3-Amino-6-bromopyridine may undergo polymerization via Buchwald–Hartwig amination in the presence of sodium tert-butoxide and XPhos(2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl) ligand yielding para-linked and meta-linked polyaminopyridines.
General procedure for the synthesis of 5-amino-2-bromopyridine from 2-bromo-5-nitropyridine: To a solution of 2-bromo-5-nitropyridine (2.03 g, 10 mmol) in ethanol (48 mL) was added sequentially iron powder (2.8 g, 50 mmol), concentrated hydrochloric acid (1.9 mL) and water (9.1 mL). The reaction mixture was stirred under reflux conditions for 5 hours. After completion of the reaction, it was cooled to room temperature and filtered. The filtrate was concentrated under reduced pressure, the pH was adjusted to 7-8 with base and subsequently extracted with dichloromethane (DCM). The organic phases were combined, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to give the reddish brown solid product 5-amino-2-bromopyridine (1.58 g, 91.3% yield).
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