1: 1.) LDA / 1.) THF, -60 deg C, 2.) THF 2: 97 percent / 3-chloroperoxybenzoic acid / CH2Cl2 / Ambient temperature 3: 100 percent / Swern oxidation reagent 4: 1.) n-BuLi, 2.) Et3N / 1.) THF, -60 deg C 5: H2O, silica gel View Scheme

1: 1.) LDA / 1.) THF, -60 deg C, 15 min, 2.) THF, 5 min 2: 96 percent / MCPBA / CH2Cl2 / 1 h / Ambient temperature 3: 1.) oxalyl chloride, DMSO, 2.) triethylamine / 1.) CH2Cl2, -60 deg C, 15 min, 2.) CH2Cl2, from -60 deg C to 0 deg C View Scheme

1.1: LDA / tetrahydrofuran / 0.25 h / -78 °C 1.2: tetrahydrofuran / 0.25 h / -78 °C 2.1: 97 percent / NaI; trifluoroacetic anhydride / acetone / 0.17 h / 0 °C View Scheme