1: 1.) 1.6 M n-BuLi / 1.) Et2O, room temp., 3 h; 2.) THF, reflux, 4 h 2: 71 percent / Na, liq. NH3 / tetrahydrofuran / 0.5 h 3: 75 percent / pyridine / 48 h / -20 °C 4: 90 percent / dibenzo-18-crown-6 / acetonitrile / a) room temp., 1 h; b) reflux, 18 h 5: tetrahydrofuran 6: 68 percent / 1 N HCl / Heating View Scheme