1: pyridine / 0 °C / several hours 2: NaI, NaHCO3 / acetone / Heating; several hours 3: 1) LDA, / 1) THF-hexane-HMPA, -55 deg C, 30 min, 2) THF-hexane-HMPA, -60 to -5 deg C, 3 h 4: 37 percent / AcOH, H2O / tetrahydrofuran / 24 h / 40 °C View Scheme