Ethyl Thioglycolate → Ethyl 4-phenyl-5-(trifluoromethyl)thiophene-2-carboxylate

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Reaction Steps

To a solution of ethyl 2-mercaptoacetate (0.88 g, 6.75 mmol) in THF (45 mL) NaH (271 mg, 6.75 mmol, 60% in mineral oil) is added at −10° C. The mixture is stirred at 0° C. for 30 min before a solution of 3-chloro-4,4,4-trifluoro-2-phenyl-but-2-enal 1.32 g (4.5 mmol) in THF (5 mL) is added. The reaction mixture is stirred at it for 45 min, then treated with 2 N aq. NaOH (2 mL). Stirring is continued for 15 min and the mixture is diluted with water (100 mL) and 1 N aq. NaOH (15 mL). The mixture is extracted with diethyl ether (70 mL). The organic extract is dried over Na2SO4 and evaporated. The crude product is purified by prep. HPLC (Waters Xterra MS18, 75×30 mm, 10 μm, 10 to 95% acetonitrile in water containing 0.5% formic acid) to give 4-phenyl-5-trifluoromethyl-thiophene-2-carboxylic acid ethyl ester (760 mg) as a brownish oil, LC-MS: tR=1.12 min; 1H NMR (CDCl3): δ 7.75-7.72 (m, 1H), 7.42 (s, 5H), 4.39 (q, J=7.0 Hz, 2H), 1.40 (t, J=7.0 Hz, 3H).

Provenance & Evidence