反应详情

温度

62.5 °C

A mixture of 1,2diamino-4,6-dimethylbenzene (424 mg, 3.11 mmole) and oxalic acid dihydrate (432 mg, 3.43 mmole, used as received) in 4N HCl (20 mL) was refluxed at 120-5° C. for 3 h, then cooled to room temperature. The mixture was centrifuged and the supernatant was removed. The yellow solid was washed with cold water (2×2 mL), collected by filtration, and dried in vacuo for 2 h, affording 516 mg of crude 5,7-dimethyl-1,4-dihydro-2,3-quinoxalinedione (87%) as a yellow powder. The crude product was taken up in 1N NaOH (10 mL) and filtered. The filtrate was acidified to pH=3, affording the pure title compound (490 mg) as a light yellow powder; mp:345-347° C. (dec); IR (KBr, cm-1):3460, 3190, 2986, 1716, 1709, 1630. 1H NMR (DMSO-d6): δ 11.858 (s, 1H), 11.173 (s, 1H), 6.766 (s, 1H), 6.745 (s, 1H), 2.280 (s, 3), 2.211 (s, 3). HRMS: calcd for C10H10N2O2 (M+) m/z: 190.0714; found: 190.0744.

1. temperaturecooled to room temperature
2. customthe supernatant was removed
3. washThe yellow solid was washed with cold water (2×2 mL)
4. filtrationcollected by filtration
5. customdried in vacuo for 2 h