On the regiospecificity of 3,5-disubstituted pyrazoles derived from C-acylated-<img src='/image/spc_char/beta.gif' border=0>-enaminonitriles and esters

Abstract

Regiospecificity of 3,5-disubstituted pyrazoles derived from reaction of phenylhydrazine with <img src='/image/spc_char/alpha.gif' border=0>-acyl-β-amino­crotononitriles 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 <img src='/image/spc_char/alpha.gif' border=0>-acyl-β-enaminones derived from enaminonitriles and enaminoesters both afford 5-substituted pyrazoles in contrast to earlier observation by Benary.