Sodium Bicarbonate → 5,8-Dibromo-(1,2,4)triazolo(1,5-a)pyrazine

Participants

Reaction Steps

N-(3,6-dibromo-pyrazin-2-yl)-N′-hydroxyformamidine (17.4 mg, 58.80 mmol) is treated with polyphosphoric acid (150 g) for one hour at 50° C. and then for 1.75 hours at 70° C. After cooling to room temperature, water is added to the reaction mixture. The resultant suspension is brought to pH 8 by careful addition of solid NaHCO3 in small portions. The precipitate formed is collected by filtration, washed once with 1N NaOH, three times with water and dried in vacuo. The residue is partitioned between ethyl acetate and 1N NaOH and the organic phase is washed one more time with 1N NaOH and once with brine. The organic phase is dried over MgSO4, filtered and evaporated to give the title compound (10.15 g) as a white solid. 1H-NMR (400 MHz, d6-DMSO) δ(ppm) 8.43 (s, 1H), 8.92 (s, 1H). LCMS: Rt 2.73 min (94.2%), m/z (APCI) 277 (M+H)+.

Provenance & Evidence