To a 100 mL three-necked round-bottomed flask was added 2-amino-5-bromobenzoic acid (5 g, 23.14 mmol, 1.00 equiv) and anhydrous ethanol (100 mL). Dry hydrogen chloride gas was passed to saturation and the reaction mixture was subsequently heated to reflux for 12 hours. Upon completion of the reaction, saturated sodium bicarbonate solution was slowly added to neutralize the reaction system. The solvent was removed by distillation under reduced pressure to give the crude product. The crude product was purified by fast column chromatography (silica gel, eluent ratio was adjusted according to the TLC results) to give ethyl 2-amino-5-bromobenzoate (2.5 g, 44% yield) as a yellow solid.
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[2] Patent: WO2014/182951, 2014, A1. Location in patent: Paragraph 00281
[3] Bioorganic and Medicinal Chemistry Letters, 2007, vol. 17, # 23, p. 6481 - 6488
[4] Patent: EP1180514, 2002, A1. Location in patent: Example 75
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