vanillin semicarbazone
acetic acid
phenylhydrazine
(E)-2-methoxy-4-(2-nitrovinyl)phenol
N-(4-hydroxy-3-methoxybenzylidene)aniline
N-Phenyl-N'-(4-hydroxy-3-methoxy-α-hydroxylamino)benzylhydrazine
N-Phenyl-N'-(3-methoxy-4-hydroxy-α-amino)benzylhydrazine
3-(4-Hydroxy-3-methoxy-phenyl)-5-(4-methoxy-phenyl)-1-phenyl-1H-pyrrolo[3,4-c]pyrazole-4,6-dione
vanillin oxime
3-(4-Hydroxy-3-methoxy-phenyl)-5-(4-methoxy-phenyl)-1-phenyl-tetrahydro-pyrrolo[3,4-c]pyrazole-4,6-dione