[CH3:1][C:2]1[N:6]([CH:7]([C:9]2[CH:14]=[CH:13][CH:12]=[CH:11][CH:10]=2)[CH3:8])[N:5]=[CH:4][C:3]=1[C:15]([O:17]C)=[O:16].O.[OH-].[Li+].O1CCCC1.Cl>O.CO>[CH3:1][C:2]1[N:6]([CH:7]([C:9]2[CH:10]=[CH:11][CH:12]=[CH:13][CH:14]=2)[CH3:8])[N:5]=[CH:4][C:3]=1[C:15]([OH:17])=[O:16]
A mixture of methyl 5-methyl-1-(1-phenylethyl)-1H-pyrazole-4-carboxylate (80 mg, 0.32 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 5-methyl-1-(1-phenylethyl)-1H-pyrazole-4-carboxylic acid as a white solid (49 mg, 62%). 1H NMR (300 MHz, d6-DMSO): δ 12.16 (s, 1H), 8.26 (s, 1H), 7.37-7.25 (m, 5H), 5.55 (q, J=7.2 Hz, 1H), 2.30 (s, 3H), 1.78 (d, J=6.9 Hz, 3H).
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