1: methanol 2: 76 percent / NaBH4 / methanol 4: 77 percent / CsF / acetone / 4 h / Heating 6: Li2CuCl4 / tetrahydrofuran / 4 h / -30 °C 7: TsOH / methanol / Heating 8: pyridine View Scheme

n-butyllithium 1.) THF, -70 deg C, 2.) -70 deg C -> 0 deg C; Yield given. Multistep reaction;