Synthesis
The general procedure for the synthesis of 2-fluoro-4-iodopyridine from 2-fluoro-3-iodopyridine was as follows: to a solution of 2-fluoro-3-iodopyridine (4.0 g, 17.9 mmol) in anhydrous THF (50 mL) was added slowly and dropwise to LDA (8.96 mL, 2 M THF solution, 17.9 mmol) at -78°C. After the reaction mixture was stirred at -78°C for 4 h, a THF (1 mL) solution of H2O (0.5 mL) was added. Subsequently, the reaction mixture was slowly warmed to room temperature and quenched by the addition of brine (30 mL). The organic layer was separated, washed with brine, dried over anhydrous Na2SO4 and concentrated to give the crude product. The crude product was purified by column chromatography to give 2-fluoro-4-iodopyridine (3.5 g, yield: 87.5%) as a white solid.LC/MS analysis showed m/z (M++H)=224.
References
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[2] Journal of Organic Chemistry, 1993, vol. 58, # 27, p. 7832 - 7838
[3] Patent: WO2004/76424, 2004, A1. Location in patent: Page 85
[4] Patent: EP1559320, 2005, A1. Location in patent: Page/Page column 6
[5] Patent: WO2013/6792, 2013, A1. Location in patent: Paragraph 0189
