Sesquiterpene lactones from Centaurea helenioides

Grosheimin (1) and cynaropicrin (3) sesquiterpenes were isolated from the flowers of Centaurea helenioides Boiss., an endemic plant of Turkey. The products are known as they occur in another species, but they were isolated and identied for the rst time from C. helenioides Boiss. In order to correlate spectral data of grosheimin, its acetyl derivative, 8-acetyl grosheimin (2) was also prepared. Their structures were deduced by FT-IR, UV, 1D and 2D NMR, LC MS/MS, GC-mass spectra (EI), optical rotation, and chemical methods. Key Words: Centaurea helenioides Boiss., Compositae, Sesquiterpene lactones, Grosheimin, Cynaropi-crin