The racemic 3-(4-oxo-3, 4-dihydroquinazolin-2-yl)-N-[1-(pyridin-2-yl) ethyl] propanamide, 1, has previously been identified as a potent but unselective inhibitor of diphtheria toxin-like ADP-ribosyltransferase 3 (ARTD3). Herein we describe synthesis and evaluation of 55 compounds in this class. It was found that the stereochemistry is of great importance for both selectivity and potency and that substituents on the phenyl ring resulted in poor solubility. ...