1: 83 percent / DIBAL / CH2Cl2; heptane / 1 h / -78 °C 2: 1.) sodium hydride / 1.) THF, r.t., 10 min, 2.) THF, r.t., 20 h 3: 76 percent / 1.) potassium hydroxide, water, 2.) conc. hydrochloric acid / tetrahydrofuran / 21 h / Heating 4: 1.) n-butyllithium, diisopropylamine / 1.) THF/hexane, -78 deg C, 10 min, 2.) THF, 1 h View Scheme