Studies on positive inotropic agents. I. Synthesis of 3,4-dihydro-6-(4-(3,4-dimethoxybenzoyl)-1-piperazinyl)-2(1H)-quinolinone and related compounds.

Many (1-piperazinyl)-2 (1H)-quinolinone derivatives were synthesized and examined for positive inotropic activities on the canine heart. Among them, 3, 4-dihydro-6-[4-(3, 4-dimethoxybenzoyl)-1-piperazinyl]-2 (1H)-quinolinone (XVIIb-1) was found to have a very potent activity.