反応 #81981

反応方程式

diethyl oxalate

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

→

title compound

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

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 gray solid collected by vacuum filtration
4. 4
   洗浄rinsed with ice-cold EtOH (10 mL) and air
5. 5
   その他dried
6. 6
   workup.DISSOLUTIONdissolved in 5 mL 1N NaOH
7. 7
   温度with heating
8. 8
   workup.ADDITIONThe solution was treated with activated charcoal
9. 9
   ろ過filtered through a pad of Celite
10. 10
    その他A white powder formed in the solution at pH=6, but a few drops 1N NaOH
11. 11
    その他slowly formed in the solution
12. 12
    ろ過These were collected by vacuum filtration
13. 13
    洗浄rinsed with 20 mL of H2O
14. 14
    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 (981 mg, 6.72 mmol) and 3-chloro-4,5-difluoro-1,2-diaminobenzene (120 mg, 0.670 mmol) was heated to reflux under N2 for 15 h. The reaction was allowed to cool to room temperature and the gray solid collected by vacuum filtration and rinsed with ice-cold EtOH (10 mL) and air dried. The solid was taken and dissolved in 5 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). A white powder formed in the solution at pH=6, but a few drops 1N NaOH cleared the solution and upon addition of a few drops 1N HCl white needles slowly formed in the solution. These were collected by vacuum filtration, rinsed with 20 mL of H2O and dried under vacuum (0.1 torr, 78° C.) to yield 24.9 (16%) of pale yellow needles. 1H NMR (d6 -DMSO) δ 7.05 (dd, 1H, J =10.5, H-8), 11.6 (br s, 1H, NH), 12.0 (br s, 1H, NH). There was 13% 6,7-difluoro-1,4-dihydro-2,3-quinoxalinedione present by NMR.

出典