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

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

1: 45 percent / LiAlH4 / diethyl ether / 3 h / 0 °C 2: 1.) lithium diisopropylamide / 1) THF, -78 deg C, 20 min; 2) THF, -78 deg C, 1 h 3: 73 percent / oxalyl chloride, DMSO / CH2Cl2 / 0.75 h / -78 °C 4: diethyl ether / 1 h / Ambient temperature 5: 95 percent / oxalyl chloride, DMSO / CH2Cl2 / 1 h / -78 °C 6: 1.) hexamethyldisilazane, n-BuLi / 1) THF, -78 deg C, 45 min; 2) THF, hexane, -78 deg C, 2 h 7: 48 percent / PTSA / toluene / Heating 8: 1.) tert-butyldimethylsilyl trifluoromethanesulfonate, pyridine / 1) CH2Cl2, 30 min; 2) CH2Cl2, , 2 h View Scheme

1: 93 percent / DCC, HOBt, Et3N / tetrahydrofuran / 5 h / Ambient temperature 2: 88 percent / TBAF / tetrahydrofuran / 0.5 h / 0 °C 3: 77 percent / MsCl, Et3N / CH2Cl2 / 16 h / Ambient temperature 4: 75 percent / MnO2 / CHCl3 / 6 h / Heating View Scheme

1: 77 percent / MsCl, Et3N / CH2Cl2 / 16 h / Ambient temperature 2: 75 percent / MnO2 / CHCl3 / 6 h / Heating View Scheme

1: 88 percent / TBAF / tetrahydrofuran / 0.5 h / 0 °C 2: 77 percent / MsCl, Et3N / CH2Cl2 / 16 h / Ambient temperature 3: 75 percent / MnO2 / CHCl3 / 6 h / Heating View Scheme

pyridine; t-butyldimethylsiyl triflate 1) CH2Cl2, 30 min; 2) CH2Cl2, , 2 h; Yield given. Multistep reaction;