A mixture of 2-[4-(2-tert-butylphenyl)piperazin-1-yl]-2-oxoacetic acid (Example 44, 1.0 g, 3.44 mmol), methyl 4-(2-aminoethyl)benzoate hydrochloride (0.83 g, 4.13 mmol), triethylamine (0.72 mL, 5.16 mmol), EDCI (0.64 g, 4.13 mmol) and HOBt (0.63 g, 4.13 mmol) in N,N-dimethylformamide (10 mL) was stirred at room temperature for 16 h. The reaction mixture was poured into saturated NaHCO3 solution and extracted with ethyl acetate. The extract was washed with saturated NaHCO3 solution and brine, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane/ethyl acetate 80:20 to 34:66) to give the title compound (1.11 g, 71%) as a white amorphous.
