Novel pyrazolone derivatives: synthesis and evaluation for analgesic activating

ABSTRACT

The synthesis of 3-amino-4-arylazo-2H-pyrazolin-5-one [III] was achieved by direct diazo-coupling of 3-aminopyrazolones or by hydrazinolysis of ethyl cyanoglyoxalate hydrazones. Acetylation of III gave the acetyl derivative IV or the pyrazol [3, 4-e] triazine V, depending on the reaction time. Benzoylation of III gave only the monobenzoyl derivative VI, whereas chloroaetylation gave the imidazol [1, 2-b] pyrazole VII. Representative examples of the products were tested for analgesic activity