4-[1-[3-(Isopropylamino)-2-pyridyl]piperazin-4-yl-carbonyl]benzoic acid (1.5 g) was dissolved in methylene chloride (50 ml) and then, triethylamine (0.7 ml) was added and cooled. Pivaloyl chloride(0.58 ml) was added slowly to the solution at 0~5° C. and the mixture was stirred at 5° C. for 2 hours. And then, triethylamine (0.7 ml) and 2-aminoethanol(1.27 g) were added in order, the solution was stirred at 0~5° C. for 2 hours and heated slowly to 20~25° C. and stirred for 30 minutes. The reaction mixture was washed with water twice and the solvent was concentrated under reduced pressure. The concentrated residue was crystallized by treatment with ether and further recrystallized using isopropanol and ether. The recrystallized product was filtered and dried to give 1.34 g (yield: 80%) of the desired compound as a white powder.
