Uses

3,6-difluoropyrazine-2-carbonitrile is used in multi-step synthesis of Favipiravir from Aminopyrazine.

Synthesis

1)Preparation of 1.4-dioxopyrazinamide: control temperature -5 ~ 5 , 2-cyanopyrazine 5.25g with glacial acetic acid 29.95g, 30% hydrogen peroxide 45.30g mixed well, warming to 95 , reflux reaction 22h, TLC shows no raw materials, 40 decompression spinning to remove solvents, add 15ml of water, decompression spinning, repeated a few times after the removal of glacial acetic acid Add 15 ml of water, add hot chloroform extraction (15 ml * 3), the aqueous layer spun dry under reduced pressure, 90% methanol recrystallization, filtration, filter cake vacuum drying to obtain a white powdery 1,4-dioxopyrazinamide 4.45 g, melting point greater than 300 , yield 57.43%.

2) 3,6-dichloro-2-cyanopyrazine preparation: 1.4-dioxopyrazine amide 6.20g added to the redistillation of trichlorophosphorus 24.53g mixed well, 50 stirring for 50min in the heating to 70 reaction for 1h, cooled to room temperature, and then added to the triethylamine 4.86g, add than warmed to 96 , reflux reaction for 6h, the TLC shows that the reaction is complete, the reaction is complete. Spin dry under reduced pressure, washed into 10mL ice water, ethyl acetate (15mL * 3) extraction, combined organic phase, saturated brine washed twice, the organic phase was dried over anhydrous sodium sulfate and filtered, the filtrate was spun dry under reduced pressure, column chromatography purification and separation after vacuum drying to obtain a yellowish solid 3,6-dichloro-2-cyanopyrazine 3.14g, yield 45.15%, melting point 90-91 .