Aminopyrazine → Imidazo(1,2-a)pyrazine

Participants

Reaction Steps

To a solution of 2-aminopyrazine (2.0 g, 21.03 mmol) in ethanol (40 mL) was added 2-bromo-1,1-dimethoxyethane (2.5 mL, 21.03 mmol) followed by 5 drops of concentrated hydrochloric acid. After refluxing for 14 hours, the solvent was evaporated. The residue was partitioned between ethyl acetate and saturated aqueous sodium bicarbonate solution. The aqueous layer was extracted with ethyl acetate (3×). The combined organic phase was washed with brine, dried over magnesium sulfate, and concentrated. The residue was purified by flash chromatography (100% ethyl acetate, 10% methanol in ethyl acetate, then 10% methanol in dichloromethane) to give 536 mg of the title compound as a solid. 1H NMR (500 MHz, CDCl3) δ 7.70 (bs, 1H), 7.82 (bs, 1H), 7.89 (d, 1H, J=4.4 Hz), 8.10 (d, 1H, J=4.6 Hz), 9.12 (s, 1H).

Provenance & Evidence