- Substrate-Tuned Domino Annulation for Selective Synthesis of Poly-substituted Benzo[ f]imidazo[2,1- a][2,7]naphthyridines and 3-Azaheterocyclic Substituted 2-Arylquinolines
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A domino annulation/oxidation of heterocyclic ketene aminals (HKAs) and 2-aminochalcones has been developed for the selective synthesis of poly-substituted benzo[f]imidazo[2,1-a][2,7]naphthyridines and 3-azaheterocyclic substituted 2-arylquinolines. These reactions proceed well under mild conditions without any additives. Plausible mechanisms for such a polycyclic ring system assembly were also proposed. Moreover, benzo[f]imidazo[2,1-a][2,7]naphthyridine 3g displayed a fluorescence effect, demonstrating the potential applications in organic optical materials.
- Ying, Zhimin,Cen, Jie,Luo, Feng,Wu, You,Liu, Shuangrong,Chen, Wenteng,Shao, Jiaan,Yu, Yongping
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- Furfuryl vinyl ethers in [4+2]-cycloaddition reactions
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For the first time [4+2]-cycloaddition reactions were carried out between furfuryl vinyl ethers and typical dienophiles and heterodienes proceeding in uncatalyzed conditions and resulting in previously unknown heterocyclic systems containing either free v
- Oparina,Vysotskaya,Stepanov,Ushakov,Apartsin,Gusarova,Trofimov
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- Enantioselective Dearomative [3 + 2] Umpolung Annulation of N-Heteroarenes with Alkynes
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Enantioselective [3 + 2] annulation of N-heteroarenes with alkynes has been developed via a cobalt-catalyzed dearomative umpolung strategy in the presence of chiral ligand and reducing reagent. A variety of electron-deficient N-heteroarenes, including qui
- Cui, Bing-Hui,Huang, Wen-Yu,Jia, Yi-Xia,Liang, Ren-Xiao,Liu, Hang,Liu, Jia-Liang,Wang, Qiang,Yang, Peng,Zhang, Xiao-Dong,Zhang, Yue-Yuan
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p. 1087 - 1093
(2022/02/09)
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- Dehydrogenation of N-Heterocyclic Compounds Using H2O2 and Mediated by Polar Solvents
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The oxidative dehydrogenation of N-heterocyclic compounds by using H2O2 as oxidant in combination with polar solvents such as 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) and H2O is described. Among these two solvents, the best yields for the heteroaromatic compounds were generally achieved in HFIP. However, it is remarkable, that the use of a non toxic solvent such as H2O gave such good yields. Furthermore, the procedure was implemented in larger-scale and HFIP was distilled from the reaction mixture and reused (up to 5 cycles) without a significant detriment in the reaction outcome. (Figure presented.).
- Llopis, Natalia,Gisbert, Patricia,Baeza, Alejandro,Correa-Campillo, Jara
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p. 1205 - 1210
(2022/02/25)
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- Manganese(III) Acetate Catalyzed Aerobic Dehydrogenation of Tertiary Indolines, Tetrahydroquinolines and an N-Unsubstituted Indoline
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A Mn(OAc)3 ? 2H2O-catalyzed aerobic dehydrogenation of five and six-membered N-heterocycles for the synthesis of N-heteroarenes is reported. Of note, this protocol can be applied to the dehydrogenation of tertiary indolines with various electron-deficient N-substituents. Preliminary mechanistic investigations support that a single-electron transfer pathway might be involved. (Figure presented.).
- Niu, Xiaokang,Yang, Lei
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supporting information
p. 4209 - 4215
(2021/08/06)
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- Visible-Light-Mediated Oxidative Cyclization of 2-Aminobenzyl Alcohols and Secondary Alcohols Enabled by an Organic Photocatalyst
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This paper describes a visible-light-mediated oxidative cyclization of 2-aminobenzyl alcohols and secondary alcohols to produce quinolines at room temperature. This photocatalytic method employed anthraquinone as an organic small-molecule catalyst and DMSO as an oxidant. According to this present procedure, a series of quinolines were prepared in satisfactory yields.
- Xu, Jing-Xiu,Pan, Nan-Lian,Chen, Jia-Xi,Zhao, Jin-Wu
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p. 10747 - 10754
(2021/08/16)
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- Efficient access to quinolines and quinazolines by ruthenium complexes catalyzed acceptorless dehydrogenative coupling of 2-aminoarylmethanols with ketones and nitriles
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Treatment of N,N,O-tridentate pyrazolyl-pyridinyl-alcohol ligands, 2-(CR1R2OH)-6-[3,5-(R3)2C3HN2]C5H3N (R1 = R2 = Me, R3 = H (L1H); R1 = Me, R2 = Ph, R3 = H (L2H); R1 = R2 = Ph, R3 = H (L3H); R1 = R2 = R3 = Me (L4H)) with RuCl3?xH2O in refluxing EtOH afforded the corresponding Ru(III) complexes L2RuCl (1a-1d), which were well characterized by IR, HR-MS and X-ray single crystal structural determination. These Ru complexes showed similarly high catalytic performance for both dehydrogenative couplings of 2-aminoarylmethanols with ketones and nitriles, giving the quinolines and quinazolines in good to excellent yields. This protocol provides an atom-economical and sustainable route to access various structurally important quinoline and quinazoline derivatives by using phosphine-free ligand based Ru catalysts.
- Feng, Qi,Han, Zhangang,Hao, Zhiqiang,Huo, Shuaicong,Kong, Siqi,Lin, Jin,Lu, Guo-Liang,Zeng, Guang
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- Rhodium-Catalyzed Dehydrogenative Annulation of N-Arylmethanimines with Vinylene Carbonate for Synthesizing Quinolines
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Here we report a novel Rh-catalyzed C-H/C-H alkenylation of N-arylmethanimines with vinylene carbonate acting as a vinylene unit. Forty examples of C3,C4-nonsubstituted quinolines were achieved from commercially available starting materials. This identified process features an exceedingly simple system, a lower loading of catalyst, and the capacity for postfunctionalization with bioactive molecules.
- Hu, Yan,Nan, Jiang,Yin, Jiacheng,Huang, Guanjie,Ren, Xin,Ma, Yangmin
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p. 8527 - 8532
(2021/11/13)
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- A Domino Heck Coupling-Cyclization-Dehydrogenative Strategy for the One-Pot Synthesis of Quinolines
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An efficient, one-pot, domino synthesis of quinolines via the coupling of iodoanilines with allylic alcohols facilitated by palladium catalysis is described. The overall synthetic process involves an intermolecular Heck coupling between 2-iodoanilines and allylic alcohols, intramolecular condensation of in situ generated ketones with an internal amine functional group, and a dehydrogenation sequence. Notably, this protocol occurs in water as a green solvent. Significantly, the method exhibits broad substrate scope and is applied for the synthesis of deuterated quinolines through a deuterium-exchange process.
- Ghora, Santanu,Satyanarayana, Gedu,Sreenivasulu, Chinnabattigalla
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- Highly Chemoselective Deoxygenation of N-Heterocyclic N-Oxides Using Hantzsch Esters as Mild Reducing Agents
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Herein, we disclose a highly chemoselective room-temperature deoxygenation method applicable to various functionalized N-heterocyclic N-oxides via visible light-mediated metallaphotoredox catalysis using Hantzsch esters as the sole stoichiometric reductant. Despite the feasibility of catalyst-free conditions, most of these deoxygenations can be completed within a few minutes using only a tiny amount of a catalyst. This technology also allows for multigram-scale reactions even with an extremely low catalyst loading of 0.01 mol %. The scope of this scalable and operationally convenient protocol encompasses a wide range of functional groups, such as amides, carbamates, esters, ketones, nitrile groups, nitro groups, and halogens, which provide access to the corresponding deoxygenated N-heterocycles in good to excellent yields (an average of an 86.8% yield for a total of 45 examples).
- An, Ju Hyeon,Kim, Kyu Dong,Lee, Jun Hee
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supporting information
p. 2876 - 2894
(2021/02/01)
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- Metal-Free Deoxygenation of Amine N-Oxides: Synthetic and Mechanistic Studies
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We report herein an unprecedented combination of light and P(III)/P(V) redox cycling for the efficient deoxygenation of aromatic amine N-oxides. Moreover, we discovered that a large variety of aliphatic amine N-oxides can easily be deoxygenated by using only phenylsilane. These practically simple approaches proceed well under metal-free conditions, tolerate many functionalities and are highly chemoselective. Combined experimental and computational studies enabled a deep understanding of factors controlling the reactivity of both aromatic and aliphatic amine N-oxides.
- Lecroq, William,Schleinitz, Jules,Billoue, Mallaury,Perfetto, Anna,Gaumont, Annie-Claude,Lalevée, Jacques,Ciofini, Ilaria,Grimaud, Laurence,Lakhdar, Sami
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p. 1237 - 1242
(2021/06/01)
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- Highly chemoselective deoxygenation of N-heterocyclic: N -oxides under transition metal-free conditions
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Because their site-selective C-H functionalizations are now considered one of the most useful tools for synthesizing various N-heterocyclic compounds, the highly chemoselective deoxygenation of densely functionalized N-heterocyclic N-oxides has received much attention from the synthetic chemistry community. Here, we provide a protocol for the highly chemoselective deoxygenation of various functionalized N-oxides under visible light-mediated photoredox conditions with Na2-eosin Y as an organophotocatalyst. Mechanistic studies imply that the excited state of the organophotocatalyst is reductively quenched by Hantzsch esters. This operationally simple technique tolerates a wide range of functional groups and allows high-yield, multigram-scale deoxygenation. This journal is
- Kim, Se Hyun,An, Ju Hyeon,Lee, Jun Hee
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supporting information
p. 3735 - 3742
(2021/05/04)
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- Evaluation of P-bridged biaryl phosphine ligands in palladium-catalysed Suzuki-Miyaura cross-coupling reactions
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A family of biaryl phosphacyclic ligands derived from phobane and phosphatrioxa-adamantane frameworks is described. The rigid biaryl phosphacycles are efficient for Suzuki-Miyaura cross-coupling of aryl bromides and chlorides. In particular, coupling reactions of the challenging sterically hindered and heterocyclic substrates were viable at room temperature.
- Holzapfel, Cedric W.,Lamola, Jairus L.,Maumela, Munaka Christopher,Moshapo, Paseka T.
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p. 26883 - 26891
(2021/08/17)
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- 2-Phosphinoimidazole Ligands: N-H NHC or P-N Coordination Complexes in Palladium-Catalyzed Suzuki-Miyaura Reactions of Aryl Chlorides
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We report the synthesis of two palladium 2-(dialkylphosphino)imidazole complexes and demonstrate their activity as catalysts for Suzuki-Miyaura reactions with (hetero)aryl chlorides at room temperature. Our mechanistic studies demonstrate that these palladium complexes exist as an equilibrium mixture between the P-N coordinated and N-H NHC forms of ligand. Our studies suggest that the N-H NHC form may be important for high catalytic activity in Suzuki-Miyaura reactions with aryl chlorides. These reactions proceed at or near room temperature in good to excellent yields. Heteroaryl chlorides are also reactive at lower catalyst loadings.
- Martinez, Erin E.,Larson, Alexandra J. S.,Fuller, Sydney K.,Petersen, Kathryn M.,Smith, Stacey J.,Michaelis, David J.
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supporting information
p. 1560 - 1564
(2021/05/29)
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- Designing biaryl phosphacyclic ligands: their characterization and evaluation in palladium-catalyzed Suzuki-Miyaura reactions of aryl bromides and chlorides
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Efficient palladium catalyst systems based on the combination of bench stable biaryl phosphacycles and Pd(OAc)2 are described for Suzuki-Miyaura cross-coupling reactions of aryl bromides and chlorides. Notably, the electronically and sterically diametric biaryl phosphacycles allowed facile coupling of sterically hindered and heterocyclic substrates.
- Holzapfel, Cedric W.,Lamola, Jairus L.,Maumela, Munaka Christopher,Moshapo, Paseka T.
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- Bioinspired Radical-Mediated Transition-Metal-Free Synthesis of N-Heterocycles under Visible Light
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A redox-active iminoquinone motif connected with π-delocalized pyrene core has been reported that can perform efficient two-electron oxidation of a class of substrates. The design of the molecule was inspired by the organic redox cofactor topaquinone (TPQ), which executes amine oxidation in the enzyme, copper amine oxidase. Easy oxidation of both primary and secondary alcohols happened in the presence of catalytic KOtBu, which could reduce the ligand backbone to its iminosemiquinonate form under photoinduced conditions. Moreover, this easy oxidation of alcohols under aerobic condition could be elegantly extended to multi-component, one-pot coupling for the synthesis of quinoline and pyrimidine. This organocatalytic approach is very mild (70 °C, 8 h) compared to a multitude of transition-metal catalysts that have been used to prepare these heterocycles. A detailed mechanistic study proves the intermediacy of the iminosemiquinonate-type radical and a critical hydrogen atom transfer step to be involved in the dehydrogenation reaction.
- K. Bains, Amreen,Ankit, Yadav,Adhikari, Debashis
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p. 324 - 329
(2020/11/30)
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- Ionic-Liquid-Catalyzed Synthesis of Imines, Benzimidazoles, Benzothiazoles, Quinoxalines and Quinolines through C?N, C?S, and C?C Bond Formation
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We report the tetramethyl ammonium hydroxide catalyzed oxidative coupling of amines and alcohols for the synthesis of imines under metal-free conditions by utilizing oxygen from air as the terminal oxidant. Under the same conditions, with ortho-phenylene diamines and 2-aminobenzenethiols the corresponding benzimidazoles and benzothiazoles were obtained. Quinoxalines were obtained from ortho-phenylene diamines and 1-phenylethane-1,2-diol, the conditions were then extended to the synthesis of quinoline building blocks by reaction of 2-amino benzyl alcohols either with 1-phenylethan-1-ol or acetophenone derivatives. The formation of C?N, C?S and C?C bonds was achieved under metal-free conditions. A broad range of amines (aromatic, aliphatic, cyclic and heteroaromatic) as well as benzylic alcohols including heteroaryl alcohols reacted smoothly and provided the desired products. The mild reaction conditions, commercially available catalyst, metal-free, good functional-group tolerance, broad range of products (imines, benzimidazoles, benzothiazoles, quinoxalines and quinolines) and applicability at gram scale reactions are the advantages of the present strategy.
- Adimurthy, Subbarayappa,Badhani, Gaurav,Joshi, Abhisek
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p. 6705 - 6716
(2021/12/31)
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- Highly Efficient and Recyclable Porous Organic Polymer Supported Iridium Catalysts for Dehydrogenation and Borrowing Hydrogen Reactions in Water
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Benzothiazole-doped porous organic polymers (POP-MBTS) were synthesized from a copolymerization reaction of 2-(6-(4-vinylphenyl)pyridin-2-yl)benzo[d]thiazole with divinylbenzene. The corresponding POP-MBTS-Ir was obtained and fully characterized using SEM, TEM, EDS, TGA, XPS, and N2 sorption isotherms, which disclosed that this catalyst has a high surface area, hierarchical porosity, and thermodynamic stability. Importantly, this catalyst revealed a high catalytic activity for ten different kinds of borrowing hydrogen and dehydrogenation reactions in water with a good recovery performance. Furthermore, mechanistic investigations were conducted for the synthesis of triazine derivatives.
- Li, Jiahao,Liu, Hongqiang,Zhu, Haiyan,Yao, Wei,Wang, Dawei
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p. 4751 - 4758
(2021/10/14)
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- N -Butylpyrrolidone (NBP) as a non-toxic substitute for NMP in iron-catalyzed C(sp2)-C(sp3) cross-coupling of aryl chlorides
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Although iron catalyzed cross-coupling reactions show extraordinary promise in reducing the environmental impact of more toxic and scarce transition metals, one of the main challenges is the use of reprotoxic NMP (NMP = N-methylpyrrolidone) as the key ligand to iron in the most successful protocols in this reactivity platform. Herein, we report that non-toxic and sustainable N-butylpyrrolidone (NBP) serves as a highly effective substitute for NMP in iron-catalyzed C(sp2)-C(sp3) cross-coupling of aryl chlorides with alkyl Grignard reagents. This challenging alkylation proceeds with organometallics bearing β-hydrogens with efficiency superseding or matching that of NMP with ample scope and broad functional group tolerance. Appealing applications are demonstrated in the cross-coupling in the presence of sensitive functional groups and the synthesis of several pharmaceutical intermediates, including a dual NK1/serotonin inhibitor, a fibrinolysis inhibitor and an antifungal agent. Considering that the iron/NMP system has emerged as one of the most powerful iron cross-coupling technologies available in both academic and industrial research, we anticipate that this method will be of broad interest.
- Bisz, Elwira,Koston, Martina,Szostak, Michal
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supporting information
p. 7515 - 7521
(2021/10/12)
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- Inhibition of (dppf)nickel-catalysed Suzuki-Miyaura cross-coupling reactions by α-halo-N-heterocycles
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A nickel/dppf catalyst system was found to successfully achieve the Suzuki-Miyaura cross-coupling reactions of 3- and 4-chloropyridine and of 6-chloroquinoline but not of 2-chloropyridine or of other α-halo-N-heterocycles. Further investigations revealed that chloropyridines undergo rapid oxidative addition to [Ni(COD)(dppf)] but that α-halo-N-heterocycles lead to the formation of stable dimeric nickel species that are catalytically inactive in Suzuki-Miyaura cross-coupling reactions. However, the corresponding Kumada-Tamao-Corriu reactions all proceed readily, which is attributed to more rapid transmetalation of Grignard reagents.
- Burton, Paul M.,Cooper, Alasdair K.,Donohoe, William,Greaves, Megan E.,Kennedy, Alan R.,Nelson, David J.,Ronson, Thomas O.
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p. 14074 - 14082
(2021/11/12)
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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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- Zinc Stabilized Azo-anion Radical in Dehydrogenative Synthesis of N-Heterocycles. An Exclusively Ligand Centered Redox Controlled Approach
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Herein we report an exclusively ligand-centered redox controlled approach for the dehydrogenation of a variety of N-heterocycles using a Zn(II)-stabilized azo-anion radical complex as the catalyst. A simple, easy-to-prepare, and bench-stable Zn(II)-complex (1b) featuring the tridentate arylazo pincer, 2-((4-chlorophenyl)diazenyl)-1,10-phenanthroline, in the presence of zinc-dust, undergoes reduction to form the azo-anion radical species [1b]- which efficiently dehydrogenates various saturated N-heterocycles such as 1,2,3,4-tetrahydro-2-methylquinoline, 1,2,3,4-tetrahydro-isoquinoline, indoline, 2-phenyl-2,3-dihydro-1H-benzoimidazole, 2,3-dihydro-2-phenylquinazolin-4(1H)-one, and 1,2,3,4-tetrahydro-2-phenylquinazolines, among others, under air. The catalyst has further been found to be compatible with the cascade synthesis of these N-heterocycles via dehydrogenative coupling of alcohols with other suitable coupling partners under air. Mechanistic investigation reveals that the dehydrogenation reactions proceed via a one-electron hydrogen atom transfer (HAT) pathway where the zinc-stabilized azo-anion radical ligand abstracts the hydrogen atom from the organic substrate(s), and the whole catalytic cycle proceeds via the exclusive involvement of the ligand-centered redox events where the zinc acts only as the template.
- Das, Siuli,Mondal, Rakesh,Chakraborty, Gargi,Guin, Amit Kumar,Das, Abhishek,Paul, Nanda D.
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p. 7498 - 7512
(2021/06/30)
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- Iron catalyzed metal-ligand cooperative approaches towards sustainable synthesis of quinolines and quinazolin-4(3H)-ones
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Herein we report simple, efficient, and economically affordable metal-ligand cooperative strategies for synthesizing quinolines and quinazolin-4(3H)-ones via dehydrogenative functionalization of alcohols. Various polysubstituted quinolines and quinazolin-4(3H)-ones were prepared in good yields via dehydrogenative coupling of readily available alcohols with ketones and 2-aminobenzamides, respectively under air using a well-defined Fe(II)-catalyst, ([FeL1Cl2] (1)) bearing a redox-active azo-aromatic pincer 2-((4-chlorophenyl)diazenyl)-1,10-phenanthroline) (L1). Control experiments and mechanistic investigation disclose that the one-electron reduced mono-anionic species [1]? bearing an iron-stabilized azo-anion radical ligand catalyzes these reactions. Both iron and the redox-active arylazo ligand participate synergistically during the different steps of these catalytic reactions.
- Mondal, Rakesh,Chakraborty, Gargi,Guin, Amit Kumar,Pal, Subhasree,Paul, Nanda D.
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- Ruthenium complex and preparation method thereof and catalytic application
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The invention discloses a ruthenium complex and a preparation method thereof and catalytic application. The ruthenium complex is reported for the first time. Research finds that the ruthenium complexhas the activity of catalytically synthesizing quinazoline and derivatives thereof or catalytically synthesizing quinoline and derivatives thereof. When the ruthenium complex provided by the inventionis used for catalytic synthesis of quinazoline and derivatives thereof or quinoline and derivatives thereof, the ruthenium complex has the advantages of mild reaction conditions, wide substrate range, high catalytic product yield and good functional group tolerance, and is significantly superior to the prior art.
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Paragraph 0104-0108; 0147-0150
(2021/01/24)
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- Porous FeO(OH) Dispersed on Mg-Al Hydrotalcite Surface for One-Pot Synthesis of Quinoline Derivatives
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The use of ubiquities elements such as iron instead of expensive precious metals as catalysts is one goal toward realizing environmentally benign synthetic chemistry. Here, we report that porous FeO(OH) dispersed on Mg?Al hydrotalcite acts as a bifunctional heterogeneous catalyst in the one-pot synthesis of 2-substituted quinoline derivatives through dehydrogenative oxidation-cyclization reactions. The catalyst was prepared by a simple grafting method using FeCl3 and Mg?Al hydrotalcite. The prepared porous FeO(OH) possesses a higher surface area than those previously reported for α-FeO(OH) particles. The one-pot quinoline synthesis proceeded effectively under non-noble-metal catalysis in air without requiring additional homogeneous bases or solvents.
- Motokura, Ken,Ozawa, Nao,Sato, Risako,Manaka, Yuichi,Chun, Wang-Jae
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p. 2915 - 2921
(2021/05/27)
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- Method for synthesizing quinoline derivatives by copper catalysis
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The invention relates to a method for synthesizing quinoline derivatives by copper catalysis. The method comprises the following steps: mixing 2-aminobenzyl alcohol, acetophenone derivatives, an alkaline reagent, a copper catalyst and a nitrogen-containing ligand in an organic solvent, and reacting at room temperature for 6-12h; and after the reaction is finished, sequentially carrying out concentration and column chromatography separation on the obtained reaction solution to obtain the corresponding quinoline derivative. Compared with the prior art, the method has the advantages that 2-aminobenzyl alcohol and acetophenone derivatives which are cheap and easy to obtain are used as raw materials, cuprous iodide CuI or cuprous bromide CuBr with stable properties is used as a catalyst, the quinoline skeleton-containing derivatives are directly constructed, use of toxic reagents is avoided, and the method conforms to the development concept of green chemistry; and the method has the advantages of simple operation, mild reaction conditions, good substrate universality and the like, and has huge application potential in the aspect of drug intermediate synthesis.
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Paragraph 0020-0025
(2021/03/24)
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- Designed pincer ligand supported Co(ii)-based catalysts for dehydrogenative activation of alcohols: Studies onN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines
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Base-metal catalystsCo1,Co2andCo3were synthesized from designed pincer ligandsL1,L2andL3having NNN donor atoms respectively.Co1,Co2andCo3were characterized by IR, UV-Vis. and ESI-MS spectroscopic studies. Single crystal X-ray diffraction studies were investigated to authenticate the molecular structures ofCo1andCo3. CatalystsCo1,Co2andCo3were utilized to study the dehydrogenative activation of alcohols forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines. Under optimized reaction conditions, a broad range of substrates including alcohols, anilines and ketones were exploited. A series of control experiments forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines were examined to understand the reaction pathway. ESI-MS spectral studies were investigated to characterize cobalt-alkoxide and cobalt-hydride intermediates. Reduction of styrene by evolved hydrogen gas during the reaction was investigated to authenticate the dehydrogenative nature of the catalysts. Probable reaction pathways were proposed forN-alkylation of amines, α-alkylation of ketones and synthesis of quinolines on the basis of control experiments and detection of reaction intermediates.
- Singh, Anshu,Maji, Ankur,Joshi, Mayank,Choudhury, Angshuman R.,Ghosh, Kaushik
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supporting information
p. 8567 - 8587
(2021/06/30)
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- Ruthenium-catalyzed acceptorless dehydrogenative coupling of o-aminobenzyl alcohols with ketones to quinolines in the presence of carbonate salt
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A ruthenium complex bearing a functional 2,2′-bibenzimidazole ligand [(p-cymene)Ru(BiBzImH2)Cl][Cl] was designed, synthesized and found to be a general and highly efficient catalyst for the synthesis of quinolines via acceptorless dehydrogenative coupling of o-aminobenzyl alcohols with ketones in the presence of carbonate salt. It was confirmed that NH units in the ligand are crucial for catalytic activity. The application of this catalytic system for the scale-gram synthesis of biologically active molecular was also undertaken. Notably, this research exhibits new potential of metal–ligand bifuctional catalysts for acceptorless dehydrogenative reactions.
- Xu, Xiangchao,Ai, Yao,Wang, Rongzhou,Liu, Liping,Yang, Jiazhi,Li, Feng
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p. 340 - 349
(2021/02/27)
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- The preparation of a Co@C3N4catalyst and applications in the synthesis of quinolines from 2-aminobenzyl alcohols with ketones
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An unsymmetrical diphenylphosphino-pyridinyl-triazole ligand was synthesized and characterized through IR, NMR and MS and the corresponding earth-abundant metal complex (cobalt) was prepared. Considering energy consumption and environmental friendliness, it is necessary to turn this diphenylphosphino-pyridinyl-triazole cobalt complex into a recyclable catalyst, which could easily be reused. Therefore, a heterogeneous catalyst was synthesized through Co-doping of C3N4, and the Co-nanoparticles on C3N4revealed high catalytic activity for the synthesis of quinolines with good recovery performance.
- Cao, Fei,Mao, Anruo,Yang, Bobin,Ge, Chenyang,Wang, Dawei
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supporting information
p. 6768 - 6772
(2021/04/22)
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- [(PPh3)2NiCl2]-Catalyzed C-N bond formation reaction via borrowing hydrogen strategy: Access to diverse secondary amines and quinolines
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Commercially available [(PPh3)2NiCl2] was found to be an efficient catalyst for the mono-N-alkylation of (hetero)- A romatic amines, employing alcohols to deliver diverse secondary amines, including the drug intermediates chloropyramine (5b) and mepyramine (5c), in excellent yields (up to 97%) via the borrowing hydrogen strategy. This method shows a superior activity (TON up to 10000) with a broad substrate scope at a low catalyst loading of 1 mol % and a short reaction time. Further, this strategy is also successful in accessing various quinoline derivatives following the acceptorless dehydrogenation pathway.
- Donthireddy,Pandey, Vipin K.,Rit, Arnab
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supporting information
p. 6994 - 7001
(2021/06/09)
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- Nickel-catalyzed α-alkylation of ketones with benzyl alcohols
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We reported an efficient method for α-alkylation of ketones with benzyl alcohols using the pyridine-bridged pincer-type N-heterocyclic carbenes nickel complexes as catalysts. A wide range of ketones and benzyl alcohols were efficiently converted into various alkylated products in moderate to high yields. In addition, these nickel complexes were also successfully applied for the synthesis of a wide range of quinoline derivatives.
- Li, Min,Liu, Jichang,Liu, Ning,Shi, Lei,Wang, Yubin,Wu, Di
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- Method for realizing oxidative dehydrogenation of nitrogen-containing heterocyclic ring by using biomass-based carbon material
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The invention provides a method for realizing oxidative dehydrogenation of a nitrogen-containing heterocyclic ring by using a biomass-based carbon material, and belongs to the field of organic synthesis. According to the method, the raw materials of the biomass-based carbon material comprise wheat, sorghum, rice, corn straw, wheat straw, peanut shells, sesame shells, bean shells and the like, and are crushed and then ground into powder, the powder is fully mixed with an inorganic alkali, and calcination is performed in an inert gas atmosphere to prepare the biomass-based carbon material; and by using air as an oxygen source, at a temperature of 50-120 DEG C, oxidative dehydrogenation of nitrogen-containing heterocyclic compounds to synthesize quinoline compounds, isoquinoline compounds, acridine compounds, quinazoline compounds, indole compounds, imine compounds, and even quinoline compounds with pharmaceutical activity can be achieved. According to the present invention, easily available wheat flour is adopted as a raw material to prepare a non-metal catalyst, the alkali is not added during the reaction process, and a remarkable industrial application prospect is achieved.
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Paragraph 0010-0011; 0020-0021
(2021/06/26)
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- Phenanthrenequinone-Sensitized Photocatalytic Synthesis of Polysubstituted Quinolines from 2-Vinylarylimines
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Visible-light-excited 9,10-phenanthrenequinone (PQ*) was used as a photocatalyst for the synthesis of polysubstituted quinolines via the electrocyclization of 2-vinylarylimines. Up to quantitative yields of 2,4-disubstituted quinolines were received after 1 h of excitation with blue LEDs at room temperature when MgCO3 was used as an additive in DCM. On the basis of experimental and DFT studies, we propose that PQ? induces one-electron oxidation of the imine substrate that triggers the electrocyclization mechanism.
- Alanko, Iida,Bulatov, Evgeny,Helaja, Juho,Koivula, Juho,P?ll?nen, Topias,Talvitie, Juulia
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supporting information
(2022/01/04)
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- Highly Ordered Mesoporous Cobalt Oxide as Heterogeneous Catalyst for Aerobic Oxidative Aromatization of N-Heterocycles
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N-heterocycles are key structures for many pharmaceutical intermediates. The synthesis of such units normally is conducted under homogeneous catalytic conditions. Among all methods, aerobic oxidative aromatization is one of the most effective. However, in homogeneous conditions, catalysts are difficult to be recycled. Herein, we report a heterogeneous catalytic strategy with a mesoporous cobalt oxide as catalyst. The developed protocol shows a broad applicability for the synthesis of N-heterocycles (32 examples, up to 99 % yield), and the catalyst presents high turnover numbers (7.41) in the absence of any additives. Such a heterogenous approach can be easily scaled up. Furthermore, the catalyst can be recycled by simply filtration and be reused for at least six times without obvious deactivation. Comparative studies reveal that the high surface area of mesoporous cobalt oxide plays an important role on the catalytic reactivity. The outstanding recycling capacity makes the catalyst industrially practical and sustainable for the synthesis of diverse N-heterocycles.
- Cao, Yue,Wu, Yong,Zhang, Yuanteng,Zhou, Jing,Xiao, Wei,Gu, Dong
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p. 3679 - 3686
(2021/06/18)
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- Iron(II)-Catalyzed Aerobic Biomimetic Oxidation of N-Heterocycles
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Herein, an iron(II)-catalyzed biomimetic oxidation of N-heterocycles under aerobic conditions is described. The dehydrogenation process, involving several electron-transfer steps, is inspired by oxidations occurring in the respiratory chain. An environmentally friendly and inexpensive iron catalyst together with a hydroquinone/cobalt Schiff base hybrid catalyst as electron-transfer mediator were used for the substrate-selective dehydrogenation reaction of various N-heterocycles. The method shows a broad substrate scope and delivers important heterocycles in good-to-excellent yields.
- Manna, Srimanta,Kong, Wei-Jun,B?ckvall, Jan-E.
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supporting information
p. 13725 - 13729
(2021/09/08)
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- Transition metal complex, mixture, composition and organic electronic device
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The invention discloses a transition metal complex containing gold (Au). The transition metal complex is shown as a general formula (1). According to the metal complex disclosed by the invention, due to a relatively stable six-membered ring aniline structure, the metal complex can be used as a doping material of a light-emitting layer in an organic electronic light-emitting device, so the stability of the device is improved, and meanwhile, the starting voltage is reduced to prolong the service life of the device.
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Paragraph 0348; 0354; 0355
(2021/06/12)
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- Transition metal complex, polymer, mixture, composition and organic electronic device
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The invention discloses a transition metal complex, a polymer, a mixture, a composition and an organic electronic device. According to the transition metal complex, due to the fact that the metal organic complex contains a ketone group and has excellent electron transmission capacity, the compound contains an arylamine group and also has excellent hole transmission capacity, and the transition metal complex has a stable six-membered ring structure, when the transition metal complex serves as a light-emitting layer doping material and is applied to an organic electronic device, especially an OLED, the light-emitting efficiency of the device can be improved, and the service life of the device can be prolonged.
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Paragraph 0225-0228
(2021/06/23)
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- Transition metal complex, polymer, mixture, composition and organic electronic device
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The invention discloses a transition metal complex, a polymer, a mixture, a composition and an organic electronic device. When the transition metal complex provided by the invention is used as a light-emitting layer doping material and is applied to an organic electronic device, especially an OLED, the light-emitting efficiency of the device can be improved, and the service life of the device can be prolonged.
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Paragraph 0304-0307
(2021/06/26)
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- Transition metal complex, polymer, mixture, composition and organic electronic device
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The invention discloses a transition metal complex. The complex is represented by general formula (1) shown in the specification, G in the specification is selected from cycloalkane or a cage group, and the cage group is coordinated with a metal center in a monovalent anion form to obtain a more stable complex structure. The transition metal complex provided by the invention is used in an OLED, especially as a luminescent layer doping material, not only can provide higher luminous efficiency and longer device life, but also can improve the brightness and current efficiency of the device, and meanwhile, reduces the starting voltage to prolong the service life of the device.
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Paragraph 0309; 0312; 0313
(2021/07/01)
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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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supporting information
p. 5268 - 5272
(2021/02/05)
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- Kinetic Resolution of 2,2-Disubstituted Dihydroquinolines through Chiral Phosphoric Acid-Catalyzed C6-Selective Asymmetric Halogenations
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A novel kinetic resolution of 2,2-disubstituted dihydroquinolines was achieved by regioselective asymmetric halogenations enabled by chiral phosphoric acid catalysis. A series of dihydroquinolines bearing 2,2-disubstitutions were well-tolerated in these reactions, generating both the recovered dihydroquinolines and C-6-brominated products with high enantioselectivities, with s-factors up to 149. In addition, this kinetic resolution protocol is also applicable for 2,2-disubstituted tetrahydroquinoline and asymmetric iodonation reaction.
- Chen, Yunrong,He, Yu-Peng,Liu, Wei,Tao, Houchao,Yang, Xiaoyu,Zhao, Fei,Zhu, Chaofan
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supporting information
p. 4104 - 4108
(2021/06/27)
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- Mild and Robust Stille Reactions in Water using Parts Per Million Levels of a Triphenylphosphine-Based Palladacycle
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An inexpensive and new triphenylphosphine-based palladacycle has been developed as a pre-catalyst, leading to highly effective Stille cross-coupling reactions in water under mild reaction conditions. Only 500–1000 ppm of Pd suffices for couplings involving a variety of aryl/heteroaryl halides with aryl/hetaryl stannanes. Several drug intermediates can be prepared using this catalyst in aqueous nanoreactors formed by 2 wt % Brij-30 in water.
- Takale, Balaram S.,Thakore, Ruchita R.,Casotti, Gianluca,Li, Xaiohan,Gallou, Fabrice,Lipshutz, Bruce H.
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supporting information
p. 4158 - 4163
(2021/02/01)
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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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- Carbocatalytic Cascade Synthesis of Polysubstituted Quinolines from Aldehydes and 2-Vinyl Anilines
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Oxidized active carbon (oAC) catalyses the formation of polysubstituted quinolines from o-vinyl anilines and aldehydes. The reaction proceeds in a cascade manner through condensation, electrocyclization and dehydrogenation, and gives access to a wide range of quinolines with alkyl and/or aryl substituents as demonstrated with 40 examples. The metal-free catalytic procedure allows a heterogeneous protocol for the synthesis of various polysubstituted quinolines. The mechanistic studies imply that both the acid and quinoidic groups in oAC are integral for the catalytic manifold. (Figure presented.).
- Bulatov, Evgeny,Helaja, Juho,Hu, Tao,Lenarda, Anna,M?kel?, Mikko K.,Malinen, Kiia,Melchionna, Michele,Nieger, Martin,Talvitie, Juulia,Wirtanen, Tom
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supporting information
p. 3775 - 3782
(2021/07/20)
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- Iron Single Atom Catalyzed Quinoline Synthesis
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The production of high-value chemicals by single-atom catalysis is an attractive proposition for industry owing to its remarkable selectivity. Successful demonstrations to date are mostly based on gas-phase reactions, and reports on liquid-phase catalysis are relatively sparse owing to the insufficient activation of reactants by single-atom catalysts (SACs), as well as, their instability in solution. Here, mechanically strong, hierarchically porous carbon plates are developed for the immobilization of SACs to enhance catalytic activity and stability. The carbon-based SACs exhibit excellent activity and selectivity (≈68%) for the synthesis of substituted quinolines by a three-component oxidative cyclization, affording a wide assortment of quinolines (23 examples) from anilines and acetophenones feedstock in an efficient, atom-economical manner. Particularly, a Cavosonstat derivative can be synthesized through a one-step, Fe1-catalyzed cyclization instead of traditional Suzuki coupling. The strategy is also applicable to the deuteration of quinolines at the fourth position, which is challenging by conventional methods. The synthetic utility of the carbon-based SAC, together with its reusability and scalability, renders it promising for industrial scale catalysis.
- Chen, Zhongxin,Song, Jingting,Peng, Xinwen,Xi, Shibo,Liu, Jia,Zhou, Wenhui,Li, Runlai,Ge, Rile,Liu, Cuibo,Xu, Haisen,Zhao, Xiaoxu,Li, Haohan,Zhou, Xin,Wang, Lu,Li, Xing,Zhong, Linxin,Rykov, Alexandre I.,Wang, Junhu,Koh, Ming Joo,Loh, Kian Ping
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- Mild and efficient copper-catalyzed oxidative cyclization of oximes with 2-aminobenzyl alcohols at room temperature: synthesis of polysubstituted quinolines
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A simple and efficient ligand-free Cu-catalyzed protocol for the synthesis of polysubstituted quinolinesviaoxidative cyclization of oxime acetates with 2-aminobenzyl alcohols at room temperature has been developed. The presented approach provides a new synthetic pathway leading to polysubstituted quinolines with good functional group tolerance under mild conditions. Moreover, this transformation can be applied for the preparation of quinolines on a gram scale. Oxime acetates serve as the internal oxidants in the reactions, thus making this method very attractive.
- Liu, Yan-Yun,Wei, Yang,Huang, Zhi-Hui,Liu, Yilin
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supporting information
p. 659 - 666
(2021/02/06)
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- Enantiodivergent Synthesis of Chiral Tetrahydroquinoline Derivatives via Ir-Catalyzed Asymmetric Hydrogenation: Solvent-Dependent Enantioselective Control and Mechanistic Investigations
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Ir-catalyzed asymmetric hydrogenation of quinolines was developed, and both enantiomers of chiral tetrahydroquinoline derivatives could be easily obtained, respectively, in high yields with good enantioselectivities through the adjustment of reaction solvents (toluene/dioxane: up to 99% yield, 98% ee (R), TON = 680; EtOH: up to 99% yield, 94% ee (S), TON = 1680). It provided an efficient and simple synthetic strategy for the enantiodivergent synthesis of chiral tetrahydroquinolines, and gram-scale asymmetric hydrogenation proceeded well with low-catalyst loading in these two reaction systems. A series of deuterium-labeling experiments, control experiments, and 1H NMR and electrospray ionization-mass spectrometry experiments have been conducted, and a reasonable and possible reaction process was revealed on the basis of these useful observations.
- Han, Zhengyu,Liu, Gang,Yang, Xuanliang,Dong, Xiu-Qin,Zhang, Xumu
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p. 7281 - 7291
(2021/06/30)
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- Synthesis of α-Alkylated Ketones via Selective Epoxide Opening/Alkylation Reactions with Primary Alcohols
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A new method for converting terminal epoxides and primary alcohols into α-alkylated ketones under borrowing hydrogen conditions is reported. The procedure involves a one-pot epoxide ring opening and alkylation via primary alcohols in the presence of an N-heterocyclic carbene iridium(I) catalyst, under aerobic conditions, with water as the side product.
- Gen?, Serta?,Gülcemal, Süleyman,Günnaz, Salih,?etinkaya, Bekir,Gülcemal, Derya
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supporting information
p. 5229 - 5234
(2021/07/19)
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- Chromium-Catalyzed Reductive Cleavage of Unactivated Aromatic and Benzylic C-O Bonds
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Reductive cleavage of aromatic and benzylic C-O bonds by chromium catalysis is reported. This deoxygenative reaction was promoted by low-cost CrCl 2precatalyst combined with poly(methyl hydrogen siloxane) as the mild reducing agent, providing a strategy in forming reduced motifs by cleavage of unactivated C-O bonds. A range of functional groups such as bromide, chloride, fluoride, hydroxyl, amino, and alkoxycarbonyl can be retained in the reduction.
- Yuan, Shuqing,Ling, Liang,Tang, Jinghua,Luo, Meiming,Zeng, Xiaoming
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supporting information
p. 3343 - 3350
(2021/07/02)
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- Quinoline derivative as well as preparation method and application thereof
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The invention belongs to the technical field of chemical drug synthesis, and particularly relates to a quinoline derivative as well as a preparation method and application thereof. In a reaction system, firstly, a metal catalyst, a ligand and a silicon hydrogen reagent interact to generate metal hydride, the metal hydride and an alkyne compound are subjected to addition, the metal hydride and an anthranil compound are subjected to an electrophilic amination reaction, and then the polysubstituted quinoline derivative is obtained through intramolecular cyclization. According to the invention, the starting raw materials such as the alkyne and the anthranil compound of the reaction are cheap and easily available, a variety of different polysubstituted quinoline derivatives can be constructed by using the one-step method, and can be rapidly converted into other compounds through the oxidation, the reduction, the coupling and other approaches of the target molecule so as to provide the good application prospect in the fields of drug development and material preparation; and the method is mild in condition, green, efficient, simple to operate and very suitable for large-scale industrial production.
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Paragraph 0089-0096
(2021/07/17)
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- NiH-Catalyzed Hydroamination/Cyclization Cascade: Rapid Access to Quinolines
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Despite the significant success of metal-H-catalyzed hydroamination methodologies, considerable limitations still exist in the selective hydroamination of alkynes, especially for terminal alkynes. Herein, we develop a highly efficient NiH catalytic system that activates readily available alkynes for a cascade hydroamination/cyclization reaction with anthranils. This mild, operationally simple protocol is amenable to a wide array of alkynes including terminal and internal, aryl and alkyl, electron-deficient and electron-rich ones, delivering structurally diverse quinolines in useful to excellent yields (>80 examples, up to 93% yield). The utility of this procedure is exhibited in the late-stage functionalization of several natural products and in the concise synthesis of an antitumor molecule graveolinine and a triplex DNA intercalator. Preliminary mechanistic experiments suggest an alkenylnickel-mediated alkyne hydroamination and an intramolecular cyclization/aromatization of putative enamine intermediates.
- Chen, Qian,Gao, Yang,Hu, Xiao-Qiang,Huo, Yanping,Li, Xianwei,Yang, Simin
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p. 7772 - 7779
(2021/06/30)
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