Synthesis and crystal structure of (±)-Goniotamirenone C

Earlier we reported the isolation of Goniotamirenone C [6-(2-chloro-1-hy­droxy-2-phenyl­eth­yl)-2H-pyran-2-one] from the leaf extracts of Goniothalamus tamirensis. Its gross structure was elucidated using NMR spectroscopic techniques and, on the basis of ECD calculations, the absolute configuration of this natural product was assigned as the syn isomer, (7S,8S)-Goniotamirenone C. In this paper we correct the structure of the natural product to the anti isomer from the semi-synthesis and single-crystal X-ray structure determination of (±)-Goniotamirenone C, which displays identical NMR spectroscopic data to the natural product.
The structure of the racemic version of the natural product Goniotamirenone C [racemic anti-6-(2-chloro-1-hy­droxy-2-phenyl­eth­yl)-2H-pyran-2-one, C13H11ClO3] at 150 K is reported. The compound crystallizes with monoclinic (P21/n) symmetry and with Z′ = 2. One independent mol­ecule is ordered while the other independent mol­ecule exhibits an inter­esting whole-mol­ecule enanti­omeric disorder with occupancies of 0.846 (4) and 0.154 (4). The independent mol­ecules are hydrogen bonded with –OH⋯O=C linkages into chains that run parallel to the a axis. This structural analysis corrects our previous assignment as the syn isomer [Meesakul et al. (2020 ▸). Phytochemistry, 171, 112248–112255].