1: NaH, n-BuLi / tetrahydrofuran; hexamethylphosphoric acid triamide; hexane / 1.) 0 deg C, 15 min; 0 deg C, 30 min, 2.) -20 deg C, 15 h 2: 31 percent / SnCl4 / CH2Cl2; H2O / 2 h / 0 °C 3: NaH / tetrahydrofuran / 1.) reflux, 1 h, 2.) r.t., 1 h 4: 1.) CuI / 1.) ether, -20 deg C, 10 min, 2.) ether, -78 deg C, 0.5 h; -20 deg C, 15 h 5: 94 percent / DIBAL / toluene / 1 h / -78 °C 6: 99 percent / pyridine, DMAP / 0.5 h / 0 °C 7: 1.) n-BuLi, Me3SnCl, 2.) LiCl / 2.) Pd(dba)2 / 1.) THF, hexane, -50 deg C, 0.5 h; -50 deg C, 3 h, 2.) DMF, 100 deg C, 4 h 8: 71 percent / CrO3, 3,5-dimethylpyrazole / CH2Cl2 / 0.5 h / -20 °C 9: 43 percent / BBr3 / CH2Cl2 / 2.5 h / -78 - -10 °C 10: 62 percent / BF3*Et2O / CH2Cl2 / 1 h / Ambient temperature 11: 67 percent / Raney nickel W-7 / ethanol / 3 h / Heating 12: 87 percent / LiAlH4 / tetrahydrofuran / 1 h / 0 °C 13: 77 percent / aq. potassium nitrosodisulfonate, KH2PO4 / acetone / 0.5 h / Ambient temperature View Scheme

With  methanesulfonyl chloride; triethylamine; lithium bromide  1.) CH2Cl2, -60 deg C, 30 min; 2.) CH2Cl2-THF, -60 deg C then -20 deg C 45 min;  Yield given. Multistep reaction;   

Multi-step reaction with 3 steps 1: 88 percent / DIBAL / toluene / 0.5 h / -78 °C2: Et3N / CH2Cl2 / 0.5 h / -78 °C3: LiBr / tetrahydrofuran; CH2Cl2 / 1 h / -20 °C  

Multi-step reaction with 12 steps 1: 1.) Mg, 1,2-dibromoethane / 1.) THF, 25 deg C, 1 h, 2.) THF, r.t., 15 h2: 98 percent / SOCl2 / pyridine / 0.17 h / -10 °C3: nBu4NF / tetrahydrofuran / 1.) 40 deg C, 20 h, 2.) r.t., 48 h4: KH / tetrahydrofuran / 1.) r.t., 0.5 h, 2.) r.t., 1 h5: 99 percent / p-TsOH*H2O / acetone; H2O / 4 h / Heating6: 79 percent / NaH, MeOH / 16 h / Heating7: 18 percent / SnCl4 / CH2Cl2; H2O / 1.) 0 deg C, 1 h, 2.) r.t., 4 h8: NaH / tetrahydrofuran / 1.) reflux, 1 h, 2.) r.t., 1 h9: 1.) CuI / 1.) ether, -20 deg C, 10 min, 2.) ether, -78 deg C, 0.5 h; -20 deg C, 15 h10: 88 percent / DIBAL / toluene / 0.5 h / -78 °C11: Et3N / CH2Cl2 / 0.5 h / -78 °C12: LiBr / tetrahydrofuran; CH2Cl2 / 1 h / -20 °C