5-broMo-7-(trifluoroMethyl)-1H-indazole

864539-96-8

1374258-43-1

General procedure for the synthesis of 5-bromo-7-(trifluoromethyl)-1H-indazole from 4-bromo-2-methyl-6-(trifluoromethyl)aniline: to a mixture of 4-bromo-2-methyl-6-(trifluoromethyl)aniline (700 mg, 2.77 mmol) and potassium acetate (325.8 mg, 3.32 mmol) in chloroform (20 mL) was added dropwise at 0 °C with acetic anhydride (846.6 mg, 8.30 mmol). The reaction mixture was stirred at room temperature for 1 hour. Subsequently, the reaction mixture was heated to 60 °C and tert-butyl nitrite (570.6 mg, 5.54 mmol) was added. After stirring at 60 °C overnight, the mixture was diluted with water and extracted twice with dichloromethane. The combined organic layers were washed with brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was dissolved in methanol (5 mL) and 6N hydrochloric acid (5 mL). The mixture was stirred at room temperature for 4 hours, alkalized with 10N aqueous sodium hydroxide and extracted twice with dichloromethane. The combined organic layers were again washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (petroleum ether/ethyl acetate = 10:1 to 3:1) to afford 5-bromo-7-(trifluoromethyl)-1H-indazole (420 mg, 57.5% yield) as a yellow oil.LC/MS (ESI) m/z: 265 (M + H).