1: 98 percent / n-BuLi / tetrahydrofuran; cyclohexane / 1.) -78 deg C, 2 min, 2.) -78 deg C, 2-5 min 2: 86 percent / aq. HCl / acetone / 0.33 h / 5 - 20 °C View Scheme

n-butyllithium; water; oxalic acid; silica gel 1.) THF, hexane, -78 deg C, 1 h, 2.) CH2Cl2, room temp., 2 h; Yield givenMultistep reaction;

1: 50 percent / BuLi / tetrahydrofuran; hexane / 1.) -78 deg C, 5 min, 2.) -78 deg C, 5 min 2: 80 percent / Dess-Martin periodinane / CH2Cl2 / 1 h / Ambient temperature 3: 75 percent / 37percent aq. HCl / acetone / 0.5 h View Scheme