1: 1.) lithium diisopropylamide / 1) THF, -78 deg C, 20 min; 2) THF, -78 deg C, 1 h 2: 73 percent / oxalyl chloride, DMSO / CH2Cl2 / 0.75 h / -78 °C 3: diethyl ether / 1 h / Ambient temperature 4: 95 percent / oxalyl chloride, DMSO / CH2Cl2 / 1 h / -78 °C 5: 1.) hexamethyldisilazane, n-BuLi / 1) THF, -78 deg C, 45 min; 2) THF, hexane, -78 deg C, 2 h 6: 48 percent / PTSA / toluene / Heating 7: 1.) tert-butyldimethylsilyl trifluoromethanesulfonate, pyridine / 1) CH2Cl2, 30 min; 2) CH2Cl2, , 2 h View Scheme

1: 67 percent / 0.08 h / 130 °C 2: HCl gas / diethyl ether / 3 h / 0 °C 3: H2O / 1 h 4: 88 percent / LiAlH4 / diethyl ether / 0.5 h / Ambient temperature View Scheme