1: 84 percent / tetrahydrofuran / Ambient temperature 2: 1.) MCPBA, methyl sulfide 2.) TBAF*3H2O / 1.) CH2Cl2, -78 deg C to room temperature, 2.) THF, overnight 3: 68 percent / pyridinium dichromate / dimethylformamide / 2 h / Ambient temperature 4: 1.) N-Bromosuccinimide, 2.) DABCO, 4-(dimethylamino)pyridine / 1.) CH2Cl2, CCl4, 50 deg C, 2.) 80 deg C, (25mm Hg) View Scheme

1: 84 percent / tetrahydrofuran / Ambient temperature 2: 1.) MCPBA, methyl sulfide 2.) TBAF*3H2O / 1.) CH2Cl2, -78 deg C to room temperature, 2.) THF, overnight 3: 68 percent / pyridinium dichromate / dimethylformamide / 2 h / Ambient temperature View Scheme