تفاعل #82572

معادلة التفاعل

diethyl oxalate

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

charcoal

→

title compound

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

المذيبات

NaOH

ظروف التفاعل

المعالجة

1. 1
   درجة الحرارةwas heated
2. 2
   درجة الحرارةto reflux under N2 for 15 h
3. 3
   ترشيحthe dark-brown solid collected by vacuum filtration
4. 4
   غسيلrinsed with EtOH (20 mL) and air
5. 5
   أخرىdried
6. 6
   أخرىto give 215 mg (42%)
7. 7
   درجة الحرارةwith heating
8. 8
   ترشيحfiltered through a pad of Celite
9. 9
   أخرىPale yellow needles slowly formed in the solution
10. 10
    ترشيحwere collected by vacuum filtration
11. 11
    غسيلrinsed with 20 mL of H2O
12. 12
    أخرىdried under vacuum (0.1 torr, 78° C.)

الإجراء التجريبي

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) δ7.09 (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), 141 (bp). EIHRMS calc. for C8H4BrF2N2O2 275.9346, found 275.9331.

المصدر