[F:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[N:12]([CH3:13])[N:11]=[CH:10][C:9]=2[C:14]([O:16]CC)=[O:15])=[CH:4][CH:3]=1.[OH-].[Na+].Cl>C(O)C>[F:1][C:2]1[CH:3]=[CH:4][C:5]([C:8]2[N:12]([CH3:13])[N:11]=[CH:10][C:9]=2[C:14]([OH:16])=[O:15])=[CH:6][CH:7]=1To a solution of the compound (14.2 g, 57.4 mmol) obtained in step 1 in ethanol (50 mL) was added 2N aqueous sodium hydroxide solution (63.2 mL, 126 mmol) at room temperature, and the mixture was heated under reflux for 1 hr. The reaction mixture was cooled to room temperature, and 2N hydrochloric acid was added until the mixture became pH 6. The precipitate was collected by filtration with ethyl acetate to give a mixture (3:2.2 (mol/mol), 13.0 g, 100%) of 5-(4-fluorophenyl)-1-methyl-1H-pyrazole-4-carboxylic acid and 3-(4-fluorophenyl)-1-methyl-1H-pyrazole-4-carboxylic acid as a white powder.
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