89167-34-0

The general procedure for the synthesis of 4-chloro-3-iodopyridine from 4-chloropyridine was as follows: suspension of 4-chloropyridine (10 g, 0.067 mol) in dry THF (150 mL) and slow dropwise addition of LDA (134 mL, 1 M hexane solution) at a temperature below -70 °C. The reaction mixture was stirred at -78 °C for 30 min before adding an anhydrous THF solution of I2 (17 g, 0.067 mol), keeping the internal temperature below -65 °C for 10 min. Subsequently, the reaction mixture was slowly warmed up to room temperature over a period of 2 hours and stirring was continued at room temperature for 30 minutes. Upon completion of the reaction, the mixture was poured into 20% aqueous Na2SO3 solution (100 mL) and extracted with EtOAc (100 mL, three times). The organic layer was washed sequentially with aqueous NaHCO3 (50 mL) and saturated aqueous NaCl (50 mL), dried and the solvent was evaporated. The product was purified by washing with petroleum ether (20 mL) to give 4-chloro-3-iodopyridine (6.2 g, 38% yield).'' HNMR (400 MHz, MeOD) δ 8.92 (s, 1H), 8.43-8.41 (d, 1H, J = 8Hz), 7.62-7.60 (d, 1H, J = 8Hz).

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[2] Journal of the American Chemical Society, 2002, vol. 124, # 4, p. 576 - 582
[3] Patent: WO2013/78254, 2013, A1. Location in patent: Paragraph 00359
[4] Heterocycles, 1996, vol. 43, # 8, p. 1641 - 1652