To a solution of 160.0 mg (0.859 mmol) thiophene-2,5-dicarboxylic acid monomethyl ester in 25 ml dichloromethane were added 253.0 mg (1.293 mmol) N′-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride, 175 mg (1.295 mmol) 1-hydroxybenzotriazole hydrate and 130.7 g (1.291 mmol) triethylamine. After 30 min at room temperature 268.0 mg (0.861 mmol) 1-[4-(4-trifluoromethoxy-benzyloxy)-phenyl]-ethylamine were added. The reaction mixture was stirred for 6.5 h. The solvent was evaporated, to the residue was added ethyl acetate and the organic phase was extracted with saturated aqueous NaHCO3 solution and with water. The organic phase was dried over MgSO4 and the solvent was evaporated. The residue was triturated with diisopropyl to provide 249 mg (0.519 mmol) 5-{1-[4-(4-trifluoromethoxy-benzyloxy)-phenyl]-ethylcarbamoyl}-thiophene-2-carboxylic acid methyl ester.
