1: CuSO4, TsOH 2: CrO3-2Pyr / CH2Cl2 / 0.5 h / 0 °C 3: tetrahydrofuran / -78 °C 4: pyridine 5: 1.) LDA, TBSCl, HMPA, 2.) Bu4NF / 1.) THF, -78 deg C, 2.) reflux, 1.5 h 7: 95 percent / p-toluenesulfonic acid / 0 °C 8: i-Pr2NEt / CH2Cl2 9: lithium aluminum hydride / diethyl ether 10: CH2Cl2 11: 1.) butyllithium, 2.) Hg(OAc)2 / 1.) heptane, 2.) THF, water 12: CrO3-2Pyr / CH2Cl2 / 0 °C 13: tetrahydrofuran / -78 °C 14: DDQ / dioxane / 10 h 15: Bu4NF / tetrahydrofuran 16: CrO3-2Pyr / CH2Cl2 / 0 °C 17: 2.) camphorsulphonic acid / 1.) THF, -100 deg C, 2.) methylene chloride, -15 deg C, 10 h 18: 1.) Cr2(OAc)4-2H2O, 2.) potassium carbonate, methanol / 1.) EtOH, 2.) water View Scheme