4-[4-(4-tert-Butylphenyl)-4-oxo-2-(4-trifluoromethoxyphenyl)butyryl]benzoic acid (10.4 g, 20.86 mmol) was dissolved in DMF (150 mL) and added EDAC (5.60 g, 29.20) and HOBt (4.23 g, 31.29 mmol). After ½ h a solution of beta-alanine methyl ester hydrochloride (4.37 g, 31.29 mmol) and DIPEA (5.36 mL, 31.29 mmol) in DMF (20 mL) was added to the above mixture and the reaction mixture was stirred night over. The reaction was concentrated to approximately 100 mL and diluted with water (200 mL) and extracted with ethyl acetate (200 mL). The water phase was extracted with additional ethyl acetate (75 mL). The combined organic phases were washed with hydrochloric acid (0.2 N, 3×150 mL), aqueous sodium chloride (50% saturation, 3×150 mL) and dried over magnesium sulphate. The dried organic phase was filtered and evaporated to dryness to afford 3-{4-[4-(4-tert-butylphenyl)-4-oxo-2-(4-trifluoromethoxyphenyl)butyryl]benzoylamino}propionic acid methyl ester (12.76 g).
