5-Bromo-2-chloro-3-iodo-pyridine

Synthesis

General procedure for the synthesis of 5-bromo-2-chloro-3-iodopyridine from 5-bromo-3-iodopyridin-2(1H)-one: 5-bromo-3-iodopyridin-2(1H)-one (9 g, 30 mmol) was dissolved in 90% phenylphosphonic dichloride (100 mL, 0.3 mol). The reaction mixture was heated with stirring at 160 °C for 4 h and the progress of the reaction was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the mixture was cooled to room temperature, followed by slow dripping into a vessel containing 1 L of water and cooled at 0 °C. The reaction solution was neutralized with NH4OH solution to neutral. The aqueous phase was extracted with ethyl acetate and the organic phase was combined. After treatment, the target product 5-bromo-2-chloro-3-iodopyridine was obtained as a white solid in 82% yield.

References

[1] Journal of Medicinal Chemistry, 2015, vol. 58, # 4, p. 1644 - 1668
[2] Patent: WO2015/132727, 2015, A1. Location in patent: Page/Page column 22; 23; 28