Acetic Anhydride → HCID 178489860, compound

Participants

Reaction Conditions

Reaction Steps

A mixture of 1,2-dihydro-4-[(3-fluoro-4-methoxyphenyl)methyl]-5-methyl-3H-pyrazol-3-one (synthesized as described in WO0236602; 4.11 g, 0.0174 mol), acetic anhydride (41 mL) and acetic acid (41 mL) was stirred at 135° C. for 8 hours and at room temperature for 12 hours. After being concentrated, the reaction mixture was diluted with toluene and then concentrated again. To the resulting residue, methanol (400 mL) and a 25 wt % methanol solution of sodium methoxide (0.37 mL) were added and stirred for 20 hours. The reaction mixture was concentrated and the resulting residue was purified by silica gel column chromatography (hexane:ethyl acetate=4:1 to 1:1) to give 1-acetyl-4-[(3-fluoro-4-methoxyphenyl)methyl]-3-hydroxy-5-methyl-1H-pyrazole (960 mg, 20%) as a colorless powder.

Provenance & Evidence