1: NaBH4 / ethanol / 0.25 h / 5 °C 2: potassium acetate / 1.5 h / 70 °C 3: 1.) water / 1.) conc. HCl / 1.) methanol, room temp., 1h; 2.) re-acetylation 4: 83 percent / tetra-n-butylammonium fluoride / tetrahydrofuran / 0.5 h / 5 °C 5: 1.) and 2.) NaOH / 1.) in methanol-water, 5 deg C, 0.5h; 2.) room temp., 2h View Scheme