1: imidazole / dimethylformamide / Ambient temperature 2: 1.) lithium diisopropylamide, HMPA / 1.) THF, hexane, -78 deg C, 40 min, 2.) THF, hexane, -78 deg C, 1.5 h 3: 1.) lithium diisopropylamide, HMPA, 2.) acetic acid / 1.) THF, hexane, -78 deg C, 0.5 h, 2.) THF, hexane, -78 deg C, 5 min 4: 83 percent / NaOH / methanol; H2O / 1.) RT, 0.5 h, 2.) 50 deg C, 1 h View Scheme