A solution of 2-[1-(2-chlorophenyl)methyl-2-propylthio-1H-imidazol-5-yl]acetic acid (0.52 g, 1.6 mmol) in tetrahydrofuran (20 mL) was stirred with N hydroxysuccinimide (0.203 g, 1.76 mmol) and dicyclohexylcarbodiimide (0.33 g, 0.16 mmol) for 30 minutes. Then L-phenylalanine methyl ester hydrochloride (0.449 g, 2.08 mmol) and triethylamine (0.21 g, 2.08 mmol) were added and the suspension was stirred at ambient temperature for 18 hours. The mixture was diluted with ethyl acetate, filtered and the concentrated filtrate was flash chromatographed over silica gel with 3:2 ethyl acetate/hexane to give 0.58 g (74%) of N-[{1-(2-chlorophenyl)methyl-2-propylthio-1H-imidazol-5-yl}methylcarbonyl]-L-phenylalanine methyl ester as an oil.
