Potassium Iodide → 2-Amino-5-fluoro-3-iodopyridine

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A stirred solution of 5-fluoro-pyridin-2-ylamine (50 g, 0.45 mol) in 2M sulfuric acid (250 mL) was treated portionwise with potassium iodate (48 g, 0.22 mol) and the mixture heated to 100° C. A solution of potassium iodide (41 g, 0.24 mol) in water (100 mL) was added dropwise over ca. 1 hour. The mixture was allowed to stir for a further 30 minutes then cooled to ambient temperature. The pH of the aqueous phase was adjusted to 8-9 and the mixture extracted with ethyl acetate (×3). The combined organic layer was washed with aqueous sodium thiosulfate solution, water and brine, dried (Na2SO4), filtered and evaporated to afford the title compound as a yellow solid (61.2 g, 58%). 1H NMR (400 MHz, CDCl3): 7.94 (d, J=2.7 Hz, 1H), 7.68 (dd, J=7.2, 2.7 Hz, 1H), 4.85 (s, 2H).

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