Ethyl 4-phenyl-5-(trifluoromethyl)thiophene-2-carboxylate → 4-Phenyl-5-(trifluoromethyl)thiophene-2-carboxylic acid

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Reaction Steps

A solution of 4-phenyl-5-trifluoromethyl-thiophene-2-carboxylic acid ethyl ester (750 mg, 2.50 mmol) in ethanol (12 mL) and 2 N aq. LiOH (6 mL) is stirred at 65° C. for 2 h. The reaction mixture is cooled to rt, diluted with water (60 mL) and extracted with DCM (50 mL). The aq. phase is acidified by adding 2 N aq. HCl (7 mL) and extracted twice with DCM (2×50 mL). These organic extracts are combined, washed with sat. aq. NaHCO3, dried over Na2SO4, evaporated and dried under high vacuum to give 4-phenyl-5-trifluoromethyl-thiophene-2-carboxylic acid (670 mg) as a brown solid, LC-MS: tR=0.97 min, 1H NMR (D6-DMSO): δ 7.57-7.54 (m, 1H), 7.46-7.42 (m, 5H).

Provenance & Evidence