Synthesis and bioactivity of 6-phenyl-4,5-dihydro-3(2H)-pyridazinone derivatives.

A series of 6-phenyl-4,5-dihydro-3(2H)-pyridazinone derivatives was prepared and examined for cardiotonic activity The structures of these new pyridazinone derivatives were confirmed by IR, 1H-NMR and mass spectrum. The cardiotonic activities of these compounds were studied on isolated perfused toad heart and compared with the activity of levosimendan (CAS 141505-33-1). Compound 5a emerged as the mostinteresting compound in this series with potential cardiotonic activity.