1: ethyl 1-tert-butyloxycarbonyl-4-piperidinecarboxylate With potassium hexamethylsilazane in tetrahydrofuran 0.5 h; Cooling with acetone-dry ice; 2: benzyl bromide in tetrahydrofuran 73 h; Cooling with acetone-dry ice;

1: ethyl 1-tert-butyloxycarbonyl-4-piperidinecarboxylate With n-butyllithium; diisopropylamine in tetrahydrofuran; hexanes T=-78°C; 0.0833333 h; 2: benzyl bromide in tetrahydrofuran; hexanes T=20°C;

1.1: sodium hydrogencarbonate / tetrahydrofuran / 0.17 h / 0 - 20 °C 1.2: 14 h / 20 °C 2.1: N-ethyl-N,N-diisopropylamine; n-butyllithium / tetrahydrofuran / 1.25 h / -75 - -35 °C / Inert atmosphere 2.2: -75 - 20 °C / Inert atmosphere View Scheme

1.1: sodium hydrogencarbonate / tetrahydrofuran / 0.17 h / 0 - 20 °C 1.2: 14 h / 20 °C 2.1: N-ethyl-N,N-diisopropylamine; n-butyllithium / tetrahydrofuran / 1.25 h / -75 - -35 °C / Inert atmosphere 2.2: -75 - 20 °C / Inert atmosphere View Scheme

1: With sodium hydroxide in methanol; water T=130°C; 0.166667 h; Microwaves; 2: With hydrogenchloride in methanol; water; ethyl acetate

1: With trifluoroacetic acid in dichloromethane T=20°C; 6 h; 2: With sodium hydrogencarbonate in dichloromethane; water