An Intramolecular CAr–H••• O= C Hydrogen Bond and the Configuration of Rotenoids

Citation:
Ren Y, Gallucci JC, Kinghorn DA. "An Intramolecular CAr–H••• O= C Hydrogen Bond and the Configuration of Rotenoids." Planta medica. 2017;83(14/15):1194-1199.

Abstract:

Over the past half a century, the structure and configuration of the rotenoids, a group of natural products showing multiple promising bioactivities, have been established by interpretation of their NMR and electronic circular dichroism spectra and confirmed by analysis of single-crystal X-ray diffraction data. The chemical shift of the H-6′ 1H NMR resonance has been found to be an indicator of either a cis or trans C/D ring system. In the present study, four structures representing the central rings of a cis-, a trans-, a dehydro-, and an oxadehydro-rotenoid have been plotted using the Mercury program based on X-ray crystal structures reported previously, with the conformations of the C/D ring system, the local bond lengths or interatomic distances, hydrogen bond angles, and the H-6′ chemical shift of these compounds presented. It is shown for the first time that a trans-fused C/D ring system of rotenoids is preferred for …

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