Iodine → 2-Amino-5-chloro-3-iodopyridine

Iodine (7.55 g; 29.73 mmol) was added to a mixture of 5-chloropyridin-2-amine (3.00 g; 22.87 mmol) and silver sulphate (9.36 g; 29.73 mmol) in ethanol (150 mL) and the mixture was stirred overnight at room temperature. The mixture was filtered over celite, washed with ethanol, and the filtrate concentrated under reduced pressure. The residue was dissolved in dichloromethane, and the solution was washed with a saturated aqueous solution of sodium thiosulphate. The organic layer was dried over magnesium sulphate, concentrated under reduced pressure and the crude material purified by flash chromatography on silica gel (eluent: 0 to 30% of ethyl acetate in heptane) to give 3.71 g (64%) of 5-chloro-3-iodopyridin-2-amine as a beige solid.