A mixture of 1-(2-tert-butyl-4-methylphenyl)piperazine dihydrochloride (Reference Example 10, 0.31 g, 1.0 mmol), (2,5-dioxoimidazolidin-4-yl)acetic acid (0.19 g, 1.2 mmol), triethylamine (420 μL, 3.0 mmol), EDCI (0.23 g, 1.2 mmol) and HOBt (0.18 g, 1.2 mmol) in N,N-dimethylformamide (5 mL) was stirred at room temperature for 2 days. The reaction mixture was poured into saturated NaHCO3 solution and extracted with ethyl acetate. The extract was washed with brine, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to give the title compound (0.33 g, 89%) as a orange solid.
