1: 99 percent / triethylamine / dimethylformamide / 20 h / 25 °C 2: 1.) ozone, 2.) NaBH4 / 1.) EtOH, -78 deg C, 2.) aq. EtOH, 25 deg C, 10 h 3: tri-n-butylphosphine / CH2Cl2 / 2 h / 25 °C 4: m-chloroperbenzoic acid (MCPBA) / CH2Cl2 / 1.) 0 deg C, 10 min, 2.) 25 deg C, 2 h 5: 1.) n-butyllithium / 1.) THF, hexane, -78 deg C, 30 min, 2.) -78 deg C, 1 h 6: tetrahydrofuran; hexane / 1.5 h / 25 °C 7: sodium amalgam / methanol; ethyl acetate / 20 h / -30 °C 8: 94 percent / Bu4NF / tetrahydrofuran / 21 h / 25 °C 9: oxalyl chloride, DMSO / CH2Cl2 / 0.42 h / -60 °C 10: 1.) di-n-butylboryl triflate, diisopropylethylamine / 1.) CH2Cl2, -78 deg C, 30 min, 2a.) -78 deg C, 1 h, 2b.) 0 deg C, 1.5 h 11: 72 percent / pyridine, CrO3 / CH2Cl2 / 0.25 h 12: 84 percent / 40percent aq. HF / acetonitrile / 1 h / 25 °C 13: 1 N aq. LiOH / 1,2-dimethoxy-ethane / 0.75 h / 25 °C View Scheme