1: pyridinium chlorochromate, Celite / CH2Cl2 / 0.75 h / Ambient temperature 2: tetrahydrofuran / 2.5 h / Ambient temperature 3: 97.1 percent / pyridinium chlorochromate, Celite / CH2Cl2 / 24 h / Ambient temperature 4: 70 percent / BBr3 / CH2Cl2 / 1.5 h / -78 °C 5: 1.) NaH, 2.) ClSO2NH2 / 1.) DMF, 0 deg C, 30 min, 2.) DMF, RT, 24 h View Scheme

1: tetrahydrofuran / 2.5 h / Ambient temperature 2: 97.1 percent / pyridinium chlorochromate, Celite / CH2Cl2 / 24 h / Ambient temperature 3: 70 percent / BBr3 / CH2Cl2 / 1.5 h / -78 °C 4: 1.) NaH, 2.) ClSO2NH2 / 1.) DMF, 0 deg C, 30 min, 2.) DMF, RT, 24 h View Scheme