1: 1.) dibal-H / 1.) ether, 40 deg C, 2 h, 2.) n-heptane, a) 0 deg C, 30 min, b) 60 deg C, 3 h 2: BF3*OEt2 / 16 h / 60 - 70 °C 3: 1.) lithium diisopropylamide, HMPA, 2.) methanol / 1.) THF, n-hexane, -78 deg C, 2 h, 2.) -78 deg C, 15 min View Scheme

1: BF3*OEt2 / 16 h / 60 - 70 °C 2: 1.) lithium diisopropylamide, HMPA, 2.) methanol / 1.) THF, n-hexane, -78 deg C, 2 h, 2.) -78 deg C, 15 min View Scheme

methanol; N,N,N',N',N'',N''-hexamethylphosphoric triamide; lithium diisopropyl amide 1.) THF, n-hexane, -78 deg C, 2 h, 2.) -78 deg C, 15 min; Yield given. Multistep reaction. Yields of byproduct given. Title compound not separated from byproducts;