1: 79 percent / BF3*Et2O / diethyl ether / 1.5 h / Ambient temperature 2: 85 percent / NaBH4 / methanol / 0 deg C to RT, 3 h 3: 1.) (COCl)2, 2.) Et3N / 1.) DMSO, CH2Cl2, -30 deg C, 20 min, 2.) -60 deg C, 25 min, then RT View Scheme

Swern oxidation;