1: diphenylphosphoryl azide; Et3N / dimethylformamide / 6 h / 20 °C 2: 4.695 g / dimethylformamide; methanol / 8 h / 65 °C 3: 59 percent / KOH / ethane-1,2-diol / 1.5 h / 110 - 115 °C View Scheme

1.1: diphenylphosphoryl azide; Et3N / dimethylformamide / 6 h / 20 °C 2.1: 4.695 g / dimethylformamide; methanol / 8 h / 65 °C 3.1: 59 percent / KOH / ethane-1,2-diol / 1.5 h / 110 - 115 °C 4.1: tetrabutylammonium hydrogen sulfate / acetonitrile / 3 h / Heating 4.2: 56 percent / NH3 / methanol / 4 h / 60 °C View Scheme

Multi-step reaction with 2 steps 1.1: N,N-dimethyl-formamide; ethyl acetate / 3 h / 95 °C2.1: lithium hydroxide hydrate; methanol / tetrahydrofuran / 1 h / 50 °C2.2: pH < 2