Sesquiterpenlactone aus Arnica chamissonis

Abstract
From the flowers of A. chamissonis Less. ssp. foliosa (Nutt.) Maguire and its variety A. c. ssp. f. var. incana (Gray) Hulten 2 new naturally occurring pseudoguaianolides were isolated and their structures established by spectroscopic methods. They are 4-O-acetyl-6-deoxychamissonolide and the propionylic ester of 11,13-dihydrohelenalin which was named arnicolide G.