3-acetyl-5-acylpyridin-2(1H)-ones and 3-acetyl-7,8-dihydro-2,5(1H,6H)-quinolinediones:: synthesis, cardiotonic activity and computational studies

A series of milrinone analogues, namely 6-substituted 3-acetyl-5-acylpyridin-2(1H)-ones 4a-c, e, f and 7-substituted or unsubstituted 3-acetyl-7,8-dihydro-2,5(1H,6H)-quinolinediones 4g-j, in which the cyano group was replaced by the acetyl function, was prepared. In a preliminary pharmacological investigation on spontaneously beating atria from reserpine-treated guinea-pigs, all new compounds did not induce any inotropic effect equivalent or higher than that of the milrinone chosen as the reference compound. In order to rationalise how the structure modifications influence the activity and the selectivity of the title compounds, a computational study has been performed. The important role of the substituents in position-3 and -6 on the pyridone nucleus has been highlighted. (C) 1999 Elsevier Science S.A. All rights reserved.