Trifluoroacetic acid → (2S)-2-{3-[(4-methyl-1-benzothien-3-yl)methyl]-2-oxo-2,3-dihydro-1H-benzimidazol-1-yl}propanoic acid

To a solution of (S)-2-[3-(4-Methyl-benzo[b]thiophen-3-ylmethyl)-2-oxo-2,3-dihydro-benzimidazol-1-yl]-propionic acid tert-butyl ester (0.12 g, 0.28 mmol) in CH2Cl2 (5 mL) was added TFA (2 mL). The reaction mixture was stirred at room temperature for 3 h. When the reaction was complete, the reaction mixture was diluted with CH2Cl2 and washed with water. The organic phase was dried over Na2SO4 and concentrated. When a small amount of CH2Cl2 (˜3 mL) was added to the resulting residue, a white solid came out of the solution. This solid was filtered and dried to afford 69 mg (66%) of the titled compound. LCMS (ESMS): m/z 367.23 (M+H+).