1: 86 percent / 2 h / 80 °C 2: 41 percent / triethylamine / dimethylformamide / 15 h / Ambient temperature 3: 32 percent / Zn powder / acetic acid / 1.5 h / Heating 4: 84 percent / 40percent aq. methylamine / 1 h / 100 °C 5: 48 percent / NaNO2 / acetic acid / 15 h View Scheme