4,8-Dihydroxy-2,3-dimethoxy-1-(3-methylbut-2-enyl)-9H-xanthen-9-one

Abstract

The title xanthone compound, C20H20O6, was isolated from the roots of Cratoxylum formosum ssp. pruniflorum. The xanthone ring system is essentially planar. The 3-methyl­but-2-enyl substituent plane is not coplanar with the attached benzene ring, the dihedral angle being 62.59 (12) A. The two meth­oxy groups are twisted away from the mean plane of the attached benzene ring. The two hydr­oxy groups are coplanar with the attached benzene rings and contribute to O—H⋯O intra­molecular hydrogen bonds which generate S(5) and S(6) ring motifs. In the crystal structure, inter­molecular O—H⋯O hydrogen bonds and weak C—H⋯O inter­molecular inter­actions connect the mol­ecules into infinite one-dimensional chains along the [201] direction. The crystal is further stabilized by C—H⋯π inter­actions.