Abstract:
Five new guainolides, in addition to four known guaianolides, have been isolated from extracts of the flowers
of Tanacetum annuum. Structures and stereochemistries were elucidated from spectral data and chemically confirmed by
correlations with a-santonin and mutual interconversion. Conformational and configurational analysis performed through the
molecular mechanic calculation corroborate those obtained by
JH,H values and NOEDIF experiments. Evidence for the possibility that the dehydrated lactones are artefacts was obtained.