N-Oxides of the quinoxaline series. I. N-Oxides of quinoxaline-2-carboxylic acid was written by Elina, A. S.;Magidson, O. Yu.. And the article was included in Zhurnal Obshchei Khimii in 1955.Name: Ethyl 3-chloroquinoxaline-2-carboxylate This article mentions the following:
2-(m-Nitrostyryl)quinoxaline (6.3 g.) heated to boiling in 200 ml. Me2CO, cooled and treated with 5% aqueous KMnO4, filtered (when colorless, the filtrate concentrated and acidified gave mixed acids which treated with 30 ml. 10% NaHCO3 followed by 10 ml. EtOH gave Na quinoxaline-2-carboxylate, which with dilute HCl gave the free acid (I), m. 210-11°, in 56.4% yield; Et ester, m. 83-4°. To 20 g. 2-methylquinoxaline in MePh (240 ml.) was slowly added 18 g. SeO2, the mixture refluxed 1.5 hrs., filtered, the filtrate steam distilled, and the distillate salted out gave quinoxaline-2-carboxaldehyde, which is extracted with Et2O; the pure aldehyde, 56.6%, m. 110° (from petr. ether); the precipitate from the reaction yielded 19.8% I. The aldehyde with thiosemicarbazide in EtOH gave the thiosemicarbazone, decompose 238-9°. The aldehyde treated with KMnO4 in Me2CO gave 72.7% I. I Et ester (4.75 g.) added over 3 hrs. at 45° to 25 ml. AcOH, 19.2 ml. Ac2O, and 23 ml. 30% H2O2 and kept 16 hrs. at 50° gave on neutralization with NaHCO3, 80.1% yellow I 4-oxide Et ester (II), m. 156-7° (from MeOH); similar treatment of I gave I 4-oxide, 80%, m. 180-2° (from EtOH), this substance also being formed in good yield on stirring its Et ester 20 min. with 7.5% NaOH. II and alc. NH3 kept 12 hrs. at room temperature gave I 4-oxide amide, m. 230-30.5° (from EtOH). II in EtOH with 85% N2H4 after 12 hrs. at room temperature gave 90% I 4-oxide hydrazide, m. 216-17° (from 50% EtOH). NH2OH.HCl (1.64 g.) in 9 ml. MeOH treated with 1.97 g. KOH in 29 ml. MeOH, followed, at 40°, by 2 g. II and kept 20 hrs. gave K quinoxaline-2-hydroxamate 4-oxide, yellowish, m. 185-6° (from H2O). To I 4-oxide (0.3 g.) in 3.5 ml. 15% NaOH and 22 ml. H2O was slowly added 0.5 g. Na2S2O4 and after 1 hr. at room temperature the mixture was acidified to Congo red, yielding 83.9% I. II (1 g.) and 10 ml. POCl3 refluxed 1.5 hrs., concentrated, quenched in ice and neutralized, gave Et 3-chloroquinoxaline-2-carboxylate, m. 41.5-2° (cf. Gowenlock, et al., C.A. 40, 341.3), which heated 1.5 hrs. with Na2CO3 in 70% MeOH gave the corresponding free acid, m. 146-7° (decomposition); passage of NH3 in EtOH solution of the Et ester at 0° gave 3-chloroquinoxaline-2-carboxamide, m. 214-15°. To 3 g. 2-methylquinoxaline 1,4-dioxide in C6H6 at reflux was added 3.5 g. SeO2 and after 2 hrs. refluxing, the filtrate yielded 2.02 g. quinoxaline-2-carboxaldehyde 1,4-dioxide, decompose 189-90°, which gives typical aldehyde reactions and liberates iodine from acidic KI solution This on oxidation with 30% H2O2 in AcOH-Ac2O at 50° 1 hr. gave I 1,4-dioxide, yellow, m. 208-9° (from AcOH); this reduced with Na2S2O4 in 5% NaOH at 20-5° to I 1-oxide, colorless, m. 180-1°; this reduced with Na2S2O4 in 3% NaOH to I. In the experiment, the researchers used many compounds, for example, Ethyl 3-chloroquinoxaline-2-carboxylate (cas: 49679-45-0Name: Ethyl 3-chloroquinoxaline-2-carboxylate).
Ethyl 3-chloroquinoxaline-2-carboxylate (cas: 49679-45-0) belongs to quinoxaline derivatives. Quinoxaline is isomeric with other naphthyridines including quinazoline, phthalazine and cinnoline. Quinoxaline and its analogues may also be formed by reduction of amino acids substituted 1,5-difluoro-2,4-dinitrobenzene (DFDNB),One study used 2-iodoxybenzoic acid (IBX) as a catalyst in the reaction of benzil with 1,2-diaminobenzene.Name: Ethyl 3-chloroquinoxaline-2-carboxylate
Referemce:
Quinoxaline – Wikipedia,
Quinoxaline | C8H6N2 | ChemSpider