Example 20: Scheme C10
2-Aminopyridine (II) (1.0 eq, 318 mmol, 30.0 g), periodate dihydrate (0.15 eq, 48 mmol, 10.7 g), and iodine (0.42 eq, 134 mmol, 32.4 g) were dissolved in a mixture of acetic acid (800 mL), water (36 mL), and sulfuric acid (6.2 mL), and heated to react at 80°C for 4 for 4 hours. Upon completion of the reaction, the reaction mixture was poured into 10% Na2S2O3 aqueous solution to quench unreacted iodine and subsequently extracted with ether. The organic phases were combined, washed with 10% NaOH aqueous solution, dried over anhydrous MgSO4 and concentrated under reduced pressure. The crude product was purified by column chromatography (elution gradient: heptane/ethyl acetate 25:75 → pure ethyl acetate) to afford the target compound 2-amino-5-iodopyridine (116) (52.0 g, 74% yield).
1H NMR (δ, CDCl3): 4.51 (2H, s), 6.35 (1H, d, J = 8 Hz), 7.62 (1H, d, J = 8 Hz), 8.21 (1H, s).
