Nor-dehydrodeguelin and nor-dehydrorotenone, C22 coumaronochromones from Lonchocarpus nicou

Lonchocarpus nicou roots lipophile extract yielded, among isoflavonoids, two coumaronochromones isomers. Spectroscopic analysis assigned the structure of nor-dehydrodeguelin to the former and (−)-nor-dehydrorotenone to the latter, the two products only differing by the cyclization of the C5 side chain. Biogenetically, the two compounds could be considered as resulting either from cyclization of the corresponding 2′-hydroxyisoflavones and/or from oxidative ring-B contraction of the dehydrorotenoids parents.