Studies on Avarol Derivatives. 2',5'-Diacetylavarol from Dysidea Avara

Abstract

The X-ray analysis of the natural product 2',5'-di-acetylavarol [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-tetrarnethyl-1 -naphthyl)methyl]-1,4-benzenediyl diacetate, C 25 H 34 O 4 , is reported. Short intramolecular contacts between the bulky substituents of the bicyclic system cause significant distortions of the molecular geometry. The Δ 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 Waals interactions.