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

Multi-step reaction with 2 steps 1: 82 percent / NaBH4, H2O / tetrahydrofuran / 1.5 h2: 94 percent / imidazole, DMAP / CH2Cl2 / 3 h / Ambient temperature