General procedure for the synthesis of 1-Cbz-4-aminopiperidine (benzyl 4-aminopiperidine-1-carboxylate) from 1-Cbz-4-BOC-aminopiperidine: 4-(N-BOC amino)-Cbz piperidine (24.4 kg, 73.42 mol), THF (65 kg), and 5M HCl (23.0 kg, 110.13 mol) were mixed and heated to 30-35 °C for 2 h. The reaction was then continued at 55 °C overnight. After completion of the reaction, the mixture was cooled to 100 °C and dichloromethane (97 kg) and 10 M NaOH (7.97 kg, 145.12 mol) were added, controlling the temperature below 25 °C. After partitioning, the organic phase was washed with 25 wt% NaCl solution (27.5 kg). The washed organic phase was concentrated by distillation at atmospheric pressure to a volume of about 70 L. Subsequently, dichloromethane (162 kg) was added and concentrated by distillation again to a volume of about 120 L to give a dichloromethane solution of the title product 1-Cbz-4-aminopiperidine (17.2 kg, 100% yield). The structure of the product was confirmed by 1H NMR (CDCl3): δ 7.33 (5H, m), 5.14 (2H, s), 4.14 (2H, br s), 2.87 (3H, m), 1.83 (2H, m), 1.66 (3H, m), 1.28 (2H, m).
