Hydrogen Bromide → 5,8-Dibromoimidazo[1,2-a]pyrazine

Participants

Reaction Steps

Bromoacetaldehyde diethyl acetal (49 mL, 326 mmol) and 48% hydrobromic acid is heated to reflux for 1.5 h, then poured into propan-2-ol (600 mL) and quenched with NaHCO3. After filtering, 2,5-dibromo-3-aminopyrazine (41.34 g, 163 mmol) is added to the solution and heated at reflux overnight. The reaction is cooled and solvents removed in vacuo, followed by addition of aq. NaHCO3 and extraction with EtOAc. The organic phase is dried over MgSO4, filtered, and concentrated in vacuo to afford a brown solid. 1H NMR (250 MHz, CDCl3) δ(ppm) 7.86 (1H, s), 7.93-7.94 (1H, d), 7.98-7.99 (1H, d); m/z (APCI) 278 (M+H)+; m.p 132-135° C.

Provenance & Evidence