sodium hydroxide in tetrahydrofuran 1.5 h; Ambient temperature;

1: 78 percent / 1 N NaOH / tetrahydrofuran / 1.5 h / Ambient temperature 2: 85 percent / Et3N / benzene / 1 h / Heating 3: 1.) LDA, HMPA, 2.) HMPA / 1.) THF, hexane, 0 deg C, 2.) THF, 1 h, room temperature 4: 1 N sodium ethoxide / ethanol; tetrahydrofuran / 4 h / Ambient temperature 5: water, AcOH / tetrahydrofuran / Ambient temperature View Scheme

1: 78 percent / 1 N NaOH / tetrahydrofuran / 1.5 h / Ambient temperature 2: 85 percent / Et3N / benzene / 1 h / Heating 3: 1.) LDA, HMPA, 2.) HMPA / 1.) THF, hexane, 0 deg C, 2.) THF, 1 h, room temperature View Scheme