STRUCTURE, CHEMISTRY AND STEREOCHEMISTRY OF CLEMENTEINS, SESQUITERPENE LACTONES FROM CENTAUREA CLEMENTEI

Article abstract of DOI:10.1016/S0040-4020(01)87328-2

The stereochemistry of clementein (1) (the first oxetane-containing sesquiterpene lactone) is determined to be 16(S) on the basis of chemical and spectroscopic data.Clementeins B (2) and C (3), isolated from the same source (Centaurea clementei D.C.) were shown to be closely related guaianolides, with an 11,13-oxetane ring.A number of chemical transformations on the oxetane in 2 and 3 have been accomplished.