Experimental

R factor = 0.041; wR factor = 0.101; data-to-parameter ratio = 8.6. 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. Related literature For a related crystal structure, see: El-Seedi et al. (1994). For puckering parameters, see: Cremer & Pople (1975)