1: 48 percent / Phosphorous tribromide / 0.17 h / Heating 2: 1) anhydrous sodium sulfite 2) dimethylformamide, thionyl chloride / 1) water, reflux, 24 h 2) benzene, reflux, 4h 3: 70 percent / Sodium azide / acetone; H2O / 12 h / Ambient temperature 4: 46 percent / 0 h / 400 °C / 3.7 - 3.8 Torr View Scheme

aluminum oxide T=320°C; P=30 Torr;

Multi-step reaction with 4 steps 1: 48 percent / Phosphorous tribromide / 0.17 h / Heating2: 1) anhydrous sodium sulfite 2) dimethylformamide, thionyl chloride / 1) water, reflux, 24 h 2) benzene, reflux, 4h3: 70 percent / Sodium azide / acetone; H2O / 12 h / Ambient temperature4: 0 h / 400 °C / 3.7 - 3.8 Torr