1: tert-butyl 4-oxo-piperidine-1-carboxylate With morpholine; toluene-4-sulfonic acid in toluene 16 h; Dean-StarkRefluxInert atmosphere; 2: benzoyl chloride With triethylamine in dichloromethane T=0 - 20°C; 4 h; 3: With hydrazine in ethanol T=20°C; 16 h;

1.1: triethylamine / dichloromethane; methanol / 16 h / 0 - 20 °C 2.1: morpholine; toluene-4-sulfonic acid / toluene / 16 h / |Dean-Stark; |Reflux; |Inert atmosphere 2.2: 4 h / 0 - 20 °C 2.3: 16 h / 20 °C View Scheme

trifluoroacetic acid in dichloromethane T=0 - 20°C; 4 h;