1: 43 percent / NaBH4 / hexamethylphosphoric acid triamide / 24 h / 100 °C 2: 76 percent / aq. HCl / tetrahydrofuran / 3 h / 55 - 60 °C 3: 30 percent / CrO3, pyridine / CH2Cl2 / 2 h / Ambient temperature View Scheme