tetrabutyl ammonium fluoride in tetrahydrofuran T=25°C; 16 h; Inert atmosphere;

toluene-4-sulfonic acid in benzene T=80°C; 1 h; optical yield given as percent ee;

1: 30 percent / p-TsOH / benzene / 9 h / Heating 2: 6N aq. HCl / tetrahydrofuran / 6 h / Heating 3: 1.) CeCl3*7H2O, NaBH4, 2.) Jones reagent / 1.) MeOH, 20 min, 2.) acetone, RT, 20 min View Scheme

1: 6N aq. HCl / tetrahydrofuran / 6 h / Heating 2: 1.) CeCl3*7H2O, NaBH4, 2.) Jones reagent / 1.) MeOH, 20 min, 2.) acetone, RT, 20 min View Scheme

1: 25 percent / (S)-(-)-proline 2: acid View Scheme

1.1: sodium dihydrogenphosphate; 3-chloro-benzenecarboperoxoic acid / dichloromethane / 10 h / 0 °C / Inert atmosphere 2.1: dipyridinium dichromate / dichloromethane / 2 h / 20 °C / Inert atmosphere; Molecular sieve 3.1: Mes3B; sodium / tetrahydrofuran / 3 h / -78 °C / Inert atmosphere 3.2: -78 - 20 °C / Inert atmosphere 4.1: toluene-4-sulfonic acid / toluene / 2 h / Inert atmosphere; Reflux View Scheme

1.1: dipyridinium dichromate / dichloromethane / 2 h / 20 °C / Inert atmosphere; Molecular sieve 2.1: Mes3B; sodium / tetrahydrofuran / 3 h / -78 °C / Inert atmosphere 2.2: -78 - 20 °C / Inert atmosphere 3.1: toluene-4-sulfonic acid / toluene / 2 h / Inert atmosphere; Reflux View Scheme

1.1: Mes3B; sodium / tetrahydrofuran / 3 h / -78 °C / Inert atmosphere 1.2: -78 - 20 °C / Inert atmosphere 2.1: toluene-4-sulfonic acid / toluene / 2 h / Inert atmosphere; Reflux View Scheme

1: sulfuric acid; water; mercury(II) oxide / 1.33 h / 60 °C 2: triethylamine / dichloromethane / 16 h / 25 °C / Inert atmosphere 3: titanium tetrachloride / dichloromethane / 18 h / -25 - -20 °C / Inert atmosphere 4: benzene-selenenyl bromide; sodium hydrogencarbonate / methanol; dichloromethane / 3 h / 25 °C / Inert atmosphere 5: tetrabutyl ammonium fluoride / tetrahydrofuran / 16 h / 25 °C / Inert atmosphere View Scheme

1: titanium tetrachloride / dichloromethane / 18 h / -25 - -20 °C / Inert atmosphere 2: benzene-selenenyl bromide; sodium hydrogencarbonate / methanol; dichloromethane / 3 h / 25 °C / Inert atmosphere 3: tetrabutyl ammonium fluoride / tetrahydrofuran / 16 h / 25 °C / Inert atmosphere View Scheme