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

The title compound, C ₂₀ H ₂₈ O ₄ [systematic name: (4b S ,8a S ,10 S )-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 P 2 ₁ , 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 10 R stereoisomer of the title compound, isolated from the roots of Premna obtusifolia (Verbenaceae), has been reported. It crystallized in the chiral space group P 2 ₁ 2 ₁ 2 ₁ , and the absolute structure was determined as (4b S ,8a S ,10 R ), by resonant scattering using Cu K α radiation [Razak et al. (2010 ▸). Acta Cryst. E 66 , o1566-o1567].