[CH3:1][C:2]1[C:6]([C:7]([O:9]C)=[O:8])=[CH:5][N:4]([CH:11]([C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=2)[CH3:12])[N:3]=1.O.[OH-].[Li+].O1CCCC1.Cl>O.CO>[CH3:1][C:2]1[C:6]([C:7]([OH:9])=[O:8])=[CH:5][N:4]([CH:11]([C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=2)[CH3:12])[N:3]=1A mixture of methyl 3-methyl-1-(1-phenylethy 1)-1H-pyrazole-4-carboxylate (90 mg, 0.37 mmol), lithium hydroxide monohydrate (57.1 mg, 1.36 mmol), tetrahydrofuran (5 mL), methanol (1 mL) and water (1 mL) was stirred at 20° C. for 4 hours. The mixture was acidified to pH=1 with concentrated hydrochloric acid and then extracted with ethyl acetate (15 mL×3). The combined organic phase was dried by sodium sulfate, and then filtered. The filtrate was concentrated in vacuo to give 3-methyl-1-(1-phenylethyl)-1H-pyrazole-4-carboxylic acid as a white solid (60 mg, 70%). 1H NMR (300 MHz, d6-DMSO): δ 12.24 (s, 1H), 7.82 (s, 1H), 7.36-7.17 (m, 5H), 5.67 (q, J=7.2 Hz, 1H), 2.43 (s, 3H), 1.79 (d, J=6.9 Hz, 3H).
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