1: 56 percent / sodium methoxide / tetrahydrofuran / 6 h / Heating 2: 1.) O3, 2.) dimethyl sulfide / 1.) acetone-water, -20 deg C, 20 min, 2.) -20 deg C -> room temperature View Scheme

dimethylsulfide; ozone 1.) acetone-water, -20 deg C, 20 min, 2.) -20 deg C -> room temperature; Yield given. Multistep reaction;