[CH3:1][N:2]1[C:6]([C:7]2[CH:8]=[C:9]([C:13]([O:15]C)=[O:14])[S:10][C:11]=2[CH3:12])=[C:5]([CH3:17])[CH:4]=[N:3]1.[OH-].[Na+]>O1CCCC1>[CH3:1][N:2]1[C:6]([C:7]2[CH:8]=[C:9]([C:13]([OH:15])=[O:14])[S:10][C:11]=2[CH3:12])=[C:5]([CH3:17])[CH:4]=[N:3]1To a 100 mL round-bottomed flask was added methyl 4-(1,4-dimethyl-1H-pyrazol-5-yl)-5-methyl-2-thiophenecarboxylate (1.31 g, 5.23 mmol) in Tetrahydrofuran (THF) (25 mL). 6N NaOH (30 mL, 180 mmol) was added slowly and the reaction stirred at 70° C. overnight. The reaction was cooled to room temperature, partitioned between CHCl3 and H2O and the pH of the aqueous layer adjusted to pH 3 by the addition of 6N HCl. The layers were separated, the organic layer was dried with Na2SO4 and the solvent was removed affording the title compound (1.3 g, 5.5 mmol, quant.) which was used without further purification: LC-MS (ES) m/z=237 (M+H)+.
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