Synthesis
Step 3. Synthesis of 2-amino-4-bromobenzaldehyde: Iron powder was added to 0.2 M of 4-bromo-2-nitrobenzaldehyde in a mixed solvent system of acetic acid and ethanol (v/v 1:1) under argon protection. The reaction mixture was stirred at room temperature for 1.5 h. The completion of the reaction was confirmed by LCMS monitoring. The insoluble solids were removed by filtration and the filtrate was concentrated under vacuum. The residue was diluted with ethyl acetate, washed sequentially with saturated sodium bicarbonate solution and brine, and the organic phase was dried over anhydrous sodium sulfate and concentrated. The crude product was purified by Biotage system using hexane solution of 15% ethyl acetate as eluent to afford the target compound 2-amino-4-bromobenzaldehyde in 38% yield.ES/MS m/z 200/202 (MH+).
References
[1] Tetrahedron Letters, 2016, vol. 57, # 45, p. 5003 - 5008
[2] Patent: WO2016/86200, 2016, A1. Location in patent: Page/Page column 219
[3] Patent: WO2007/117607, 2007, A2. Location in patent: Page/Page column 333-334
[4] Chemische Berichte, 1909, vol. 42, p. 3697
[5] Bioorganic and Medicinal Chemistry, 2006, vol. 14, # 7, p. 2462 - 2467
