Quinoxaline N-oxides. I. The oxidation of quinoxaline and its Bz-substituted derivatives was written by Landquist, Justus K.. And the article was included in Journal of the Chemical Society in 1953.Formula: C8H5ClN2 This article mentions the following:
Quinoxaline (I) and its Bz-substituted-alkyl, alkoxy, halo, and acylamino derivatives are oxidized to 1- and 1,4-dioxides by organic peroxy acids. Resistance to N-oxidation is encountered in 5- and 8-substituted I. Reduction of 2,3-(O2N)2C6H3OEt with H and Raney Ni gave 3,1,2-EtOC6H3(NH2)2, oil (picrate, m. 210-12°). 2,4-Br(O2N)C6H3Me nitrated with HNO3 and H2SO4 at 40-5° gave 2,4,5-Br(O2N)2C6H2Me, m. 94-5°, which, treated with NH3 in alc. 5 h. at 120° and then reduced with Zn dust and NaOH in EtOH, yielded the 4,5-(H2N)2 analog, m. 140-1°. The following general procedure for preparation of I derivatives was used: (CHO.NaHSO3)2, an ο-phenylenediamine, and H2O were stirred 3 h. at 60°, then made alk. with KOH, and the I derivative was filtered off. The following derivatives were prepared (substituent, m.p., m.p. of 1-oxide, m.p. of 1,4-dioxide): 5-Me, 20-1°, b15, 120°, 131-2°, 192-4°; 5-EtO, 63-4°, b18 165-6°, 114-16°, -; 5-Cl (II), 60-2°, 177-9°, -; 6-iodo, 114-15°, -, -; 6-NC (III), 176-8°, -, -; 6,7-Me2, 100-1°, -, 220°; 6,7-benzo, 125-6°, -, -; 6,7-ClMe (IV), 120-2°, 166-8°, 227°; 6,7-BrMe (V), 127-8°, 167-8°, 222-4°; 6,7-Cl2 (VI), 210°, -, 206-8°; 5,8-Cl2 (VII), 205-7°, -, -; 6-Br (VIII)(prepared by the Sandmeyer reaction from the 6-NH2 compound), 48-9°, b18 146-9°, -, 223-5°; 6-AcNH (prepared from the 6-NH2 compound with Ac2O), 196.5°, -, 245-7°; 5-AcNH, -, 175-8°, 230-2° (insufficient for anal.). The following N-oxides were also prepared (substituent, m.p. 1-oxide, m.p. 1,4-dioxide): 6-Me (IX), -, 218-19°; 5,6-benzo, 158-9°, 215-16°; 5,6:7,8-dibenzo, 243-4°, -; 5-MeO, -, 222°; 6-MeO, -, 227-8°; 6-EtO, -, 192-4°; 5,6-(MeO)2, 138-40°, 220-2°; 6,7-(MeO)2, -, 264-5°; 2-Cl, 150-2°, -; 6-Cl (X), 151-2°, 211-12°. I is oxidized with equimolar AcO2H to quinoxaline 1-oxide, m. 122-3° (XI) while excess peroxy acid yields quinoxaline 1,4-dioxide, m. 241-3° (XII). Simultaneous with N-oxide formation there were obtained 2,3-dihydroxyquinoxalines which are listed below: (substituent, % yield, m.p.): IX, 1, 112°; II, 30, 142-3°; X, 15-30, 144°; VIII, 28, 132°; VII, 65, 160-1°; VI, 43, 170-70.5°; IV, 10, 172-3°; V, 12-6, 160-1°; III, 50, -; 6-O2N, 60, 150°. XI and MeI in MeCN set aside in the dark 36 h., precipitated 1-methylquinoxalinium iodide 4-oxide, m. 188-9°. XI was added cautiously to POCl3, and the mixture boiled 15 min. after the reaction subsided, poured on ice, made alk. with KOH, extracted with Et2O, and concentrated to yield 2-chloroquinoxaline, m. 46-8°. Under similar conditions XII yielded 2,3-dichloroquinoxaline; 5-methylquinoxaline 1-oxide gave 2-chloro-5-methylquinoxaline, m. 95°; and 5,6-benzoquinoxaline 1-oxide yielded 2-chloro-5,6-benzoquinoxaline, m. 120.5°. 2-C10H7NHCH2CO2Et dissolved treated in EtOH with PhN2Cl yielded 1,2-Ph2NC10H6NHCH2CO2Et, m. 135-6°, hydrogenated with Raney Ni at 60° and 50 atm. to 1,2,3,4-tetrahydro-2-oxo-7,8-benzoquinoxaline (XIII), m. 197-8°. XIII with alk. H2O2 gave 2-hydroxy-7,8-benzoquinoxaline, isolated as the hydrate, m. 275-5.5°, which was converted with POCl3 into 2-chloro-7,8-benzoquinoxaline, m. 128-9°. N-(6-nitro-o-tolyl)glycine in EtOH hydrogenated over Raney Ni at 60° and 60 atm. yielded 1,2,3,4-tetrahydro-5-methyl-2-oxoquinoxaline, m. 177-80°, readily oxidized to 2-hydroxy-5-methylquinoxaline, m. 282-3°. 2-Chloro-7,8-benzoquinoxaline and piperidine refluxed 1.5 h. gave 2-piperidino-7,8-benzoquinoxaline, m. 101.5-2.5°. 2-Piperidino-5,6-benzoquinoxaline, m. 124-5°, was similarly prepared Cl slowly passed 1 h. into 5,6-benzoquinoxaline in glacial HOAc, and the solution filtered and diluted with H2O yielded, on purification, dichloro-5,6-benzoquinoxaline, m. 187-8°. Methylation of 2,3-dihydroxy-6-nitroquinoxaline with Me2SO4 gave 3-hydroxy-1-methyl-6(or 7)-nitro-2(1H)-quinoxalinone, m. 344°. 6(or 7)-Cyano-3-hydroxy-1-methyl-2(1H)-quinoxalinone, m. 353-4°, is similarly prepared In the experiment, the researchers used many compounds, for example, 6-Chloroquinoxaline (cas: 5448-43-1Formula: C8H5ClN2).
6-Chloroquinoxaline (cas: 5448-43-1) belongs to quinoxaline derivatives. Condensed heterocycles of quinoxalines have become attractive targets in synthetic and medicinal chemistry due to their significant biological activities. 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.Formula: C8H5ClN2
Referemce:
Quinoxaline – Wikipedia,
Quinoxaline | C8H6N2 | ChemSpider