1: 1.) ozone 2.) PPh3 / 1.) CH2Cl2, MeOH, -60 deg C, 40 min. 2.) CH2Cl2, MeOH, -60 to 0 deg C 2: 90 percent / NaHCO3 / ethanol / 1.5 h / Heating View Scheme

With  sulfur dioxide  Heating;  Yield given. Yields of byproduct given;   

With  sulfur dioxide  Heating;  Yield given. Yields of byproduct given;   

Multi-step reaction with 5 steps 1: 42 percent / imidazole / dimethylformamide / 1.5 h / 20 °C2: sodium hydrogen carbonate / aq. ethanol / 1.5 h / Heating3: N-methylmorpholine N-oxide monohydrate, selenium dioxide / CH2Cl2; methanol / 0.83 h / Heating4: imidazole / dimethylformamide / 1.5 h / 20 °C5: liq. SO2 / diethyl ether / 0.5 h / Heating  

Multi-step reaction with 3 steps 1: N-methylmorpholine N-oxide monohydrate, selenium dioxide / CH2Cl2; methanol / 0.83 h / Heating2: imidazole / dimethylformamide / 1.5 h / 20 °C3: liq. SO2 / diethyl ether / 0.5 h / Heating  

Multi-step reaction with 2 steps 1: 35 percent / ImH / dimethylformamide / 20 °C2: SO2 / Heating