Synthesis and properties of several isomers of the cardioactive steroid ouabain

The ouabain isomers 1, 6, 20, 21, and 22 have been synthesized and shown to be readily separable by HPLC, which indicates that they do not correspond to a putative endogenous ouabain-like cardioregulator. 11-epi-Ouabain (1) is of interest as a safer alternative to ouabain.