反应详情

2-Bromo-3,4-difluoro-6-nitroaniline was prepared using an adaptation of the method of Mitchell et al. (Mitchell, R. H. et al., J. Org. Chem. 44: 4733 (1979)). To a solution of 4,5-difluoro-2-nitroaniline (500 mg, 2.87 mmol) in DMF (25 mL) under N2 was added all at once N-bromosuccinimide (511 mg, 2.87 mmol) in dry DMF (16 mL). The reaction was allowed to stir overnight. TLC (1:1 hexanes:ethyl acetate) showed still some starting material present. Additional N-bromosuccinimide (100 mg) was added and the reaction stirred another 12 h. The solution was then poured into 100 ml H2O and the resulting cloudy suspension extracted with 3×20 mL methylene chloride. The combined organic phases were washed with 4×25 mL H2O and 25 mL saturated NaCl solution and dried (MgSO4). The MgSO4 was vacuum filtered and the solvent rotary evaporated to yield a yellow brown oil which slowly crystallized to yield 700 mg (96%). 1H NMR (CDCl3) δ 6.70 (br s, 2H, NH2), 7.99 (m, 1H, H-5).

1. stirringthe reaction stirred another 12 h
2. extractionthe resulting cloudy suspension extracted with 3×20 mL methylene chloride
3. washThe combined organic phases were washed with 4×25 mL H2O and 25 mL saturated NaCl solution
4. dry with materialdried (MgSO4)
5. filtrationfiltered
6. customthe solvent rotary evaporated
7. customto yield a yellow brown oil which
8. customslowly crystallized
9. customto yield 700 mg (96%)