1: 88 percent / benzene / 17 h / Heating 2: 1.) LiNEt2 / 1.) HMPT, benzene, THF, -45 deg C, 1.5 h, 2.) -45 deg C, 30 min; room temp., overnight 3: 10percent aq. HCl / hexamethylphosphoric acid triamide; benzene; tetrahydrofuran / 11.5 h / Heating View Scheme

1: 1.) O3, 2.) Me2S / 1.) CH2Cl2, -60 deg C, 2.) -60 deg C, then room temp. 2: 89 percent / 1percent aq. NaOH / diethyl ether / 72 h / Ambient temperature View Scheme

dimethylsulfide; ozone 1.) CH2Cl2, -60 deg C, 2.) -60 deg C, then room temp.; Yield given. Multistep reaction;