Ammonia → 3-(Difluoromethyl)-[1,2,4]triazolo[4,3-a]pyrazine

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반응 단계

2,2-Difluoro-N′-pyrazin-2-yl-acetohydrazide difluoroacetate 23b (2 g, 0.01 mol) was dissolved in 10 mL of polyphosphoric acid. After stirring at 140° C. for 7 hours, the reaction mixture was cooled to 50° C. and stirred for another 12 hours. The reaction mixture was poured into 50 mL of ice-water while hot, 30% aqueous ammonia was added dropwise until the pH of the reaction mixture was between 7 and 8, and the solution was extracted with ethyl acetate (30 mL×3). The organic phase was combined, dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated under reduced pressure. The resulting residue was dissolved in 30 mL of ethyl acetate and added with activated carbon. After stirring for 30 minutes, the mixture was filtered and the filtrate was concentrated under reduced pressure to obtain 3-(difluoromethyl)-[1,2,4]triazolo[4,3-a]pyrazine 23c (460 mg, yield 30%) as a yellow solid.

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