1: 83 percent / conc. HCl / acetone / 4.5 h / Ambient temperature 2: 91 percent / BF3*Et2O / tetrahydrofuran / 2.75 h / Heating 3: t-BuOK / tetrahydrofuran / 2 h / -20 - -15 °C 4: 58 percent / Na / liquid ammonia; tetrahydrofuran / 1 h / -4 °C View Scheme

hydrogenchloride 5 h; Ambient temperature;