Synthesis
5-Bromosalicylaldehyde (5 g, 25 mmol, 1.0 eq.) and cesium carbonate (8.2 g, 25 mmol, 1.0 eq.) were dissolved in 80 ml of DMF and stirred well. Subsequently, ethyl bromoacetate (8.3 g, 50 mmol, 2.0 eq.) was slowly added to the reaction system. The reaction mixture was stirred at room temperature for 30 min. After that, the reaction temperature was increased to 120 °C for 2 hours. The reaction progress was monitored by TLC. After completion of the reaction, the mixture was cooled to room temperature and poured into ice water and stirred vigorously for 30 minutes. The precipitate was collected by filtration, the filter cake was washed with water and dried to give the yellow powdery solid product ethyl 5-bromobenzofuran-2-carboxylate (4 g, 59.7% yield).
References
[1] Patent: CN106478564, 2017, A. Location in patent: Paragraph 0216; 0217; 0218
[2] Patent: CN107383024, 2017, A. Location in patent: Paragraph 0473
[3] Patent: US2004/209865, 2004, A1
[4] Bioorganic and Medicinal Chemistry Letters, 2008, vol. 18, # 20, p. 5591 - 5593
