(4aS,4bR,7R,10aS)-3,7-Dimethyl-10a-(propan-2-yl)-1,4,4a,4b,5,6,7,8,10,10a-deca-hydro-phenanthrene-1,4-dione.

In the title compound, C(19)H(26)O(2), the A ring adopts a chair conformation, whereas the B and C rings both adopt distorted half-chair conformations with the quaternary C atom common to both rings lying 0.577 (3) and 0.648 (3) Å out of the approximate plane defined by the remaining five C atoms (r.m.s. deviations = 0.1386 and 0.1156 Å) for the B and C rings, respectively. Mol-ecules are assembled in the crystal through C-H⋯O inter-actions involving both carbonyl O atoms, which lead to supra-molecular chains aligned along the b axis.