Crystal structure and Hirshfeld surface analysis of dimethyl (1 R ,3a S ,3a 1 R ,6a S ,9 R ,9a S )-3a 1 ,5,6,9a-tetra-hydro-1 H ,4 H ,9 H -1,3a:6a,9-di-epoxy-phenalene-2,3-di-carboxyl-ate

The title di-epoxy-phenalene derivative, C H O , comprises a fused cyclic system containing four five-membered rings (two di-hydro-furan and two tetra-hydro-furan) and one six-membered ring (cyclo-hexa-ne). The five-membered di-hydro-furan and tetra-hydro-furan rings adopt envelope conformations, and the six-membered cyclo-hexane ring adopts a distorted chair conformation. Two methyl carboxyl-ate groups occupy adjacent positions (2- and 3-) on a tetra-hydro-furan ring. In the crystal, two pairs of C-H⋯O hydrogen bonds link the mol-ecules to form inversion dimers, enclosing two (6) ring motifs, that stack along the -axis direction and are arranged in layers parallel to the plane.