Acta Crystallographica Section E (Jun 2010)
Xyloccensin E
Abstract
The title compound (also known as phragmalin triacetate), C35H42O14, is a phragmalin-type limonoid extracted from X. rumphii. The molecule consists of eight rings with the orthoacetate group bridged at positions 1, 8 and 9. The two five-carbocyclic rings (A1 and A2) and the dioxolane ring (G) adopt a distorted envelope conformation. The 1,3-dioxane ring (E) exists in a chair conformation. The six-carbocyclic rings (B and C) exhibit a twisted-boat conformation. The lactone ring has a half-chair conformation and the furan ring is planar (r.m.s. deviation = 0.002 Å). Rings A1/B, A2/B, B/C, C/D and C/G are all cis-fused. The two acetoxy groups attached to ring B and the furan ring attached to the lactone ring are in equatorial positions. The porous crystal packing exhibits voids of 688 Å3 and weak intermolecular C—H...O interactions. The absolute configuration was assigned on the basis of literature data.