To the solution of 1 (ibuprofen, 3.87 g, 18.8 mmol) in 80 mL of dimethylformamide, hydroxybenzotriazole (2.8 g, 20.7 mmol) and DCC (4.27 g, 20.7 mmol) were added with stirring at 0° C. for 1 h. To the reaction mixture 4-hydroxybenzamide (2, 3.9 g, 28 mmol) was added and stirred for 1 h at 0° C. and 2 h at room temperature. After filtration, the filtrate was evaporated under reduced pressure to remove the solvent. The oily residue thus obtained was dissolved in ethyl acetate; the organic layer was washed with brine, with NaHCO3 5%, with citric acid 10% and than dried on anhydrous MgSO4, filtered and the solvent evaporated. The crude product 3 was loaded on a silica gel open column and eluted with CH2Cl2/MeOH (9.5/0.5), from which 4-carbamoylphenyl 2-(4-isobutylphenyl)propanoate (3) was obtained (2.48 g, 40% yield).
