phenyl isocyanate; triethylamine in benzene T=45 - 50°C; 72 h;

1: 95 percent / PhSO3H / benzene / Heating 2: 65 percent / PhNCO, Et3N / benzene / 72 h / 45 - 50 °C View Scheme

1: 56 percent / aq. KOH / Heating 2: 95 percent / PhSO3H / benzene / Heating 3: 65 percent / PhNCO, Et3N / benzene / 72 h / 45 - 50 °C View Scheme