On the regiospecificity of 3,5-disubstituted pyrazoles derived from C-acylated-β-enaminonitriles and esters

Abstract

Regiospecificity of 3,5-disubstituted pyrazoles derived from reaction of phenylhydrazine with α-acyl-β-amino-crotononitriles and esters is primarily deduced on the basis of spectral analyses. The present work provides direct and unambiguous evidences in support of the regiospecificity of these pyrazoles. In addition, this work also shows that α-acyl-β-enaminones derived from enaminonitriles and enaminoesters both afford 5-substituted pyrazoles in contrast to earlier observation by Benary.