“…The pyridazine ring is an important structural feature in a number of pharmaceutical compounds, such as hydralazine (brand name Apresoline, vasodilator, US, FDA), cefozopran (anti-bacterial agent, Japan), and pipofezine (brand name Azafen or Azaphen, antidepressant, STADA, Nizhny Novgorod, Russia). Pyridazine derivatives have been reported to possess various pharmacological activities and intermediates for drugs synthesis, including antimicrobial, analgesic, anticancer, antitubercular, antidiabetic, antifungal, antihypertensive, anticonvulsant, anti-HIV, antiasthma, anti-inflammatory, phosphodiesterase (PDE) inhibitors, cyclooxygenase (COX) inhibitors, antipyretic, insecticidal, and neurological [66,67,68,69,70,71,72,73]. The reaction of arylazo 10d and ethylacetoacetate 11b in either acetic acid or ethanolic KOH, followed by reflux to afford pyridazinones 15d , has been reported.…”