1-(2-Bromo-ethyl)-3-(4-methyl-benzo[b]thiophen-3-ylmethyl)-1,3-dihydro-benzimidazol-2-one (30 mg, 0.075 mmol) is dissolved in CH3CN (0.5 mL)) and Methoxycarbonylmethyl-ammonium chloride (11 mg, 0.09 mmol) and Et3N (0.025 mL, 0.18 mmol) are added. The mixture is first stirred at room temperature for 16 hr. And then 11 mg of Na2CO3 is added and the mixture is stirred at room temperature for another 48 hr. Since the reaction is not completed, another 11 mg of Methoxycarbonylmethyl-ammonium chloride, 0.025 mL of Et3N and 11 mg of Na2CO3 are added. The mixture is then heated at 80° C. for 20 hrs. Then 10 mL of water is added and the mixture is extracted with EtOAc (3×15 mL). The organic layers are combined, dried and concentrated to give crude product. Purification by flash column chromatography affords 30 mg (98%) of {2-[3-(4-Methyl-benzo[b]thiophen-3-ylmethyl)-2-oxo-2,3-dihydro-benzimidazol-1-yl]-ethylamino}-acetic acid methyl ester.
