1.1: 4-(dimethylamino)pyridine / CH2Cl2 / 2 h / 20 °C 2.1: 69 percent / HCl / acetone; methanol / 2 h / 60 °C 3.1: 95 percent / pyridinium chlorochromate / CH2Cl2 / 1 h / 20 °C 4.1: 77 percent / NaOH / methanol; tetrahydrofuran / 3 h / 20 °C 5.1: NH2NH2*H2O / bis-(2-hydroxy-ethyl) ether; ethanol / 1 h / Heating; Huang-Minlon reduction 5.2: 77 percent / KOH / 2 h / Heating View Scheme