Some reactions of 3-formyl-4,5- [1H] pyrazolinedione-4- [phenylhydrazone]

The 3-hydroxyiminomethylpyrazole derivative II existed in ketoenol as evidenced by the production of two acetyl derivatives IV and V, respectively. The enol form III gave the benzoyl derivative VI. Treatment of III with benzoyl chloride in pyridine, for a long time, gave the bicyclic derivative VII. The 3-thiosemicarbazone derivative also existed in ketoenol forms. Both gave the acetyl bicyclic derivatives X and XI upon acetylation. The enol form IX also formed the benzoyl bicyclic derivative XII. The 3-formyl derivative I condensed with hydrazine hydrate and methylhydrazine to give the corresponding hydrazones XIII and XIV, characterized by giving the acetyl derivatives XVII and XVIII, respectively