During the course of the past two decades, our group has worked towards the development of increasingly
potent inotropic agents by making structural modifications to compounds derived from 3,4-dihydro-2(1H)-quinolinone
(DHQO) and related analogues. Herein, we describe the design and synthesis of a new series of DHQO derivatives and
the subsequent evaluation of their positive inotropic activity towards left atrium stroke volume in isolated rabbit-heart
preparations. Some of these derivatives presented favorable in vitro activities compared with the reference drug,
milrinone, and compound 10a, in particular is currently being investigated as a preclinical drug candidate. This review
also describes our progress towards the development of DHQO derivatives and related analogues with positive inotropic
activities from 1999 to 2013.