General procedure for the synthesis of 6-iodopyridin-2-amine from 2-amino-6-bromopyridine: 2-bromo-6-aminopyridine (519 mg), cuprous iodide (29 mg), sodium iodide (899 mg), and N,N-dimethylethylenediamine (26 mg) were dissolved in dioxane (5 mL) and heated to react for 6 hours at 110 °C in an inert atmosphere. Upon completion of the reaction, concentrated ammonia (8 mL) was added, followed by water (10 mL). The reaction mixture was extracted with dichloromethane (3 x 15 mL) and the organic phase was dried with anhydrous magnesium sulfate, filtered and concentrated. The crude product was purified by rapid chromatography on silica gel using a 0-10% methanol/dichloromethane gradient elution to afford 6-iodopyridin-2-amine as a beige solid (530 mg, 80% yield). The structure of the product was confirmed by 1H NMR (CDCl3): δ 4.60 (s, 2H), 6.41-6.44 (m, 1H), 7.00-7.08 (m, 2H); mass spectrometry (MS) showed the molecular ion peak m/z 221 (MH+).
