[C:1]1([C:7]2[C:15]([CH:16]=[CH:17][C:18]([O:20]C)=[O:19])=[C:10]3[CH:11]=[CH:12][CH:13]=[CH:14][N:9]3[N:8]=2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1>[OH-].[Na+].CO>[C:1]1([C:7]2[C:15]([CH:16]=[CH:17][C:18]([OH:20])=[O:19])=[C:10]3[CH:11]=[CH:12][CH:13]=[CH:14][N:9]3[N:8]=2)[CH:2]=[CH:3][CH:4]=[CH:5][CH:6]=1A mixture of methyl 3-(2-phenylpyrazolo[1,5-a]pyridin-3-yl)acrylate (trans isomer) (4.05 g) in 1 N sodium hydroxide solution (58.3 ml) and methanol (80 ml) was refluxed for 1 hour and evaporated in vacuo. The residue was dissolved in water and washed with chloroform. The aqueous layer was acidified with 1 N hydrochloric acid. The resulting precipitates were filtered and recrystallized from isopropyl alcohol to give crystals of 3-(2-phenylpyrazolo[1,5-a]pyridin-3-yl)acrylic acid (2.65 g).
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