- 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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- Boron-Catalyzed Hydrogenative Reduction of Substituted Quinolines to Tetrahydroquinolines with Hydrosilanes
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A metal-free procedure for the hydrogenative reduction of substituted N-heteroaromatics has been developed by using hydrosilanes as reducing agents. The optimized conditions were successfully applied to the reactions of quinolines, quinoxalines, and quinoline N -oxides. They were also effective for the reduction of quinolines bearing amino or hydroxy groups, where H 2 was evolved through dehydrogenative silylation of the amine or hydroxy moieties. Preliminary mechanistic studies revealed that the initial step in the catalytic cycle involves 1,4-addition of the hydrosilane to the quinoline to give a 1,4-dihydroquinoline; this is followed by (transfer) hydrogenation to deliver the tetrahydroquinoline as the final product.
- Gandhamsetty, Narasimhulu,Park, Sehoon,Chang, Sukbok
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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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- 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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- 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 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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- 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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- 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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- 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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- 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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- 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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- Organocatalytic Approach for Transfer Hydrogenation of Quinolines, Benzoxazines and Benzothiazines
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Abstract: This study reports on the thiourea dioxide catalyzed transfer hydrogenation of diverse C=N–containing heterocyclic compounds with Hantzsch ester as the hydrogen source. With this cost effective and readily available catalyst, a wide range of 2-s
- Qiao, Xiang,Bao, Zongbi,Xing, Huabin,Yang, Yiwen,Ren, Qilong,Zhang, Zhiguo
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p. 1673 - 1678
(2017/06/20)
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- Method for reducing benzo aroma nitrogen-heterocyclic compound
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The invention discloses a method for reducing benzo aroma nitrogen-heterocycle. According to the method, the benzo aroma nitrogen-heterocycle is taken as a raw material, dual-boric acid is taken as a hydrogen source, lewis acid is taken as a catalyst, acetonitrile is taken as a solvent and the benzo aroma nitrogen-heterocyclic compound is acquired under suitable temperature and at suitable time. The method for reducing the benzo aroma nitrogen-heterocyclic compound, provided by the invention, has the advantages of mild condition, low cost, high yield, simplicity in post-processing and suitability for industrial production. The process route is as follows.
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Paragraph 0111; 0112; 0113; 0114
(2017/07/20)
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- Chiral phosphoric acid catalyzed oxidative kinetic resolution of cyclic secondary amine derivatives including tetrahydroquinolines by hydrogen transfer to imines
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A chiral Bronsted acid catalyzed dehydrogenative kinetic resolution of tetrahydroquinoline derivatives, which are representative of cyclic secondary amines, based on their hydrogen transfer to aromatic imines was efficiently achieved with high enantioselectivities. This hydrogen transfer of tetrahydroquinolines to imines was not driven by their aromatization to quinolines. This dehydrogenative kinetic resolution could be also applied to the asymmetric synthesis of various benzofused heterocycles containing secondary amine cores.
- Saito, Kodai,Miyashita, Hiromitsu,Akiyama, Takahiko
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p. 16648 - 16651
(2015/11/25)
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- A general method for N-methylation of amines and nitro compounds with dimethylsulfoxide
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DMSO methylates a broad range of amines in the presence of formic acid, providing a novel, green and practical method for amine methylation. The protocol also allows the one-pot transformation of aromatic nitro compounds into dimethylated amines in the presence of a simple iron catalyst. Not just a solvent: DMSO methylates a broad range of amines in the presence of formic acid, providing a novel, green and practical method for amine methylation. The protocol also allows the one-pot transformation of aromatic nitro compounds into dimethylated amines in the presence of a simple iron catalyst. Copyright
- Jiang, Xue,Wang, Chao,Wei, Yawen,Xue, Dong,Liu, Zhaotie,Xiao, Jianliang
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- Thiourea as an efficient organocatalyst for the transfer hydrogenation of 2-substituted quinoline derivatives
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This study reports on the first transfer hydrogenation of 2-substituted quinolines promoted by a thiourea catalyst with Hantzsch ester as the hydrogen source. A wide range of quinoline derivatives, including 2-alkylquinolines and 2-arylquinolines, were ef
- Qiao, Xiang,Zhang, Zhiguo,Bao, Zongbi,Su, Baogen,Xing, Huabin,Yang, Qiwei,Ren, Qilong
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p. 42566 - 42568
(2015/02/19)
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- Efficient entry into 2-substituted tetrahydroquinoline systems through alkylative ring expansion: Stereoselective formal synthesis of (±)-martinellic acid
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(Chemical Equation Presented) A new efficient synthesis of 2-substituted tetrahydroquinolines has been achieved by the domino reaction of N-indanyl(methoxy)amines, which consists of three types of reactions: elimination of an alcohol, the rearrangement of an aryl group, and the addition of an organolithium or magnesium reagent. The synthetic utility of this approach is demonstrated by the stereoselective formal synthesis of (±)- martinellic acid.
- Ueda, Masafumi,Kawai, Sayuri,Hayashi, Masataka,Naito, Takeaki,Miyata, Okiko
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experimental part
p. 914 - 921
(2010/06/16)
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