1: 21 percent / 1,8-diazabicyclo<5.4.0>undec-7-ene / tetrahydrofuran / 168 h / 4 °C 2: 73 percent / KOH, H2O / ethanol / 24 h / Ambient temperature 3: 1) sec-BuLi, 2) Ac2O / 1) THF, hexane, -78 deg C, 2 h, 2) THF, -78 deg C, 2 h View Scheme