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

Participants

Reaction Steps

2-Pyrazinamine (9.51 g, 100 mmol) was dissolved in ethanol (300 ml) and 2-bromo-1,1-bis(ethyloxy)ethane (21.06 ml, 140 mmol) was added. 48% hydrobromic acid (33.3 ml) was added and the mixture heated at reflux for 24 hr. The solution was concentrated in vacuo to a crude solid that was basified with 10% ammonia-ice (300 ml). The solution was extracted in to ethyl acetate (3×300 ml), the combined extracts were washed with brine, dried over anhydrous sodium sulfate and concentrated in vacuo to afford a crude solid, (4.76 g). The solid was purified by flash chromatography (Biotage SP4, 40+M, eluting with a 0-100% [25% 2M ammonmia/methanol in dichloromethane] in dichloromethane gradient) to afford imidazo[1,2-a]pyrazine (2.86 g, 24.01 mmol, 24.01% yield).).

Provenance & Evidence