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

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Reaction Steps

A solution of methyl 4-(4-ethyl-1-methyl-1H-pyrazol-5-yl)-5-methyl-2-thiophenecarboxylate (145 mg, 0.55 mmol) in 6N sodium hydroxide (1.8 ml, 10.97 mmol) and tetrahydrofuran (4.8 ml) was stirred at 60° 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-(4-ethyl-1-methyl-1H-pyrazol-5-yl)-5-methyl-2-thiophenecarboxylic acid (137 mg, 0.55 mmol, 100% yield) as a yellow oil: LCMS (ES) m/e 250 (M+H)+.

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