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

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Reaction Conditions

Reaction Steps

NCS (1.355 g, 10.15 mmol) was added in portions to a 150 mL sealed tube reactor containing methyl 5-methyl-4-(1-methyl-1H-pyrazol-5-yl)-2-thiophenecarboxylate (2.0 g, 8.46 mmol) [prepared according to the procedure of Preparation 10] in Tetrahydrofuran (THF) (40 ml) at room temperature. The mixture was heated to 70° C. for 2 h. 6N NaOH (28 ml, 168 mmol) was added and the mixture stirred at 70° C. for an additional 2 h. The mixture was cooled to room temperature and partitioned between CHCl3 and H2O. The pH of the aqueous layer was adjusted to ˜3 by the addition of 6N HCl. The aqueous phase was washed several times with DCM and the combined organic fractions were dried with Na2SO4 and concentrated affording the title compound (2.36 g, 9.19 mmol, quant.): LC-MS (ES) m/z=257 (M+H)+.

Provenance & Evidence