Sodium Hydroxide → 5-chloro-4-(4-fluoro-1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylic acid

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Reaction Steps

A solution of methyl 5-chloro-4-(4-fluoro-1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylate (65 mg, 0.237 mmol) in 6N sodium hydroxide (0.39 ml, 2.37 mmol) and tetrahydrofuran (2 ml) was stirred at 70° C. in a sealed tube for 1 h. The resulting solution was cooled and then partitioned between H2O-DCM. The aqueous phase was adjusted to pH ˜4 and then washed several times with DCM. The combined organic fractions were dried over Na2SO4 and concentrated affording 5-chloro-4-(4-fluoro-1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylic acid (54 mg, 0.17 mmol, 72% yield) as a yellow oil; LCMS (ES) m/e 261, 263 (M, M+2)+.

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