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

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Reaction Steps

A solution of methyl 5-chloro-4-(1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylate (304 mg, 1.18 mmol) in 6N sodium hydroxide (2 ml, 12 mmol) and Tetrahydrofuran (10 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 ˜3 and then washed several times with DCM. The combined organic fractions were dried over Na2SO4 and concentrated affording the desired product (276 mg, 1.14 mmol, 96% yield) as a yellow oil: LC-MS (ES) m/e 244 (M+H)+.

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