Aminopyrazine → Imidazo(1,2-a)pyrazine

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).

1. temperatureAfter refluxing for 14 hours
2. customthe solvent was evaporated
3. customThe residue was partitioned between ethyl acetate and saturated aqueous sodium bicarbonate solution
4. extractionThe aqueous layer was extracted with ethyl acetate (3×)
5. washThe combined organic phase was washed with brine
6. dry with materialdried over magnesium sulfate
7. concentrationconcentrated
8. customThe residue was purified by flash chromatography (100% ethyl acetate, 10% methanol in ethyl acetate

ORD record

ord-71282a848c334cb8a6af41afb4094590

Source dataset

uspto-grants-2013_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08440668B2