反応 #81984

反応方程式

diethyl oxalate

3-bromo-4,5-difluoro-1,2-diaminobenzene

charcoal

→

title compound

5-Bromo-6,7-difluoro-1,4-dihydro-2,3-quinoxalinedione

溶媒

NaOH

反応条件

後処理

1. 1
   温度was heated
2. 2
   温度to reflux under N2 for 15 h
3. 3
   ろ過the dark-brown solid collected by vacuum filtration
4. 4
   洗浄rinsed with EtOH (20 mL) and air
5. 5
   その他dried
6. 6
   その他to give 215 mg (42%)
7. 7
   温度with heating
8. 8
   ろ過filtered through a pad of Celite
9. 9
   その他Pale yellow needles slowly formed in the solution
10. 10
    ろ過were collected by vacuum filtration
11. 11
    洗浄rinsed with 20 mL of H2O
12. 12
    その他dried under vacuum (0.1 torr, 78° C.)

実験手順

The title compound was prepared using an adaptation of the method of Cheeseman. (Cheeseman, G. W. H. J. Chem. Soc. 1171 (1962)). A mixture of diethyl oxalate (2.70 g, 18.5 mmol) and 3-bromo-4,5-difluoro-1,2-diaminobenzene (410 mg, 1.85 mmol) was heated to reflux under N2 for 15 h. The reaction was allowed to cool to room temperature and the dark-brown solid collected by vacuum filtration and rinsed with EtOH (20 mL) and air dried to give 215 mg (42%). A portion of this solid (150 mg) was taken and dissolved in 20 mL 1N NaOH with heating. The solution was treated with activated charcoal and filtered through a pad of Celite. The resulting solution was carefully acidified with 1N HCl (pH=1). Pale yellow needles slowly formed in the solution and were collected by vacuum filtration, rinsed with 20 mL of H2O and dried under vacuum (0.1 torr, 78° C.) to yield 67.8 mg of powdery pale yellow crystals, mp 306°-310° C. (dec). 1H NMR (d6 -DMSO) δ 7.09 (dd, 1H, J=7.5, H-8), 11.3 (br s, 1H, NH), 12.1 (br s, 1H, NH). EIMS m/z 278 (M+2, 75), 276 (M+, 77), 250 (56), 248 (57), 14 1 (bp). EIHRMS calc. for C8H4BrF2N2O2 275.9346, found 275.9331.

出典