triethylamine in diethyl ether T=-10°C; 2 h; Yield given;

1: H2S/triethylamine / diethyl ether / 0.83 h / Ambient temperature 2: p-toluenesulfonic acid / acetic acid / 1.5 h / 90 - 95 °C 3: gaseous HCl / 3 h / 55 °C 4: 5percent aq NaOH / methanol / 3 h / 40 °C View Scheme