hydrogen; palladium dihydroxide in ethyl acetate P=2068.65 Torr; 24 h;

1: tert-butyl 4-oxo-piperidine-1-carboxylate With potassium hexamethylsilazane in tetrahydrofuran; toluene T=20°C; 2 h; 2: methyl iodide in tetrahydrofuran; toluene T=20°C;

1: 3-methyl-1-(phenylmethyl)-4-piperidinone With hydrogenchloride; hydrogen; palladium dihydroxide in 1,4-dioxane; methanol P=2585.81 Torr; 2: di-tert-butyl dicarbonate With triethylamine in tetrahydrofuran 2 h;

N,N-dimethylethylenediamine in dichloromethane T=20°C; 2.5 h;

1: C14H23NO5 With hydrogenchloride in water 48 h; Reflux; 2: di-tert-butyl dicarbonate With sodium carbonate in tetrahydrofuran; water

1: potassium borohydride / ethanol / 2.5 h / 0 - 20 °C 2: hydrogenchloride / 1,4-dioxane / 2 h / 20 °C View Scheme

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

hydrogenchloride in ethanol; dichloromethane T=0 - 25°C;

sodium tetrahydroborate in methanol T=0 - 20°C; 3.5 h;

1.1: n-butyllithium; diisopropylamine / hexane; tetrahydrofuran / 0.5 h / -78 °C / |Inert atmosphere 1.2: -78 - 20 °C / |Inert atmosphere 2.1: tetrakis(triphenylphosphine) palladium(0); potassium carbonate / ethylene glycol dimethyl ether / 0.33 h / 80 °C / |Microwave irradiation; |Inert atmosphere 3.1: trifluoroacetic acid / dichloromethane / 0.5 h / 20 °C View Scheme