Synthesis
1. Dissolve piperazine (112 mmol, 6.0 eq.) in THF (180 mL) at 0 °C to prepare a solution.
2. 2,6-dichlorobenzyl bromide (4.5 g, 18.8 mmol) was dissolved in THF (20 mL) to prepare a solution and slowly added dropwise to the THF solution of piperazine over 10 minutes.
3. After the dropwise addition was completed, the reaction mixture was slowly warmed to room temperature and stirred continuously for 24 hours.
4. Upon completion of the reaction, the THF solvent was removed by distillation under reduced pressure.
5. The crude product was resuspended in a mixture of dichloromethane (DCM) and water and extracted twice with DCM.
6. The organic layers were combined, dried over anhydrous sodium sulfate (Na2SO4), filtered and concentrated.
7. The crude product was purified using combiflash fast chromatography eluting with a gradient of 0 to 20% methanol in DCM to afford the target compound 1-(2,6-dichlorobenzyl)piperazine (2.3 g, 50% yield).
8. The structure of the product was confirmed by 1H NMR, 13C NMR and HRMS.
1H NMR (400 MHz, methanol-d4) δ 7.62-7.30 (m, 2H), 7.23 (dd, J = 8.7, 7.4 Hz, 1H), 3.74 (s, 2H), 2.92-2.69 (m, 4H), 2.56 (t, J = 4.9 Hz, 4H).
13C NMR (101 MHz, MeOD) δ 136.76, 133.67, 129.18, 128.24, 56.55, 53.41, 44.95.
HRMS (m/z): [M+] calculated value C11H14Cl2N2 245.15, measured value 245.06.
References
[1] Patent: WO2015/184349, 2015, A2. Location in patent: Paragraph 0221
[2] Patent: WO2016/176338, 2016, A1. Location in patent: Paragraph 0132
[3] European Journal of Medicinal Chemistry, 2019, vol. 161, p. 22 - 38
