Triphenylphosphine → 4-bromo-1-(3-methylbut-3-en-2-yl)-1H-pyrazole

Participants

Reaction Conditions

Reaction Steps

(E)-Di-tert-butyl diazene-1,2-dicarboxylate (940 mg, 4.08 mmol) was added slowly to a stirred solution of 3-methylbut-3-en-2-ol (293 mg, 3.40 mmol), triphenylphosphine (1.07 g, 4.08 mmol), and 4-bromo-1H-pyrazole (500 mg, 3.40 mmol) in THF (10 mL) at 0° C. The reaction was stirred for 10 min at 0° C. and then allowed to warm to RT for 1 hour. The reaction was quenched into water and the product was extracted with ethyl acetate (2×20 mL), dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to afford an oil. The oil was dissolved in 20% trifluoroacetic acid in dichloromethane (5 mL) and stirred for 20 minutes. The reaction mixture was concentrated under reduced pressure and the residue was dissolved in ethyl acetate, washed with 10% aqueous sodium bicarbonate, dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to afford the crude residue. The crude residue was purified by column chromatography on silica (20-100% ethyl acetate/hexanes) to afford 4-bromo-1-(3-methylbut-3-en-2-yl)-1H-pyrazole. MS ESI calcd. for C8H12BrN2 [M+H]+ 215 and 217. found 215 and 217.

Provenance & Evidence