A solution of tert-butyl 3-aminopropylcarbamate (121.39 g, 697 mmol) in N,N-dimethylformamide (200 mL) was slowly added to a solution of 2,4-dichloro-5,6-dimethyl-3-nitropyridine (110 g, 498 mmol) and triethylamine (104 mL, 746 mmol) in N,N-dimethylformamide (900 mL). After stirring at ambient temperature for 20 hours the reaction mixture was heated to 55° C. At 24 hours 0.1 equivalents of the carbamate was added. The reaction mixture was allowed to cool to ambient temperature overnight and then concentrated under reduced pressure. The residue was dissolved in ethyl acetate (3 L). The solution was divided into 3 aliquots (1 L each). Each aliquot was washed with water (2×1 L). The pH of the aqueous washes was adjusted to 10 with potassium carbonate and then they were extracted with ethyl acetate. All of the ethyl acetate layers were combined, dried over sodium sulfate and then concentrated under reduced pressure to provide 181 g of crude product. This material was recrystallized from acetonitrile to provide 138 g of tert-butyl 3-[(2-chloro-5,6-dimethyl-3-nitropyridin-4-yl)amino]propylcarbamate as a yellow solid.
