3-Iodo-imidazo[1,2-a]pyridine

274-76-0

307503-19-1

Example 1 Synthesis of 3-iodoimidazo[1,2-a]pyridine In a 250 mL three-necked round-bottomed flask equipped with a magnetic stirrer, thermocouple, nitrogen inlet and outlet, and an ice bath cooling device, 11.61 g (98.27 mmol) of imidazo[1,2-a]pyridine was added to a 100 mL acetonitrile solution. At 0 °C, 24.32 g (108.1 mmol, 1.1 eq.) of N-iodosuccinimide solid was added in batches and the reaction mixture gradually changed to a yellow suspension. The reaction system was then slowly warmed to room temperature and stirred overnight. Upon completion of the reaction, the solvent was removed by rotary evaporation to give 39.2 g of dark solid crude product. The crude product was dissolved in 0.5 L of dichloromethane and washed sequentially with 10% aqueous KOH (2 x 250 mL) and water (200 mL). The organic phase was separated and dried with anhydrous Na2SO4. After filtration, the solvent was removed by rotary evaporation to give a dark colored residue. The residue was dissolved in boiling ethyl acetate and recrystallized by adding hexane. The precipitated white solid was collected by filtration, washed with 40 mL of hexane and dried under a stream of nitrogen to constant weight to give 20.8 g (86% yield) of the target product 3-iodoimidazo[1,2-a]pyridine. The product characterization data were as follows: - Rf = 0.42 (Expander: EtOAc/hexane = 1:1) - 1H NMR (CDCl3, δ): 8.12 (d, 1H, J = 6.8 Hz), 7.69 (s, 1H), 7.62 (d, 1H, J = 6.8 Hz), 7.24 (t, 1H, J = 6.8 Hz), 6.94 (t, 1H, J = 6.8 Hz) - 13C NMR (CDCl3, δ): 147.52, 140.02, 126.08, 125.23, 117.76, 113.43, 60.91 - LC-MS (ESI): m/z 245 [M+H]+ (C7H5N2I)