organic compounds
The title compound, 4,4,8,11b-tetramethyl-2,3,4,4a,5,6,6a,7,10a,11,11a,11b-dodecahydro-1H,9H-6a:7,10a:11-diepoxyphenanthro[3,2-b]furan-9-one, C20H26O4, a natural ent-abietane diterpenoid, is composed of four fused rings with the expected cis and trans junctions. In the crystal structure, the molecules stack along the b axis and are linked by C—HO hydrogen bonds.