General procedure for the synthesis of 1-(3-hydroxypropyl)-4-methylpiperazine from N-methylpiperazine and 3-bromo-1-propanol: Intermediate 7: 3-(4-methylpiperazin-1-yl)-propan-1-ol. Dissolve N-methylpiperazine (6.99 mL, 63 mmol) in toluene (30 mL). 3-Bromo-1-propanol (2.62 mL, 30 mmol) was added slowly and the reaction mixture was stirred at room temperature overnight. Subsequently, the reaction mixture was heated to 80 °C and kept for 2 h, and then cooled to room temperature. The reaction mixture was filtered and the filter cake was washed thoroughly with toluene. After removal of toluene under reduced pressure, the residue was subjected to Kugelrohr distillation (boiling point: 180 °C/2 mbar) to give a colorless oily product (4.08 g, 25.8 mmol, 86% yield). 1H NMR (CDCl3): δ= 1.70 (pseudo quintuple peak, J = 5.8 Hz, 2H), 2.26 (s, 3H), 2.35-2.60 (m, 8H), 2.60 (pseudo triple peak, J = 5.8 Hz, 2H), 3.77 (pseudo triple peak, J = 5.3 Hz, 2H), 4.09 (broad single peak, 1H).
