2,5-dibromopyrazine → 3-(5-Bromo-2-pyrazinyl)-3-oxetanol

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Reaction Steps

2,5-Dibromopyrazine (1 g, 4.2 mmol) was dissolved in toluene (20 mL) under nitrogen and cooled to −78° C. n-Butyllithium (2.5M solution in hexanes, 1.77 mL) was added slowly with stirring and allowed to stir for a further 10 minutes upon complete addition. Oxetan-3-one (270 μL, 4.62 mmol) was added, and the reaction mixture was stirred at −78° C. for 30 minutes. The reaction mixture was allowed to warm to room temperature and the solvent was removed in vacuo. The residue was taken up in DCM (50 mL) and washed with saturated aqueous sodium bicarbonate solution (40 mL). The aqueous layer was re-extracted with DCM (50 mL). The organic extracts were combined, dried over sodium sulfate and concentrated in vacuo. The crude brown oil was purified by chromatography on silica (Biotage, 25 g cartridge), eluting with 0 to 100% ethyl acetate in heptanes, to afford the title compound (470 mg, 45%) as a yellow solid. Method B HPLC-MS: MH+ m/z 231, RT 1.13 minutes.

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