Diterpenes from Heteropappus altaicus

The aerial parts of Heteropappus altaicus afforded, in addition to more widespread compounds and known clerodane derivatives, three new ones and a seco-clerodane acid. Furthermore, a neryl geraniol derivative was present. The structures were elucidated by spectroscopic methods. The stereochemistry was solved by NOE difference spectroscopy and by the Horeau method.     

Clerodane diterpenoids from Aster alpinus

The aerial parts of Aster alpinus afforded, in addition to dammadienyl acetate and dammadienone, two clerodane derivatives related to salviarin and bacchotricuneatin A. The structures were elucidated by spectroscopic methods, especially high-field NMR. The chemotaxonomic situation is discussed briefly.     

Diterpenes from Baccharis species

The investigation of ten Baccharis species afforded in addition to known compounds eight new diterpenes, four ent-labdanes, three kaurenes and a clerodane derivative. Furthermore, two new p-hydroxyacetophenones, a flavone, 3′-methoxyxanthomicrol and two matricaria ester derivatives were isolated. The structures were elucidated by spectroscopic methods and a few chemical transformations. The chemotaxonomic situation of the large genus is discussed briefly.     

Isolation and structure of stephalic acid,a new clerodane diterpene from Stevia polycephala

From the methanolic extract of Stevia polycephala a new clerodane-type diterpene, stephalic acid, was isolated. The structure and stereochemistry were determined by a combination of spectral data and single-crystal X-ray analysis.     

Three diterpenes from Conyza podocephala

The investigation of Conyza podocephala afforded, in addition to known compounds, two clerodane derivatives and a dihydroxyfarnesyl methylfuran. Furthermore two new resorcinol derivatives were isolated. The structures were elucidated by spectroscopic methods and by chemical transformations. The chemotaxonomic situation within the genus is discussed briefly.     

Diterpenes from Koanophyllon species

The investigation of two Koanophyllon species afforded, in addition to known compounds, several new diterpenes, two new geranylgeraniol derivatives and four diterpenes, most probably closely related to clerodanes; their structures, however, could not be deduced with certainty. The chemotaxonomic situation of this genus is discussed briefly.     

Diterpenes from Mikania species

The investigation of four further Mikania species afforded several diterpenes, four geranylgeraniol derivatives and three kaurane epoxides. The structures were elucidated by spectroscopic methods and a few chemical transformations.     

Diterpenes with a new carbon skeleton from Printzia Laxa

The aerial parts of the South African composite Printzia laxa contain two manoyl oxides and three clerodane derivatives together with two further acids, which belong to a new type of diterpene, biogenetically closely related to the clerodanes. The structures have been elucidated by spectroscopic methods. The constituents may indicate some relationship of Printzia to the tribe Astereae.     

Diterpenes related to grindelic acid and further constituents from Grindelia species

The aerial parts of Grindelia stricta afforded in addition to known compounds 21 diterpenes, all closely related to grindelic acid. The aerial part     

Some sesqui- and diterpenes from the tribe eupatorieae

The aerial parts of Trichogonia salviaefolia afforded a new ent-kaurenic acid derivative and a germacranolide which, most likely, is the precursor of the trichosalviolides. The aerial parts of Liatris spicata gave 1α-hydroxybacchotricuneatin A and a guaianolide, which may be the precursor of spicatin. From Brickellia vernicosa some further dehydronerolidol derivatives were isolated.     

Diterpenes from Baccharis species

The aerial parts of Baccharis minutiflora afforded in addition to known compounds eight new ent-kaurane derivatives, one being a homo kaurane, while the aerial parts of B. alatemoides gave two pairs of epimeric clerodane derivatives, which, however, had to be modified chemically before they could be separated. The stereochemistry of these diterpenes could not be elucidated with certainty.     

Diterpenes from Palafoxia texana

The investigation of Palafoxia texana afforded in addition to the known compound jesromotetrol two new rosene derivatives: 3β-acetoxy-jesromotetrol and 3β,19-diacetoxy-jesromotetrol. The structures were determined by spectroscopic methods and chemical transformations.     

Sesquiterpenes,guaianolides and diterpenes from Stevia myriadenia

The investigation of Stevia myriadenia afforded in addition to known compounds a new clerodane and a labdane derivative, two guaianolides, a bisabolene and a germacrene derivative. The structures were elucidated by spectroscopic methods. The chemotaxonomic situation is discussed briefly.     

Sandaracopimarene derivatives from Senecio subrubriflorus

Several new sandaracopimarene derivatives were isolated from Senecio subrubriflorus. A triphenyl acetate of shikimic acid and a 4, 7-oxide of bisabolene were also present. The structures were elucidated by high field ¹H NMR spectroscopy. The chemistry of this species differs considerably from that of other Senecio species.     

Diterpenes and sesquiterpene lactones from Mikania congesta

The chloroform extract of the aerial parts of Mikania congesta, afforded four new geranylnerol derivatives, new analogs of deoxyelephantopin, a new melampolide and several known compounds. Structures were elucidated by spectroscopic methods and chemical transformations.     

Sesquiterpene and diterpene derivatives from Solidago species

The investigation of four Solidago species afforded, in addition to known compounds, four new caryophyllene derivatives, two eudesmanes, two abietanes, a clerodane, two labdanes, three kauranes and an anol angelate. The structures were elucidated by spectroscopic methods and by some chemical transformations. While the diterpenes isolated are widespread in the genus Solidago, the sesquiterpenes have not been obtained before from any species. The overall picture of the large genus, however, is relatively uniform.     

Diterpenes and sesquiterpenes from Osteospermum species

The investigation of several Osteospermum species afforded in addition to known compounds three diterpenes from the rare cassane type, two further sandaracopimarene derivatives, two 6-desoxyglucosides of cubebol and 13-hydroxycaryophyllene, respectively, an isomer of 7-hydroxycalamenene, two p-hydroxyacetophenone derivatives derived from toxol, a thymol derivative and the palmitates of lupeol, taraxasterol and 3β,20-dihydroxydammarene. The structures were elucidated by spectroscopic methods. The chemotaxonomy of the genus is discussed briefly.     

Thirteen kolavane derivatives from Symphyopappus species

The aerial parts of Symphyopappus compressus afrorded three new kolavane derivatives and those of S. reticulatus ten diterpenes of this type, two of them esterified with long chain fatty acids. Furthermore, a dihydroxyphenylpropanol, also esterified with long chain fatty acids, was present in both species. The roots of S. reticulatus afforded a new tremetone derivative. The structures were elucidated by spectroscopic methods and some chemical transformations.