1: mercuric oxide, mercuric chloride / acetone; H2O / 8 h / Ambient temperature 2: 90 percent / dimethylformamide / 20 h / Ambient temperature 3: 80 percent / n-BuLi / tetrahydrofuran / 1.) -78 deg C, 2.) to room temperature 4: tetra-n-butyl ammonium fluoride / tetrahydrofuran / 4 h / 60 °C View Scheme