Isolation and Structural Elucidation of Related Impurities in Canrenone

Ten steroidal compounds as impurities in canrenone were isolated from the enriched mother liquor by using various chromatographic methods. Their structures were elucidated by spectrometric analysis, among which three new compounds were characterized as 3-(3-oxo-7$\alpha$-(ethoxycarbonyl)methyl-17$\beta$-hydroxy-4-androsten-17$\alpha$-yl) propionic acid $\gamma$-lactone (1), 3-(3-oxo-7$\alpha$-ethoxy-17$\beta$-hydroxy-4-androsten-17$\alpha$-yl) propionic acid $\gamma$-lactone (2) and 3-(3-oxo- 5$\beta$-propionic acid-$\gamma$-lactone-6$\beta$,17$\beta$-hydroxy-4-androstan-17$\alpha$-yl) propionic acid $\gamma$-lactone (3).