The general procedure for the synthesis of N1-(5-bromopyridin-2-yl)ethane-1,2-diamine from 2,5-dibromopyridine and ethylenediamine was as follows: 1 g (4.22 mmol) of 2,5-dibromopyridine was dissolved in 10 mL of ethylenediamine, and the resulting solution was stirred and reacted for 15 hours at 100 °C. Upon completion of the reaction, the mixture was cooled to room temperature and the excess ethylenediamine was removed by distillation under reduced pressure. Subsequently, the concentrate was diluted by adding 50 mL of dichloromethane to the concentrate and the diluted solution was washed with 30 mL of distilled water. The aqueous phase was extracted twice with 50 mL of dichloromethane to recover the residual organic product. All organic layers were combined, dried with anhydrous sodium sulfate, and then concentrated under reduced pressure to afford 0.89 g (4.12 mmol) of the target compound N1-(5-bromopyridin-2-yl)ethane-1,2-diamine as a light yellow liquid in 98% yield. The product was characterized by 1H NMR (400 MHz, CDCl3): δ 8.10 (d, J = 1.6 Hz, 1H), 7.45 (dd, J1 = 8.8 Hz, J2 = 2.4 Hz, 1H), 6.33 (d, J = 8.8 Hz, 1H), 4.95 (brs, 1H), 3.34 (q, J = 6 Hz, 2H), 2.94 (t , J = 6 Hz, 2H).
