Hydrogen Bromide → Imidazo(1,2-a)pyrazine

2-Aminopyrazine (100 mg, 1.1 mmol) and bromoacetaldehyde dimethylacetal (253 mg, 1.6 mmol) were dissolved in ethanol (4.5 ml), hydrobromic acid (48%, 0.5 ml) added and the mixture was heated under reflux for 18 h. The solution was allowed to cool to room temperature then pre-adsorbed directly onto silica. Purification by silica gel chromatography eluting with dichloromethane and 1% conc. ammonia on a gradient of methanol (1-4%) gave imidazo[1,2-α]pyrazine (90 mg, 72%) as a white crystalline solid: δH (360 MHz, CDCl3) 6.70 (1H, s), 7.82 (1H, s), 7.88 (1H, d, J 4), 8.29 (1H, d, J 4), 9.12 (1H, s).

1. temperaturethe mixture was heated
2. temperatureunder reflux for 18 h
3. customPurification by silica gel chromatography
4. washeluting with dichloromethane and 1% conc. ammonia on a gradient of methanol (1-4%)

ORD record

ord-965bb456b74c4974b53565bd25e76edc

Source dataset

uspto-grants-2005_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06914063B2