diethylamino-sulfur trifluoride in dichloromethane T=-78 - 20°C; Inert atmosphere;

1: ethyl bromoacetate With chloro-trimethyl-silane; ethylene dibromide; zinc in tetrahydrofuran T=20 - 60°C; 2 h; 2: tert-butyl 4-oxo-piperidine-1-carboxylate in tetrahydrofuran 72 h; 3: With water in tetrahydrofuran

1: ethyl acetate With lithium hexamethyldisilazane in tetrahydrofuran T=-70°C; 0.166667 h; 2: tert-butyl 4-oxo-piperidine-1-carboxylate in tetrahydrofuran T=-70 - 0°C;