Crystal structure of 7β-hy-droxy-royleanone isolated from Taxodium ascendens (B.)

The title compound, C₂₀H₂₈O₄ [systematic name: (4bS,8aS,10S)-3,10-dihy-droxy-2-isopropyl-4b,8,8-trimethyl-4b,5,6,7,8,8a,9,10-octa-hydro-phenanthrene-1,4-dione], is an abietane-type diterpene, which was isolated from Taxodium ascendens (B.). The compound crystallizes in the chiral space group P2₁, but it was not possible to determine the absolute structure of the mol-ecule in the crystal by resonant scattering. The mol-ecular structure is stabilized by two intra-molecular O-H⋯O hydrogen bonds, enclosing S(5) and S(6) ring motifs. In the crystal, mol-ecules are linked by O-H⋯O and C-H⋯O hydrogen bonds, forming chains along the [010] direction. The crystal structure of the 10R stereoisomer of the title compound, isolated from the roots of Premna obtusifolia (Verbenaceae), has been reported. It crystallized in the chiral space group P2₁2₁2₁, and the absolute structure was determined as (4bS,8aS,10R), by resonant scattering using Cu Kα radiation [Razak et al. (2010 ▸). Acta Cryst. E66, o1566-o1567].