1: 4.3 g / 3percent KOH / methanol / 2.5 h 2: 3.7 g / pyridinium tosylate / tetrahydrofuran / 24 h / Ambient temperature 3: n-BuLi / tetrahydrofuran; hexane / 1 h / Heating 4: 270 mg / n-BuLi / tetrahydrofuran; hexane / 2 h / Ambient temperature 5: pyridinium tosylate / methanol / 20 h / Ambient temperature 6: cyclohexanone, aluminium isopropoxide / toluene / 0.5 h / Heating View Scheme