1: 2.1 g / KOH / methanol; tetrahydrofuran / 1.5 h / 16 °C 2: 5.8 g / Jones' reagent / acetone / 0.25 h 3: 4.02 g / NaHCO3 / pyridine; H2O / 2.5 h / 100 °C 4: 3.3 g / Zn / acetic acid / 0.75 h / 90 °C View Scheme