Multi-step reaction with 2 steps 1.1: anhydrous iron chloride; carbon; hydrazine hydrate / isopropyl alcohol / 22 h / 30 - 80 °C / |Large scale2.1: sodium hydride / N,N-dimethyl-formamide / 0.5 h / 0 °C2.2: 0.5 h / 0 - 25 °C