Received 24 October 2012
The title sesquiterpene [systematic name: 6-methoxy-10-methyl-7-(propan-2-yl)-2-oxatricyclo[6.3.1.04,12]dodeca-1(11),4,6,8(12),9-pentaen-5-ol], C16H18O3, was isolated from pathogen-infected stele tissue of Gossypium barbadense. There are two molecules in the asymmetric unit and the dihedral angle between their naphthofuran systems is 86.48 (2)°. In the crystal, O-HO hydrogen bonds between the hydroxy groups and etheric O atoms link the molecules into centrosymmetric tetramers. These tetramers are assembled into (010) layers via stacking interactions between the naphthofuran systems [interplanar distance 3.473 (3) Å] and short C-HO contacts.
For the isolation and chemical structure determination of related cotton sesquiterpenoid phytoalexins and their intermediates, see: Bell et al. (1975); Stipanovic et al. (1975). For the role of terpenoid aldehydes as phytoalexins (active defense agents) in response to infection by wilt fungi, see: Mace (1978). For information on the mechanism of action, see: Mace et al. (1995). For the mechanism of O-methylation of desoxyhemigossypol, see: Liu et al. (2002). For general information about antimicrobial compounds produced by cotton, see: Bell (1995).
Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: GK2530 ).
This work was supported by the CRDF project UZB2-31001-TA02.
Bell, A. A. (1995). in Challenging the Future: Proceedings of the World Cotton Research Conference-1, edited by G. A. Constable & N. W. Forrester, pp. 225-235. Melbourne: CSIRO.
Bell, A. A., Stipanovic, R. D., Howell, C. R. & Fryxell, P. A. (1975). Phytochemistry, 14, 225-231.
Liu, J., Benedict, C. R., Stipanovic, R. D., Magill, C. W. & Bell, A. A. (2002). J. Agric. Food Chem. 50, 3165-3172.
Mace, M. E. (1978). Physiol. Plant Path. 12, 1-11.
Mace, M. E. & Stipanovic, R. D. (1995). Pestic. Biochem. Physiol. 53, 205-209.
Oxford Diffraction (2009). CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, England.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.
Stipanovic, R. D., Bell, A. A. & Howell, C. R. (1975). Phytochemistry, 14, 1809-1811.