1: 88 percent / triethylamine / diethyl ether / 5 h / Ambient temperature 2: 70 percent / P4S10 / pyridine / 16 h / Heating View Scheme

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

phosgene in dichloromethane; benzene 72 h; Ambient temperature;