反应详情

To a solution of 5-fluoro-4-(pyrazol-1-yl)phenylamine (2.56 g, 14.5 mmol) in tetrahydrofuran (50 ml) was added dropwise a solution of pyridinium tribromide (5.09 g, 15.9 mmol) in tetrahydrofuran (50 ml). The mixture was stirred for 1 h at room temperature then diluted with diethyl ether (250 ml). After stirring for a further 30 min the precipitate was filtered and washed with diethyl ether (50 ml×2). The white solid was dissolved in water (200 ml) and extracted with ethyl acetate (100 ml×3). The combined organic phases were dried over magnesium sulphate, filtered and the solvent removed to leave an orange oil. Purification by chromatography (silica gel, CH2Cl2) gave 2-bromo-5-fluoro-4(pyrazol-1-yl)phenylamine as a white solid: MS (ES+) m/z 256 and 258 [M+H]+.

1. stirringAfter stirring for a further 30 min the precipitate
2. filtrationwas filtered
3. washwashed with diethyl ether (50 ml×2)
4. dissolutionThe white solid was dissolved in water (200 ml)
5. extractionextracted with ethyl acetate (100 ml×3)
6. dry with materialThe combined organic phases were dried over magnesium sulphate
7. filtrationfiltered
8. customthe solvent removed
9. customto leave an orange oil
10. customPurification by chromatography (silica gel, CH2Cl2)