- Acid-Activatable Michael-Type Fluorescent Probes for Thiols and for Labeling Lysosomes in Live Cells
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A Michael addition is usually taken as a base-catalyzed reaction. Most fluorescent probes have been designed to detect thiols in slightly alkaline solutions (pH 7-9). The sensing reactions of almost all Michael-type fluorescent probes for thiols are faster in a high pH solution than in a low pH solution. In this work, we synthesized a series of 7-substituted 2-(quinolin-2-ylmethylene)malonic acids (QMAs, substituents: NEt2, OH, H, Cl, or NO2) and their ethyl esters (QMEs) as Michael-type fluorescent probes for thiols. The sensing reactions of QMAs and QMEs occur in distinct pH ranges, pH 7 for QMEs. On the basis of experimental and theoretic studies, we have clarified the distinct pH effects on the sensing reactivity between QMAs and QMEs and demonstrated that two QMAs (NEt2, OH) are highly sensitive and selective fluorescent probes for thiols in acidic solutions (pH 7) and promising dyes that can label lysosomes in live cells.
- Dai, Chun-Guang,Du, Xiao-Jiao,Song, Qin-Hua
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Read Online
- Preparation method of 7-chloroquinaldine with recyclable raw materials
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The invention relates to the technical field of organic synthesis, in particular to a preparation method of 7-chloroquinaldine with recyclable raw materials, which comprises the following steps: taking 7-chloroquinaldine and crotonaldehyde as raw materials, and carrying out skraup reaction under the action of 3-nitrochlorobenzene to synthesize the 7-chloroquinaldine. In the preparation method provided by the invention, the 3-nitrochlorobenzene can be subjected to reduction reaction to be converted into the raw material m-chloroaniline, so that the raw material can be recycled, the utilization rate of the raw material is greatly improved, the preparation process is simplified, the emission of three wastes is low, and the target product is high in yield and purity.
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Paragraph 0028-0043
(2021/11/03)
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- Visible light mediated selective oxidation of alcohols and oxidative dehydrogenation of N-heterocycles using scalable and reusable La-doped NiWO4nanoparticles
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Visible light-mediated selective and efficient oxidation of various primary/secondary benzyl alcohols to aldehydes/ketones and oxidative dehydrogenation (ODH) of partially saturated heterocycles using a scalable and reusable heterogeneous photoredox catalyst in aqueous medium are described. A systematic study led to a selective synthesis of aldehydes under an argon atmosphere while the ODH of partially saturated heterocycles under an oxygen atmosphere resulted in very good to excellent yields. The methodology is atom economical and exhibits excellent tolerance towards various functional groups, and broad substrate scope. Furthermore, a one-pot procedure was developed for the sequential oxidation of benzyl alcohols and heteroaryl carbinols followed by the Pictet-Spengler cyclization and then aromatization to obtain the β-carbolines in high isolated yields. This methodology was found to be suitable for scale up and reusability. To the best of our knowledge, this is the first report on the oxidation of structurally diverse aryl carbinols and ODH of partially saturated N-heterocycles using a recyclable and heterogeneous photoredox catalyst under environmentally friendly conditions.
- Abinaya, R.,Balasubramaniam, K. K.,Baskar, B.,Divya, P.,Mani Rahulan, K.,Rahman, Abdul,Sridhar, R.,Srinath, S.
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p. 5990 - 6007
(2021/08/24)
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- Synthetic method 7-chloroquinaldine (by machine translation)
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The process 7 - comprises the following steps, dissolving, 1 with 3 - (3 - chlorine-anilino) - butyraldehyde as a raw material, in a solvent to obtain, chloroquinaldine A under the action of an acidic catalyst 3 - (3 - and dehydrating the intermediate) - into a reaction solvent, to carry out an oxidation reaction 1;2 to obtain the intermediate 1 of the intermediate compound B as the reaction solution 2;3 and adding an oxidizing agent to the intermediate 2 as a raw material, to carry out dehydration reaction under the action of an acidic catalyst solution.]. The reaction, is carried out under the action of the acidic catalyst solution of the intermediate body . 5 - The method reduces, 7 - chloroquinaldine. (by machine translation)
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Paragraph 0035; 0044-0045; 0050; 0059-0061; 0070-0072
(2020/04/17)
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- Reusable, homogeneous water soluble photoredox catalyzed oxidative dehydrogenation of N-heterocycles in a biphasic system: Application to the synthesis of biologically active natural products
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Herein, a simple and efficient method for the oxidative dehydrogenation (ODH) of tetrahydro-β-carbolines, indolines and tetrahydro-(iso)quinolines is described using a reusable, homogeneous cobalt-phthalocyanine photoredox catalyst in a biphasic medium. A biphasic system offers an advantage of easy separation of the product and an efficient reusability of the homogeneous photoredox catalyst. Also, the current system significantly helps to overcome the solubility issue of the substrate and catalyst at room temperature. Its potential applications to organic transformations are demonstrated by the synthesis of various biologically active N-heterocycles such as indoles, (iso)quinolines and β-carbolines and natural products such as eudistomin U, norharmane, and harmane and precursors to perlolyrine and flazin. Without isolation and purification, the catalyst solution can be reused up to 5 times with almost comparable reactivity. Furthermore, the efficiency of the reaction was demonstrated on a gram scale. To the best of our knowledge, this is the first report on ODH reactions using a non noble, reusable and homogeneous cobalt photoredox catalyst under environmentally friendly conditions.
- Abinaya, R.,Baskar, B.,Mariappan, M.,Prasanth, Arun,Sridhar, R.,Srinath, S.
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p. 2575 - 2587
(2020/05/13)
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- Nickel-Catalyzed Dehydrogenation of N-Heterocycles Using Molecular Oxygen
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Herein, an efficient and selective nickel-catalyzed dehydrogenation of five- and six-membered N-heterocycles is presented. The transformation occurs in the presence of alkyl, alkoxy, chloro, free hydroxyl and primary amine, internal and terminal olefin, trifluoromethyl, and ester functional groups. Synthesis of an important ligand and the antimalarial drug quinine is demonstrated. Mechanistic studies revealed that the cyclic imine serves as the key intermediate for this stepwise transformation.
- Banerjee, Debasis,Bera, Atanu,Bera, Sourajit
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supporting information
(2020/09/02)
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- Corrigendum: Organo-Photoredox Catalyzed Oxidative Dehydrogenation of N-Heterocycles (Chemistry - A European Journal, (2017), 23, 57, (14167-14172), 10.1002/chem.201703642)
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The authors have been alerted to an error that was unfortunately missed at the time of publication. Table was duplicated with Table 4. The correct version of Table 2 is shown below. The authors apologise for any inconvenience caused. Organo-photoredox catalyzed oxidative dehydrogenation of tetrahydroquinolines (THQ).[a,b] (Table presented.) [a] Reaction conditions: 1 (0.5 mmol), rose bengal (1.0 mol %), N,N-dimethylacetamide (2.0 mL), open air atmosphere under visible-light irradiation at room temperature for 24 h. [b] Isolated yields. [c] 0.1 mol % of photoredox catalyst for 28 h.
- Sahoo, Manoj K.,Jaiswal, Garima,Rana, Jagannath,Balaraman, Ekambaram
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p. 7038 - 7038
(2019/05/17)
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- Room temperature catalytic dehydrogenation of cyclic amines with the liberation of H2 using water as a solvent
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Catalytic dehydrogenation of cyclic amines, in particular partially saturated N-heterocycles to N-heterocyclic arenes, with the removal of molecular hydrogen as the sole byproduct in water is reported. This dehydrogenation reaction proceeds smoothly under very mild and benign conditions and operates at room temperature. This distinctive reactivity has been achieved under dual catalytic conditions by merging the visible-light active [Ru(bpy)3]2+ as the photoredox catalyst and a newly synthesized cobalt complex as the proton-reduction catalyst. A detailed mechanistic study (control experiments, electrochemical studies, UV-visible experiments) is presented for the present dual catalysis.
- Sahoo, Manoj K.,Balaraman, Ekambaram
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supporting information
p. 2119 - 2128
(2019/04/26)
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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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- Synthesis method of 7-chloroquinaldine
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The invention discloses a synthesis method of 7-chloroquinaldine. 2-nitrotoluene, SiO2-HEPIMBr, m-chloroaniline, crotonaldehyde, TEOS, 2-bromoethanol, imidazole and 3-chloropropyltriethoxysilane are taken as main raw materials. According to the synthesis process, m-chloroaniline and crotonaldehyde are subjected to Skraup reaction under action of an immobilized ion catalyst SiO2-HEPIMBr, and 7-chloroquinaldine is obtained. SiO2 immobilized hydroxyl ionic liquid HEPIMBr is prepared with a grafting method, in the reaction, few by-products are produced and no 5-isomer is produced, so that the separation and purification process is reduced, purity of a product is improved, yield of the product is increased, and higher market competitiveness is achieved.
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Paragraph 0010; 0012-0030
(2018/11/27)
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- Organo-Photoredox Catalyzed Oxidative Dehydrogenation of N-Heterocycles
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We report here for the first time the catalytic oxidative dehydrogenation of N-heterocycles by a visible-light organo-photoredox catalyst with low catalyst loading (0.1–1 mol %). The reaction proceeds efficiently under base- and additive-free conditions with ambient air at room temperature. The utility of this benign approach is demonstrated by the synthesis of various pharmaceutically relevant N-heteroarenes such as quinoline, quinoxaline, quinazoline, acridine, and indole.
- Sahoo, Manoj K.,Jaiswal, Garima,Rana, Jagannath,Balaraman, Ekambaram
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supporting information
p. 14167 - 14172
(2017/10/16)
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- Synthesis of quinolines and naphthyridines: Via catalytic retro-aldol reaction of β-hydroxyketones with ortho -aminobenzaldehydes or nicotinaldehydes
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A Cu(i)-catalyzed retro-aldol reaction of β-hydroxyketones with ortho-aminobenzaldehydes and nicotinaldehydes is reported that produces a range of quinolines and naphthyridines with high efficiency and selectivity. This reaction uses β-hydroxyketones as a regiospecific ketone-protected enolate source via copper-catalyzed retro-aldol Cα-Cβ bond cleavage. The in situ generated copper enolate undergoes kinetically favorable cyclization with ortho-amino aryl aldehydes to produce quinolines and naphthyridines in a chemo- and regioselective manner. The mild and weakly basic reaction conditions also suppress possible side reactions of benzaldehydes under strongly basic conditions, resulting in improved reaction yields.
- Zhang, Song-Lin,Deng, Zhu-Qin
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p. 8966 - 8970
(2016/10/05)
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- Quinolines synthesis by reacting 1,3-butanediol with anilines in the presence of iron catalysts
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2-, 4-, 6-, 7-, and 8-substituted quinolines were synthesized in 78–95% yield by the reaction of 1,3- butanediol with anilines in the presence of iron catalysts in carbon tetrachloride.
- Khusnutdinov,Bayguzina,Aminov
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p. 1613 - 1618
(2016/08/26)
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- Quinoline Synthesis by the Reaction of Anilines with 1,2-diols Catalyzed by Iron Compounds
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The synthesis of quinoline derivatives by cyclocondensation of anilines with 1,2-ethanediol, 1,2-propanediol, and 1,2-butanediol in the presence of iron-containing catalysts was performed for the first time.
- Khusnutdinov, Ravil,Bayguzina, Alfiya,Aminov, Rishat,Dzhemilev, Usein
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supporting information
p. 1022 - 1029
(2016/07/28)
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- Copper-Promoted Tandem Reaction of Azobenzenes with Allyl Bromides via N=N Bond Cleavage for the Regioselective Synthesis of Quinolines
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A copper-promoted tandem reaction of a variety of azobenzenes and allyl bromides via N=N bond cleavage to regioselectively construct quinoline derivatives has been developed. The azobenzenes act as not only construction units but also an oxidant for quinoline formation.
- Yi, Xiangli,Xi, Chanjuan
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p. 5836 - 5839
(2015/12/11)
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- Discovery and efficient synthesis of a biologically active alkaloid inspired by thiostrepton biosynthesis
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Thiostrepton, a natural peptide macrocycle, is of great interest due to its structural complexity and numerous biological activities, including anti-bacterial, anti-tumor, and anti-plasmodial activities. The quinaldic acid (QA) moiety-containing side ring (loop 2) was proven to play an important role in carrying out these functions. Previously, we proposed biosynthetic logic for thiostrepton loop 2 and demonstrated the formation mechanism of QA. Herein, we report the discovery and efficient synthesis of a biologically active alkaloid, that is, a key intermediate involved in the thiostrepton biosynthetic pathway. A chemo-enzymatic method was performed to synthesize the molecule, and a series of analogs were prepared for bioassays, which included the examination of anti-bacterial and anti-tumor activities.
- Zheng, Qingfei,Wang, Shoufeng,Liu, Wen
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p. 7686 - 7690
(2014/12/10)
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- Magnetically separable palladium-graphene nanocomposite as heterogeneous catalyst for the synthesis of 2-alkylquinolines via one pot reaction of anilines with alkenyl ethers
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The present Letter describes the use of magnetically separable palladium-graphene nanocomposite, a complete magnetically separable catalyst for the synthesis of 2-alkyl quinolines via reaction of anilines with alkenyl ethers. Because of the uniform decoration of the Pd nanoparticles on support, the catalyst exhibited higher catalytic efficiency and it remains unaltered even after six repeated cycles.
- Verma, Sanny,Verma, Deepak,Jain, Suman L.
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p. 2406 - 2409
(2014/05/06)
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- Synthesis of substituted quinolines by the reaction of anilines with alcohols and CCl4 in the presence of Fe-containing catalysts
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Substituted quinolines were synthesized by the reaction of aniline derivatives with aliphatic alcohols and CCl4 upon the action of the FeCl3·6H2O catalyst.
- Khusnutdinov,Bayguzina,Aminov
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p. 133 - 137
(2013/11/19)
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- Assembly of substituted 2-alkylquinolines by a sequential palladium-catalyzed Ci-N and Ci-C bond formation
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Diversity: A range of substituted 2-alkylquinolines can be prepared in a general and efficient synthetic approach that employs mild reaction conditions (see scheme). The synthesis is based on a sequential palladium-catalyzed Ci-N and Ci-C bond formation, followed by palladium-catalyzed aromatization, and results in the formation of the desired compounds in one step. Copyright
- Matsubara, Yoshio,Hirakawa, Saori,Yamaguchi, Yoshihiro,Yoshida, Zen-Ichi
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experimental part
p. 7670 - 7673
(2011/10/05)
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- Synthesis of quinaldines and lepidines by a Doebner-Miller reaction under thermal and microwave irradiation conditions using phosphotungstic acid
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A simple and efficient method has been developed for the synthesis of quinaldines and lepidines by a one-pot reaction of anilines with crotonaldehyde or methyl vinyl ketone using phosphotungstic acid, a Keggins-type heteropoly acid, under both thermal and microwave irradiation conditions.
- Sivaprasad, Ganesabaskaran,Rajesh, Rengasamy,Perumal, Paramasivan T.
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p. 1783 - 1785
(2007/10/03)
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- 7-chloroquinaldine synthesis
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An improved process is described which utilizes tetrachloro-1,4(or 1,2)-quinone as an oxidant in the Doebner-Miller synthesis of 7-chloroquinaldine, a starting material in the preparation of leukotriene antagonists. The process improves yield and eliminates the need of forming a ZnCl2 complex to isolate the end product.
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- Preparation and Cyclodehydration of β-Arylaminocrotonaldehyde
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β-Arylaminocrotonaldehydes (3) were prepared by alkaline hydrolysis of 1-arylamino-3-arylimino-1-butenes (2).On treatment with sulfuric acid, β-anilinocrotonaldehyde (3b) and p-methyl- (3a), m-chloro- (3c), and p-chloro- (3d) derivatives were cyclodehydrated to give the corresponding quinaldines in quantitative yields.The protonation of 3 was proved to take place at the oxygen atom on the basis of spectral evidence.The mechanism of the cyclodehydration is discussed.Keywords-Combes reaction; cyclodehydration; hydrolysis; β-arylaminocrotonaldehyde; 1-arylamino-3-arylimino-1-butene; quinaldine derivative; protonation
- Ono, Machiko,Todoriki, Reiko,Tamura, Shinzo
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p. 463 - 470
(2007/10/02)
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- A Kinetic Study of Cyclodehydration of β-Arylaminocrotonaldehyde Derivatives
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Cyclodehydration of β-arylaminocrotonaldehydes (1) was studied kinetically in comparison with those of β-(p-toluidino)acrolein (2a) and 4-(p-toluidino)-3-penten-2-one (3a).The rate constants k1 of cyclodehydration of 1 were not consistent with the Zucker-Hammett hypothesis, i.e., log k1 was related linearly to -H0, but the slopes were between 1.28 and 1.36.Bunnett-Olsen plots for log k1 were linear.Statistically corrected values of log k0r/KSH(+) were applied to Jaffe's four-parameter Hammett equation.The reaction constant for the site of the aromatic ring at which cyclodehydration takes place was evaluated to be -8.54, and that for the oxobutenylamino group was evaluated to be +0.72.The effect of substituents on the aromatic ring upon the reactivity is discussed.Keywords - kinetic study; cyclodehydration; Combes reaction; β-arylaminocrotonaldehyde; quinaldine derivative; Zucker-Hammett hypothesis; Bunnett-Olsen plot; four-parameter Hammett equation
- Ono, Machiko,Todoriki, Reiko,Tamura, Shinzo
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p. 1468 - 1472
(2007/10/02)
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- The Rhodium Complex-catalyzed Synthesis of Quinolines from Aminoarenes and Aliphatic Aldehydes
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A variety of aminoarenes react with aliphatic aldehydes in the presence of a catalytic amount of a rhodium complex and an excess amount of the corresponding nitroarenes at 180 deg C to give 2-alkyl- and 2,3-dialkyl-substituted quinolines in excellent yields.Among the rhodium complexes examined, 2 exhibits the highest activity as a catalyst.Thus, 2-methyl-, 2-ethyl-3-methyl-, 2-propyl-3-ethyl-, 2-butyl-3-propylquinoline derivatives are readily obtained from aminoarenes and ethanal, propanal, butanal, and pentanal respectively.
- Watanabe, Yoshihisa,Shim, Sang Chul,Mitsudo, Take-aki
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p. 3460 - 3465
(2007/10/02)
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