1: 15 percent / potassium cyanide, benzyltriethylammonium chloride / CH2Cl2; H2O / 52 h 2: 59 percent / conc.aq.HBr / acetic acid / 0.33 h / Heating 3: 90 percent / 3 h / 150 °C / 0.02 Torr View Scheme