The natural naphtho­quinone sterekunthal-B

The title structure, 15,18-di­methyl-5-dioxo-14-oxapenta­cyclo­[11.4.1.0^2,15.0^4,13.0^6,11]­octadeca-3,6,8,10-tetraene-18-carb­aldehyde, C₂₀H₁₈O₄, is a novel naphtho­quinone, isolated from Stereospermum personatum. In the bicyclic system, all three six-membered rings adopt a boat conformation. Two intermolecular C=O...H—C interactions link the mol­ecules into a chain.