Sodium Hydroxide → 4-(3-chloro-4-ethyl-1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylic acid

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Reaction Steps

A solution of methyl 4-(3-chloro-4-ethyl-1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylate (135 mg, 0.47 mmol) in 6N sodium hydroxide (1.6 ml, 9.48 mmol) and tetrahydrofuran (5.4 ml) was stirred at 70° C. in a sealed tube for 12 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 4-(3-chloro-4-ethyl-1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylic acid (120 mg, 0.41 mmol, 87% yield) as a white foam: LCMS (ES) m/e 270, 272 (M, M+2)+.

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