- Studies on methylglyoxal 1. Fluorometric determination of methylglyoxal using high-performance liquid chromatography
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A high-performance liquid chromatographic (HPLC) method has been developed for the determination of methylglyoxal (MG). When MG was treated with o-phenylenediamine and trichloroacetic acid, it was converted to a highly fluorescent new compound, 2-(2-benzimidazolyl)-3-methylquinoxaline (BIMQ) the chemical structure of which was elucidated by NMR and MS. BIMQ was analyzed by HPLC using a 4 mm x 25 mm column packed with LiChrosorb Si-60 (10 μ). This method is highly sensitive and was satisfactorily applied to the measurement of MG in biological materials.
- Matsuura,Yoshino,Ooki,et al.
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- KINETICS AND MECHANISM OF THE ACID-CATALYZED REACTIONS OF METHYLATED TRIOSES
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In aqueous hydrochloric acid, 2,3-di-O-methyl-D-glyceraldehyde and 1,3-dimethoxy-2-propanone undergo acid-catalyzed reactions producing 2-oxopropanal.The kinetics of these two reactions were studied polarographically.The kinetic data obtained and the incorporation of deuterium from the medium into the 2-oxopropanal formed (isolated as 2-methylquinoxaline and analyzed mass spectrometrically), allowed formulation of a mechanism for the acid-catalyzed reaction of both methylated trioses.The mechanism proposed are in agreement with quantum-chemical calculations of the charge distribution in the compounds studied and in some of their important intermediates.
- Fedoronko, Michal,Temkovic, Peter,Mihalov, Vincent,Tvaroska, Igor
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- Bio-inspired Maillard-Like reactions enable a simple and sensitive assay for colorimetric detection of methylglyoxal
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A simple and selective assay for detecting methylglyoxal (MGO), a metabolite associated with diabetes, was developed by combining a bio-inspired chemical reaction with the anti-aggregation of gold nanoparticles. This assay could detect MGO at as low as 1 μM by the naked eye and 0.05 μM by UV/vis spectrometry, within the clinical range marking oxidative stress in diabetes, and demonstrated high selectivity over other physiologically relevant ketones and aldehydes.
- Wang, Shih-Ting,Lin, Yiyang,Spicer, Christopher D.,Stevens, Molly M.
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Read Online
- Method for site-selective alkylation of Diazine-N-oxide using phosphonium ylides
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- N - Oxide (Diazine -)N-The position selective Oxides-C alkylation of H) relates to a method alkylation. To the present invention, a plurality of diazine compounds can be alkylated by selectively introducing an alkyl group to a diazine compound known as a core unit structure in a medicine, and synthesis of a plurality of diazine compounds (varenicline) paenibacillin A, which is a natural product, can be synthesized.
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Paragraph 0146; 0147; 0233; 0237; 0240
(2021/04/06)
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- Decarboxylation of Aromatic Carboxylic Acids by the Prenylated-FMN-dependent Enzyme Phenazine-1-carboxylic Acid Decarboxylase
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Phenazine-1-carboxylic acid decarboxylase (PhdA) is a member of the expanding class of prenylated-FMN-dependent (prFMN) decarboxylase enzymes. These enzymes have attracted interest for their ability to catalyze (de)carboxylation reactions on aromatic rings and conjugated double bonds. Here we describe a method to reconstitute PhdA with prFMN that produces an active and stable form of the holo-enzyme that does not require prereduction with dithionite for activity. We establish that oxidized phenazine-1-carboxylate (PCA) is the substrate for decarboxylation, withkcat= 2.6 s-1andKM= 53 μM. PhdA also catalyzes the much slower exchange of solvent deuterium into the product, phenazine, with an apparent turnover number of 0.8 min-1. The enzyme was found to catalyze the decarboxylation of a broad range of polyaromatic carboxylic acids, including anthracene-1-carboxylic acid. Previously described prFMN-dependent aromatic (de)carboxylases have utilized electron-rich phenolic or heterocyclic molecules as substrates. PhdA extends the substrate range of prFMN-dependent (de)carboxylases to electron-poor and unfunctionalized aromatic systems, suggesting that it may prove a useful catalyst for the regioselective (de)carboxylation of otherwise unreactive aromatic molecules.
- Datar, Prathamesh M.,Marsh, E. Neil G.
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p. 11723 - 11732
(2021/09/28)
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- Method for synthesizing quinoxaline compound under visible light induced iron catalysis condition
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The invention belongs to the technical field of compound synthesis, and particularly relates to a method for synthesizing quinoxaline compounds under visible light induced iron catalysis conditions. The method comprises the following steps: by taking non-activated aliphatic amine and o-phenylenediamine as raw materials, under the action of a photosensitizer, under the illumination of visible light, reacting in a solvent at room temperature and under oxygen conditions to generate the quinoxaline compound. The method has better substrate universality and relatively mild reaction conditions, not only realizes synthesis of the quinoxaline compound for the first time, but also widens the field of organic synthesis.
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Paragraph 0035-0041; 0287-0308
(2021/07/10)
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- NaOH-Mediated Direct Synthesis of Quinoxalines from o-Nitroanilines and Alcohols via a Hydrogen-Transfer Strategy
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A NaOH-mediated sustainable synthesis of functionalized quinoxalines is disclosed via redox condensation of o-nitroamines with diols and α-hydroxy ketones. Under optimized conditions, various o-nitroamines and alcohols are well tolerated to generate the desired products in 44-99% yields without transition metals and external redox additives.
- Wang, Yan-Bing,Shi, Linlin,Zhang, Xiaojie,Fu, Lian-Rong,Hu, Weinan,Zhang, Wenjing,Zhu, Xinju,Hao, Xin-Qi,Song, Mao-Ping
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p. 947 - 958
(2021/01/14)
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- Iron-catalyzed one-pot synthesis of quinoxalines: Transfer hydrogenative condensation of 2-nitroanilines with vicinal diols
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Here, we report iron-catalyzed one-pot synthesis of quinoxalines via transfer hydrogenative condensation of 2-nitroanilines with vicinal diols. The tricarbonyl (η4-cyclopentadienone) iron complex, which is well known as the Kn?lker complex, catalyzed the oxidation of alcohols and the reduction of nitroarenes, and the corresponding carbonyl and 1,2-diaminobenzene intermediates were generated in situ. Trimethylamine N-oxide was used to activate the iron complex. Various unsymmetrical and symmetrical vicinal diols were applied for transfer hydrogenation, resulting in quinoxaline derivatives in 49-98% yields. A plausible mechanism was proposed based on a series of control experiments. The major advantages of this protocol are that no external redox reagents or additional base is needed and that water is liberated as the sole byproduct. This journal is
- Chun, Simin,Hong, Junhwa,Hong, Suckchang,Lee, Seok Beom,Oh, Dong-Chan,Putta, Ramachandra Reddy
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p. 18225 - 18230
(2021/06/03)
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- Hydrogen Auto-transfer Synthesis of Quinoxalines from o-Nitroanilines and Biomass-based Diols Catalyzed by MOF-derived N,P Co-doped Cobalt Catalysts
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A Co-based heterogeneous catalyst supported on N,P co-doped porous carbon (Co@NCP) is prepared via a facile in-situ doping-carbonization method. The Co@NCP composite features a large surface area, high pore volume, high-density and strong basic sites. Furthermore, doping of P atoms can regulate the electronic density of Co. Therefore, Co@NCP exhibits good performance for the synthesis of quinoxalines from o-nitroanilines and biomass-derived diols under alkali-free conditions.
- Sun, Kangkang,Li, Dandan,Lu, Guo-Ping,Cai, Chun
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p. 373 - 381
(2020/12/09)
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- Tetrabutylammonium Bromide-Catalyzed Transfer Hydrogenation of Quinoxaline with HBpin as a Hydrogen Source
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A metal-free environmentally benign, simple, and efficient transfer hydrogenation process of quinoxaline has been developed using the HBpin reagent as a hydrogen source. This reaction is compatible with a variety of quinoxalines offering the desired tetrahydroquinoxalines in moderate-to-excellent yields with Bu4NBr as a noncorrosive and low-cost catalyst.
- Chen, Jingchao,Fan, Baomin,Guo, Qi,Lu, Guangfu,Shen, Guoli,Tang, Yan,Wu, Shiyuan,Yang, Xuemei,Zhu, Yuanbin
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- Application of a reusable Co-based nanocatalyst in alcohol dehydrogenative coupling strategy: Synthesis of quinoxaline and imine scaffolds
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A nitrogen doped carbon supported cobalt catalyzed efficient synthesis of imines and quinoxaline motifs is reported. Co(OAc)2-Phen/Carbon-800 (Co-phen/C-800) showed the superior reactivity compared to other materials prepared at different temperature, in the synthesis of quinoxalines by the coupling between diamines and diols. Moreover, applying the transfer hydrogenation and acceptorless dehydrogenative coupling strategy, imines and quinoxaline derivatives were synthesized from the nitro compounds. The practical applicability of this protocol was demonstrated by the gram-scale synthesis and the reusability of the catalyst upto 8th cycle. Furthermore, several kinetic experiments were carried out to realize the probable mechanism.
- Panja, Dibyajyoti,Paul, Bhaskar,Balasubramaniam, Bhuvaneshwari,Gupta, Raju K.,Kundu, Sabuj
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- Nickel-Catalyzed Direct Synthesis of Quinoxalines from 2-Nitroanilines and Vicinal Diols: Identifying Nature of the Active Catalyst
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The inexpensive and simple NiBr2/1,10-phenanthroline system-catalyzed synthesis of a series of quinoxalines from both 2-nitroanilines and 1,2-diamines is demonstrated. The reusability test for this system was performed up to the seventh cycle, which afforded good yields of the desired product without losing its reactivity significantly. Notably, during the catalytic reaction, the formation of the heterogeneous Ni-particle was observed, which was characterized by PXRD, XPS, and TEM techniques.
- Shee, Sujan,Panja, Dibyajyoti,Kundu, Sabuj
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p. 2775 - 2784
(2020/03/13)
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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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- Hydrogenation or Dehydrogenation of N-Containing Heterocycles Catalyzed by a Single Manganese Complex
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A highly chemoselective base-metal catalyzed hydrogenation and acceptorless dehydrogenation of N-heterocycles is presented. A well-defined Mn complex operates at low catalyst loading (as low as 2 mol %) and under mild reaction conditions. The described catalytic system tolerates various functional groups, and the corresponding reduced heterocycles can be obtained in high yields. Experimental studies indicate a metal-ligand cooperative catalysis mechanism.
- Borghs, Jannik C.,Rueping, Magnus,Zubar, Viktoriia
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supporting information
(2020/05/19)
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- Nanocatalosomes as Plasmonic Bilayer Shells with Interlayer Catalytic Nanospaces for Solar-Light-Induced Reactions
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Interest and challenges remain in designing and synthesizing catalysts with nature-like complexity at few-nm scale to harness unprecedented functionalities by using sustainable solar light. We introduce “nanocatalosomes”—a bio-inspired bilayer-vesicular design of nanoreactor with metallic bilayer shell-in-shell structure, having numerous controllable confined cavities within few-nm interlayer space, customizable with different noble metals. The intershell-confined plasmonically coupled hot-nanospaces within the few-nm cavities play a pivotal role in harnessing catalytic effects for various organic transformations, as demonstrated by “acceptorless dehydrogenation”, “Suzuki–Miyaura cross-coupling” and “alkynyl annulation” affording clean conversions and turnover frequencies (TOFs) at least one order of magnitude higher than state-of-the-art Au-nanorod-based plasmonic catalysts. This work paves the way towards next-generation nanoreactors for chemical transformations with solar energy.
- Cho, Yoon-Kyoung,Dubbu, Sateesh,Kim, Inki,Koo, Jung Hun,Kumar, Amit,Kumar, Sumit,Kumari, Nitee,Kwon, Taewan,Lee, In Su,Lim, Jongwon,Rho, Junsuk
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supporting information
p. 9460 - 9469
(2020/05/04)
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- Hydrogenation/dehydrogenation of N-heterocycles catalyzed by ruthenium complexes based on multimodal proton-responsive CNN(H) pincer ligands
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Ru complexes based on lutidine-derived pincer CNN(H) ligands having secondary amine side donors are efficient precatalysts in the hydrogenation and dehydrogenation of N-heterocycles. Reaction of a Ru-CNN(H) complex with an excess of base produces the formation of a Ru(0) derivative, which is observed under catalytic conditions.
- álvarez, Eleuterio,Hernández-Juárez, Martín,López-Serrano, Joaquín,Paneque, Margarita,Rendón, Nuria,Sánchez, Práxedes,Santos, Laura L.,Suárez, Andrés
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supporting information
p. 9583 - 9587
(2020/07/30)
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- Manganese(I)-Catalyzed Sustainable Synthesis of Quinoxaline and Quinazoline Derivatives with the Liberation of Dihydrogen
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Direct synthesis of N-heterocycles via the acceptorless dehydrogenative coupling is very challenging and scarcely reported under 3d transition-metal catalysis. Here, we have developed an efficient Mn(I)-catalyzed sustainable synthesis of various quinoxalines from 1,2-diaminobenzenes and 1,2-diols via the acceptorless dehydrogenative coupling reaction. Further, this strategy was successfully applied for the unprecedented synthesis of quinazolines by the reaction of 2-aminobenzyl alcohol with primary amides. The present protocol provides an atom-economical and sustainable route for the synthesis of various quinoxaline and quinazoline derivatives by employing an earth-abundant manganese salt and simple phosphine-free NNN-tridentate ligand.
- Mondal, Akash,Sahoo, Manoj Kumar,Subaramanian, Murugan,Balaraman, Ekambaram
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p. 7181 - 7191
(2020/07/21)
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- Site-Selective C-H Alkylation of Diazine N-Oxides Enabled by Phosphonium Ylides
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The synthesis of alkylated diazine derivatives is important for their practical utilization as pharmaceuticals and for other purposes. Herein, we describe the metal-free site-selective C-H alkylation of diazine N-oxides using phosphonium ylides that affords a variety of alkylated diazine derivatives with broad functional group tolerance. The utility of this method is showcased by the late-stage functionalization of a commercially available drug such as varenicline. Notably, the sequential C-H alkylation of pyrazine N-oxides for the total synthesis of a pyrazine-containing natural product, paenibacillin A, highlights the importance of this method.
- Ghosh, Prithwish,Kwon, Na Yeon,Han, Sangil,Kim, Saegun,Han, Sang Hoon,Mishra, Neeraj Kumar,Jung, Young Hoon,Chung, Sang J.,Kim, In Su
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supporting information
p. 6488 - 6493
(2019/08/20)
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- Transition metal-free α-methylation of 1,8-naphthyridine derivatives using DMSO as methylation reagent
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A practical approach to the direct α-methylation of 1,8-naphthyridines under mild reaction conditions has been developed using simple and readily available DMSO as a convenient and environmentally friendly carbon source. This method is transition metal-free and highly chemoselective, shows good functional group tolerance, and uses DMSO as a methyl source, providing efficient and rapid access to an important compound class, 2-methyl-1,8-naphthyridines.
- Jiang, Shaohua,Yang, Zhihai,Guo, Ziyin,Li, Yibiao,Chen, Lu,Zhu, Zhongzhi,Chen, Xiuwen
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p. 7416 - 7424
(2019/08/15)
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- Cooperative iridium complex-catalyzed synthesis of quinoxalines, benzimidazoles and quinazolines in water
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Herein, an efficient methodology for the synthesis of a diverse class of N-heterocyclic moieties, such as quinoxalines, benzimidazoles and quinazolines, was developed in water using bio-renewable alcohols. The quinoxalines were successfully synthesized from a wide range of diamines and nitroamines with diols in air. Interestingly, benzimidazoles and quinazolines were synthesized with excellent isolated yields without using any external base. Finally, the preparative scale synthesis of various N-heterocycles and pharmaceutically active quinoxalines established the practicability of this protocol. For this iridium system, a metal-ligand cooperative mechanism was proposed based on kinetic and DFT studies.
- Chakrabarti, Kaushik,Maji, Milan,Kundu, Sabuj
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supporting information
p. 1999 - 2004
(2019/04/27)
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- Potassium tert-Butoxide-Promoted Acceptorless Dehydrogenation of N-Heterocycles
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Potassium tert-butoxide-promoted acceptorless dehydrogenation of N-heterocycles was efficiently realized for the generation of N-heteroarenes and hydrogen gas under transition-metal-free conditions. In the presence of KOtBu base, a variety of six- and five-membered N-heterocyclic compounds efficiently underwent acceptorless dehydrogenation to afford the corresponding N-heteroarenes and H2 gas in o-xylene at 140 °C. The present protocol provides a convenient route to aromatic nitrogen-containing compounds and H2 gas. (Figure presented.).
- Liu, Tingting,Wu, Kaikai,Wang, Liandi,Yu, Zhengkun
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supporting information
p. 3958 - 3964
(2019/08/01)
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- A Acipimox preparation method
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The invention belongs to the field of medical synthesis, in particular discloses a Acipimox preparation method, the invention to 5 - methyl pyrazine - 2 - carboxylic acid as the starting material, in the oxidation reaction under alkaline conditions, the "one-pot" preparation to obtain the target product Acipimox. The present invention provides a method for the preparation of "one-pot", the operation step is simple, through the oxidation reaction under alkaline conditions, so that the reaction completely and simultaneously reduces peroxide impurities, not only improves the yield, improve the product quality, so as to overcome the previous process operation is complex, the yield of the high, the quality of the product is not high, is suitable for industrial production.
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Paragraph 0055-0056
(2019/04/02)
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- Cobalt complex catalyzed atom-economical synthesis of quinoxaline, quinoline and 2-alkylaminoquinoline derivatives
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A new phosphine-free Co(ii) complex-catalyzed synthesis of various quinoxalines via dehydrogenative coupling of vicinal diols with both o-phenylenediamines and 2-nitroanilines is reported. This complex was also effective for the synthesis of quinolines. The practical aspect of this catalytic system was revealed by the one-pot synthesis of 2-alkylaminoquinolines.
- Shee, Sujan,Ganguli, Kasturi,Jana, Kalipada,Kundu, Sabuj
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supporting information
p. 6883 - 6886
(2018/06/26)
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- Acceptorless Dehydrogenation of N-Heterocycles and Secondary Alcohols by Ru(II)-NNC Complexes Bearing a Pyrazoyl-indolyl-pyridine Ligand
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Ruthenium(II) hydride complexes bearing a pyrazolyl-(2-indol-1-yl)-pyridine ligand were synthesized and structurally characterized by NMR analysis and X-ray single crystal crystallographic determinations. These complexes efficiently catalyzed acceptorless dehydrogenation of N-heterocycles and secondary alcohols, respectively, exhibiting highly catalytic activity with a broad substrate scope. The present work has established a strategy to construct highly active transition metal complex catalysts and provides an atom-economical and environmentally benign protocol for the synthesis of aromatic N-heterocyclic compounds and ketones.
- Wang, Qingfu,Chai, Huining,Yu, Zhengkun
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p. 584 - 591
(2018/03/08)
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- Vanadium-Catalyzed Dehydrogenation of N-Heterocycles in Water
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In this paper, the dehydrogenation of tetrahydroquinolines using oxovanadium(V) catalysts under mild conditions in water and oxygen atmosphere is described. This catalytic technology was successfully applied to a range of other structurally related N-heterocycles, and a reaction mechanism is proposed.
- Zumbr?gel, Nadine,Sako, Makoto,Takizawa, Shinobu,Sasai, Hiroaki,Gr?ger, Harald
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supporting information
p. 4723 - 4727
(2018/08/23)
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- Synthesis of Pyrazines and Quinoxalines via Acceptorless Dehydrogenative Coupling Routes Catalyzed by Manganese Pincer Complexes
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Base-metal catalyzed dehydrogenative self-coupling of 2-amino alcohols to selectively form functionalized 2,5-substituted pyrazine derivatives is presented. Also, 2-substituted quinoxaline derivatives are synthesized by dehydrogenative coupling of 1,2-diaminobenzene and 1,2-diols. In both cases, water and hydrogen gas are formed as the sole byproducts. The reactions are catalyzed by acridine-based pincer complexes of earth-abundant manganese.
- Daw, Prosenjit,Kumar, Amit,Espinosa-Jalapa, Noel Angel,Diskin-Posner, Yael,Ben-David, Yehoshoa,Milstein, David
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p. 7734 - 7741
(2018/08/03)
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- C-N Bond Formation Catalyzed by Ruthenium Nanoparticles Supported on N-Doped Carbon via Acceptorless Dehydrogenation to Secondary Amines, Imines, Benzimidazoles and Quinoxalines
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Ruthenium nanoparticles (NPs) supported on N-doped carbon (Ru/N?C) were prepared by the pyrolysis of cis-Ru(phen)2Cl2 loaded onto carbon powder (VULCAN XC72R) at 800 °C. Ru/N?C NPs (0.2 mol% Ru) selectively catalyzed either acceptorless dehydrogenation coupling (ADC) or auto-transfer-hydrogen (ATH) reactions of amines with alcohols to imines and secondary amines. Such selectivity could be controlled by the choice of alkali metal ion associated with the base. Under similar catalytic conditions, the ADC cross-coupling of diamines with primary alcohols or diols afforded the corresponding benzimidazoles and quinoxalines in good to excellent yields. This catalytic system displayed good activity, recyclability, and wide applicability to a diverse range of substrates.
- Guo, Bin,Li, Hong-Xi,Zhang, Shi-Qi,Young, David James,Lang, Jian-Ping
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p. 5627 - 5636
(2018/12/04)
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- Palladium Nanoparticles Stabilized by Metal–Carbon Covalent Bonds as an Expeditious Catalyst for the Oxidative Dehydrogenation of Nitrogen Heterocycles
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The first method for the dehydrogenation of nitrogen heterocycles catalyzed by a palladium nanocatalyst was developed. Carbon–metal covalent-bond-stabilized nanoparticles were found to be efficient for the dehydrogenation process in the presence of tert-butyl hydroperoxide. A variety of N-heterocycles were transformed into functionalized quinolines in medium to excellent yields in water as the solvent under mild conditions by a simple operation.
- Sun, Xiao-Tao,Zhu, Jie,Xia, Yun-Tao,Wu, Lei
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p. 2463 - 2466
(2017/07/12)
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- Dendrimer-Stabilized Metal Nanoparticles as Efficient Catalysts for Reversible Dehydrogenation/Hydrogenation of N-Heterocycles
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Nanoparticles (Pd, Pt, Rh) stabilized by G4OH PAMAM dendrimers and supported in SBA-15 (MNPs/SBA-15 with M = Pd, Pt, Rh) were efficiently used as catalysts in the acceptorless dehydrogenation of tetrahydroquinoline/indoline derivatives in toluene (release of H2) at 130 °C. These catalysts are air stable, very active, robust, and recyclable during the process. The reverse hydrogenation reaction of quinoline derivatives (H2 storage) was also optimized and successfully performed in the presence of the same catalysts in toluene at 60 °C under only 1 atm of hydrogen gas. Such catalysts may be essential for the adoption of organic hydrogen-storage materials as an alternative to petroleum-derived fuels. Hot filtration test confirmed that the reaction follows a heterogeneous pathway. Moreover, PdNPs/SBA-15 was an excellent catalyst for the direct arylation at the C-2 position (via C-H activation) of indole in water in the presense of a hypervalent iodine oxidant. Thus, a one-pot dehydrogenation/direct arylation cascade reaction between indoline and an arylated agent was efficaciously performed in water, demonstrating the potential of the system to catalyze tandem heterogeneous/homogeneous processes by choice of the appropriate oxidant/reductant.
- Deraedt, Christophe,Ye, Rong,Ralston, Walter T.,Toste, F. Dean,Somorjai, Gabor A.
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p. 18084 - 18092
(2017/12/26)
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- 2,6-Difluorobenzamide Inhibitors of Bacterial Cell Division Protein FtsZ: Design, Synthesis, and Structure–Activity Relationships
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A wide variety of drug-resistant microorganisms are continuously emerging, restricting the therapeutic options for common bacterial infections. Antimicrobial agents that were originally potent are now no longer helpful, due to their weak or null activity toward these antibiotic-resistant bacteria. In addition, none of the recently approved antibiotics affect innovative targets, resulting in a need for novel drugs with innovative antibacterial mechanisms of action. The essential cell division protein filamentous temperature-sensitive Z (FtsZ) has emerged as a possible target, thanks to its ubiquitous expression and its homology to eukaryotic β-tubulin. In the latest years, several compounds were shown to interact with this prokaryotic protein and selectively inhibit bacterial cell division. Recently, our research group developed interesting derivatives displaying good antibacterial activities against methicillin-resistant Staphylococcus aureus, as well as vancomycin-resistant Enterococcus faecalis and Mycobacterium tuberculosis. The aim of the present study was to summarize the structure–activity relationships of differently substituted heterocycles, linked by a methylenoxy bridge to the 2,6-difluorobenzamide, and to validate FtsZ as the real target of this class of antimicrobials.
- Straniero, Valentina,Zanotto, Carlo,Straniero, Letizia,Casiraghi, Andrea,Duga, Stefano,Radaelli, Antonia,De Giuli Morghen, Carlo,Valoti, Ermanno
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p. 1303 - 1318
(2017/09/01)
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- Transition-Metal-Free Regioselective Alkylation of Pyridine N-Oxides Using 1,1-Diborylalkanes as Alkylating Reagents
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Reported herein is an unprecedented base-promoted deborylative alkylation of pyridine N-oxides using 1,1-diborylalkanes as alkyl sources. The reaction proceeds efficiently for a wide range of pyridine N-oxides and 1,1-diborylalkanes with excellent regioselectivity. The utility of the developed method is demonstrated by the sequential C?H arylation and methylation of pyridine N-oxides. The reaction also can be applied for the direct introduction of a methyl group to 9-O-methylquinine N-oxide, thus it can serve as a powerful method for late-stage functionalization.
- Jo, Woohyun,Kim, Junghoon,Choi, Seoyoung,Cho, Seung Hwan
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supporting information
p. 9690 - 9694
(2016/08/10)
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- Highly efficient synthesis of quinoxaline derivatives catalized by iridium complex
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A novel iridium complex was used to catalyze a mild reaction of phenylenediamine with propanediol that led to formation of quinoxaline derivatives with moderate to high yields. The reaction diemonstrated strong compatibility with substrates bearing various functional groups.
- Lv,Xie,Gu,Wu,Wan
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p. 2887 - 2890
(2017/03/22)
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- Efficient synthesis of quinoxalines from 2-nitroanilines and vicinal diols via a rutheniumcatalyzed hydrogen transfer strategy
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Via a ruthenium-catalyzed hydrogen transfer strategy, we have demonstrated a one-pot method for efficient synthesis of quinoxalines from 2-nitroanilines and biomass-derived vicinal diols for the first time. In such a synthetic protocol, the diols and the nitro group serve as the hydrogen suppliers and acceptors, respectively. Hence, there is no need for the use of external reducing agents. Moreover, it has the advantages of operational simplicity, broad substrate scope and the use of renewable reactants, offering an important basis for accessing various quinoxaline derivatives.
- Xie, Feng,Zhang, Min,Jiang, Huanfeng,Chen, Mengmeng,Lv, Wan,Zheng, Aibin,Jian, Xiujuan
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supporting information
p. 279 - 284
(2018/04/16)
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- Synthesis of quinoxalines or quinolin-8-amines from N-propargyl aniline derivatives employing tin and indium chlorides
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Pyrazino compounds such as quinoxalines are 1,4-diazines with widespread occurrence in nature. Quinolin-8-amines are isomerically related and valuable scaffolds in organic synthesis. Herein, we present intramolecular main group metal Lewis acid catalyzed formal hydroamination as well as hydroarylation methodology using mono-propargylated aromatic ortho-diamines. The annulations can be conducted utilizing equal aerobic conditions with either stannic chloride or indium(iii) chloride and represent primary examples for main group metal catalyzed 6-exo-dig and 6-endo-dig, respectively, cyclizations in such settings. Both types of reactions can also be utilized in a one-pot manner starting from ortho-nitro N-propargyl anilines using stoichiometric amounts SnCl2·2H2O or In powder. Mechanistic considerations are presented regarding the substituent-depending regioselectivity.
- Aichhorn, Stefan,Himmelsbach, Markus,Sch?fberger, Wolfgang
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p. 9373 - 9380
(2015/09/15)
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- Copper-catalyzed synthesis of valuable heterocyclic compounds using a tandem oxidation process approach
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The synthesis of quinoxalines via a tandem oxidation process using a copper acetate monohydrate/2,2,6,6-tetramethylpiperidine N-oxyl (TEMPO) oxidative system has been described. Using this approach, a series of quinoxaline derivatives were formed in good yields within short reaction times under microwave irradiation. The oxidative system was also extended to the selective synthesis of dihydropyrazines and pyrazines.
- Jeena, Vineet,Sithebe, Siphamandla,Robinson, Ross S.
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supporting information
p. 1484 - 1491
(2015/05/20)
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- Palladium-catalyzed cross-coupling reaction of trialkylbismuthines with 2-haloazines and diazines
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An efficient method for the cross-coupling reaction of primary trialkybismuth reagents with 2-haloazines and diazines is reported. The reaction functions with pyridines, pyrimidines, pyridazines and pyrazines and tolerates many functional groups. This method gives access to 2-alkylazines and diazines, a class of compounds which is important in medicinal chemistry.
- Petiot, Pauline,Gagnon, Alexandre
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p. 1615 - 1624
(2016/10/12)
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- Ruthenium(II) η6-arene complexes containing a dinucleating ligand based on 1,8-naphthyridine
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Ruthenium arene complexes, [(η6-p-cymene)2Ru2(L)Cl2](PF6)2 [3b, L = 2, 7-bis(di-2-pyridinyl)-1,8-naphthyridine] and [(η6-p-cymene)Ru(L′)Cl](PF6) [4, L′ = tri(2-pyridinyl)amine], were synthesized and characterized by spectroscopic and analytical techniques. The molecular structure of [(η6-p-cymene)2Ru2(L)Cl2]Cl2 (3a) was further determined by single-crystal X-ray analysis. The use of these ruthenium complexes as pre-catalysts for oxidative coupling of 1,2-diols/1,2-aminoalcohol with o-phenylenediamines leading to quinoxalines was investigated. Complex 3b appeared to be a good catalyst for this transformation.
- Tang, Wei-Hung,Liu, Yi-Hung,Peng, Shie-Ming,Liu, Shiuh-Tzung
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- The synthesis of benzimidazoles and quinoxalines from aromatic diamines and alcohols by iridium-catalyzed acceptorless dehydrogenative alkylation
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Benzimidazoles and quinoxalines are important N-heteroaromatics with many applications in pharmaceutical and chemical industry. Here, the synthesis of both classes of compounds starting from aromatic diamines and alcohols (benzimidazoles) or diols (quinoxalines) is reported. The reactions proceed through acceptorless dehydrogenative condensation steps. Water and two equivalents of hydrogen are liberated in the course of the reactions. An Ir complex stabilized by the tridentate P^N^P ligand N2,N 6-bis(di-isopropylphosphino)pyridine-2,6-diamine revealed the highest catalytic activity for both reactions. Aromatic diamines were reacted with alcohols and diols to form benzimidazoles or quinoxalines, respectively (see scheme). In the course of the reactions, water and two equivalents of hydrogen gas were eliminated/liberated. An Ir complex stabilized by a tridentate PNP ligand was found to be an efficient catalyst in these reactions.
- Hille, Toni,Irrgang, Torsten,Kempe, Rhett
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supporting information
p. 5569 - 5572
(2014/05/20)
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- An environmentally friendly, cost effective synthesis of quinoxalines: The influence of microwave reaction conditions
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A convenient, environmentally friendly and novel synthesis of quinoxalines using silica gel as the catalyst is described. The choice of microwave conditions has been shown to have a substantial impact on the reaction outcome with closed-vessel microwave irradiation resulting in the formation of quinoxalines in high yields and short reaction times. Preliminary mechanistic investigations have indicated that a slight build-up in pressure has a major impact on the reaction outcome.
- Jeena, Vineet,Robinson, Ross S.
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supporting information
p. 642 - 645
(2014/01/23)
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- Microwave-assisted α-halogenation of 2-methylquinolines with tetrabutylammonium iodide and 1,2-dichloroethane (1,2-dibromoethane)
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A simple and efficient methodology permitting the halogenation of 2-methylquinolines into 2-(chloromethyl)quinolines or 2-(bromomethyl)quinolines in the tetrabutylammonium iodide and 1,2-dichloroethane (1,2-dibromoethane) system has been developed for the first time. The halogenation can be rapidly completed with good to excellent yields and high selectivity under microwave irradiation.
- Xie, Yuanyuan,Li, Lehuan
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supporting information
p. 3892 - 3895
(2014/07/08)
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- Asymmetric organocatalytic tandem cyclization/transfer hydrogenation: A synthetic strategy for enantioenriched nitrogen heterocycles
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An asymmetric organocatalytic tandem reaction comprising cyclization/transfer hydrogenation has been established in a compatible and synergistic way, leading to the step-economical synthesis of enantioenriched tetrahydroquinoxalines and dihydroquinoxalinones from readily accessible materials in excellent enantioselectivity of up to >99% ee. This protocol of a one-operation tandem reaction combines the merits of both tandem reactions and asymmetric organocatalysis, providing an efficient strategy for concisely and enantioselectively synthesizing nitrogen heterocycles with biological relevance. Copyright
- Shi, Feng,Tan, Wei,Zhang, Hong-Hao,Li, Mei,Ye, Qin,Ma, Guan-Hua,Tu, Shu-Jiang,Li, Guigen
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p. 3715 - 3726
(2014/01/06)
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- Acceptorless dehydrogenation of nitrogen heterocycles with a versatile iridium catalyst
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Gas up: A cyclometalated iridium complex is found to catalyze the dehydrogenation of various benzofused N-heterocycles, thus releasing H 2. Driven by as low as 0.1 mol % catalyst, the reaction affords quinolines, indoles, quinoxalines, isoquinolines, and β-carbolines in high yields. Copyright
- Wu, Jianjun,Talwar, Dinesh,Johnston, Steven,Yan, Ming,Xiao, Jianliang
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supporting information
p. 6983 - 6987
(2013/07/26)
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- A green synthesis of quinoxalines and 2,3-dihydropyrazines
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Quinoxaline and dihydropyrazine derivatives were obtained in high yields by simple addition of 1,2-diamines and 1,2-dicarbonyl compounds in water. In some cases, the products spontaneously precipitated from the reaction mixture, making it possible to recover and reuse the mother liquor for further condensations. The very mild reaction conditions, the high yields of the products, and the absence of any catalyst make this methodology an efficient and green route to quinoxalines and dihydropyrazines. Georg Thieme Verlag Stuttgart New York.
- Delpivo, Camilla,Micheletti, Gabriele,Boga, Carla
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p. 1546 - 1552
(2013/06/27)
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- Combined theoretical and experimental study on the molecular structure, FT-IR, and NMR spectra of cyadox and 1,4-bisdesoxycyadox
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1,4-Bisdesoxycyadox, a deoxidized metabolite of cyadox, was synthesised and characterized. Structural and conformational analyses were performed using theoretical calculations employing density functional theory (DFT). The molecular geometry was optimized using B3LYP method with 6-311+G(d,p) basis set and then it was compared with X-ray diffraction data of similar molecular compounds. From the optimized geometry of the molecule, vibrational frequencies of the title compounds were calculated via B3LYP/6-311+G(d,p) approach. The 1H and 13C NMR chemical shift were calculated by gauge-including atomic orbital method with B3LYP/6-311++G(2df,2pd) approach. Comparison of the experimental and calculated 1H and 13C chemical shifts resulted in the reliable assignment of cyadox and 1,4-bisdesoxycyadox. The first, second, total, and mean NO bond dissociation enthalpies were also obtained theoretically.
- Li, Zongyang,Zhang, Jiaheng,Li, Yubo,Gao, Haixiang
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- 2-alkoxypropenals as synthetic equivalents of methylglyoxal in the synthesis of heterocycles
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One-pot synthesis of 2-methylquinoxaline, 3-hydroxy-2-methylimidazo[1,2-a] pyridine, and 2-methyl-3,7-dihydroimidazo[1,2-a]pyrazin-3-one via cycloaddition of N,N-binucleophilic o-phenylenediamine, 2-aminopyridine, and 2-aminopyrazine, respectively, to methylglyoxal generated in situ by hydrolysis of 2-alkoxypropenals is reported for the first time. Thus 2-alkoxypropenals in weakly acidic medium (25-80 C, 1-4 h) are convenient synthetic equivalents of methylglyoxal in the synthesis of heterocyclic compounds.
- Keiko,Vchislo,Larina
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p. 428 - 431
(2013/07/26)
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- Biomass into chemicals: One-pot two- and three-step synthesis of quinoxalines from biomass-derived glycols and 1,2-dinitrobenzene derivatives using supported gold nanoparticles as catalysts
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An efficient and selective one-pot two-step method, for the synthesis of quinoxalines by oxidative coupling of vicinal diols with 1,2-phenylenediamine derivatives, has been developed by using gold nanoparticles supported on nanoparticulated ceria (Au/CeO2) or hydrotalcite (Au/HT) as catalysts and air as oxidant, in the absence of any homogeneous base. Reaction kinetics shows that the reaction controlling step is the oxidation of the diol to α-hydroxycarbonyl compound. Furthermore, a one-pot three-step synthesis of 2-methylquinoxaline starting from 1,2-dinitrobenzene and 1,2-propanediol has been successfully carried out with 98% conversion and 83% global yield to the final product.
- Climent,Corma,Hernandez,Hungria,Iborra,Martinez-Silvestre
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p. 118 - 129
(2012/10/08)
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- Degradation of glucose: reinvestigation of reactive α-dicarbonyl compounds
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Maillard reactions influence the formation of flavor and color in processed foods in an important way. Reducing sugars and amino acids ultimately react to stable end products. To elucidate the complex formation pathways a vast number of experiments have b
- Jenny, Gobert,Glomb, Marcus A.
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experimental part
p. 8591 - 8597
(2010/07/15)
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- Asymmetric hydrogenation of quinoxalines catalyzed by iridium/PipPhos
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A catalyst made in situ from the (cyclooctadiene)iridium chloride dimer, [Ir(COD)Cl]2, and the monodentate phosphoramidite ligand (S)-PipPhos was used in the enantioselective hydrogenation of 2- and 2,6-substituted quinoxalines. In the presence
- Mrsic, Natasa,Jerphagnon, Thomas,Minnaard, Adriaan J.,Feringa, Ben L.,De Vries, Johannes G.
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experimental part
p. 2549 - 2552
(2009/12/27)
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- Oxidative ammonolysis of 2-methylquinoxaline on vanadium-titanium oxide catalyst
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The behavior of 2-methylquinoxaline in the course of oxidative ammonolysis on V-Ti oxide catalyst in a wide range of conditions was studied, and this reaction was examined as a route to 2-quinoxalinecarbonitrile.
- Postnikov,Korovina,Kagarlitskii,Krichevskii
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p. 320 - 322
(2008/09/19)
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- An efficient and convenient protocol for the synthesis of quinoxalines and dihydropyrazines via cyclization-oxidation processes using HClO4·SiO2 as a heterogeneous recyclable catalyst
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A convenient and straightforward method has been developed for the synthesis of quinoxalines and dihydropyrazines (DHPs) using α-bromo ketones and 1,2-diamines in the presence of silica supported perchloric acid (HClO4·SiO2) at room temperature. The quinoxalines and DHPs were presumably formed via cyclization-oxidation. The catalyst works under heterogeneous conditions and can be recycled.
- Das, Biswanath,Venkateswarlu, Katta,Suneel, Kanaparthy,Majhi, Anjoy
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p. 5371 - 5374
(2008/02/10)
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- Isolation, identification, and quantification of roasted coffee antibacterial compounds
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Coffee brew is a widely consumed beverage with multiple biological activities due both to naturally occurring components and to the hundreds of chemicals that are formed during the roasting process. Roasted coffee extract possesses antibacterial activity against a wide range of microorganisms, including Staphylococcus aureus and Streptococcus mutans, whereas green coffee extract exhibits no such activity. The naturally occurring coffee compounds, such as chlorogenic acids and caffeine, cannot therefore be responsible for the significant antibacterial activity exerted by coffee beverages against both bacteria. The very low minimum inhibitory concentration (MIC) found for standard glyoxal, methylglyoxal, and diacetyl compounds formed during the roasting process points to these α-dicarbonyl compounds as the main agents responsible for the antibacterial activity of brewed coffee against Sa. aureus and St. mutans. However, their low concentrations determined in the beverage account for only 50% of its antibacterial activity. The addition of caffeine, which has weak intrinsic antibacterial activity, to a mixture of α-dicarbonyl compounds at the concentrations found in coffee demonstrated that caffeine synergistically enhances the antibacterial activity of α-dicarbonyl compounds and that glyoxal, methylglyoxal, and diacetyl in the presence of caffeine account for the whole antibacterial activity of roasted coffee.
- Daglia, Maria,Papetti, Adele,Grisoli, Pietro,Aceti, Camilla,Spini, Valentina,Dacarro, Cesare,Gazzani, Gabriella
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body text
p. 10208 - 10213
(2009/09/25)
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