Brasilixanthone

Abstract

The title xanthone [systematic name: 5,13-dihydroxy-3,3,10,10-Tetramethyl- 3H-dipyrano[3,2-a:2′,3′-i]xanthen-14(10H)-one], C23H 20O6, was isolated from the roots of Cratoxylum formosum ssp. pruniflorum. There are two mol-ecules (A and B) in the asymmetric unit, which show chemical but not crystallographic inversion symmetry. The xanthone skeleton in both mol-ecules is approximately planar, with an r.m.s. deviation of 0.0326 (9) Å for mol-ecule A and 0.0355 (9) Å for mol-ecule B from the plane through the 14 non-H atoms. The pyran rings in both mol-ecules adopt sofa conformations. Intra-molecular O - H⋯O hydrogen bonds generate S(5) and S(6) ring motifs. Viewed onto the bc plane, the crystal structure resembles a herringbone pattern. Stacks of mol-ecules are stabilized by π-π inter-actions with centroid-centroid distances of 3.600 (5) Å. The crystal structure is further stabilized by weak C - H⋯O and C - H⋯π inter-actions.