Uses
7-Chloro-1-ethyl-6-fluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic Acid (Norfloxacin EP Impurity A) is a Norfloxacin intermediate. Norfloxacin EP Impurity A; Norfloxacin USP Related Compound A (7-Chloro-1-ethyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic Acid).
Synthesis
Ethyl 7-chloro-1-ethyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylate (2.75 g, 9.24 mmol) was used as a raw material and dissolved in 60 mL of methanol. Subsequently, a 1:1 solution of hydrochloric acid (31.5 mL, 189 mmol) was added. The reaction mixture was heated to reflux for 2 h. Upon completion of the reaction, a white solid precipitated. The solid product was collected by filtration and washed with plenty of water. Finally, the product was dried in a vacuum oven for 2 h to afford 7-chloro-1-ethyl-6-fluoro-1,4-dihydro-4-carbonylquinoline-3-carboxylic acid (2.46 g, yield: 89.5%).
References
[1] Journal of Medicinal Chemistry, 2009, vol. 52, # 14, p. 4257 - 4265
[2] Liebigs Annalen der Chemie, 1987, p. 29 - 37
[3] Chemical Communications, 2018, vol. 54, # 15, p. 1869 - 1872
[4] Journal of Medicinal Chemistry, 1980, vol. 23, # 12, p. 1358 - 1363
[5] Patent: CN107445892, 2017, A. Location in patent: Paragraph 0016
