Synthesis
Tert-butyl 4-(4-nitrobenzyl)piperazine-1-carboxylate (1.100 g, 3.423 mmol) was added to a solvent mixture of tetrahydrofuran solution (20 mL) of ammonium chloride (0.915 g, 17.114 mmol) and zinc powder (1.119 g, 17.114 mmol) with water (20 mL) as starting material, and the reaction was stirred for 12 h at room temperature. . Upon completion of the reaction, the reaction mixture was filtered to remove solid impurities. Water was added to the filtrate and subsequently extracted with ethyl acetate. The organic layer was washed with saturated aqueous sodium chloride solution, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The resulting product, tert-butyl 4-(4-aminobenzyl)piperazine-1-carboxylate (0.900 g, 90.2% yield), was a yellow solid and could be used in subsequent reactions without further purification.
References
[1] Bioorganic and Medicinal Chemistry, 2005, vol. 13, # 19, p. 5592 - 5599
[2] Patent: US2004/34033, 2004, A1. Location in patent: Page/Page column 12; Sheet 1
[3] Patent: WO2017/18803, 2017, A1. Location in patent: Paragraph 1492; 1493; 1494
[4] Patent: WO2016/146220, 2016, A1. Location in patent: Page/Page column 26; 27
[5] Journal of Medicinal Chemistry, 2018, vol. 61, # 4, p. 1499 - 1518
