a) Synthesis of 2-iodo-5-trifluoromethylpyridine: Sodium iodide (43.3 g, 289.1 mmol) was added to a solution of 2-chloro-5-trifluoromethylpyridine (15.0 g, 82.6 mmol) in acetonitrile (400 mL), and the reaction mixture was stirred at 88 °C until the sodium iodide was completely dissolved. Subsequently, acetyl chloride (8.8 mL, 12.3 mmol) was slowly added dropwise to the solution and precipitation was observed. The reaction mixture was refluxed for 24 hours, cooled and concentrated to give an oil. The oil was dissolved in dichloromethane, washed sequentially with 10% sodium thiosulfate solution, 10% sodium carbonate solution and saturated saline, dried over anhydrous magnesium sulfate, filtered and concentrated. The residue was purified by column chromatography using dichloromethane as eluent to give 10.9 g (48.4% yield) of light yellow target product.1H NMR (CDCl3): δ 8.68 (s, 1H), 7.88 (m, 1H), 7.49 (d, J = 9.9 Hz, 1H).
