Synthesis
General procedure for the synthesis of 5-bromo-2-fluoroaniline from 4-bromo-1-fluoro-2-nitrobenzene: 5-bromo-2-fluoro nitrobenzene (698 g) was dissolved in 95% ethanol (0.90 L), which was subsequently added to a mixed system of powdered iron (711 g) and saturated aqueous ammonium chloride (2.0 L). The reaction mixture was stirred continuously at 70°C for 24 hours (the reaction process was monitored by HPLC until complete). Upon completion of the reaction, the mixture was cooled to room temperature, filtered through diatomaceous earth and the filtrate was concentrated under reduced pressure to remove the solvent. The residue was subjected to liquid-liquid extraction with ethyl acetate (2 L) and water (2 L) to separate the organic and aqueous phases. The aqueous phase was further extracted once with ethyl acetate (1L). All organic phases were combined, washed with water (1 L), dried with anhydrous magnesium sulfate, filtered and the organic phase was concentrated under reduced pressure. Finally, 545.76 g of 5-bromo-2-fluoroaniline was obtained in 91% yield by high vacuum treatment for 5 h to completely remove the residual ethyl acetate.
References
[1] Patent: WO2006/48761, 2006, A2. Location in patent: Page/Page column 32
[2] Bioorganic and Medicinal Chemistry Letters, 2015, vol. 25, # 19, p. 4337 - 4341
[3] Patent: WO2005/94822, 2005, A1. Location in patent: Page/Page column 44
[4] Patent: WO2004/52847, 2004, A2. Location in patent: Page 171
[5] Patent: CN104530107, 2016, B. Location in patent: Paragraph 0022
