1: 1) NaH, HMPA / THF 2: m-CPBA / CH2Cl2 / -10 °C 3: Sharpless-Reich reaction 4: m-CPBA / CH2Cl2 / 0 °C 5: 1) NaH, HMPA / THF 6: Sharpless-Reich reaction 7: DEAD, PPh3 8: KOH, aq. EtOH / tetrahydrofuran 9: KH / tetrahydrofuran 12: 1) I2, sieves, 2) aq. Na2SO3 / 1) THF 13: m-CPBA / CH2Cl2 / 60 h / -10 °C 15: CAN, SiO2 / H2O; acetonitrile 16: KOH / H2O; methanol / Heating 17: Na, NH3 / tetrahydrofuran / -60 °C View Scheme