RESUMO
THE TITLE SESQUITERPENE [SYSTEMATIC NAME: 6-methoxy-10-methyl-7-(propan-2-yl)-2-oxatricyclo[6.3.1.0(4,12)]dodeca-1(11),4,6,8(12),9-pentaen-5-ol], C(16)H(18)O(3), was isolated from pathogen-infected stele tissue of Gossypium barbadense. There are two mol-ecules in the asymmetric unit and the dihedral angle between their naphtho-furan systems is 86.48â (2)°. In the crystal, O-Hâ¯O hydrogen bonds between the hy-droxy groups and etheric O atoms link the mol-ecules into centrosymmetric tetra-mers. These tetra-mers are assembled into (010) layers via stacking inter-actions between the naphtho-furan systems [inter-planar distance 3.473â (3)â Å] and short C-Hâ¯O contacts.
RESUMO
The title compound, C16H20O3 [systematic name: 1-hy-droxy-7-meth-oxy-1,6-dimethyl-4-(propan-2-yl)naphthalen-2(1H)-one], is a sesquiterpene isolated from foliar tissues of the cotton plant and is of inter-est with respect to its anti-bacterial properties. Its phenyl ring is ideally planar, and the maximum of deviation in the second ring is 0.386â (3)â Å. The hy-droxy group and the methyl group are oriented in an equatorial fashion and axial, respectively, to the second ring. In the crystal, inversion dimers are formed through pairs of O-Hâ¯O hydrogen bonds. Weak C-Hâ¯O hydrogen bonds link the dimers into columns along the c axis. These columns form a crystal structure with a crystal packing factor of 0.66.
RESUMO
The isolation and structure of a phytoalexin, malvone A (2-methyl-3-methoxy-5,6-dihydroxy-1,4-naphthoquinone) is reported. Malvone A formation is induced in Malva sylvestris L. by the plant pathogen Verticillium dahliae. In a turbimetric assay for toxicity to V. dahliae, it had an ED50 value of 24 microg/ml. The structure of malvone A was determined by MS and NMR spectroscopy, and by X-ray crystallographic analysis. The X-ray analysis showed water molecules were located in channels that run along the a-axis.