A mixture of 3-methoxy-4-(N′-phenylureido)phenylacetic acid (180 mg, 0.6 mmol), 2-(2-(4-ethoxycarbonylphenyl)ethynyl)pyrrolidine (146 mg, 0.6 mmol), EDC (173 mg, 0.9 mmol), DMAP (73 mg, 0.6 mmol), and cat. HOBt in DMF (10 mL) was stirred overnight. The mixture was poured into 1 N HCl and the solid was collected with suction. The residue was dissolved in CHCl3 and dried over MgSO4. After removal of the solvent, the residue was chromatographed on silica-gel with CHCl3-MeOH (10:1, v/v) as eluent to give 192 mg (61%) ethyl 4-[2-[1-[3-methoxy-4-(N′-phenylureido)phenylacetyl]-2-pyrrolidinyl]ethynyl]benzoate as a light yellow amorphous solid. 1H-NMR (CDCl3) δ 1.38 (3 H, t, J=6.8 Hz), 1.98–2.24 (4 H, m), 3.48–3.89 (2 H, m), 3.53 (2 H, s), 3.62 (3 H, s), 4.33–4.40 (2 H, m), 4.78–5.04 (1 H, m), 6.77–8.00 (14 H, m).
