1: triphenylbenzyl-phosphonium bromide in tetrahydrofuran; hexane T=-78°C; 1 h; Inert atmosphere; 2: N-Benzyliden-toluol-ω-sulfonsaeureamid in tetrahydrofuran; hexane T=-78 - 20°C; 12 h; Inert atmosphere; optical yield given as percent destereoselective reaction;

T=150 - 180°C; 0.5 h;

trifluorormethanesulfonic acid; trifluoromethylsulfonic anhydride in 1,2-dichloro-ethane T=35°C; 3 h;

1: Phosphorus pentachloride 2: CHCl3; benzene 3: 9 percent / Trioxane, CH3SO3H, Acetic anhydride / 1,2-dichloro-ethane / 4 h / 35 °C 4: 44 percent / Trifluoromethanesulphonic acid, Trifluoromethanesulphonic anhydride / 1,2-dichloro-ethane / 3 h / 35 °C View Scheme

1: 9 percent / Trioxane, CH3SO3H, Acetic anhydride / 1,2-dichloro-ethane / 4 h / 35 °C 2: 44 percent / Trifluoromethanesulphonic acid, Trifluoromethanesulphonic anhydride / 1,2-dichloro-ethane / 3 h / 35 °C View Scheme