To 10 ml of methanol were added 1.6 g of 2-amino-4-bromo-5-chloro-3-fluoro-6-(1,1,3,3-tetramethylbutylamino)pyridine together with 0.47 g of triethylamine and 0.09 g of 10% palladium on carbon, and the mixture was hydrogenated at room temperature for 39 hours. The catalyst was separated by filtration, and the solvent and the like were distilled off under reduced pressure. To the residue was added 50 ml of chloroform, and the mixture was washed with 50 ml of distilled water. The chloroform layer was dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was subjected to chromatography (silica gel, 25 g; eluent: chloroform) to obtain 0.75 g of 2-amino-3-fluoro-6-(1,1,3,3-tetramethylbutylamino)pyridine as a pale brown oil, and 0.2 g of 2-amino-4-bromo-3-fluoro-6-(1,1,3,3-tetramethylbutylamino)pyridine as a brown oil.
