2-Chlorophenylhydrazine hydrochloride → 5-(4-bromo-phenyl)-1-(2-chloro-phenyl)-3-pentafluoroethyl-4,5-dihydro-1H-pyrazole

Participants

Reaction Conditions

Reaction Steps

1-(4-Bromo-phenyl)-4,4,5,5,5-pentafluoro-pent-1-en-3-one (8.0 g, 24.3 mmol) prepared in Step 2 and 2-chlorophenylhydrazine hydrochloride (5.7 g, 31.6 mmol) were added to acetic acid (116.0 mL). The reaction mixture was stirred at 125° C. for 4 hours, concentrated under reduced pressure, and then ethyl acetate was added thereto. The mixture was washed with a saturated solution of sodium hydrogen carbonate, dried on anhydrous magnesium sulfate, and then concentrated under reduced pressure to give a yellow liquid residue. The resulting residue was purified by silica gel column chromatography (eluent: ethyl acetate/n-hexane=1/60) to give 8.5 g of the titled compound as a yellow liquid.

Provenance & Evidence