Structure of 5-Methyl-4-[(arylamino)methylene]-2,4-dihydro-3H-pyrazol-3-ones

Abstract

5-Methyl-4-[(arylamino)methylene]-2,4-dihydro-3H-pyrazol-3-ones have been synthesized. Of the 12 possible tautomeric forms it has been shown that they exist as the (ary1amino)methylene tautomerwith intramolecular hydrogen bonding between the CO and exocyclic NH groups.