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.