1: H2O2 / tetrahydrofuran / 2.5 h / 25 °C 2: 2 h / 55 °C 3: Jones reagent 4: 1.) THF, -20 deg C, 30 min, 2.) DME, -20 deg C, 15 min 5: THF, -78 deg C, 30 min 6: Et3N / CH2Cl2 / 0.5 h / -5 °C 7: DBU / benzene / 25 °C 8: 81 percent / hydrogen, pyridine / Pd/C 9: ethanol / 7 h / 25 °C 10: LDA / tetrahydrofuran / -78 - 0 °C 11: Li,liquid NH3 12: 97 percent 13: 63 percent / KOH / ethanol / 16 h / 25 °C 14: pyridine / 8 h / 0 °C 15: 86 percent / DBU / pyridine / 3 h / 115 °C 16: aq. AcOH / tetrahydrofuran 17: 60 percent / PCC / CH2Cl2 / 2 h / 25 °C 18: 68 percent / NaH, n-BuLi / tetrahydrofuran / 0.25 h / 0 °C 19: 63 percent / Zn(BH4)2 / hexane / 1 h / 0 °C 20: p-TsOH*H2O / benzene / 0.5 h / 25 °C View Scheme