1: 100 percent / hydrazine hydrate / acetic acid / 3 h / 100 °C 2: 58 percent / dimethylformamide / 2.5 h / 100 °C 3: 67 percent / SnCl2*2H2O; conc. HCl / dimethylformamide / 0.5 h / 5 - 10 °C 4: 82 percent / CF3COOH / 1 h / 80 °C 5: 63 percent / methanol / 0.5 h / 50 °C 6: 76 percent / 2N NaOH / 5 h / 100 °C View Scheme