A series of quinazoline derivatives with various 4-heterocyclylpiperidino groups at the 4-position was synthesized and tested for cardiotonic activity in anesthetized dogs. Among them, several 6,7-dimethoxyquinazoline derivatives showed potent cardiotonic activity.
A series of piperidine derivatives with various heterocyclic rings at the 4-position was prepared and tested for antihypertensive activity and other biological activities. The antihypertensive effects of the present compounds in the spontaneous hypertensive rat were less potent than those of previously reported compounds. However, among the compounds tested for antiulcer activity and antiinflammatory activity, some exhibited interesting properties.