3,6-dihydroxy-2-(1 1-phenylundecanoyl)cyclohex-2-en-1-one from Virola venosa bark

The structure of the title compound, C23H32O4, an arylalkanone isolated from the petroleum ether fraction of the ethanol extract of the bark of Virola venosa, has been established by NMR spectroscopy and, for the first time, by X-ray structure analysis. Two independent molecules of the same enantiomer are present in the unit cell. Both molecules exhibit an intramolecular hydrogen bond, which can be correlated with a rare signal observed at 18.28 p.p.m. in the 1H NMR spectrum. The packing, in space group P1, is determined by a pseudo-center of symmetry leading to a short intermolecular contact, which is present in one molecule but does not occur in the other. As a consequence, the O-C-C-O torsion angles [-16.9 (3) and -12.7 (3) degrees ] through the ketone and its adjacent hydroxy group are significantly different in the two molecules.