Synthesis
Step 1: Preparation of 5-nitro-2,3-dihydrobenzofuran
2,3-Dihydrobenzofuran (36 g, 0.3 mol) was dissolved in glacial acetic acid (100 mL) and heated to 65°C. The reaction temperature was maintained at a constant temperature. Under constant temperature, concentrated nitric acid (25 mL, 0.36 mol) was slowly added dropwise, and the reaction temperature was controlled to be maintained between 65-75°C. The reaction was carried out at a constant temperature. After the dropwise addition was completed, the reaction mixture was continued to be stirred for 0.5 hours. After completion of the reaction, the mixture was cooled to room temperature, the solid product was separated by filtration, washed with water to remove the residual acid, and dried to give 5-nitro-2,3-dihydrobenzofuran (22 g, 44.4% yield).
References
[1] Journal of Medicinal Chemistry, 2014, vol. 57, # 13, p. 5579 - 5601
[2] Bioorganic and Medicinal Chemistry, 2013, vol. 21, # 13, p. 3821 - 3830
[3] Patent: EP2532665, 2012, A1. Location in patent: Page/Page column 41
[4] Patent: WO2003/82787, 2003, A1. Location in patent: Page/Page column 138-139
[5] Journal of Medicinal Chemistry, 2010, vol. 53, # 18, p. 6681 - 6698
