294877-29-5

27246-81-7

123-54-6

294877-29-5

A solution was prepared from 3-bromophenylhydrazine hydrochloride (45 g, 200 mmol) and acetylacetone (30.2 g, 302 mmol) in dichloromethane (225 mL). Concentrated sulfuric acid (1.073 mL, 20.13 mmol) was slowly added to the solution under nitrogen protection and the reaction was stirred at room temperature for 16 hours. After completion of the reaction, the reaction mixture was diluted with dichloromethane (500 mL) and washed with deionized water (2 x 250 mL). The organic layer was dried with anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent. The crude product was purified by column chromatography on silica gel (100-200 mesh) with hexane solution of 5% ethyl acetate as eluent to afford 1-(3-bromophenyl)-3,5-dimethyl-1H-pyrazole (59% yield) as a light brown liquid.1H NMR (CDCl3, 400 MHz) δ: 7.71 (t, J = 2 Hz, 1H), 7.57-7.49 (m 2H), 7.46-7.40 (t, J = 8 Hz, 1H), 6.07 (s, 1H), 2.31 (s, 3H), 2.18 (s, 3H).