1: 86 percent / BuLi / tetrahydrofuran / -50 °C 2: 90 percent / LiBEt3H / tetrahydrofuran / 24 h / Ambient temperature 3: 50.1 percent / BuLi / tetrahydrofuran / 1.) 1 h, 0-10 deg C; 2.) -70 deg C 4: 95.8 percent / CrO3 / acetone; H2O; H2SO4 / 0.5 h / -15 °C View Scheme

1: 86 percent / BuLi / tetrahydrofuran / -50 °C 2: 90 percent / LiBEt3H / tetrahydrofuran / 24 h / Ambient temperature 3: 50.1 percent / BuLi / tetrahydrofuran / 1.) 1 h, 0-10 deg C; 2.) -70 deg C 4: 95.8 percent / CrO3 / acetone; H2O; H2SO4 / 0.5 h / -15 °C 5: 1.) Al(CH3)3 / 1.) toluene, from RT to Bp, 4 h; 2.) 0 to Rt, 1 h View Scheme

1: 86 percent / BuLi / tetrahydrofuran / -50 °C 2: 90 percent / LiBEt3H / tetrahydrofuran / 24 h / Ambient temperature View Scheme