Guaianolides from tanacetum argenteum subsp. canum var. canum

The aerial parts of Tanacetum argenteum subsp. canum var. canum (Compositae) afforded six guaianolides, five of them (2-6) being new: flabellin (1), epoxyflabellin (2), Delta3(4)-15-oxo-flabellin (3), Delta3(4)-15-hydroxydihydroflabellin (4), 11alpha-dihydroflabellin (5), and 11beta-dihydroflabellin (6). The structures of the compounds were elucidated by spectral methods including NMR (1H NMR, COSY, APT, HETCOR, NOE) and X-ray diffraction, as well as by some chemical reactions.