23099-72-1

5625-67-2

103-63-9

23099-72-1

General procedure for the synthesis of 4-phenylethylpiperazin-2-one from 2-piperazinone and β-bromophenethylene: β-bromophenethylene (4.10 mL, 30.0 mmol), piperazin-2-one (3.00 g, 30.0 mmol), and potassium carbonate (K2CO3, 4.90 g, 36.0 mmol) in dimethylsulfoxide (DMSO, 60.0 mL) in a The suspension was stirred at 80 °C for the reaction. After completion of the reaction, the mixture was cooled to room temperature and filtered. The filtrate was washed with water (200 mL) and subsequently extracted with dichloromethane (2 x 100 mL). The organic layers were combined, washed with saturated brine and dried over anhydrous magnesium sulfate (MgSO4). The resulting yellow solid was dissolved in 1N hydrochloric acid (120 mL) and washed with dichloromethane. The aqueous layer was separated, alkalized with 6N sodium hydroxide and subsequently extracted with dichloromethane (3 x 100 mL). The organic layers were combined, dried over anhydrous magnesium sulfate (MgSO4), filtered and concentrated. The residue was recrystallized with hexane and filtered. The solid obtained by filtration was dried under reduced pressure to give 4-phenethylpiperazin-2-one (4.50 g, 74% yield) as an off-white solid. Its 1H NMR (500 MHz, CDCl3) data were as follows: δ 7.31-7.28 (m, 2H), 7.23-7.19 (m, 3H), 6.17 (br s, 1H), 3.40-3.37 (m, 2H), 3.23 (s, 2H), 2.83-2.79 (m, 2H), 2.73-2.67 (m, 4H).