sodium azide in N,N-dimethyl-formamide 72 h; Ambient temperature;

1: 94 percent / phosgene / CH2Cl2; benzene / 72 h / Ambient temperature 2: 93 percent / sodium azide / dimethylformamide / 72 h / Ambient temperature View Scheme

1: 88 percent / triethylamine / diethyl ether / 5 h / Ambient temperature 2: 70 percent / P4S10 / pyridine / 16 h / Heating 3: 94 percent / phosgene / CH2Cl2; benzene / 72 h / Ambient temperature 4: 93 percent / sodium azide / dimethylformamide / 72 h / Ambient temperature View Scheme

1: 81.5 percent / BF3*OEt2 / diethyl ether / 12 h / 23 °C 2: 20 percent / pyridine / 16 h / 23 °C View Scheme

Multistep reaction;