The general procedure for the synthesis of cyclopropyl (piperazin-1-yl)methanone hydrochloride from tert-butyl 4-(cyclopropanecarbonyl)piperazine-1-carboxylate was as follows: to a stirring solution of tert-butyl 4-(cyclopropanecarbonyl)piperazine-1-carboxylate (3.7 g, 14.5 mmol) in methanol (15 mL) was added slowly at 0 °C a hydrochloric acid/methanol solution (15 mL, 3M). After addition, the reaction mixture was stirred at room temperature overnight. Upon completion of the reaction, the solvent was removed by concentration under reduced pressure to afford cyclopropyl (piperazin-1-yl)methanone hydrochloride (2.74 g, 100% yield) as an off-white solid. The product was characterized by 1H-NMR (400 MHz, DMSO-d6): δ 0.71-0.76 (m, 4H), 1.96-2.03 (m, 1H), 3.04-3.16 (m, 4H), 3.69-4.08 (m, 4H), 9.58 (s, 2H); LC-MS (ESI) m/z: 155 (M + 1)+.
