Crystal structure of (4b,8a)-1-isopropyl-4b,8,8-trimethyl-7-oxo-4b,7,8,8a,9,10-hexa-hydro-phenanthren-2-yl acetate.

The title compound, CHO, was prepared by a direct acetyl-ation reaction of naturally occurring totarolenone. The mol-ecule contains three fused rings, which exhibit different conformations. The central ring has a half-chair conformation, while the non-aromatic oxo-substituted ring has a screw-boat conformation. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds and C-H⋯π inter-actions, forming sheets parallel to the plane. The carbonyl O atoms and the C atom at the 6-position of the cyclo-hexene ring are each disordered over two sets of sites with major occupancy components of 0.63 (7) and 0.793 (14), respectively.