17β-<i>O</i>-Aminoalkyloximes of 5β-Androstane-3β,14β-diol with Digitalis-like Activity: Synthesis, Cardiotonic Activity, Structure−Activity Relationships, and Molecular Modeling of the Na<sup>+</sup>,K<sup>+</sup>-ATPase Receptor
with a 17-aminoalkoxyiminoalkyl or -alkenyl substituent was synthesized and evaluated for inhibition of Na(+),K(+)-ATPase and for inotropic activity. The highest inhibition was found with compounds having the substituent in configuration 17beta and the amino group at a distance of 6 or 7 bonds from C(17) of the digitoxigenin skeleton. The presence of the oxime function strengthens the interaction with