[O:1]1[CH:5]=[CH:4][C:3]([C:6]2[N:10]([CH3:11])[N:9]=[CH:8][C:7]=2/[CH:12]=[CH:13]/[C:14]([O:16]CC)=[O:15])=[CH:2]1.O1CCCC1.[OH-].[Na+].Cl>C(O)C>[O:1]1[CH:5]=[CH:4][C:3]([C:6]2[N:10]([CH3:11])[N:9]=[CH:8][C:7]=2/[CH:12]=[CH:13]/[C:14]([OH:16])=[O:15])=[CH:2]1To a mixture of ethyl (2E)-3-[5-(3-furyl)-1-methyl-1H-pyrazol-4-yl]acrylate (800 mg), tetrahydrofuran (10 ml) and ethanol (10 ml) was added 2N aqueous sodium hydroxide solution (6.5 ml) and the mixture was stirred at 60° C. for 1 hr. 1N Hydrochloric acid was poured into the reaction mixture, and the precipitated solids were collected by filtration, washed with water and dried with airflow to give (2E)-3-[5-(3-furyl)-1-methyl-1H-pyrazol-4-yl]acrylic acid (703 mg, 99%) as crystals. Recrystallization thereof from ethyl acetate-hexane gave colorless prism crystals. melting point: 218-219° C.
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