Two proazulenes from Achillea ceretanica Sennen

From flower heads of a tetraploid clone of Achillea ceretanica two further guaianolides were isolated by repeated column chromatography and HPLC. The constitution and the stereochemistry of these new, unstable compounds were determined by MS, one- and two-dimensional NMR-techniques (H-1-,C-13-NMR, C OSY-, HSQC-, TOCSY-, selective TOCSY- and NOE-experiments) as well as by co mparison to the data of the literature. The two substances were identified as 2 alpha,8 alpha-dihydroxy-1 alpha,5 alpha,6 beta,7 alpha,11 beta H-guaia -3,10(14)-dien-12,6-olide and its 8 alpha-acetate. (C) 1998 Elsevier Scienc e Ltd. All rights reserved.