piperidine in ethanol T=20°C; 0.666667 h;

potassium carbonate in N,N-dimethyl-formamide 3 h; Ambient temperature;

1: 77 percent / ethanol / 0.25 h / Heating 2: 88 percent / sodium nitrite, AcOH / H2O / 0 °C View Scheme

1: 77 percent / ethanol / 0.25 h / Heating 2: 88 percent / sodium nitrite, AcOH / H2O / 0 °C 3: 61 percent / Zn / 0.25 h / Heating 4: 80 percent / formic acid / formamide; H2O / 0.5 h / Heating 5: 90 percent / Br2, AcOH / acetic acid / 1 h / 60 °C 6: 18 percent / KOH / 12 h / Heating View Scheme