Reactivities of the Pyrazole Ring

An example delineating the ramification of unsymmetrical pyrazole s tautomerization is shown below  

In the same vein, Michael additions of unsymmetrically substituted pyrazoles also result in two regioisomers. 3,4-Diphenylpyrazole was treated with acrylonitrile in ethanolic KOH to afford the adduct in 69% yield, which contained 92% of the 3,4-diphenyl isomer, along with 8% of the 4,5-diphenyl isomer. The major isomer was then converted into the corresponding 3,4-l//-diphenylpyrazole-l-propanamines as anti-depressants. 

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