General procedure for the synthesis of 2-(N-Boc-4-piperidinyl)ethylamine from 1-Boc-4-(cyanomethyl)piperidine: tert-butyl 4-(cyanomethyl)piperidine-1-carboxylate (20 g, 89.29 mmol) and NH4OH (9 mL) were dissolved in methanol (200 mL) and Raney Ni (6 g, 101.69 mmol) was added. The reaction was carried out at 50°C for 5 h under H2 pressure of 50 psi. Upon completion of the reaction, the mixture was filtered through a diatomaceous earth pad and the filtrate was concentrated to afford the target product 2-(N-Boc-4-piperidinyl)ethylamine (20.5 g, 100%) as a colorless oil.1H NMR (400 MHz, CDCl3) δ 1.06-1.19 (m, 2H), 1.44 (d, J = 7.41 Hz, 2H), 1.47 (s 9H), 1.50-1.58 (m, 1H), 1.66 (d, J = 12.49 Hz, 2H), 2.09 (br.s., 2H), 2.70 (t, J = 12.29 Hz, 2H), 2.75-2.83 (m, 2H), 4.08 (br.s., 2H).
