- Silica gel catalyzed synthesis of quinoxialine 1,4-dioxides under solvent-free conditions using microwave irradiation
-
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.
- Sumiyoshi, Yusuke,Saito, Hiroaki,Miyairi, Shinichi,Takabatake, Tohru
-
scheme or table
p. 905 - 909
(2009/09/29)
-
- Thermochemical and Theoretical Study of Some Quinoxaline 1,4-Dioxides and of Pyrazine 1,4-Dioxide
-
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.
- 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 reactions of benzofuroxan with carbonyl compounds on the surface of solid catalysts
-
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
- Takabatake,Hasegawa,Hasegawa
-
p. 1477 - 1480
(2007/10/02)
-
- Reactions of Benzofuroxan with 1,3-Diketones or β-Ketoesters on Silica Gel or Alumina
-
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
- Hasegawa, Minoru,Takabatake, Tohru
-
-
- Quinoxaline derivatives
-
The synthesis of quinoxaline and benzimidazole-N-oxides and of ester and amide derivatives of 3-hydroxy-2-quinoxalinecarboxylic acid by a novel process consisting of the reaction between a benzofuroxan and an activated methylene-containing compound under basic conditions.
- -
-
-