camphor-10-sulfonic acid in methanol T=40°C; 6 h;

1: With sodium hydroxide; sodium tetrahydroborate; potassium carbonate in methanol T=20°C; 2: With hydrogenchloride in methanol pH=2; 0.25 h;

1: 91 percent / glacial acetic acid; NaCNBH3 / ethanol / 20 °C 2: 89 percent / camphosulfonic acid / methanol / 6 h / 40 °C View Scheme

1: 94 percent / AlCl3 / CH2Cl2 / 0 °C 2: 91 percent / NBS / CCl4 / 1.5 h / Heating 3: 90 percent / NaOAc / hexamethylphosphoric acid triamide; toluene / 20 °C 4: 91 percent / sodium cyanoborohydride; AcOH / ethanol / 20 °C 5: 89 percent / camphorsulfonic acid / methanol / 6 h / 40 °C View Scheme

1: 91 percent / NBS / CCl4 / 1.5 h / Heating 2: 90 percent / NaOAc / hexamethylphosphoric acid triamide; toluene / 20 °C 3: 91 percent / sodium cyanoborohydride; AcOH / ethanol / 20 °C 4: 89 percent / camphorsulfonic acid / methanol / 6 h / 40 °C View Scheme

1: 90 percent / NaOAc / hexamethylphosphoric acid triamide; toluene / 20 °C 2: 91 percent / sodium cyanoborohydride; AcOH / ethanol / 20 °C 3: 89 percent / camphorsulfonic acid / methanol / 6 h / 40 °C View Scheme