1865-11-8

2-Quinoxalinecarboxylic Acid Methyl Ester has been used as a reactant in the synthesis of quinoxaline derivatives that show antimycobacterial activity, while displaying minor activity itself. In addit ion to having the substructure that exhibits antitumor activity, it is also used in the design of guanine-guanine selective DNA cleaving agents.

2-Quinoxaline carboxylic acid (1.0 g, 5.7 mmol, 1.0 eq.) was dissolved in 20 mL of methanol and thionyl chloride (1.25 mL, 17.2 mmol, 3.0 eq.) was added slowly. The reaction mixture was heated to reflux for 3 hours. After completion of the reaction, it was cooled to room temperature and concentrated under reduced pressure to remove the solvent. The residue was extracted with ethyl acetate, washed with water, partitioned and the organic phase was dried over anhydrous sodium sulfate. After filtration, the organic phase was concentrated under reduced pressure. Purification by silica gel column chromatography (eluent: petroleum ether/ethyl acetate=5:1) afforded the light yellow solid product methyl quinoxaline-2-carboxylate (1.01 g, yield 93.5%).

[1] Advanced Synthesis and Catalysis, 2009, vol. 351, # 16, p. 2549 - 2552
[2] Patent: CN107383024, 2017, A. Location in patent: Paragraph 0395
[3] Patent: WO2018/116072, 2018, A1. Location in patent: Page/Page column 74
[4] Supramolecular Chemistry, 2015, vol. 27, # 11-12, p. 780 - 786
[5] Tetrahedron, 2016, vol. 72, # 10, p. 1375 - 1380