Phosphorus oxychloride → 5-Chloro-1,3-dimethyl-1H-dipyrazolo[1,5-a:4',3'-e]pyrazine-6-carboxylic acid, ethyl ester

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Reaction Steps

92.5 gms. of 5-hydroxy-1,3-dimethyl-1H-dipyrazolo[1,5-a:4',3'-e]pyrazine-6-carboxylic acid, ethyl ester, together with 300 ml. of phosphorus oxychloride and 3 ml. of dimethylformamide are refluxed for 5 hours. After distilling off the phosphorus oxychloride, the reaction mixture is poured onto ice and the crude 5-chloro-1,3-dimethyl-1H-dipyrazolo[1,5-a:4',3'-e]pyrazine-6-carboxylic acid ethyl ester, is filtered under suction, then recrystallized from acetone, yield 83 gms. of white crystals, m.p. 130°-132°.

Provenance & Evidence