1: 1.) 60percent NaH, 2.) p-toluenesulfonic acid monohydrate / 1.) THF, r.t., overnight, 2.) acetone, 0-5 deg C, 3 h 2: 86 percent / diethyl ether; tetrahydrofuran / 3 h / Ambient temperature 3: 104 mg / SOCl2 / pyridine / 17 h / 0 - 5 °C 4: 5 percent / BBr3 / CH2Cl2 / 2 h / -70 °C View Scheme

1: 87 percent / p-toluenesulfonic acid monohydrate / acetone / 3 h / 0 - 5 °C 2: 86 percent / diethyl ether; tetrahydrofuran / 3 h / Ambient temperature View Scheme

1: 87 percent / p-toluenesulfonic acid monohydrate / acetone / 3 h / 0 - 5 °C 2: 86 percent / diethyl ether; tetrahydrofuran / 3 h / Ambient temperature 3: 70 percent / cerium(IV) ammonium nitrate / CHCl3; acetonitrile; H2O / 0.17 h / Ambient temperature View Scheme

1: 87 percent / p-toluenesulfonic acid monohydrate / acetone / 3 h / 0 - 5 °C 2: 86 percent / diethyl ether; tetrahydrofuran / 3 h / Ambient temperature 3: 70 percent / cerium(IV) ammonium nitrate / CHCl3; acetonitrile; H2O / 0.17 h / Ambient temperature 4: 27 percent / AgO, 40percent HNO3 / acetone / 0.17 h / Ambient temperature View Scheme

toluene-4-sulfonic acid in acetone T=0 - 5°C; 3 h;