Tert-butyl 4-cyclopropylpiperazine-1-carboxylate (0.792 g, 3.50 mmol) was used as a raw material, which was dissolved in a 1,4-dioxane solution (4.37 mL, 17.50 mmol) in 4 M HCl. The reaction mixture was stirred at room temperature for 3 hours under nitrogen protection. Upon completion of the reaction, the mixture was filtered and washed with ether to afford the crude product 1-cyclopropylpiperazine (0.659 g) as a white solid. Subsequently, the crude product was purified by ion exchange chromatography through SCX column. The target compound 1-cyclopropylpiperazine was eluted from the column using 3.5 M NH3/MeOH solution, and the pure grades were collected and evaporated to dryness to give the final 1-cyclopropylpiperazine (0.264 g, 59.7% yield) as a yellow oil. The structure of the product was confirmed by 1H NMR (399.9 MHz, DMSO-d6) with chemical shifts δ 0.25-0.30 (2H, m), 0.35-0.40 (2H, m), 1.54-1.60 (1H, m), 2.43 (4H, t), 2.60-2.65 (4H, t), 3.30 (1H, s).
