反应详情

1.0 g (3.8 mmol) 4,5-dimethyl-2-nitroaniline in 30 ml tetrahydrofuran:dimethylformamide: 25% aqueous ammonia (30:10:0.7) was hydrogenated at atm. pressure by using 60 mg 5% Pt-C as a catalyst. The precipitate was filtered off and washed with tetrahydrofuran. The filter cake was washed several times with 1N aqueous potassium hydroxide, and the filtrate was acidified with concentrated hydrochloric acid. The precipitate was filtered off and washed with water, ethanol and ether to give 0.13 g (17%) of 6,7-dimethyl-1-hydroxyquinoxaline-2,3(1H,4H)-dione. M.p. decomp. 1H-NMR (DMSO-d6): 11.9 (1H, broad s), 7.3 (1H, s), 7.0 (1H, s), 2.3 (6H, s). MS (m/e): 206 (M+, 70%), 161 (100%).

1. filtrationThe precipitate was filtered off
2. washwashed with tetrahydrofuran
3. washThe filter cake was washed several times with 1N aqueous potassium hydroxide
4. filtrationThe precipitate was filtered off
5. washwashed with water, ethanol and ether