1: With oxalyl dichloride; dimethyl sulfoxide in dichloromethane T=-78°C; 2: With triethylamine in dichloromethane T=20°C;

chromium(VI) oxide; sulfuric acid; acetic acid in water Ambient temperature;

1: 70 percent / Ac2O / 136 h / 170 °C / Heating 2: ozone, methyl sulfide / 1) CH3OH, -35 deg C, 2) -35 deg C, 0.5 h View Scheme

1.1: acetic anhydride / 36 h / 90 °C / Inert atmosphere 1.2: 24 h / 70 °C / Inert atmosphere 2.1: oxalyl dichloride; dimethyl sulfoxide / dichloromethane / 0.5 h / -78 °C / Inert atmosphere 2.2: -78 °C / Inert atmosphere View Scheme

dimethylsulfide; ozone 1) CH3OH, -35 deg C, 2) -35 deg C, 0.5 h; Yield given. Multistep reaction;

1: With hydrogenchloride in diethyl ether 2: With hydrogenchloride; isopentyl nitrite in tetrahydrofuran; diethylene glycol 3 h; Heating / reflux;