反应详情

To a 0° C. mixture of 4-bromo-3-(trifluoromethyl)phenol (Apollo, 10.8 g, 44.8 mmol) in AcOH (40 mL) was added concentrated sulfuric acid (1.5 mL) followed by fuming nitric acid (5.2 g) and the mixture was stirred for 30 min. Additional concentrated sulfuric acid (9 mL) was added and the temperature was allowed to rise to ambient temperature and stirred for 3 h at rt. The mixture was poured into ice water (500 mL) and the aqueous solution was extracted with EtOAc (3×50 mL). The combined organic phase was washed with brine (50 mL), dried over anhydrous Na2SO4 and filtered. The filtrate was evaporated in vacuo and the residue was purified by column chromatography on silica gel (eluting with 10-20% EtOAc in petroleum ether) to give 4-bromo-2-nitro-5-(trifluoromethyl)phenol (4.7 g, 36%) as yellow oil. 1H NMR (DMSO-d6, 400 MHz): δ 12.0 (brs, 1H), 8.31 (s, 1H), 7.54 (s, 1H).

1. customto rise to ambient temperature
2. stirringstirred for 3 h at rt
3. extractionthe aqueous solution was extracted with EtOAc (3×50 mL)
4. washThe combined organic phase was washed with brine (50 mL)
5. dry with materialdried over anhydrous Na2SO4
6. filtrationfiltered
7. customThe filtrate was evaporated in vacuo
8. customthe residue was purified by column chromatography on silica gel (eluting with 10-20% EtOAc in petroleum ether)