1: 79 percent / phosphorus oxychloride / 0.5 h / 60 °C 2: sodium / Ambient temperature 3: NaOH / methanol; H2O / 1 h / 65 °C 4: 1.) triethylamine, ethylchloroformate / 1.) DMF, 0 deg C, 30 min, 2.) room temp. overnight View Scheme

trichlorophosphate T=60°C; 0.5 h;