4-HYDROXYANTIPYRINE

4-hydroxy-1,5-dimethyl-2-phenylpyrazol-3-one

4-hydroxy-1,5-dimethyl-2-phenyl-pyrazol-3-one

4-HYDROXY-2,3-DIMETHYL-1-PHENYL-3-PYRAZOLIN-5-ONE

1,5-Dimethyl-2-phenyl-4-hydroxy-4-pyrazoline-3-one

2,3-Dihydro-4-hydroxy-1,5-dimethyl-2-phenyl-1H-pyrazol-3-one