反应详情

2-Chloro-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 (16 mL) under N2 was added N-chlorosuccinimide (401 mg, 3.00 mmol) in DMF. The reaction was allowed to stir 48 h. The solution was then poured into 75 mL H2O. the cloudy orange suspension which formed was then extracted with 4×25 mL of methylene chloride. The combined organic extracts were washed with 5×20 mL of H2O and 25 mL sat'd NaCl solution. The organic phase was dried (MgSO4) and the drying agent removed by vacuum filtration. The solvent was rotary evaporated to yield a yellow orange oil which crystallized on standing. 1H NMR showed this solid to be mixture of chlorinated product and starting material. The mixture was separated by flash chromatography (silica gel, 3:1 hexanes:ethyl acetate) to yield 162 mg of a yellow crystalline solid (27%). 1H NMR (CDCl3) δ 6.60 (br s, 2H, NH2), 8.00 (m, 1H, H-5). There was 17% starting material contamination by NMR.

1. customthe cloudy orange suspension which formed
2. extractionwas then extracted with 4×25 mL of methylene chloride
3. washThe combined organic extracts were washed with 5×20 mL of H2O and 25 mL
4. dry with materialThe organic phase was dried (MgSO4)
5. customthe drying agent removed by vacuum filtration
6. customThe solvent was rotary evaporated
7. customto yield a yellow orange oil which
8. customcrystallized
9. additionmixture of chlorinated product
10. customThe mixture was separated by flash chromatography (silica gel, 3:1 hexanes:ethyl acetate)