1: 97 percent / SOCl2, dimethylformamide / benzene / 1 h / Heating 2: 90 percent / NaN3 / acetone; H2O / 0.5 h 3: aq. acetic acid / 0.33 h / 85 - 90 °C 4: 40 percent / aq. HCl; 2.5 N NaOH / 3 h / Heating View Scheme