Xanthchrysones A-C: Rearranged Phenylpropanoyl-Phloroglucinol Dimers with Unusual Skeletons from Xanthostemon chrysanthus.

Three pairs of dimeric phenylpropanoyl-phloroglucinol enantiomers, (+)- and (-)-xanthchrysones A-C [(+)- and (-)-1-3], as well as their postulated biosynthetic precursors, were isolated and identified from the leaves of Xanthostemon chrysanthus. Compound 1 featured an unprecedented bis-phenylpropanoyl-benzo[b]cyclopent[e] oxepine tricyclic backbone. Compounds 2 and 3 represent the first examples of 1-(cyclopentylmethyl)-3-(3-phenylpropanoyl)benzene scaffold. The structures and absolute configurations of 1-3 were determined by spectroscopic and X-ray diffraction analysis as well as electronic circular dichroism (ECD) calculation. Both (+)-2 and (-)-2 showed moderate antibacterial activities including several multidrug-resistant strains.