1: piperazine-1-carboxylic acid benzyl ester; tert-butyl 4-oxo-piperidine-1-carboxylate With hydrogen; acetic acid; palladium 10 on activated carbon in methanol 96 h; 2: benzyl chloroformate With sodium hydrogencarbonate in water; acetone T=0°C; 3.5 h;

1: With acetic acid in 1,2-dichloro-ethane T=20°C; 1 h; 2: With sodium tris(acetoxy)borohydride in 1,2-dichloro-ethane T=20°C; Inert atmosphere;

palladium on activated charcoal; hydrogen in isopropyl alcohol T=20°C; P=2585.81 Torr; Inert atmosphere;