1: diphenylphosphoryl azide; triethylamine; / 2-methyl-propan-2-ol / 1.5 h / Heating 2: 1) 25percent HBr in HAc; 2)15percent aq. NH3; / diethyl ether / 1.5 h / 0 °C 3: polyphosphoric acid / Heating View Scheme

1: 88 percent / aq.NaOH / ethanol / 5 h / Heating 2: diphenylphosphoryl azide; triethylamine; acetic acid; NaOH; View Scheme

1: 93 percent / sulfur / xylene / 5 h / Heating 2: 88 percent / aq.NaOH / ethanol / 5 h / Heating 3: diphenylphosphoryl azide; triethylamine; acetic acid; NaOH; View Scheme

sodium hydroxide; diphenylphosphoranyl azide; acetic acid; triethylamine Multistep reaction;

PPA Heating;