1: 1) n-BuLi, triphenylmethane / 1) ether, HMPA, hexane, 0 deg C, 2) ether, 0 deg C, 15 min 2: diethyl ether; hexane; hexamethylphosphoric acid triamide / 3 h / Ambient temperature 3: 1) n-BuLi / 1) THF, HMPA, hexane, -78 deg C, 45 min, 2) THF, -78 deg C to room temperature, overnight 4: 52 percent / Cu(OAc)2*H2O / tetrahydrofuran; H2O / 0.67 h 5: 1) sodium hydride / 1) DMSO, room temperature, 15 min, 2) DMSO, 60 deg C, 3 h 6: p-toluenesulphonic acid / acetone / 5 h View Scheme

1: 1) n-BuLi, triphenylmethane / 1) ether, HMPA, hexane, 0 deg C, 2) ether, 0 deg C, 15 min 2: diethyl ether; hexane; hexamethylphosphoric acid triamide / 3 h / Ambient temperature 3: 1) n-BuLi / 1) THF, HMPA, hexane, -78 deg C, 45 min, 2) THF, -78 deg C to room temperature, overnight 4: 52 percent / Cu(OAc)2*H2O / tetrahydrofuran; H2O / 0.67 h View Scheme

1: aq. HCl / tetrahydrofuran 2: HCl, NaBH3CN, KOH / methanol View Scheme