Synthesis
The general procedure for the synthesis of [1,2,4]triazolo[1,5-a]pyrazines from the compound (CAS:51519-20-1) is as follows: polyphosphoric acid (250 g) was added to (Z)-N'-hydroxy-N-(pyrazin-2-yl)carbamoylamide (25.07 g, 181 mmol), followed by immediately heating the reaction mixture to 90 °C. The reaction mixture was kept stirred at this temperature for 4 hours. After completion of the reaction, the hot reaction mixture was slowly poured into ice water and the pH was adjusted to basic with sodium bicarbonate. Subsequently, the aqueous phase was extracted with dichloromethane (1 L, followed by 3 x 0.5 L). All organic phases were combined and dried with anhydrous sodium sulfate (Na2SO4), after which the organic phase was concentrated. The crude product was purified by batch crystallization from ethanol. A final product of 18.10 g was obtained in 83% yield.
