STUDIES ON AVAROL DERIVATIVES - 2',5'-DIACETYLAVAROL FROM DYSIDEA-AVARA

The X-ray analysis of the natural product 2/,5'-diacetylavarol [De Giulio, De Rosa, Di Vincenzo & Strazzullo (1990). Tetrahedron, 46, 7971-7976], 2-[(1 ,2,3,4,4a,7,8,8a-Octahydro-1,2,4a,5-tetramethyl-1-naphthyl)methyl]-1,4-benzenediyl diacetate, C25H34O4, is reported. Short intramolecular contacts between the bulky substituents of the bicyclic system cause significant distortions of the molecular geometry. The Delta(3,4) cyclohexene ring adopts a conformation intermediate between half chair and half boat, and the cyclohexane ring is in a nearly ideal chair conformation. The hydroquinone system is almost perpendicular to the trans-fused sesquiterpene residue. The acetyl groups are oriented on the opposite sides of the aromatic ring with the carbonyl O atoms cis relative to their respective ring C atoms. Crystal packing exhibits normal van der WaaIs interactions.