491-35-0Relevant articles and documents
A novel approach to vapor-phase synthesis of 2- and 4-methylquinoline from lactic acid and aniline
Li, An,Huang, Chen,Luo, Cai-Wu,Li, Li-Jun,Yi, Wen-Jun,Liu, Tian-Wei,Chao, Zi-Sheng
, p. 13 - 16 (2017)
A novel and green route for vapor-phase synthesis of 2- and 4-methylquinoline was provided in this work, in which lactic acid as one of the reactants was for the first time employed. Various influencing factors, including types of catalysts, reaction temperature and stability of catalyst were investigated systematically. The results showed that a 67.6% total yield of quinolines was obtained over the HBeta catalyst. The characterization by using BET, NH3-TPD and pyridine-IR techniques revealed that strong Br?nsted acid sites are favorable for generation of 2- and 4-methylquinoline whereas Lewis acid sites could increase the proportion of 4-methylquinoline in target products. Besides, a feasible reaction pathway to synthesize 2- and 4-methylquinoline was proposed on the basis of the reaction products.
Reactivity of quinoline- and isoquinoline-based heteroaromatic substrates in palladium(0)-catalyzed benzylic nucleophilic substitution
Legros, Jean-Yves,Primault, Gaelle,Toffano, Martial,Riviere, Marie-Alix,Fiaud, Jean-Claude
, p. 433 - 436 (2000)
(Formula presented) Quinolylmethyl, 1-(isoquinolyl)ethyl, and 1-(quinolyl)ethyl acetates reacted with dimethylmalonate anion in the presence of a Pd(0) catalyst to give products of nucleophilic substitution and/or byproducts, depending upon the substitution pattern. The observed side reactions were reduction in the case of primary acetates and elimination or elimination/Michael-type addition sequence for secondary substrates.
Vapour-phase synthesis of 2-methyl- and 4-methylquinoline over BEA* zeolites
Brosius, Roald,Gammon, David,Van Laar, Frederik,van Steen, Eric,Sels, Bert,Jacobs, Pierre
, p. 362 - 368 (2006)
4-Methylquinoline and 2-methylquinoline were synthesized from acetaldehyde and aniline in the gas phase over BEA* zeolite catalysts. High combined yields of 2- and 4-methyl-substituted quinolines were obtained with H-BEA* zeolite and with BEA*-F synthesized in fluoride medium, with 4-methylquinoline being the predominant isomer. Postsynthesis fluorination of the H-BEA* with ammonium fluoride leads to dealumination and formation of extra-framework aluminium fluoride compounds. Product selectivities changed with time over this catalyst, such that 2-methylquinoline became the predominant product. New insight into the reaction mechanism is offered, and previous propositions can be rationalized based on these new results.
Synthesis of Quinolines via the Metal-free Visible-Light-Mediated Radical Azidation of Cyclopropenes
Smyrnov, Vladyslav,Muriel, Bastian,Waser, Jerome
, p. 5435 - 5439 (2021/07/21)
We report the synthesis of quinolines using cyclopropenes and an azidobenziodazolone (ABZ) hypervalent iodine reagent as an azide radical source under visible-light irradiation. Multisubstituted quinoline products were obtained in 34-81% yield. The reaction was most efficient for 3-trifluoromethylcyclopropenes, affording valuable 4-trifluoromethylquinolines. The transformation probably proceeds through the cyclization of an iminyl radical formed by the addition of the azide radical on the cyclopropene double bond, followed by ring-opening and fragmentation.
Visible-light-mediated organoboron-catalysed metal-free dehydrogenation of N-heterocycles using molecular oxygen
Wei, Lanfeng,Wei, Yu,Xu, Liang,Zhang, Jinli
supporting information, p. 4446 - 4450 (2021/06/30)
The surge of photocatalytic transformation not only provides unprecedented synthetic methods, but also triggers the enthusiasm for more sustainable photocatalysts. On the other hand, oxygen is an ideal oxidant in terms of atom economy and environmental friendliness. However, the poor reactivity of oxygen at the ground state makes its utilization challenging. Herein, a visible-light-induced oxidative dehydrogenative process is disclosed, which uses an organoboron compound as the photocatalyst and molecular oxygen as the sole oxidant.Viathis approach, an array of N-heterocycles have been accessed under metal-free mild conditions, in good to excellent yields.
Highly Ordered Mesoporous Cobalt Oxide as Heterogeneous Catalyst for Aerobic Oxidative Aromatization of N-Heterocycles
Cao, Yue,Wu, Yong,Zhang, Yuanteng,Zhou, Jing,Xiao, Wei,Gu, Dong
, p. 3679 - 3686 (2021/06/18)
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.
Iron(II)-Catalyzed Aerobic Biomimetic Oxidation of N-Heterocycles
Manna, Srimanta,Kong, Wei-Jun,B?ckvall, Jan-E.
supporting information, p. 13725 - 13729 (2021/09/08)
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.
Efficient acceptorless dehydrogenation of hydrogen-rich N-heterocycles photocatalyzed by Ni(OH)2@CdSe/CdS quantum dots
Liu, Yanpeng,Yu, Tianjun,Zeng, Yi,Chen, Jinping,Yang, Guoqiang,Li, Yi
, p. 3810 - 3817 (2021/06/18)
Hydrogen storage using liquid organic hydrogen carriers (LOHCs) is a promising hydrogen storage technology; however, the hydrogen release process typically requires a high temperature. Developing dehydrogenation technology under mild conditions is highly desirable. Herein, a new approach for photocatalytic acceptorless dehydrogenation of hydrogen-rich LOHCs using Ni(OH)2@CdSe/CdS QDs as the photocatalyst was demonstrated. 1,2,3,4-Tetrahydroquinoline (THQ), iso-THQ, indoline, and their derivatives were selected as hydrogen-rich substrates, which exhibit excellent dehydrogenation efficiency with the release of hydrogen photocatalyzed by Ni(OH)2@CdSe/CdS QDs. Up to 100% yields of hydrogen and over 90% yields of complete dehydrogenation products were obtained at ambient temperature. Isotope tracer studies indicate a stepwise pathway, beginning with the photocatalytic oxidation of the substrate to release a proton and followed by proton exchange with heavy water. This work provides a promising alternative strategy to develop highly efficient, low cost and earth-abundant photocatalysts for acceptorless dehydrogenation of hydrogen-rich LOHCs.
Method for realizing oxidative dehydrogenation of nitrogen-containing heterocyclic ring by using biomass-based carbon material
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Paragraph 0010-0011; 0014-0015, (2021/06/26)
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.
Highly Chemoselective Deoxygenation of N-Heterocyclic N-Oxides Using Hantzsch Esters as Mild Reducing Agents
An, Ju Hyeon,Kim, Kyu Dong,Lee, Jun Hee
supporting information, p. 2876 - 2894 (2021/02/01)
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).
