7-Hydroxy-3,6,9-trimethyl-2,3,5,6-tetrahydronaphtho[1,8-b,c]pyran-4,8-dione

Abstract

The title sesquiterpenoid quinone compound, C15H16O4, was isolated from Thespesia populnea. There are two independent mol­ecules (A and B) with identical conformations in the asymmetric unit. In both mol­ecules, the dihydro­pyran rings adopt envelope conformations, with the methyl­ene C as the flap atom, whereas the cyclo­henene rings are in screw-boat conformations. Intra­molecular O—H⋯O hydrogen bonds generate S(5) ring motifs in both mol­ecules. The mol­ecules are linked into chains along the a axis through weak C—H⋯O inter­molecular inter­actions. The crystal structure is stabilized by intra­molecular O—H⋯O hydrogen bonds, and weak C—H⋯O intra- and inter­molecular inter­actions. C—H⋯π inter­actions involving the cyclo­hexa­diene ring are observed in the crystal structure.