3-tert-butyl-1,4-dihydropyrazol-5-one

Conditions: temp:60.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 5-tert-butyl-2,4-dihydro-3H-pyrazol-3-one (5.00 g, 35.7 mmol), methyl 4-(bromomethyl)benzoate (17.16 g, 74.91 mmol), potassium carbonate (10.5 g, 76.0 mmol) and N,N-dimethylformamide (50 mL) was stirred overnight at 60° C. Water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The extract washed with aqueous sodium chloride solution, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was subjected to silica gel column chromatography (ethyl acetate:hexane=1:3) to give the title compound (6.90 g, yield 44%) as a colorless oil. melting point 93-94° C. the mixture was extracted with ethyl acetate The extract washed with aqueous sodium chloride solution dried over anhydrous magnesium sulfate concentrated under reduced pressure