- Flavosemiquinone Model Systems. Part 2. Methyl-substituted Quinoxaline Radical Ions
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2,3-Dimethyl-, 6,7-dimethyl-, and 2,3,6,7-tetramethyl-quinoxaline were reduced in aprotic (THF) and acidic media (DMF - HClO4) to yield the corresponding quinoxaline radical anions and 1,4-dihydroquinoxaline radical cations.Analysis of their e.s.r. spectra was accomplished by computer simulation; a consistent assignment of coupling constants in quinoxaline radical ions could be made on the basis of the methyl substitution pattern.The hyperfine splitting is in agreement with Hueckel MO correlations and may be used to explain the spin distribution in flavosemiquinones.
- Kaim, Wolfgang
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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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- 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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- 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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- 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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- 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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- Glycerin and CeCl3 7H2O: A new and efficient recyclable reaction medium for the synthesis of quinoxalines
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An efficient and environmentally benign process for the synthesis of quinoxalines has been developed using glycerine-cerium chloride as a reaction medium. This method is applicable to a variety of diketones and 1,2-phenylenediamines to afford the corresponding quinoxaline derivatives in excellent yields. The reaction medium was recovered and reused for further reactions without any problem. Taylor & Francis Group, LLC.
- Venkat Narsaiah,Kranthi Kumar
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experimental part
p. 883 - 892
(2012/03/11)
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- Asymmetric hydrogenation of 2-and 2,3-substituted ouinoxalines with chiral cationic ruthenium diamine catalysts
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The enantioselective hydrogenation of 2-alkyl- and 2-aryl-subsituted quinoxalines and 2,3-disubstituted quinoxalines was developed by using the cationic Ru(η6-cymene)(monosulfonylated diamine)(BArF) system in high yields with up to 99% ee. The counteranion was found to be critically important for the high enantioselectivity and/or diastereoselectivity.
- Qin, Jie,Chen, Fei,Ding, Ziyuan,He, Yan-Mei,Xu, Lijin,Fan, Qing-Hua
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supporting information; experimental part
p. 6568 - 6571
(2012/02/13)
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- Samarium triflate catalyzed efficient synthesis of quinoxalines
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A highly efficient method for the synthesis of quinoxalines derivatives has been developed using samarium triflate as catalyst. The method is applicable to a variety of 1,2-diketones and 1,2-diamines to afford the corresponding quinoxalines derivatives in high yields. All the reactions were carried out at acetonitrile reflux.
- Raghuveerachary,Devanna
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experimental part
p. 1628 - 1630
(2012/01/05)
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- Synthesis of quinoxalines in presence of zinc triflate
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A simple and efficient method for the synthesis of quinoxaline derivatives has been developed. The reactions were carried out in presence of zinc triflate in acetonitrile reflux. The method is applicable to a variety of diketones and 1,2-phenylenediamines to afford the corresponding derivatives in excellent yields.
- Subrahmanyam, C. Siva,Narayanan
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experimental part
p. 1331 - 1333
(2011/12/21)
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- Niobium (V) chloride: An efficient catalyst for the synthesis of quinoxalines
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A simple and efficient method for the synthesis of quinoxalines derivatives has been developed. All the reactions were carried out in presence of niobium (V) chloride at acetonitrile reflux conditions. The method is applicable to a variety of diketones and 1, 2-phenylenediamines to afford the corresponding derivatives in excellent yields.
- Venkateswarlu,Leelavathi
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experimental part
p. 208 - 211
(2011/07/08)
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- Quinoxalino-fused sultines and their application in Diels-Alder reactions
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The synthesis of 7,8-disubstituted quinoxalino[2,3-d]-[1,2λ4]oxathiine 2-oxides 7a-c, precursors for quinoxalino-o-quinodimethanes 3a-c, and their application in the Diels-Alder reactions are reported.
- Chung, Wen-Sheng,Liu, Jing-Horng
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p. 205 - 206
(2007/10/03)
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- Tyrphostins. 5. Potent inhibitors of platelet-derived growth factor receptor tyrosine kinase: Structure-activity relationships in quinoxalines, quinolines, and indole tyrphostins
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A series of 3-indoleacrylonitrile tyrphostins, 2-chloro-3- phenylquinolines, and 3-arylquinoxalines were prepared and tested for inhibition of platelet-derived growth factor receptor tyrosine kinase (PDGF- RTK) activity. The potency of the inhibitors was found to be quinoxalines > quinolines > indoles. Lipophilic groups (methyl, methoxy) in the 6 and 7 positions and phenyl at the 3 position of quinoxalines and quinolines were essential for potency, in contrast to the hydrophilic catechol group in tyrphostins active against EGFR kinase inhibition at different sites. The inhibitors showed selectivity for PDGF and were not active against EGF receptor and HER-2/c-ErbB-2 receptor.
- Gazit, Aviv,App, Harald,McMahon, Gerald,Chen, Jefferey,Levitzki, Alexander,Bohmer, Frank D.
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p. 2170 - 2177
(2007/10/03)
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- Electrochemical and Spectroscopic Characterization of N,N'-Dialkylquinoxalinium Redox Systems
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The outstanding position of the 1,4-isomer, quinoxaline, among the diazanaphthalenes is confirmed by comparing LUMO energies from HMO perturbation calculations.Diquaternary salts +)2(quin)>(X-)2, R = Me, Et; quin = quinoxaline, 2,3- and 6,7-dimethyl- and 2,3,6,7-tetramethylquinoxaline, X = BF4- or SbCl6- (4a-g), were isolated and characterized as compounds which are sensitive to reduction and hydrolysis.Cyclic voltammetry of the two-step redox systems of the Weitz type showed two reversible one-electron reductions with an extraordinarily stable radical cation intermediate (lg Kc > 12).The redox potentials are less negative than those of the 4,4'-bipyridinium systems but also less positive in comparison to the values of N,N'-dialkylphenazinium compounds.The radical cation intermediates which include a TCNQ- radical salt cannot only be characterized by ESR, but also by absorption spectroscopy in comparison to the respective dications.
- Schulz, Andreas,Kaim, Wolfgang
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p. 129 - 139
(2007/10/02)
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- 13C Nuclear Magnetic Resonance Spectra of Quinoxaline Derivatives
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The 13C n.m.r. spectra of a series of 5-, 6-, and 2-substituted quinoxalines have been analysed by consideration of their 1H coupled spectra.Typical values of the coupling constants are: C(2,3), 1JCH 181.9, 2JCH 11.4, C(5,8), 1JCH 162.6, 3JCH 6.5, C(6.7), 1JCH 159.4, 3JCH 9.1; C(9), 3JCH(2) = 3JCH(7) = 10.0, 3JCH(5) 5.4; C(10), 3JCH(3) = 3JCH(6) = 10.0, 3JCH(8) 5.4 Hz.The magnitudes of the coupling constants in the benzenoid ring are similar to these for the corresponding positions in naphthalene, but application of naphthalene chemical shift substitutions effects leads in some cases to the wrong peak sequence in the related quinoxalines.Within the quinoxaline series itself, however, acceptable additivity of substituent effects is found (+/- 0.8 p.p.m.), provided that the reference compounds are carefully chosen.Analysis of mixtures of quinoxalines from substituted o-phenylenediamines and α-oxo-aldehydes is possible by consideration of the multiplicity of the ring-junction quaternary carbon signals in the fully coupled spectra.
- McNab, Hamish
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p. 357 - 364
(2007/10/02)
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