- Sustainable synthesis of quinolines (pyridines) catalyzed by a cheap metal Mn(I)-NN complex catalyst
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This study represents the first example of a bidentate phosphine-free manganese(I)-NN complex catalyst for the synthesis of quinolines (pyridines) through acceptorless dehydrogenative condensation of various secondary alcohols with amino alcohols. The coupling reactions occurred at 3 mol% catalyst loading and 110°C, and tolerated diverse functional groups. Moderate to excellent yields ranging from 45% to 89% were achieved after 12 hr of reaction. The present protocol provides a concise and environmentally friendly method for the construction of heterocyclic compounds.
- Chai, Huining,Tan, Weiqiang,Lu, Yuanyuan,Zhang, Guangyao,Ma, Jiping
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- Pyridine mediated transition-metal-free direct alkylation of anilines using alcohols: via borrowing hydrogen conditions
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Herein, we report pyridine and other similar azaaromatics as efficient biomimetic hydrogen shuttles for a transition-metal-free direct N-alkylation of aryl and heteroaryl amines using a variety of benzylic and straight chain alcohols. Mechanistic studies including deuterium labeling and the isolation of dihydro-intermediates of the benzannulated pyridine confirmed the role of pyridine and a borrowing hydrogen process operating in these reactions. In addition, we have extended this methodology for the development of dehydrogenative synthesis of quinolines and indoles, as well as the transfer hydrogenation of ketones. This journal is
- Pothikumar, Rajagopal,Bhat, Venugopal T,Namitharan, Kayambu
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supporting information
p. 13607 - 13610
(2020/11/17)
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- Superbase-Mediated Indirect Friedl?nder Reaction: A Transition Metal-Free Oxidative Annulation toward Functionalized Quinolines
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A superbase mediated indirect Friedl?nder reaction towards functionalized quinolines has been realized. The reaction was performed with o-aminobenzyl alcohol and ketones having an active methylene moiety in the presence of KOH and in DMSO. The reaction proceeds predominantly via initial formation of an imine intermediate and subsequent oxidation of the benzyl alcohol functionality and condensation to afford substituted quinolines. We could also demonstrate that a minor fraction of the reaction proceeds via a chalcone intermediate. The transition metal-free oxidative annulation was found to be general affording 2-substituted, 2,3-disubstituted/fused or multi-substituted quinolines. The reaction was extended towards the functionalization of natural products and the applicability of the reaction for gram-scale synthesis of quinolines was also demonstrated.
- Rahul,Nitha,Omanakuttan, Vishnu K.,Babu, Sheba Ann,Sasikumar,Praveen, Vakayil K.,Hopf, Henning,John, Jubi
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p. 3081 - 3089
(2020/05/08)
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- Unsymmetrical triazolyl-naphthyridinyl-pyridine bridged highly active copper complexes supported on reduced graphene oxide and their application in water
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A novel unsymmetrical triazolyl-naphthyridinyl-pyridine ligand was designed and synthesized, and employed in the synthesis of a heterogeneous copper complex on reduced graphene oxide. The resulting copper composite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX). This supported copper catalyst containing unsymmetrical triazolyl-naphthyridinyl-pyridine (only 0.1 mol%) showed excellent catalytic activity in water with good recyclability. Various functionalized quinoline derivatives were successfully synthesized in high yields through the green strategy in water. Other heterocyclic compounds, such as pyridine, 2-(pyridin-2-yl)quinoline, 1,8-naphthyridine, 5,6-dihydronaphtho[1,2-b][1,8]naphthyridine and 2-(pyridin-2-yl)-1,8-naphthyridine derivatives, were achieved in water with more than 80% yields. Mechanism studies revealed that this transformation occurs via dehydrogenation, condensation, and transfer hydrogenation and dehydrogenation processes which was supported by a deuterium labeling experiment.
- Hu, Wenkang,Zhang, Yilin,Zhu, Haiyan,Ye, Dongdong,Wang, Dawei
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supporting information
p. 5345 - 5351
(2019/10/11)
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- Green synthesis of silver nanoparticles using green alga (Chlorella vulgaris) and its application for synthesis of quinolines derivatives
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Nanoparticles have been used century ago but have regained their importance in recent years being simple, ecofriendly, pollutant free, nontoxic, low-cost approach, and due good atom economy. In this report, we have demonstrated the synthesis of silver nanoparticles using green algae (Chlorella vulgaris) which in turn was used for synthesis of biologically important quinolines. Algal extract was prepared and treated with silver nitrate solution for the synthesis of silver nanoparticles. Synthesized nanoparticles were characterized with the help of analytical tools like UV, FTIR, X-ray, and SEM and used as a catalyst for the synthesis of quinolines.
- Mahajan, Akhil,Arya, Anju,Chundawat, Tejpal Singh
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supporting information
p. 1926 - 1937
(2019/05/17)
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- Nonbifunctional Outer-Sphere Strategy Achieved Highly Active α-Alkylation of Ketones with Alcohols by N-Heterocyclic Carbene Manganese (NHC-Mn)
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The unusual nonbifunctional outer-sphere strategy was successfully utilized in developing an easily accessible N-heterocyclic carbene manganese (NHC-Mn) system for highly active α-alkylation of ketones with alcohols. This system was efficient for a wide range of ketones and alcohols under mild reaction conditions, and also for the green synthesis of quinoline derivatives. The direct outer-sphere mechanism and the high activity of the present system demonstrate the potential of nonbifunctional outer-sphere strategy in catalyst design for acceptorless dehydrogenative transformations.
- Lan, Xiao-Bing,Ye, Zongren,Huang, Ming,Liu, Jiahao,Liu, Yan,Ke, Zhuofeng
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supporting information
p. 8065 - 8070
(2019/10/11)
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- π-Allylpalladium Species in Micelles of FI-750-M for Sustainable and General Suzuki-Miyaura Couplings of Unactivated Quinoline Systems in Water
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General, clean, and sustainable Suzuki-Miyaura cross-couplings of 2-and 4-quinoline and isoquinoline systems have been demonstrated with use of π-allyl Pd catalyst in the nanomicelles of environmentally benign, proline-derived surfactant FI-750-M. Optimiz
- Handa, Sachin,Ibrahim, Faisal,Ansari, Tharique N.,Gallou, Fabrice
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p. 4229 - 4233
(2018/09/21)
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- Iron-catalyzed cross-coupling of N-heterocyclic chlorides and bromides with arylmagnesium reagents
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A simple, practical iron salt catalyzed procedure allows fast cross-couplings of N-heterocyclic chlorides and bromides with various electron-rich and -poor arylmagnesium reagents. A solvent mixture of THF and tBuOMe is found to be essential for achieving high yields mainly by avoiding homocoupling side reactions.
- Kuzmina, Olesya M.,Steib, Andreas K.,Knochel, Paul,Flubacher, Dietmar
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supporting information
p. 4818 - 4821,4
(2012/12/12)
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- Pd-catalyzed cross-coupling of aryl carboxylic acids with propiophenones through a combination of decarboxylation and dehydrogenation
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A palladium-catalyzed cross-coupling reaction of aryl carboxylic acids with saturated propiophenones through a combination of decarboxylation and dehydrogenation to form Heck-type products was reported. In a glove box, a 25 mL tube equipped with a stir bar was charged with Pd(OAc)2, PCy3, propiophenone, 2-nitrobenzoic acid, Ag2CO3 and nBu4NOAc HOAc. Then, the mixture was heated under nitrogen at 90°C in DMF for 24 h. After cooling down, the crude reaction mixture was analyzed by GC with n-dodecane as an internal standard to obtain 3a in 75% GC yield. Relatively weak bases, such as carboxylate salts, facilitated this reaction and the effect of the bases was a function of their solubility, while strong bases, such as K3PO4 and K2CO3 shut down the reaction completely. The simultaneous use of carboxylate salts and equimolar carboxylic acids significantly improved the yield of 3a, although the use of acetic acid alone was ineffective for the reaction.
- Zhou, Jun,Wu, Ge,Zhang, Min,Jie, Xiaoming,Su, Weiping
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supporting information; experimental part
p. 8032 - 8036
(2012/08/13)
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- Highly enantioselective hydrogenation of quinolines using phosphine-free chiral cationic Ruthenium catalysts: Scope, mechanism, and origin of enantioselectivity
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Asymmetric hydrogenation of quinolines catalyzed by chiral cationic η6-arene-N-tosylethylenediamine-Ru(II) complexes have been investigated. A wide range of quinoline derivatives, including 2-alkylquinolines, 2-arylquinolines, and 2-functionalized and 2,3-disubstituted quinoline derivatives, were efficiently hydrogenated to give 1,2,3,4-tetrahydroquinolines with up to >99% ee and full conversions. This catalytic protocol is applicable to the gram-scale synthesis of some biologically active tetrahydroquinolines, such as (-)-angustureine, and 6-fluoro-2-methyl-1,2,3,4-tetrahydroquinoline, a key intermediate for the preparation of the antibacterial agent (S)-flumequine. The catalytic pathway of this reaction has been investigated in detail using a combination of stoichiometric reaction, intermediate characterization, and isotope labeling patterns. The evidence obtained from these experiments revealed that quinoline is reduced via an ionic and cascade reaction pathway, including 1,4-hydride addition, isomerization, and 1,2-hydride addition, and hydrogen addition undergoes a stepwise H+/H- transfer process outside the coordination sphere rather than a concerted mechanism. In addition, DFT calculations indicate that the enantioselectivity originates from the CH/π attraction between the η6-arene ligand in the Ru-complex and the fused phenyl ring of dihydroquinoline via a 10-membered ring transition state with the participation of TfO- anion.
- Wang, Tianli,Zhuo, Lian-Gang,Li, Zhiwei,Chen, Fei,Ding, Ziyuan,He, Yanmei,Fan, Qing-Hua,Xiang, Junfeng,Yu, Zhi-Xiang,Chan, Albert S. C.
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supporting information; experimental part
p. 9878 - 9891
(2011/08/10)
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- A recyclable palladium-catalyzed modified Friedl?nder quinoline synthesis
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2-Aminobenzyl alcohol reacts with an array of ketones in toluene/poly(ethylene glycol) (PEG-2000) at 100 °C in the presence of a palladium catalyst along with KOH under an atmosphere of air to give the corresponding quinolines in good yields. The catalytic system could be recovered and reused five times without any loss of catalytic activity.
- Cho, Chan Sik,Ren, Wen Xiu
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p. 4182 - 4186
(2008/02/10)
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- A copper(II)-catalyzed protocol for modified Friedl?nder quinoline synthesis
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2-Aminobenzyl alcohol reacts with an array of ketones in dioxane at 100 °C in the presence of a catalytic amount of CuCl2 along with KOH under O2 atmosphere to afford the corresponding quinolines in good yields. 2-Aminobenzyl alcohol is also oxidatively coupled and cyclized with various aldehydes by step-by-step procedure, an initial treatment of 2-aminobenzyl alcohol in the presence of CuCl2 and KOH in dioxane under O2 atmosphere and subsequent addition of aldehyde to the mixture followed by stirring under argon atmosphere, to give 3-substituted quinolines in moderate to good yields.
- Cho, Chan Sik,Ren, Wen Xiu,Shim, Sang Chul
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p. 6781 - 6785
(2007/10/03)
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- Multifunctional catalysis of a ruthenium-grafted hydrotalcite: One-pot synthesis of quinolines from 2-aminobenzyl alcohol and various carbonyl compounds via aerobic oxidation and aldol reaction
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The Ru-grafted hydrotalcite was found to be an excellent multifunctional catalyst for one-pot synthesis of quinolines from 2-aminobenzyl alcohol and various carbonyl compounds. These quinolines were obtained through aerobic oxidation by the Ru species, followed by aldol reaction on base sites of the hydrotalcite.
- Motokura, Ken,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
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p. 6029 - 6032
(2007/10/03)
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- Ruthenium-catalysed oxidative cyclisation of 2-aminobenzyl alcohol with ketones: modified Friedlaender quinoline synthesis
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2-Aminobenzyl alcohol is oxidatively cyclised with an array of ketones in dioxane at 80 deg C in the presence of a catalytic amount of a ruthenium catalyst and KOH to afford the corresponding quinolines in high yields.
- Cho, Chan Sik,Kim, Bok Tae,Kim, Tae-Jeong,Shim, Sang Chul
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p. 2576 - 2577
(2007/10/03)
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- The palladium-catalyzed transfer hydrogenation/heterocyclization of β- (2-aminophenyl)-α,β-ynones. An approach to 2-aryl- and 2-vinylquinolines
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The palladium-catalyzed transfer hydrogenation/cyclization of readily available β-(o-aminophenyl)-α,β-ynones I affords 2-aryl- and 2- vinylquinolines 3 in good yield.
- Cacchi, Sandro,Fabrizi, Giancarlo,Marinelli, Fabio
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p. 401 - 404
(2007/10/03)
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