5,6,7,8-TETRAHYDROIMIDAZO[1,2-A]PYRAZINE

Application

Imidazolo[1,2-a]pyrazine is a synthetic building block with strong pharmacological activity among nitrogen-containing heterocyclic compounds. 5,6,7,8-Tetrahydroimidazole[1,2-A]pyrazine is a common pharmaceutical and chemical intermediate used in laboratory research and development processes.

Synthesis

The general procedure for the synthesis of 5,6,7,8-tetrahydroimidazo[1,2-a]pyrazine from indolo[1,2-A]pyrazine was as follows: imidazo[1,2-a]pyrazine (7.2 g, 60.44 mmol) was dissolved in 2-methoxyethanol (100 mL). Platinum (IV) oxide (1.2 g, 5.13 mmol) was added to the solution and the mixture was transferred to an autoclave. The reaction mixture was stirred overnight at room temperature and 4 bar hydrogen pressure. Upon completion of the reaction, the hydrogen in the autoclave was replaced with nitrogen and the reaction mixture was filtered through diatomaceous earth to remove the catalyst. The filtrate was concentrated under reduced pressure and co-evaporated with toluene to remove residual solvent. Finally, the target product 5,6,7,8-tetrahydroimidazo[1,2-a]pyrazine was purified by column chromatography using a methanol solution of dichloromethane/7N ammonia (95:5, v/v) as eluent to give the target product 5,6,7,8-tetrahydroimidazo[1,2-a]pyrazine in a yield of 5.7 g (76% yield).

References

[1] Journal of Chemical Research, Miniprint, 1984, # 2, p. 468 - 480
[2] Patent: US2008/153843, 2008, A1. Location in patent: Page/Page column 67
[3] Patent: CN103864799, 2016, B. Location in patent: Paragraph 0032 - 0335
[4] Patent: EP2604610, 2013, A1. Location in patent: Paragraph 0089; 0091
[5] Patent: US2013/131068, 2013, A1. Location in patent: Paragraph 0117; 0118