2-Propenoic acid, 2-cyano-3-ethoxy-, ethyl ester → 5-Amino-4-ethoxycarbonyl-1-(2,3,5,6-tetrafluoro-4-trifluoromethyl-phenyl)-pyrazole

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Reaction Steps

To a stirred solution of 15.7 grams (0.634 mole) of 2,3,5,6-tetrafluoro-4-trifluoromethylphenylhydrazine in 40 mL of anhydrous ethanol was added 10.7 grams (0.634 mole) of ethyl 2-cyano-3-ethoxyacrylate. The reaction mixture was heated at reflux for 21 hours, then cooled, and the solvent was removed by distillation under reduced pressure, leaving a residue. This residue was suspended in 80 mL of a 50:50 mixture of diethyl ether/n-pentane. A solid formed and was removed by filtration to yield 20.4 grams of ethyl 5-amino-1-(2,3,5,6-tetrafluoro-4-trifluoromethylphenyl)pyrazol-4-ylcarboxylate, m.p. 166-168° C. The nmr spectrum was consistent with the proposed structure.

Provenance & Evidence