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1.
Jean M. J. Tronchet Kamal Mekhael Joëlle Graf-Poncet Rachid Benhamza Michel Geoffroy 《Helvetica chimica acta》1985,68(7):1893-1896
Sugar Free Radicals. VIII. Spin-Labeled Nucleosides Analogs A series of 5′-deoxy-5′-hydroxylamino derivatives of adenosine and uridine have been prepared by reduction of the corresponding oxime or nitrone. ‘Second generation’ 3′-deoxy-3′-N-aryl(or N-alkyl) hydroxylamino-β-D -xylofuranosyluracils have also been synthesized by a one-pot reaction including the following elementary steps: deblocking of the starting material, reduction of the 3′-deoxy-3′-oximinouridine, condensation of the resulting hydroxylamine with an aldehyde, reduction of the nitrone formed. The deoxy-hydroxylaminonucleosides oxidized spontaneously in the air (or in presence of traces of PbO2) to give the corresponding nitroxide free radicals, ESR spectra of which furnished useful informations on their structures. Some of these modified nucleosides bore notable cytotoxic or antiviral activities. 相似文献
2.
T. I. Yaroshenko V. N. Elokhina A. S. Nakhmanovich L. I. Larina T. N. Komarova S. V. Amosova 《Russian Journal of General Chemistry》2009,79(6):1197-1200
Propargyl bromide with quinoxaline-2,3-dithiol in DMSO in the presence of K2CO3 affords 2,3-bis-(2-propynylsulfanyl)quinoxaline in good yield whereas in absolute methanol in the presence of sodium methoxide at 20°C a 1:2 mixture of 2,3-bis(2-propynylsulfanyl)quinoxaline and 3-(2-propynylsulfanyl)-2(1H)-quinoxalinethione is formed. Individual 3-(2-propynylsulfanyl)-2(1H)-quinoxalinethione was obtained by crystallization of this mixture from ether. The reaction of 1,3-dibromopropyne with quinoxaline-2,3-dithiol in ethanol in the presence of NaOH at heating results in 2-bromomethylidene-1,4-(3H)-dithiino[2,3-b]quinoxaline in 77% yield. Performing this reaction in methanol in the presence of sodium methoxide during long heating (16 h) led to 2,3-bis[(3-bromo-2-propynyl)sulfanyl]quinoxaline in 72% yield. 相似文献
3.
Coupling of the appropriate 3-hydroxy--pyrone derivatives with labile diazonium compounds (phenyldiazonium oxide hydrate or in particular phenyldiazohydrate) gives 3,4-dioxo-2, 3-dihydropyran-2-phenylhydrazone (V), 3, 4-dioxo-6-carboxy-2, 3-dihydropyran-2-phenylhydrazone (VI), 3,4-dioxo-6-ethoxy-carbonyl-2,3-dihydropyran-2-phenylhydrazone (VIII), 5-(benzenazo)-3,4-dioxo-6-carboxy-2, 3-dihydropyran-2-phenylhydrazone (VIII), 4-oxo-3, 3-dihydroxy-6-hydroxymethyl-2, 3-dihydropyran-2-phenylhydrazone (IX). The hydrazone VI is also formed by coupling phenyldiazohydrate with meconic acid or with the ferric chelate of comenic acid. Compounds VI–VIII are characterized as their quinoxaline derivatives. Isomerization of the appropriate phenylhydrazones gives 2-(benzenazo)-3-hydroxy--pyrone, 6-(benzenazo)kojic acid, and the hitherto undescribed in the literature 6-(benzenazo)comenic and 3, 6-bis(benzenazo)kojic acids.For part VIII see [1].We wish to express our gratitude to V. V. Kolpakova and A. P. Cherezova, for carrying out the Analyses. 相似文献
4.
Heinz Hoberg Georg Burkhart C. Krüger Y.-H. Tsay 《Journal of organometallic chemistry》1981,222(2):343-352
The complex (Ph3P)Ni(PhNCNPh) (II) is formed from (Ph3P)2Ni(PhNCNPh) (I) in toluene at 60°C. II can also be prepared directly from (COD)2Ni, Ph3P and PhNCNPh (45% yield). (COD)2Ni reacts with dairylcarbodiimides in THF to give (ArNCNAr)3Ni(THF) (VIII). The structure of VIIIa (Ar phenyl) has been determined by X-ray crystallography. The molecule is shown to contain a [3.3.0]nickela bicyclic group in which the carbodiimide molecules are linked to form a 2,5,8-h3-carbene ligand. Some properties and reactions of II and VIII are described. 相似文献
5.
[4 + 2] Heterocyclization for Efficient Formation of Substituted Quinoxalines through Carbon–Oxygen Bonds Cleavage
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Man‐Su Tu Hai‐Wei Xu Wei Fan Bo Jiang Shu‐Jiang Tu 《Journal of heterocyclic chemistry》2015,52(3):719-725
A new domino strategy for efficient synthesis of highly functionalized quinoxaline derivatives via [4 + 2] heterocyclization involving ring‐opening of oxirane process has been developed. The reaction promoted by Cs2CO3 was easy to perform in a simple operation from common and inexpensive starting materials. The bisfunctionalization of quinoxaline framework including C2 benzylation and C3 arylation was readily achieved in domino fashion that involved the cleavage of three C–O bonds of 1,3‐diaryl‐2,3‐epoxypropan‐1‐one. 相似文献
6.
A. S. Elina L. G. Tsyrul'nikova E. M. Peresleni Yu. N. Sheinker 《Chemistry of Heterocyclic Compounds》1966,2(1):72-78
Acyl derivatives of 2-aminoquinoxaline and their 1-N -oxides, as well as methyl derivatives of some of those compounds, are synthesized. IR spectra of these compounds in the solid state, and UV spectra of their solutions, showed that, with respect to the ability of its 2-acylamino derivatives to tautomerize to the imido form, quinoxaline is close to pyrimidine, and below quinoline and pyridine. With respect to the amideimide tautomerism equilibrium position, N-oxides of 2-acylaminoquinoxalines differ little from acylamides of quinoxaline themselves. The action of benzene sulfochloride on 2-aminoquinoxaline-1-N-oxide in pyridine below 0°leads to deoxidation of the N O group, and introduction of the benzene sulfonyloxy group at position 3 in the quinoxaline ring.For Part VIII see [17]. 相似文献
7.
《Thermochimica Acta》1987,122(2):403-412
The chloro and bromo compounds of quinoxaline with manganese(II), cobalt(II), nickel(II) and copper(II) have been prepared in ethanolic solution. The thermal behaviour of these compounds was studied by thermogravimetry (TG) and differential thermal analysis (DTA). The thermal decomposition studies show that the compounds dichlorobis(quinoxaline) cobalt(II), dibromobis(quinoxaline) cobalt(II) and dibromobis(quinoxaline) manganese(II) form intermediate compounds before the metal halide is produced. The other compounds undergo decomposition with loss of organic ligand and the formation of the metal halide. Electrical conductivities at room temperature range from 1.4 × 10−6 Ω−1 m−1 for MnCl2Q to 2.3 × 10−3 Ω−1 m−1 for both CoCl2Q2 and CoBr2Q2. There appears to be a correlation between electrical conductivity and coordination number of the metal atom. From the temperature dependence of conductivity, information has been obtained for donor or acceptor ionization energies. Decomposition temperature, as electrically determined, is in good agreement with the TG method. 相似文献
8.
Boltacheva N. S. Slepukhin P. A. Pervova M. G. Filyakova V. I. Charushin V. N. 《Russian Journal of General Chemistry》2019,89(3):416-423
Novel quinoxaline derivatives have been synthesized via the reaction of 3-trifhioromethyl-1,2,3-propanetrione-2-oximes with 1,2-diaminobenzene or 2,3-diaminonaphthalene: 2-trifluoromethyl-3-aroylquinoxaline and 2-trifluoromethyl-3-aroylbenzo[g]quinoxaline. Under similar conditions, 3-RF-1,2,3-propanetrione-2-oximes [RF = C3F7, H(CF2)4, C4F9, and C6F13] with the same diaminoarenes have given a mixture of the condensation and fragmentation products in different ratios. The structure of (4-methylphenyl)[3-(tri-fluoromethyl)benzo[g]quinoxalin-2-yl]methanone has been elucidated by means of X-ray diffraction analysis.
相似文献9.
Zora Popovi Gordana Pavlovi Boris‐Marko Kukovec 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(5):m181-m183
The title compound, [Cu(C9H5N2O3)2(C2H6OS)2], consists of octahedrally coordinated CuII ions, with the 3‐oxo‐3,4‐dihydroquinoxaline‐2‐carboxylate ligands acting in a bidentate manner [Cu—O = 1.9116 (14) Å and Cu—N = 2.1191 (16) Å] and a dimethyl sulfoxide (DMSO) molecule coordinated axially via the O atom [Cu—O = 2.336 (5) and 2.418 (7) Å for the major and minor disorder components, respectively]. The whole DMSO molecule exhibits positional disorder [0.62 (1):0.38 (1)]. The octahedron around the CuII atom, which lies on an inversion centre, is elongated in the axial direction, exhibiting a Jahn–Teller effect. The ligand exhibits tautomerization by H‐atom transfer from the hydroxyl group at position 3 to the N atom at position 4 of the quinoxaline ring of the ligand. The complex molecules are linked through an intermolecular N—H...O hydrogen bond [N...O = 2.838 (2) Å] formed between the quinoxaline NH group and a carboxylate O atom, and by a weak intermolecular C—H...O hydrogen bond [3.392 (11) Å] formed between a carboxylate O atom and a methyl C atom of the DMSO ligand. There is a weak intramolecular C—H...O hydrogen bond [3.065 (3) Å] formed between a benzene CH group and a carboxylate O atom. 相似文献
10.
Studies on Nickel Oxide Mixed Catalysts. VIII. Catalytic Properties of NiO? Al2O3/SiO2 Catalysts Catalytic properties of NiO? Al2O3/SiO2 catalysts prepared by precipitation-deposition and impregnation have been investigated in dimerization of ethene and isomerization of but-1-ene. It was found that the catalytic activity is mainly determined by the interaction between the catalyst components where a X-ray amorphous nickel alumolayersilicate is formed. The dimerization of ethene proceeds by participation of coordinatively unsaturated nickel ions with aluminum ions in the neighbourhood. The catalytic activity in the isomerization of but-1-ene depends on the surface acidic properties of the catalyst. 相似文献
11.
Ligia Rebelo Gomes John Nicolson Low Ana S. M. C. Rodrigues James L. Wardell Marcus V. N. de Souza Thais C. M. Noguiera Alessandra C. Pinheiro 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(8):920-926
(E)‐2‐(2‐Benzylidenehydrazinylidene)quinoxaline, C15H12N4, crystallized with two molecules in the asymmetric unit. The structures of six halogen derivatives of this compound were also investigated: (E)‐2‐[2‐(2‐chlorobenzylidene)hydrazinylidene]quinoxaline, C15H11ClN4; (E)‐2‐[2‐(3‐chlorobenzylidene)hydrazinylidene]quinoxaline, C15H11ClN4; (E)‐2‐[2‐(4‐chlorobenzylidene)hydrazinylidene]quinoxaline, C15H11ClN4; (E)‐2‐[2‐(2‐bromobenzylidene)hydrazinylidene]quinoxaline, C15H11BrN4; (E)‐2‐[2‐(3‐bromobenzylidene)hydrazinylidene]quinoxaline, C15H11BrN4; (E)‐2‐[2‐(4‐bromobenzylidene)hydrazinylidene]quinoxaline, C15H11BrN4. The 3‐Cl and 3‐Br compounds are isomorphous, as are the 4‐Cl and 4‐Br compounds. In all of these compounds, it was found that the supramolecular structures are governed by similar predominant patterns, viz. strong intermolecular N—H...N(pyrazine) hydrogen bonds supplemented by weak C—H...N(pyrazine) hydrogen‐bond interactions in the 2‐ and 3‐halo compounds and by C—H...Cl/Br interactions in the 4‐halo compounds. In all compounds, there are π–π stacking interactions. 相似文献
12.
Yong Zhang Min Yang Chengli Jia Prof. Min Ji 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(60):13709-13713
A method for the synthesis of novel fused four-ring quinoxaline skeleton has been described by an I2 promoted sp3 C−H functionalization between 1,2,3,3-tetramethyl-3H-indolium iodides and 1,2-diamines. This transformation proceeds smoothly under metal- and peroxide-free conditions through a sequential iodination, oxidation, annulation and rearrangement. Moreover, 8,9-dichloro-5,12,12-trimethyl-2-(trifluoromethyl)-5,12-dihydroquinolino[2,3-b]quinoxaline showed good photophysical properties and was used in live cell imaging, indicating the potential value of this skeleton as a fluorophore in probes. 相似文献
13.
《Annales de Chimie Science des Materiaux》2002,27(2):27-35
New fluoride glasses were obtained in the InF3-BaF2-YF3 system. Evidence for phase separation was found in this basic ternary system, suggesting that glasses based on yttrium fluoride could be formed. Indeed such glasses could be prepared by fast cooling. The mean sample thickness was 2–3 mm. Glass transition, crystallization and melting temperatures were measured. 相似文献
14.
Alvaro Delgadillo Paola Romo AnaMaria Leiva Brbara Loeb 《Helvetica chimica acta》2003,86(6):2110-2120
A series of substituted pyrazino[2,3‐f][1,10]‐phenanthroline (Rppl) ligands (with R=Me, COOH, COOMe) were synthetized (see 1 – 4 in Scheme 1). The ligands can be visualized as formed by a bipyridine and a quinoxaline fragment (see A and B ). Homoleptic [Ru(R1ppl)3](PF6)2 and heteropleptic [Ru(R1ppl){(R2)2bpy}2](PF6)2 (R1=H, Me, COOMe and R2=H, Me) metal complexes 5 – 7 and 8 – 13 , respectively, based on these ligands were also synthesized and characterized by conventional techniques (Schemes 2 and 3, resp.). In the heteroleptic complexes, the R1‐ppl ligand reduces at a less‐negative potential than the bpy ligand, reflecting the acceptor property conferred by the quinoxaline moiety. The potentiality of some of these complexes as solar‐cell dyes is discussed. 相似文献
15.
Alexis A. Sosa Toa S. Rivera Mirta N. Blanco Luis R. Pizzio Gustavo P. Romanelli 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1071-1079
Abstract A green, simple, and fast procedure has been developed for the preparation of quinoxaline derivatives by a condensation of 1,2-diamines with 1,2-dicarbonyl compounds in the presence of zirconium oxide modified with tungstophosphoric acid (H3PW12O40) as a heterogeneous catalyst, in a solvent-free medium using conventional heating. Quinoxaline derivatives were formed in short-time periods and excellent yields (65–100%). The reaction work-up is very simple and the catalyst can be easily separated from the reaction mixture and reused several times in subsequent reactions without appreciable loss of the catalytic activity. Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional text. 相似文献
16.
Athanassios I. Philippopoulos Nektaria Tsantila Constantinos A. Demopoulos Catherine P. Raptopoulou Vlassis Likodimos Polycarpos Falaras 《Polyhedron》2009
The reaction of RhCl3·3H2O with the ligand L = 2-(2′-pyridyl)quinoxaline (pqo) in a 1:2 molar ratio formed the mononuclear complex cis-[RhL2Cl2]Cl (1), which has been characterized by elemental analysis, FT-IR, FT-Raman, 1H, 13C NMR, electronic absorption spectroscopy and by electrospray mass spectrometry. The molecular structure of 1 (needle like and prismatic polymorphs) in the crystal has been elucidated by single-crystal X-ray diffraction, revealing a bidentate behavior of L, while the geometry around the Rh(III) atom is that of a distorted octahedron.. Preliminary biological tests revealed that this compound inhibited PAF-induced rabbit platelet aggregation. 相似文献
17.
Thomas Thoma V.G. Pleshakov N.S. Prostakov Yu.A. Ustynyuk A.N. Nesmeyanov N.A. Ustynyuk 《Journal of organometallic chemistry》1980,192(3):359-365
Reactions of 2- and 4-azafluorenes (I, II) and their methyl derivatives, 3-methyl-2-azafluorene (III) and 7-methyl-4-azafluorene (IV) with chromium hexacarbonyl in a diglyme/heptane mixture at 140°C have been studied. A N-donor complex, C12H9NCr(CO)5 is formed in the reaction of I with Cr(CO)6. Compounds II–IV react to give arenechromiumtricarbonyl derivatives with benzene rather than pyridine ring bound to the metal. [η6-(4b,5,6,7,8,9b)-4-Azafluorene]chromiumtricarbonyl (VIII) gives the corresponding hydrochloride under the action of HCl. Methyl iodide decomposes VIII to produce 4-azafluorene iodomethylate. Deprotonation of VIII with BuLi in ether at ?20°C followed by dilution with hexane leads to precipitation of the corresponding Li salt (Xb), having η6-structure. Methylation of Xb with methyl iodide proceeds stereospecifically to yield the exo-methyl derivative XII. Treatment of VIII with excess t-BuOK at 25°C in THF results in a mixture of η6-(Xa) and η5-anions (XI), the former predominating. 相似文献
18.
An unprecedented three-dimensional (3D) polymer [Cu2(quinoxaline)2Mo4O13]n, formed from ξ-octamolybdate chains as building units and pairs of 1D [Cu(quinoxaline)]nn+ polymeric chains as linkers, provides the first example of an extended higher dimensional structure based on octamolybdate chain. The basic building block of the octamolybdate chain included in the title compound is first reported to be constructed from ξ-isomer of octamolybdate unit. 相似文献
19.
The kinetics of the Os(VIII)-catalyzed oxidation of glycine, alanine, valine, phenylalanine, isoleucine, lycine, and glutamic acid by alkaline hexacyanoferrate(III) reveal that these reactions are zero order in hexacyanoferrate(III) and first order in Os(VIII). The order in amino acid as well as in alkali is 1 at [amino acid] ?2.5 × 10?2M and [OH?] ?1.3 × 10?M, but less than unity at higher concentrations of amino acids or alkali. The active oxidizing species under the experimental conditions is OsO4(H2O) (OH)?. The ferricyanide is merely used up to regenerate the Os(VIII) species from Os(VI) formed during the reaction. The structural influence of amino acids on the reactivity has been discussed. The amino acids during oxidation are shown to be degraded through intermediate keto acids. The kinetic data are accommodated by considering the interaction between the conjugate base of the amino acids and the active oxidizing species of Os(VIII) to form a transient complex in the primary rate-determining step. The catalytic effect of hexacyanoferrate(II) has been rationalized. 相似文献
20.
A. M. Simonov I. G. Uryukina A. F. Pozharskii 《Chemistry of Heterocyclic Compounds》1972,8(3):380-382
The transformations that occur during the reduction of 1-(o-nitrophenyl)-2-formylimidazole with sodium hydrosulfite in the presence of ammonia were studied. The 4-amino derivatives of imidazo[1,2-a]quinoxaline and the bisulfite derivatives of 1-(o-aminophenyl)-2-formylimidazole are formed along with the previously described imidazo[1,2-a]quinoxaline. 4-Aminoimidazo[1,2-a]quinoxaline was also obtained by alternative synthesis by amination of imidazo-[1,2-a]quinoxaline with sodium amide in dimethylaniline. The major product of the transformation is 4,4-bisimidazo[1,2-a]quinoxalyl when the reaction is carried out in xylene.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 416–418, March, 1972. 相似文献