Two androsterone derivatives as inhibitors of androgen biosynthesis

The title compounds, (3R,5S,5'R,8R,9S,10S,13S,14S)-10,13-dimethyl-5'-(2-methyl­prop­yl)tetra­deca­hydro-6'H-spiro­[cyclo­penta­[a]phenanthrene-3,2'-[1,4]oxazinane]-6',17(2H)-dione, C₂₆H₄₁NO₃, (I), and methyl (2R)-2-[(3R,5S,8R,9S,10S,13S,14S)-10,13-dimethyl-2',17-dioxohexa­deca­hydro-3'H-spiro­[cyclo­penta­[a]phenanthrene-3,5'-[1,3]oxazolidin-3'-yl]]-4-methyl­penta­noate, C₂₈H₄₃NO₅, (II), possess the typical steroid shape (A-D rings), but they differ in their extra E ring. The aza­lactone E ring in (I) shows a half-chair conformation, while the carbamate E ring of (II) is planar. The orientation of the E-ring substituent is clearly established and allows a rationalization of the biological results obtained with such androsterone derivatives.