1593-08-4Relevant articles and documents
Electron localisation in electrochemically reduced mono- and bi-nuclear rhenium(I) complexes with bridged polypyridyl ligands
Page, Simon E.,Flood, Amar,Gordon, Keith C.
, p. 1180 - 1187 (2002)
A number of mono- and bi-nuclear rhenium(I) complexes have been prepared and their physical properties, including the infrared spectra of the reduced complexes, have been studied. These compounds have the general formula [Re(CO)3Cl(L)] and [Cl(CO)3Re(μ-L)Re(CO)3Cl], where L can be 2,3-(2′,2″)-diquinolylquinoxaline, 6,7-dimethyl-2,3-(2′,2″)-diquinolylquinoxaline, 2,3-(2′,2″)-diquinolylbenzoquinoxaline, 6,7-dichloro-2,3-(2′,2″)-diquinolylquinoxaline, 2,3-(2′,2″)-diquinoxalylquinoxaline, 6,7-dimethyl-2,3-(2′,2″)-diquinoxalylquinoxaline, 2,3-(2′,2″)-diquinoxalylbenzoquinoxaline and 6,7-dichloro-2,3-(2′,2″)-diquinoxalylquinoxaline. The electrochemical studies show that the first reduction potential of the free ligands correlates with the reductions of the corresponding mono- and bi-nuclear complexes. The properties of the complexes have been modelled using semi-empirical methods. These show linear correlations between: (a) the energy of the MLCT transitions versus the difference in energy between the LUMO and the HOMO and (b) the change in carbonyl force constant with reduction vs. the wavefunction amplitude of the π* LUMO at the site of coordination. The experimental data and calculations point to significant alterations in the π* LUMO with substitution at the ligand and with the chelation of a second Re(I) center.
Biocatalytic oxidation of 2-methylquinoxaline to 2-quinoxalinecarboxylic acid
Wong, John W.,Watson Jr., Harry A.,Bouressa, James F.,Burns, Michael P.,Cawley, James J.,Doro, Albert E.,Guzek, Donald B.,Hintz, Michael A.,McCormick, Ellen L.,Scully, Douglas A.,Siderewicz, Joseph M.,Taylor, William J.,Truesdell, Susan J.,Wax, Richard G.
, p. 477 - 481 (2002)
A microbial process using the fungus Absidia repens ATCC 14849 is described for the oxidation of 2-methylquinoxaline to 2-quinoxalinecarboxylic acid. A campaign consisting of three 14000-L runs produced 20.5 kg of the acid with a 28% overall yield. The bioconversion gave a lower yield compared with a three step chemical synthesis (35%), but was carried out in one pot, and avoided safety issues with a di-N-oxide intermediate. Although successfully scaled to produce kilograms of 2-quinoxalinecarboxylic acid for synthesis of a drug candidate, the A. repens bioconversion is unsuitable for further scale-up due to low product concentration (～1 g/L). A second microbial process using Pseudomonas putida ATCC 33015 is also described for the oxidation of 2-methylquinoxaline. The P. putida bioconversion gave an 86% in situ yield at 8-L scale and yielded a product concentration approximately 10-fold greater than that of the A. repens bioconversion.
Towards echinomycin mimetics by grafting quinoxaline residues on glycophane scaffolds
Jarikote, Dilip V.,Li, Wei,Jiang, Tao,Eriksson, Leif A.,Murphy, Paul V.
, p. 826 - 835 (2011)
Echinomycin is a natural depsipeptide, which is a bisintercalator, inserting quinoxaline units preferentially adjacent to CG base pairs of DNA. Herein the design and synthesis of echinomycin mimetics based on grafting of two quinoxaline residues onto a macrocyclic scaffold (glycophane) is addressed. Binding of the compounds to calf-thymus DNA was studied using UV-vis and steady state fluorescence spectroscopy, as well as thermal denaturation. An interesting observation was enhancement of fluorescence emission for the peptidomimetics on binding to DNA, which contrasted with observations for echinomycin. Molecular dynamics simulations were exploited to explore in more detail if bis-intercalation to DNA was possible for one of the glycophanes. Bis-intercalating echinomycin complexes with DNA were found to be stable during 20 ns simulations at 298 K. However, the MD simulations of a glycophane complexed with a DNA octamer displayed very different behaviour to echinomycin and its quinoxaline units were found to rapidly migrate out from the intercalation site. Release of bis-intercalation strain occurred with only one of the quinoxaline chromophores remaining intercalated throughout the simulation. The distance between the quinoxaline residues in the glycophane at the end of the MD simulation was 7.3-7.5 , whereas in echinomycin, the distance between the residues was ～11 , suggesting that longer glycophane scaffolds would be required to generate bis-intercalating echinomycin mimetics.
Combined theoretical and experimental study on the molecular structure, FT-IR, and NMR spectra of cyadox and 1,4-bisdesoxycyadox
Li, Zongyang,Zhang, Jiaheng,Li, Yubo,Gao, Haixiang
, p. 69 - 75 (2013)
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.
Synthesis, crystal structures, and fluorescent properties of zinc(II) complexes with benzazino-2-carboxalidin-2-aminophenols
Nosova, Emiliya,Stupina, Tatyana,Chupakhin, Artem,Lipunova, Galina,Valova, Marina,Slepukhin, Pavel,Charushin, Valery
, p. 61 - 67 (2015)
Complexes ZnL2 with novel fluorinated benzazines as tridentate ligands (HL = 6,7-difluoroquinoxalinand 6,7-difluoroquinolincarboxalidin-2-aminophenol) have been prepared. The photophisical properties of the ligands and the complexes has been studied.
Novel quinoxalinyl chalcone hybrid scaffolds as enoyl ACP reductase inhibitors: Synthesis, molecular docking and biological evaluation
Desai, Vidya,Desai, Sulaksha,Gaonkar, Sonia Naik,Palyekar, Uddesh,Joshi, Shrinivas D.,Dixit, Sheshagiri K.
, p. 2174 - 2180 (2017)
We report herein, first ever synthesis of series of novel differently substituted quinoxalinyl chalcones using Claisen Schmidt condensation, its molecular docking studies, and potential to be good anti-microbial, anti-tubercular and anti-cancer agents. Th
Copper-Catalyzed Aerobic Oxidation of Azinylmethanes for Access to Trifluoromethylazinylols
Zheng, Gang,Liu, Hao,Wang, Mang
, p. 519 - 523 (2016)
A copper-catalyzed oxygenation of methylazaarenes was found to occur in the absence of both ligand and additive, and has been successfully employed for the synthesis of trifluoromethylazinylketols. This synthetic strategy incorporates aerobic oxidation and a trifluoromethylation in one-pot and provides a novel method for the trifluoromethylation of aliphatic C-H bond.
Iodine-catalyzed oxidative annulation: Facile synthesis of pyrazolooxepinopyrazolones: Via methyl azaarene sp3C-H functionalization
Zhang, Xin-Ke,Miao, Xiao-Yu,Zhou, Yu,Wang, Yu-Mei,Song, Ying-Chun,Liu, Hang,Xiong, Yi-Lu,Li, Ling-Yu,Wu, An-Xin,Zhu, Yan-Ping
supporting information, p. 1236 - 1242 (2022/02/19)
An iodine-catalyzed methyl azaarene sp3 C-H functionalization has been developed for the synthesis of a seven-membered O-heterocyclic architecture containing three different heterocyclic aromatic hydrocarbons. This method can be applied to a wide range of substituted methyl azaarenes and diverse 2,4-dihydro-3H-pyrazol-3-ones, and brings about the efficient preparation of 2,9-dihydrooxepino[2,3-c:6,5-c′]dipyrazol-3(7H)-ones in high yields with the merits of low catalyst loading, good functional group tolerance and metal-free conditions.
Iodine-imine Synergistic Promoted Povarov-Type Multicomponent Reaction for the Synthesis of 2,2′-Biquinolines and Their Application to a Copper/Ligand Catalytic System
Hu, Qi-Qi,Gao, Yan-Ting,Sun, Jia-Chen,Gao, Jing-Jing,Mu, Hong-Xiao,Li, Yi-Ming,Zheng, Ya-Nan,Yang, Kai-Rui,Zhu, Yan-Ping
supporting information, p. 9000 - 9005 (2021/11/24)
An efficient iodine-imine synergistic promoted Povarov-type multicomponent reaction was reported for the synthesis of a practical 2,2′-biquinoline scaffold. The tandem annulation has reconciled iodination, Kornblum oxidation, and Povarov aromatization, where the methyl group of the methyl azaarenes represents uniquely reactive input in the Povarov reaction. This method has broad substrate scope and mild conditions. Furthermore, these 2,2′-biquinoline derivatives had been directly used as bidentate ligands in metal-catalyzed reactions.
Methanol as a formylating agent in nitrogen heterocycles
Xu, Zhengbao,Zhang, Lizhi
, p. 9476 - 9482 (2021/11/17)
A radical mediated C-H direct formylation of N-heteroarenes with methanol is reported. The reaction features a novel iron-catalyzed Minisci oxidative coupling process using commercially available methanol as a formylating reagent. It effectively solved the long-standing problems associated with using methanol as a formylating reagent in these types of reactions. Compared to the traditional Minisci C-H formylation methods, this protocol is highly atom-economical, simple to operate, and environmentally friendly and shows good functional group tolerance. This Minisci formylation strategy is a straightforward approach for the late-stage functionalization of N-heteroarenes. This journal is
