Cardiotonic agents. 1. Synthesis and structure-activity relationships in a new class of 3-, 4- and 5-pyridyl-2(1H)-quinolone derivatives

A series of 3-, 4-, and 5-pyridyl-2(1H)-quinolone derivatives with H or HO or CH3O substituents in the 8-position were prepared and tested for positive inotropic activity. Several derivatives, especially 29, 9b, and 27 with a pyridyl ring in the 5-position, were ca. 2-10 times more potent on left guinea pig atria than sulmazole (ARL-115) and milrinone used as references. Some structure-activity relationships are discussed.