Diterpene glycosides and other constituents from argentinian baccharis species

The investigation of the aerial parts of nine Baccharis species from Argentina gave 37 new compounds, seven ent-clerodanes, 13 ent-labdanes, two friedolabdanes, a nor-labdane ketone, seven coumaric acid derivatives, two umbelliferone derivatives, a flavanone, three sesquiterpenes including a nor-furanocadinene and a propiophenone derivative. Ten of the diterpenes were glycosides. The structures and the configurations were determined by highfield NMR spectroscopy and some chemical transformations. The absolute configurations of the diterpenes were proposed following observed Cotton-effects and in one case by using the Horeau-method together with ¹H NMR determination of the configuration of the main phenylbutyrate obtained. The chemotaxonomy is discussed.