Biebsanin — A new susquiterpene lactone fromAchillea biebersteinii andA. santolina
Continuing a study of the lactones of Achillea biebersteinii [i] and A. santolina, from the mother liquors [2, 3] by means of the systems chloroform-ethanol (30:1) and benzene--ethyl acetate (1:1) we have isolated a new chlorine-containing sesquiterpene lactone with the composition C15HzgO~CI (ethyl acetate), mp 258-259°C (in a preheated metal block), [u]~ ° --34 ° (c 1.0; pyridine), M + 330, which we have called biebsanin (I).
Rupicolin-A and -B, rupin-A and -B, and cumambrin-B oxide from Artemisia tripartita ssp. Rupicola
Abstract Five new sesquiterpene Iactones have been isolated from Artemisia tripartita Rydb. ssp. rupicola Beetle. The compounds, all guaianolides, are structurally related in what appears to be a sequence in which epoxidation plays the principal role.
Circular dichroism and optical rotatory dispersion of sesquiterpene lactones
Abstract The CD curves of a large number of sesquiterpene lactones together with a limited number of ORD curves have been measured. A simple correlation between the sign of the Cotton effect (CE) and the stereochemistry of the α-methylene-γ-lactone chromophore can be deduced from the resulting data. In addition the CE of several ketones (both saturated and unsaturated) and pyrazolines are reported.