40016-70-4Relevant academic research and scientific papers
Silica gel catalyzed synthesis of quinoxialine 1,4-dioxides under solvent-free conditions using microwave irradiation
Sumiyoshi, Yusuke,Saito, Hiroaki,Miyairi, Shinichi,Takabatake, Tohru
scheme or table, p. 905 - 909 (2009/09/29)
We report on the simple and quick synthesis of quinoxaline 1,4-dioxides in solvent-free conditions under microwave irradiation. Heating of various benzofuroxans and β-ketoesters or 1,3-diketones adsorbed on silica gel in a microwave oven for two minutes affords diverse biologically attractive quinoxaline 1,4-dioxides in high to excellent yields. Silica gel functions not only as support using microwave but also as catalyst and dehydration reagent.
The enthalpies of dissociation of the N-O bonds in two quinoxaline derivatives
Gomes, Jose R. B.,Monteiro, Andre R.,Campos, Bruno B.,Gomes, Paula,Ribeiro Da Silva, Maria D. M. C.
experimental part, p. 17 - 23 (2009/07/26)
The present work reports the first experimental thermochemical study of mono-N-oxides derived from quinoxaline, namely, 3-methoxycarbonyl-2-methyl- quinoxaline N-oxide and 3-ethoxycarbonyl-2-methyI-quinoxaIine N-oxide. The values of the enthalpies of formation, in the condensed state, and of the enthalpies of sublimation, derived from static bomb calorimetry and Calvet microcalorimetry measurements, respectively, are combined to derive the standard molar enthalpies of formation in the gaseous phase for these two compounds. From the latter values, the first and second N-O bond dissociation enthalpies for the corresponding di-N-oxides have been obtained. The gas-phase experimental results are also compared with calculated data obtained with a density functional theory approach. Copyright
Synthesis of new quinoxaline-2-carboxylate 1,4-dioxide derivatives as anti-Mycobacterium tuberculosis agents
Jaso, Andrés,Zarranz, Belén,Aldana, Ignacio,Monge, Antonio
, p. 2019 - 2025 (2007/10/03)
Twenty-nine new 6(7)-substituted quinoxaline-2-carboxylate 1,4-dioxide derivatives were synthesized and evaluated for in vitro antituberculosis activity. In general, the in vitro activity is significantly affected by substituents on the quinoxaline nucleu
Thermochemical and Theoretical Study of Some Quinoxaline 1,4-Dioxides and of Pyrazine 1,4-Dioxide
Acree Jr.,Powell, Joyce R.,Tucker, Sheryl A.,Ribeiro da Silva, Maria D.M.C.,Matos, M. Agostinha R.,Goncalves,Santos,Morais,Pilcher
, p. 3722 - 3726 (2007/10/03)
The following standard molar enthalpies of formation in the gaseous state at 298.15 K were determined from the enthalpies of combustion of the crystalline solids, and their enthalpies of sublimation and the mean (N-O) bond dissociation enthalpies were derived. ΔfHm0(g); 〈D(N-O)〉 (kJ mol-1): quinoxaline 1,4-dioxide, 227.1 ± 2.4; 255.8 ± 2.0; 2-methylquinoxaline 1,4-dioxide, 169.9 ± 7.2; 268.3 ± 4.9; 2-methyl-3-acetylquinoxaline 1,4-dioxide, 33.1 ± 5.0; 251.6 ± 4.2; 2-phenyl-3-benzoylquinoxaline 1,4-dioxide, 355.2 ± 7.1; 227.3 ± 5.4; 2-methyl-3-carbomethoxyquinoxaline 1,4-dioxide, -148.7 ± 3.2; 242.3 ± 3.9; pyrazine 1,4-dioxide, 186.5 ± 1.9; 254.0 ± 2.3; 2-methyl-5-pyrazinecarboxylic acid, -213.6 ± 1.7. Unconstrained geometry optimizations by ab initio calculations showed the effect of steric hindrance on changes in extended delocalizations and were in accord with the trends in the mean bond dissociation enthalpies.
The reactions of benzofuroxan with carbonyl compounds on the surface of solid catalysts
Takabatake,Hasegawa,Hasegawa
, p. 1477 - 1480 (2007/10/02)
The cyclocondensations of benzofuroxan 1a with carbonyl compounds were smoothly and efficiently carried out by the adsorption of the components on the surface of silica gel or a molecular sieve to form a 2,3-disubstituted quinoxaline 1,4-dioxide. When the
An Improved and Efficient Synthesis of Quinoxalinecarboxamide 1,4-Dioxides from Benzofuroxan and Acetoacetamides in the Presence of Calcium Salts
Stumm, G.,Niclas, H.-J.
, p. 736 - 744 (2007/10/02)
An improved and efficient method for the preparation of the title compounds 3 is described.Thus, quinoxalinecarboxamide 1,4-dioxides 3 are synthesized in high yields by reaction of benzofuroxan 1 with acetoacetamides 2 in the presence of catalytic amounts of calcium salts and ethanolamine.The reaction is assumed to involve a chelate mechanism with 4 as intermediate.Side reactions are studied by means of HPLC and TLC.
Reactions of Benzofuroxan with 1,3-Diketones or β-Ketoesters on Silica Gel or Alumina
Hasegawa, Minoru,Takabatake, Tohru
, p. 938 (2007/10/02)
The cyclocondensation of benzofuroxan with 1,3-diketones, 3-oxoalkanoic esters, butanedioic esters, or 3-oxoalkanamides in the presence of silica gel (adsorption of the components on silica gel) represents a convenient method for the synthesis of 2,3-disu
