Sodium borohydride (0.82 g, 22 mmole) was added to a solution of nickel(II) chloride hydrate (1.43 g, 6 mmole) in methanol (300 mL). The addition caused a black solid to form along with gas evolution. The resulting heterogeneous mixture was stirred at ambient temperature for about 30 minutes. A solution containing N2,N2,N4 -Tris(phenylmethyl)-5,6,7,8-tetrahydro-3-nitroquinolin-2,4-diamine (5.73 g, 12 mmole) in methylene chloride (20 mL) was added followed by 5 successive additions of sodium borohydride (0.38 g, 10 mmole each addition). The reaction mixture was stirred at ambient temperature for about 15 minutes then filtered through a layer of silica gel. The filtrate was evaporated. The residue was taken up in a minimum amount of methylene chloride then placed on a layer of silica gel. The silica gel was eluted with hexane:ethyl acetate 80:20. The organic phase was collected then evaporated to provide 5.0 g of the desired product as a green oil.
