Synthesis
The general procedure for the synthesis of 5-nitroquinoxaline from the compound (CAS:131543-46-9) and 3-nitro-o-phenylenediamine was as follows: general method 108: Acetaldehyde (40% aqueous solution, 1.43 mL, 31.3 mmol) was added to a solution of 3-nitro-o-phenylenediamine (600 mg, 3.9 mmol) in ethanol (15 mL). The reaction mixture was heated to reflux at 85 °C for 2 hours. After completion of the reaction, the solvent was removed by distillation under reduced pressure, the residue was diluted with an appropriate amount of water and the aqueous phase was extracted with dichloromethane (DCM). The organic phases were combined, dried with anhydrous sodium sulfate (Na2SO4), filtered and concentrated under reduced pressure. The crude product was purified by column chromatography using dichloromethane/methanol (99:1, v/v) as eluent to afford the target compound 5-nitroquinoxaline (666 mg, 97% yield). Molecular weight (MW): 175.15. High performance liquid chromatography-mass spectrometry (HPLC-MS, Method C) analysis: [m/z]: 176.
References
[1] Patent: US2012/214803, 2012, A1. Location in patent: Page/Page column 174
[2] Patent: WO2016/77240, 2016, A2. Location in patent: Page/Page column 68
[3] Patent: CN107805223, 2018, A. Location in patent: Paragraph 0019
[4] Bioorganic and Medicinal Chemistry, 2008, vol. 16, # 14, p. 6707 - 6723
[5] Patent: EP1147083, 2004, B1. Location in patent: Page 38
