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

Participants

Reaction Conditions

Reaction Steps

NBS (1.84 g, 10.33 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 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 1 h. 6N NaOH (28 ml, 168 mmol) was then added and the mixture stirred at 70° C. for 2 h. The mixture was partitioned between CHCl3 and H2O and the aqueous layer was made acidic with 6N HCl. The aqueous phase was washed several times with CHCl3 and the organic fractions were combined, dried over Na2SO4 and concentrated affording the title compound (2.68 g, 8.9 mmol, quant.): LC-MS (ES) m/z=302 (M+H)+.

Provenance & Evidence