Hydrochloric Acid → N2-(tert-butyl)-3,5-difluoropyridine-2,6-diamine

To 60 ml of methanol were added 10.7 g of the crude 2-benzylamino-6-(t-butylamino)-3,5-difluoropyridine as described above together with 1.10 g of 10% palladium carbon and 3.8 g of concentrated hydrochloric acid, and the mixture was hydrogenated for one day. The catalyst was separated by filtration, and the solvent and the like were distilled off under reduced pressure. To the residue was added 150 ml of chloroform, and the mixture was washed with 80 ml of 10% aqueous solution of sodium carbonate, and the washings were extracted again with 50 ml of chloroform. The chloroform layers were combined, and dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was subjected to chromatography (silica gel, 100 g; eluent:chloroform:n-hexane, 2:1, and then, chloroform) to obtain 3.3 g of the title compound as a pale brown oil.