Cis- and trans-isoshinanolone from Dioncophyllum thollonii: absolute configuration of two 'known', wide-spread natural products

From the rare West African liana, Dioncophyllum thollonii (Dioncophyllaceae ), the known acetogenic tetralones, cis- and trans-isoshinanolone, were iso lated. Exemplarily on this material, a new ruthenium-catalyzed oxidative de gradation procedure, related to the well-established stereoanalysis of 1,3- dimethyltetrahydroisoquinolines lines, was ela berated. The method allo ws to unambiguously attribute the absolute configuration of these natural prod ucts, which likewise occur in several other plant species. For the rapid di scrimination between the four possible stereoisomeric forms of isoshinanolo ne (i.e. the cis- and transdiastereomers and their enantiomers), an HPLC-an alytical procedure on a chiral stationary phase has been developed. (C) 199 9 Elsevier Science Ltd. All rights reserved.