1: 65 percent / diisobutylaluminium hydride (DIBAL) / toluene; tetrahydrofuran / 1 h / -80 - -72 °C 2: 1.) t-BuOK / 1.) THF, RT, 30 min, 2.) THF, -15 to -10 deg C, 4 h View Scheme

1: 65 percent / diisobutylaluminium hydride (DIBAL) / toluene; tetrahydrofuran / 1 h / -80 - -72 °C 2: 1.) t-BuOK / 1.) THF, RT, 30 min, 2.) THF, -15 to -10 deg C, 4 h 3: 38 percent / DBU / acetone / 4 h / Ambient temperature View Scheme