1: 85 percent / LiAlH4 / diethyl ether / 2 h / Ambient temperature 2: 0.25 h / Ambient temperature 3: LiI, hexamethylphosphoric triamide (HMPA) / tetrahydrofuran / 6 h / Heating 4: 54 percent / trimethoxyborohydride, hexamethylphosphoric triamide / 3 h / Ambient temperature View Scheme

lithium diisopropyl amide 1.) THF, hexane, -75 deg C, 30 min, 2.) THF, hexane, a) -75 deg C, 90 min, b) RT, 90 min; Yield given. Multistep reaction;