motoo,Uno, Hiroto
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- A proton-responsive annulated mesoionic carbene (MIC) scaffold on IR complex for proton/hydride shuttle: An experimental and computational investigation on reductive amination of aldehyde
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A Cp*Ir(III) complex (1) bearing a proton-responsive hydroxy unit on an annulated imidazo[1,2-a][1,8]naphthyridine based mesoionic carbene scaffold was synthesized by two different synthetic routes. The molecular structure of 1 revealed an anionic lactam form of the ligand. The acid?base equilibrium between the lactam-lactim tautomers on the ligand scaffold was examined by 1H NMR and UV?vis spectra. The pKa of the appendage ?OH group in the lactim form of 1 was estimated to assess the proton transfer property of the catalyst. The catalytic efficacy of 1 for reductive amination of aldehyde was evaluated by utilizing three different hydrogen sources: molecular H2iPrOH/KOtBu combination, and HCOOH/Et3N (5:2) azeotropic mixture. The HCOOH/Et3N (5:2) azeotropic mixture rotocol was found to be the best amon the three different h dro enation methods. Catalyst 1 hydrogenates imines chemoselectively over carbonyls under the reaction conditions. A range of aldehydes was reductively aminated to the corresponding secondary amines using the HCOOH/Et3N (5:2) azeotropic mixture. Further, catalyst 1 showed high efficiency for the reduction of a wide variety of N-heterocyclic imine derivatives. The lactam-lactim tautomerization of the ligand system is proposed for direct hydrogenation, whereas only the lactam form operates in the strongly basic medium (iPrOH/KOtBu). Under HCOOH/Et3N (5:2) conditions, the lactam scaffold is not protonated; rather, an outer-sphere hydride transfer from formate to the Ir is proposed, which is supported by 1H NMR and DFT calculations. Finally, ligand-promoted hydride transfer from metal-hydride to the protonated imine affords the corresponding amine. A close agreement between the experimentally estimated and computed thermodynamic/kinetic parameters gives credence to the metal-ligand cooperative mechanism for the imine hydrogenation reaction using the HCOOH/Et3N (5:2) azeotropic mixture.
- Bera, Jitendra K.,Daw, Prosenjit,Din Reshi, Noor U.,Ehmann, Kira R.,H?lscher, Markus,Leitner, Walter,Pandey, Pragati
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p. 3849 - 3863
(2020/11/23)
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- A General Catalyst Based on Cobalt Core–Shell Nanoparticles for the Hydrogenation of N-Heteroarenes Including Pyridines
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Herein, we report the synthesis of specific silica-supported Co/Co3O4 core–shell based nanoparticles prepared by template synthesis of cobalt-pyromellitic acid on silica and subsequent pyrolysis. The optimal catalyst material allows for general and selective hydrogenation of pyridines, quinolines, and other heteroarenes including acridine, phenanthroline, naphthyridine, quinoxaline, imidazo[1,2-a]pyridine, and indole under comparably mild reaction conditions. In addition, recycling of these Co nanoparticles and their ability for dehydrogenation catalysis are showcased.
- Beller, Matthias,Chandrashekhar, Vishwas G.,Jagadeesh, Rajenahally V.,Kreyenschulte, Carsten,Murugesan, Kathiravan
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supporting information
p. 17408 - 17412
(2020/08/21)
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- Simple manganese carbonyl catalyzed hydrogenation of quinolines and imines
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Manganese-catalyzed hydrogenation of unsaturated molecules has made tremendous progresses recently benefiting from non-innocent pincer or bidentate ligands for manganese. Herein, we describe the hydrogenation of quinolines and imines catalyzed by simple manganese carbonyls, Mn2(CO)10 or MnBr(CO)5, thus eliminating the prerequisite pincer-type or bidentate ligands.
- Wang, Zelong,Chen, Lei,Mao, Guoliang,Wang, Congyang
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p. 1890 - 1894
(2020/03/04)
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- Enantioselective Synthesis of Tetrahydroquinolines via One-Pot Cascade Biomimetic Reduction?
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A novel and efficient protocol for the synthesis of chiral tetrahydroquinoline derivatives with excellent enantioselectivities and high yields has been developed through one-pot cascade biomimetic reduction. The detailed reaction pathway includes the acid-catalyzed and ruthenium-catalyzed formation of aromatic quinoline intermediates and biomimetic asymmetric reduction.
- Zhao, Zi-Biao,Li, Xiang,Chen, Mu-Wang,Wu, Bo,Zhou, Yong-Gui
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p. 1691 - 1695
(2020/11/03)
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- Half-Sandwich Ruthenium Complexes for One-Pot Synthesis of Quinolines and Tetrahydroquinolines: Diverse Catalytic Activity in the Coupled Cyclization and Hydrogenation Process
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Four types of half-sandwich ruthenium complexes with an N,O-coordinate mode based on hydroxyindanone-imine ligands have been prepared in good yields. These stable ruthenium complexes exhibited high activity in the catalytic synthesis of quinolines from the reactions of amino alcohols with different types of ketones or secondary alcohols under very mild conditions. Moreover, the methodology for the direct one-pot synthesis of tetrahydroquinoline derivatives from amino alcohols and ketones has been also developed on the basis of the continuous catalytic activity of this ruthenium catalyst in the selective hydrogenation of the obtained quinoline derivatives with a low catalyst loading. The corresponding products, quinolines and tetrahydroquinoline derivatives, were afforded in good to excellent yields. The efficient and diverse catalytic activity of these ruthenium complexes suggested their potential large-scale application. All of the ruthenium complexes were characterized by various spectroscopies to confirm their structures.
- Yun, Xue-Jing,Zhu, Jing-Wei,Jin, Yan,Deng, Wei,Yao, Zi-Jian
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supporting information
p. 7841 - 7851
(2020/06/04)
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- Synthesis of Tetrahydroquinolines via Borrowing Hydrogen Methodology Using a Manganese PN3Pincer Catalyst
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A straightforward and selective synthesis of 1,2,3,4-tetrahydroquinolines starting from 2-aminobenzyl alcohols and simple secondary alcohols is reported. This one-pot cascade reaction is based on the borrowing hydrogen methodology promoted by a manganese(I) PN3 pincer complex. The reaction selectively leads to 1,2,3,4-tetrahydroquinolines thanks to a targeted choice of base. This strategy provides an atom-efficient pathway with water as the only byproduct. In addition, no further reducing agents are required.
- Hofmann, Natalie,Homberg, Leonard,Hultzsch, Kai C.
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supporting information
p. 7964 - 7970
(2020/11/02)
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- Sublimation-Induced Sulfur Vacancies in MoS2 Catalyst for One-Pot Synthesis of Secondary Amines
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MoS2 catalysts with abundant S and Mo defects have been developed for the one-pot reductive amination of nitro compounds with aldehydes to synthesize secondary amines. The combination of multiple structural characterizations demonstrates that the density of S vacancies can be tuned by changing the thermal sublimation temperature. The experimental results and DFT calculations demonstrate that S vacancies on the surface of MoS2 are the active sites for the hydrogenation of the intermediate imines to the final products secondary amines.
- Zhang, Yunrui,Gao, Yongjun,Yao, Siyu,Li, Siwei,Asakura, Hiroyuki,Teramura, Kentaro,Wang, Haijun,Ma, Ding
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p. 7967 - 7975
(2019/08/21)
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- CONVERSION OF TETRAHYDROQUINOLINE DERIVATIVES TO QUINOLINE USING AZOCOMPOUND
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The present invention relates to a method of converting tetrahydroquinoline derivatives into quinoline using an azo compound and, more specifically, to a conversion method which is performed in a deuterium chloroform (CDCl_3) or chloroform (CHCl_3) solution including dialkyl azodicarboxylate, which is a method of producing quinoline through a dehydrogenation reaction of 1,2,3,4-tetrahydroquinoline. According to the present invention, a dehydrogenation reaction rate is dependent on the electronic and steric properties of used dialkyl azodicarboxylate; and chloroform shows better results than other substances in solvents screened with diethyl azodicarboxylate. Various types of 1,2,3,4-tetrahydroquinoline undergo the dehydration reaction of the present invention to produce the corresponding quinoline in a yield of at least 90%; and diethyl hydrazo dicarboxylate, which is a reduced form of diethyl azodicarboxylate, is readily separated and recyclable.COPYRIGHT KIPO 2020
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Paragraph 0041-0042; 0080; 0112-0116; 0122
(2020/03/10)
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- Method for conducting catalytic hydrogenation on nitrogen-containing unsaturated heterocyclic compound
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The invention provides a method for conducting catalytic hydrogenation on a nitrogen-containing unsaturated heterocyclic compound, and belongs to the technical field of catalytic hydrogenation. The provided method for conducting catalytic hydrogenation on the nitrogen-containing unsaturated heterocyclic compound comprises the following step: in the presence of hydrogen and a manganese catalyst, with the nitrogen-containing unsaturated heterocyclic compound as a substrate, carrying out a hydrogenation reaction. According to the method for conducting catalytic hydrogenation on the nitrogen-containing unsaturated heterocyclic compound, he adopted manganese catalyst is an NNP-type pincer manganese catalyst, has the advantages of being cheap, easy to obtain and low in toxicity compared with noble metal catalysts, has the advantages of being wide in substrate applicability and high in target product yield compared with an existing cheap metal iron catalyst or cobalt catalyst, and is higher in electron donating ability and smaller in steric hindrance compared with a PNP-type pincer manganese catalyst, and thus shows higher reaction activity in a series of hydrogenation reactions, and thetarget product yield is up to 99%.
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Paragraph 0094-0104
(2020/01/03)
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- Iridium-Catalyzed Hydrogenation and Dehydrogenation of N-Heterocycles in Water under Mild Conditions
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An efficient catalytic method is presented for the hydrogenation of N-heterocycles. The iridium-based catalyst operates under mild conditions in water without any co-catalyst or stoichiometric additives. The catalyst also promotes the reverse reaction of dehydrogenation of N-heterocycles, hence displaying appropriate characteristics for a future hydrogen economy based on liquid organic hydrogen carriers (LOHCs).
- Wang, Shengdong,Huang, Haiyun,Bruneau, Christian,Fischmeister, Cédric
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p. 2350 - 2354
(2019/05/21)
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- Silver-Catalyzed Reduction of Quinolines in Water
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A ligand- and base-free silver-catalyzed reduction of quinolines and electron-deficient aromatic N-heteroarenes in water has been described. Mechanistic studies revealed that the effective reducing species was Ag-H. This versatile catalytic protocol provided facile, environmentally friendly, and practical access to a variety of 1,2,3,4-tetrahydroquinoline derivatives at room temperature.
- Wang, Yan,Dong, Baobiao,Wang, Zikun,Cong, Xuefeng,Bi, Xihe
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supporting information
p. 3631 - 3634
(2019/05/24)
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- Activation of Quinolines by Cationic Chalcogen Bond Donors
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The application of already established as well as novel selenium- and sulfur-based cationic chalcogen bond donors in the catalytic activation of quinoline derivatives is presented. In the presence of selected catalysts, rate accelerations of up to 2300 compared to virtually inactive reference compounds are observed. The catalyst loading can be reduced to 1 molpercent while still achieving nearly full conversion for electron-poor and electron-rich quinolines. Contrary to expectations, preorganized catalysts were less active than the more flexible variants.
- Huber, S. M.,Steinke, T.,Wonner, P.
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supporting information
p. 1673 - 1678
(2019/08/26)
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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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- 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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- A robust iron catalyst for the selective hydrogenation of substituted (iso)quinolones
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By applying N-doped carbon modified iron-based catalysts, the controlled hydrogenation of N-heteroarenes, especially (iso)quinolones, is achieved. Crucial for activity is the catalyst preparation by pyrolysis of a carbon-impregnated composite, obtained from iron(ii) acetate and N-aryliminopyridines. As demonstrated by TEM, XRD, XPS and Raman spectroscopy, the synthesized material is composed of Fe(0), Fe3C and FeNx in a N-doped carbon matrix. The decent catalytic activity of this robust and easily recyclable Fe-material allowed for the selective hydrogenation of various (iso)quinoline derivatives, even in the presence of reducible functional groups, such as nitriles, halogens, esters and amides. For a proof-of-concept, this nanostructured catalyst was implemented in the multistep synthesis of natural products and pharmaceutical lead compounds as well as modification of photoluminescent materials. As such this methodology constitutes the first heterogeneous iron-catalyzed hydrogenation of substituted (iso)quinolones with synthetic importance.
- Sahoo, Basudev,Kreyenschulte, Carsten,Agostini, Giovanni,Lund, Henrik,Bachmann, Stephan,Scalone, Michelangelo,Junge, Kathrin,Beller, Matthias
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p. 8134 - 8141
(2018/11/20)
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- Nanolayered Cobalt-Molybdenum Sulfides as Highly Chemo- and Regioselective Catalysts for the Hydrogenation of Quinoline Derivatives
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Herein, a general protocol for the preparation of a broad range of valuable N-heterocyclic products by hydrogenation of quinolines and related N-heteroarenes is described. Interestingly, the catalytic hydrogenation of the N-heteroarene ring is chemoselectively performed when other facile reducible functional groups, including alkenes, ketones, cyanides, carboxylic acids, esters, and amides, are present. The key to successful catalysis relies on the use of a nanolayered cobalt-molybdenum sulfide catalyst hydrothermally synthesized from earth-abundant metal precursors. This heterogeneous system displays a tunable composition of phases that allows for catalyst regeneration. Its catalytic activity depends on the composition of the mixed phase of cobalt sulfides, being higher with the presence of Co3S4, and could also be associated with the presence of transient Co-Mo-S structures that mainly vanish after the first catalytic run.
- Sorribes, Iván,Liu, Lichen,Doménech-Carbó, Antonio,Corma, Avelino
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p. 4545 - 4557
(2018/05/22)
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- Fluorobissulfonylmethyl Iodides: An Efficient Scaffold for Halogen Bonding Catalysts with an sp3-Hybridized Carbon-Iodine Moiety
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The halogen-bond donors FBSM-I and FBDT-I, which contain an sp3-hybridized carbon-iodine (Csp3-I) moiety, were designed and synthesized. The highly electron-withdrawing nature of the fluorobissulfonyl-methane scaffold leads to the ge
- Matsuzaki, Kohei,Uno, Hiroto,Tokunaga, Etsuko,Shibata, Norio
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p. 6601 - 6605
(2018/06/25)
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- Cyclometalated Half-Sandwich Iridium Complex for Catalytic Hydrogenation of Imines and Quinolines
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Several C,N-chelate cyclometalated half-sandwich iridium-based catalysts for imines and quinoline derivatives reduction have been prepared through metal-mediated C-H bond activation based on benzothiazole ligands. These iridium complexes exhibited high catalytic activity for hydrogenation of various types of imines with high yields. The most active catalyst was obtained from methoxyl substituted complex 2, showing the catalytic TOF value of 975 h-1 for the reduction of imine 6a. Additionally, these half-sandwich complexes also showed high efficiency for the catalytic hydrogenation of N-heterocyclic quinoline derivatives. Good catalytic activity was displayed for various kinds of substrates with either electron-donating or electron-withdrawing groups. Complexes 1-5 were fully characterized by NMR, IR, and elemental analysis. Molecular structures of complexes 1 and 4 were further confirmed by X-ray diffraction analysis.
- Yao, Zi-Jian,Lin, Nan,Qiao, Xin-Chao,Zhu, Jing-Wei,Deng, Wei
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p. 3883 - 3892
(2018/11/24)
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- Cu-catalyzed reduction of azaarenes and nitroaromatics with diboronic acid as reductant
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A ligand-free copper-catalyzed reduction of azaarenes with diboronic acid as reductant in an aprotic solvent under mild conditions has been developed. Most interestingly, the nitroazaarenes could be reduced exclusively to give the corresponding amines without touching the azaarene moieties. Furthermore, the reductive amination of aromatic nitro compounds and aromatic aldehydes has also been realized. A series of hydrogenated azaarenes and secondary amines were obtained with good functional group tolerance.
- Pi, Danwei,Zhou, Haifeng,Zhou, Yanmei,Liu, Qixing,He, Renke,Shen, Guanshuo,Uozumi, Yasuhiro
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p. 2121 - 2129
(2018/03/23)
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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 0015; 0016; 0017; 0018
(2018/11/27)
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- Transfer hydrogenation of nitrogen heterocycles using a recyclable rhodium catalyst immobilized on bipyridine-periodic mesoporous organosilica
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Transfer hydrogenation of unsaturated nitrogen heterocycles using a rhodium catalyst immobilized on bipyridine-periodic mesoporous organosilica (BPy-PMO) is described. The immobilized catalyst was prepared by mixing [Cp?RhCl2]2 (Cp?
- Matsui, Kazuma,Maegawa, Yoshifumi,Waki, Minoru,Inagaki, Shinji,Yamamoto, Yoshihiko
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p. 534 - 539
(2018/02/07)
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- Synthesis and kinetic resolution of substituted tetrahydroquinolines by lithiation then electrophilic quench
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Treatment of N-Boc-2-Aryl-1,2,3,4-Tetrahydroquinolines with n-butyllithium in THF at-78 °C resulted in efficient lithiation at the 2-position and the organolithiums were trapped with a variety of electrophiles to give substituted products. Variable temper
- Carter, Nicholas,Li, Xiabing,Reavey, Lewis,Meijer, Anthony J.H.M.,Coldham, Iain
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p. 1352 - 1357
(2018/02/09)
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- Aerobic oxidative dehydrogenation of N-heterocycles catalyzed by cobalt porphyrin
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An efficient catalytic procedure has been developed for the aerobic oxidative dehydrogenation of N-heterocycles by cobalt porphyrin in the absence of any additives. The catalytic system could tolerate various 1,2,3,4-tetrahydroquinoline derivatives and some other N-heterocycles. The corresponding N-heteroaromatics could be obtained in 59–86% yields. The mechanism investigation suggested that the aerobic oxidative dehydrogenation might proceed with imine intermediate through radical paths.
- Zhou, Weiyou,Chen, Dongwei,Sun, Fu'an,Qian, Junfeng,He, Mingyang,Chen, Qun
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supporting information
p. 949 - 953
(2018/02/09)
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- Efficient dehydrogenation of 1,2,3,4-tetrahydroquinolines mediated by dialkyl azodicarboxylates
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Various dialkyl azodicarboxylates were investigated for the dehydrogenation of 1,2,3,4-tetrahydroquinolines to quinolines. The dehydrogenation rates varied according to the electronic and steric nature of the used dialkyl azodicarboxylates. Among solvents screened with diethyl azodicarboxylate, chloroform exhibited superior results to others. A variety of 1,2,3,4-tetrahydroquinolines underwent the present dehydrogenation to produce the corresponding quinolines. Diethyl hydrazodicarboxylate, which is a reduced species of diethyl azodicarboxylate, was easily separated for recycle.
- Bang, Saet Byeol,Kim, Jinho
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p. 1291 - 1298
(2018/04/05)
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- Chemoselective One-Pot Synthesis of Functionalized Amino-azaheterocycles Enabled by COware
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Functionalized bicyclic amino-azaheterocycles are rapidly accessed in a one-pot cross-coupling/reduction sequence enabled by the use of COware. Incompatible reagents are physically separated in a single reaction vessel to effect two chemoselective transformations - Suzuki-Miyaura cross-coupling and heteroarene reduction. The developed method allows access to novel heterocyclic templates, including semisaturated Hedgehog and dual PI3K/mTOR inhibitors, which show enhanced physicochemical properties compared to their unsaturated counterparts.
- Clohessy, Thomas A.,Roberts, Alastair,Manas, Eric S.,Patel, Vipulkumar K.,Anderson, Niall A.,Watson, Allan J. B.
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p. 6368 - 6371
(2017/12/08)
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- Iron-Catalyzed Intramolecular Aminations of C(sp3)?H Bonds in Alkylaryl Azides
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The nucleophilic iron complex Bu4N[Fe(CO)3(NO)] (TBA[Fe]) catalyzes the direct intramolecular amination of unactivated C(sp3)?H bonds in alkylaryl azides, which results in the formation of substituted indoline and tetrahydroquinoline derivatives.
- Alt, Isabel T.,Guttroff, Claudia,Plietker, Bernd
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p. 10582 - 10586
(2017/08/22)
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- “Naked” Iridium(IV) Oxide Nanoparticles as Expedient and Robust Catalysts for Hydrogenation of Nitrogen Heterocycles: Remarkable Vicinal Substitution Effect and Recyclability
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Iridium(IV) oxide nanoparticles were facilely prepared from iridium trichloride hydrate and sodium hydroxide by a ball-milling reaction at room temperature. The “naked” iridium nanocatalyst showed high stability and activity for the hydrogenation of a series of nitrogen heterocycles, for the first time, under a hydrogen balloon at room temperature with a selectivity of higher than 99%. Besides, an unprecedented substitution-dependent effect was discovered, where substrates with vicinal substituents on 2-, 3-, or 8-positions exhibited distinctly higher reaction rates than unsubstituted or remote substituted ones. Extraordinary recyclability was discovered in the hydrogenation of 2-methylquinoline for 30 runs without loss of activity. (Figure presented.).
- Ji, Yi-Gang,Wei, Kai,Liu, Teng,Wu, Lei,Zhang, Wei-Hua
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supporting information
p. 933 - 940
(2017/03/27)
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- Cyclopentadiene-based Br?nsted acid as a new generation of organocatalyst for transfer hydrogenation of 2-substituted quinoline derivatives
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A simple and readily available cyclopentadiene-based Br?nsted acid was employed to catalyze the transfer hydrogenation of 2-substituted quinolines using Hantzsch ester as the hydrogen source. This conceptually new designed organocatalyst demonstrates remarkably high efficiency for this transformation and a variety of substituted 1,2,3,4-tetrahydroquinoline derivatives were afforded in excellent yields under mild reaction conditions.
- Qiao, Xiang,El-Shahat, Mahmoud,Ullah, Bakhtar,Bao, Zongbi,Xing, Huabin,Xiao, Li,Ren, Qilong,Zhang, Zhiguo
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supporting information
p. 2050 - 2053
(2017/05/04)
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