Step 1: 2-Chloro-5-nitropyridin-4-amine (4.50 g, 25.93 mmol) was dissolved in ethyl acetate (100 mL) and nickel ruanne (0.45 g) was added. The reaction mixture was stirred at room temperature for 2 hours in a hydrogen atmosphere. After completion of the reaction, the catalyst was removed by filtration and the filtrate was concentrated under reduced pressure to give the crude 6-chloropyridine-3,4-diamine (4.00 g, about 100% yield) as a yellow oil. Mass spectrometry (ESI) analysis showed: m/z = 144.3 [M + 1]+.
