1: 1.) tin(II) triflate, N-ethylpiperidine / 1.) CH2Cl2, -45 deg C, 3 h, 2.) CH2Cl2, -80 deg C, 20 min 2: 82 percent / NaBH4, H2O / tetrahydrofuran / 1.5 h 3: 94 percent / imidazole, DMAP / CH2Cl2 / 3 h / Ambient temperature 4: 93 percent / H2 / 5percent Pd/C / ethyl acetate / 15 h / Ambient temperature 5: N-methylmorpholine N-oxide / (Ph3P)3RuCl2 / acetone / 72 h / Ambient temperature 6: BuLi / diethyl ether / 1.) -30 deg C, 30 min, 2.) -50 to 0 deg C, 1 h 7: BF3*Et2O / 2 h / Ambient temperature 8: t-BuOK, 18-crown-6 / pentane / 2.5 h / Ambient temperature 9: BuLi / diethyl ether / 1.) -80 to -30 deg C, 1.5 h, 2.) -60 deg C to r.t., 5 h 10: H2SO4, H2O / tetrahydrofuran / 0.42 h / Ambient temperature 11: HF, I2, H2O / acetonitrile / 48 h / Ambient temperature 12: 82 percent / 2,6-lutidine / CH2Cl2 13: 14 percent / CeCl3*7H2O, NaBH4 / methanol / 1.67 h / -60 - 0 °C 14: DMAP, pyridine / CH2Cl2 / 12 h / Ambient temperature 15: pyridine*HF / tetrahydrofuran / 1 h / Ambient temperature 16: Dess-Martin periodinane / 0.67 h / Ambient temperature 17: tetrahydrofuran / 1 h / -80 - -47 °C 18: Dess-Martin periodinane / CH2Cl2 / 0.42 h / Ambient temperature 19: pyridine, CSA / CH2Cl2 / 1 h / Ambient temperature 20: 88 percent / K2CO3 / methanol / 60 h / Ambient temperature 21: 90 percent / 2,6-lutidine / CH2Cl2 22: 1.) dicyclohexylmagnesium bromide / 1.) THF, -65 to -50 deg C, 35 min, 2.) THF, -65 to -50 deg C, 40 min 23: 93 percent / TBAF / tetrahydrofuran / 34 h / Ambient temperature 24: 3 Angstroem molecular sieves, TFA / CH2Cl2 / 0.6 h / Ambient temperature View Scheme