Recently we reported the positive inotropic activity of 4, 5-dihydro-6-[4-(1H-imidazol-l-yl) phenyl]-3 (2H)-pyridazinone (Ia, CI-914) 1a1b and related compounds from our laboratory. It has been found that the introduction of a methyl substituent at the 5-position of the 4, 5- dihydropyridazinone ring (DHPZ) in CI-914 augments activity and leads to a more potent compound (Ib, CI-930). In order to extend the structure-activity relationships of these freely ...
