To a THF (8 mL) solution of tert-butyl 4-[4-(2-{[tert-butyl(dimethyl)silyl]oxy}-ethyl)benzyl]piperazine-1-carboxylate (0.96 g) was added 1.0 M solution of TBAF in THF (2.32 mL) at 0° C. The resultant mixture was stirred at room temperature for 2.5 hours. After cooling to 0° C., the reaction mixture was diluted with AcOEt and water. The organic layer was washed with saturated aqueous NaCl, dried over anhydrous MgSO4, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (CH2Cl2/MeOH=40/1) to afford tert-butyl 4-[4-(2-hydroxyethyl)benzyl]piperazine-1-carboxylate (0.55 g) as a colorless oil.
