Methyl 2-({[4-(2-{ethyl[4-(trifluoromethyl)benzyl]amino}-2-oxoethyl)phenyl]thio}methyl)benzoate (640 mg, 1.276 mmol) was dissolved in THF (20 ml). Lithium hydroxide (61 mg, 2.552 mmol) in water (10 ml) was added. The mixture was stirred at room temperature and the reaction was followed by LC-MS. After 24 hours, more lithium hydroxide (30 mg) and water (10 ml) were added. After in total 70 hour, LC-MS showed the reaction was complete. The mixture was evaporated to remove THF. The residue was washed with diethyl ether, then acidified with 10% HCl, pH=2, and extracted with EtOAc (×2). The extracts were combined and washed with brine, dried with magnesium sulphate and evaporated. Chromatography of the residue on a column (ISOLUTE SI, 5 g/25 ml), using DCM and then MeOH/DCM (0.5:99.5, then 1:99) as eluant, gave the title compound (510 mg), yield 82%.
