Study of reactions of pentafluorophenylhydrazine with activated enol ethers. Synthesis of N-pentafluorophenylpyrazoles.

Activated enol ethers derived from methyl or ethyl acetoacetate/cyanoacetates or nitriles and pentane-2,4- dione react with pentafluorophenylhydrazine through the primary amino-group to afford pyrazoles bearing a preferred 5-amino- over 5-methyl- or 5-hydroxy-substituent in the resulting 4-substituted pyrazoles. [ABSTRACT FROM AUTHOR]