1: 96 percent 2: 75 percent / (bipyH2)-CrOCl5 / 8 h / 40 °C / pyridinium chlorochromate, 40 degC, 48 h is also possible 3: 1) LDA/C6H5SeSeC6H5, 2) H2O2 View Scheme

1: 1.) O3; 2.) NaBH4 / methanol; 1.) -50 deg C, 0.25 h; 2.) -30 deg C, 1 h 2: pyridine / 18 h / Ambient temperature 3: 81 percent / CrO3 / pyridine; CH2Cl2 / 1.5 h / Ambient temperature 4: 1.) 1.6 M n-BuLi / 1.) Et2O, room temp., 3 h; 2.) THF, reflux, 4 h 5: 71 percent / Na, liq. NH3 / tetrahydrofuran / 0.5 h 6: 75 percent / pyridine / 48 h / -20 °C 7: 90 percent / dibenzo-18-crown-6 / acetonitrile / a) room temp., 1 h; b) reflux, 18 h 8: tetrahydrofuran 9: 68 percent / 1 N HCl / Heating View Scheme

1: 96 percent 2: 75 percent / (bipyH2)-CrOCl5 / 8 h / 40 °C / pyridinium chlorochromate, 40 degC, 48 h is also possible 3: 1) LDA/C6H5SeSeC6H5, 2) H2O2 View Scheme