Synthesis and positive inotropic effect of 1-alkyl- and 1-acyl-6,7-dimethoxy-3-dimethylamino-1,2,3,4-tetrahydroquinolines

Abstract In the search for new positive inotropic agents we have investigated a series of 3-dimethylamino-1,2,3,4-tetrahydroquinolines with various substituents on the nitrogen of the quinoline ring. The N -isobutyryl derivative 20 (S903) was selected as the most interesting compound. Interestingly, while cardiac contractility was increased in vitro , heart rate was unchanged or slightly decreased. The positive inotropic activity was partly dependent on an indirect sympathomimetic effect. The ( S ) absolute configuration of the (-)enantiomer of S903 was established by correlation with ( S )- l -dopa.