Unusual reactions of enhydrazinopyrazolones and dipyrazolylmethanes with 5-oxopyrazoles

The reaction of 6-phenyl-1,2,4-triazine-4-oxide 1 with pyrazolones 2a–d gives enhydrazino-derivatives 3a–d. On heating with pyrazolones 2, products 3 are transformed into the corresponding symmetrical 4 or unsymmetrical derivatives 5 of dipyrazolylmethane. Heating of dipyrazolylmethane derivatives 4 with pyrazolones 2 results in the substitution of some pyrazolone residues for others.