Imidazo[1,2-a]pyrazine-2-carboxylic acid

Synthesis

Lithium chloride monohydrate (6.50 g, 0.156 mol) was added to ethyl imidazo[1,2-a]pyrazine-2-carboxylate (9.73 g, 0.05 mol) in a mixed ethanol/water (400 mL/100 mL) solvent and the reaction was stirred at room temperature for 8 hours. After completion of the reaction, the solvent was removed by distillation under reduced pressure. The pH of the reaction mixture was adjusted to 3-4 with aqueous 1 N hydrochloric acid under cooling in an ice bath and a solid was precipitated. The precipitate was collected by filtration and washed sequentially with acetone and dichloromethane. The filter cake was dried at 50 °C and the residual solvent was removed under reduced pressure to afford imidazo[1,2-a]pyrazine-2-carboxylic acid (7.69 g, 9.4 mmol) in pink solid powder form in 93.7% yield.

References

[1] Patent: CN103965194, 2016, B. Location in patent: Paragraph 0214-0216
[2] Journal of Medicinal Chemistry, 1984, vol. 27, # 2, p. 206 - 212
[3] Farmaco, Edizione Scientifica, 1981, vol. 36, # 1, p. 61 - 80