potassium tert-butylate in dimethyl sulfoxide 0.5 h;

1: 64 percent / CH2Cl2 / 48 h / 25 °C 2: 1) n-BuLi / 1) hexane, THF, -70 deg C, 15 min, 2a) -70 deg C, 1 h, b) r t., 10 min 3: 1) n-BuLi / 1) hexane, THF, -70 deg C, 15 min, 2a) -70 deg C, 1 h, b) 25 deg C, 10 min 4: 67 percent / NaBH4 / ethanol / 4 h / 25 °C 5: N(Et)3 / CH2Cl2 / 0.25 h / -5 °C 6: 63 percent / KOtBu / dimethylsulfoxide / 0.5 h View Scheme