Xyloccensin e

Abstract

The title compound (also known as phragmalin triacetate), C 35H42O14, is a phragmalin-type limonoid extracted from X. rumphii. The mol-ecule 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 A 1/B, A 2/B, B/C, C/D and C/G are all cis-fused. The two acet-oxy 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 inter-molecular C - H⋯O inter-actions. The absolute configuration was assigned on the basis of literature data.