1: dimethylsulfoxide / 24 h / 70 - 75 °C 2: NaOMe / methanol / 24 h / 25 °C 3: 80 percent / xylene / 72 h / Heating; 4-Angstroem sieves 4: 100 percent / MCPBA / CH2Cl2 / 30 h / 25 °C 5: 1.) lithium hexamethyldisilazide, 2.) 1 M HCl / 1.) THF, 0 deg C; 25 deg C, 2 h, 2.) 10 min View Scheme