1: 95 percent / n-Butyllithium/hexane / diethyl ether / 0.5 h / Heating 2: hexamethylphosphoric acid triamide / 20 h / 100 °C 3: 66 percent / n-Butyllithium / diethyl ether / 0.5 h / Heating 4: 99 percent / Ethanethiol, NaH / dimethylformamide / 3 h / Heating View Scheme