4,4,6a,6b,11,12,14b-Heptamethyl-16-oxo-1,2,3,4,4a,5,6,6a,6b,7,8,9,10,11,12,12a,14a,14b-octadecahydro-12b,8a-(epoxymethano)picen-3-yl acetate

The title compound, C32H48O4, which was extracted from the bark of Rhododendron arboreum, consists of five fused rings to which an acetate and seven methyl groups are attached. The A, D and E rings adopt chair conformations, the B ring is in a distorted chair and the C ring is in a half-chair conformation. The five-membered ring formed by the lactone group, which bridges from the A/B to the B/C ring junctions, is an approximate envelope with the C atom of the methyne group as the flap [displacement from the other four atoms = 0.753 (2) Å]. There are no identified directional interactions in the crystal structure.