Crystal structure and Hirshfeld surface analysis of 2-oxo-13-epi-manoyl oxide isolated from Sideritis perfoliata

The title compound, C20H32O2 (systematic name: 3-ethenyl-3,4a,7,7,10a-penta­methyl­dodeca­hydro-9H-benzo[f]chromen-9-one), was isolated from Sideritis perfoliata. In the crystal, mol­ecules pack in helical supra­molecular chains along the 21 screw axis running parallel to the a axis, bound by C—H...O hydrogen bonds. These chains are efficiently inter­locked in the other two unit-cell directions via van der Waals inter­actions. Hirshfeld surface analysis shows that van der Waals inter­actions constitute the major contribution to the inter­molecular inter­actions, with H...H contacts accounting for 86.0% of the surface.