1: sodium acetate; hydroxylamine hydrochloride / isopropyl alcohol / 1.5 h / 20 °C 2: Acid orange 52; sodium cyanoborohydride; hydrogenchloride / methanol / 1 h / 20 °C 3: sodium cyanoborohydride / tert-butyl alcohol / 16 h / |Inert atmosphere; |Sealed tube; |Microwave irradiation 4: zinc; trifluoroacetic acid; water / dichloromethane / 20 °C View Scheme