sodium dithionite in methanol; ammonium hydroxide 1.) 30 min, 2.) refrigerator, 1 h;

1: 88 percent / pyridine / 8 h / 85 °C 2: fuming nitric acid, aq. acetic acid / 24 h / steam bath 3: 60 percent / sodium dithionite / methanol; aq. NH3 / 1.) 30 min, 2.) refrigerator, 1 h View Scheme

1: 88 percent / pyridine / 8 h / 85 °C 2: fuming nitric acid, aq. acetic acid / 24 h / steam bath 3: 60 percent / sodium dithionite / methanol; aq. NH3 / 1.) 30 min, 2.) refrigerator, 1 h View Scheme