HELIESPIRONE-A - THE FIRST MEMBER OF A NOVEL FAMILY OF BIOACTIVE SESQUITERPENES

(-)-Heliespinore A, the first member of a novel family of bioactive se squiterpenes, a potential allelopathic agent, has been isolated from c ultivar sunflowers var. SH-222(R) (Helianthus annuus L.). The structur e displays an unusual previously unknown spirosesquiterpene skeleton o f Heliespirane. The structure elucidation of Heliespinone A was perfor med by home-and hetero-nuclear 2D-NMR spectral data. On the basis of c ombined studies of the theoretical conformations and NOEDIFF data its relative stereochemistry is proposed. (C) 1997 Elsevier Science Ltd. A ll rights reserved.