Weitere furanoeremophilane aus Othonna-arten

The investigation of further Othonna species affords 23 new furanoeremophilanes and a new benzofuran-derivative. All these compounds are closely related to those isolated before from other Othonna species. Highly oxidized furanoeremophilanes seem to be typical of this genus.     

Neue C10-säureamide,furanoeremophilane und andere inhaltsstoffe aus bolivianischen Senecio-arten

The investigation of seven Bolivian Senecio species afforded in addition to known compounds five new furanoeremophilanes, two C₁₀-amides, a new isoeugenol ester and the isomer of pterophorin. The structures are elucidated mainly by spectroscopic methods. While most of the new compounds are closely related to those isolated before from Senecio species, four of them are unusual. Another is a new type of a furanoeremophilane; its biogenesis however, can be explained easily from known types.     

Hilliardinolester und andere furanoeremophilane aus Senecio mauricei

Senecio mauricei contains seven new furanoeremophilanes, all being highly oxidized. Intensive ¹H-NMR-studies led to the configurations of these unusual compounds. The acetstes of four of them show very unusual chemical shifts of the acetate methyls. Furthermore a new eremophilane is present: 8,12-dihydroxy-7,11,9,10-tetrahydroeremophilane. The chemotaxonomic aspects are discussed briefly.     

Neue furanoeremophilane und andere sesquiterpene aus vertretern der gattung Euryops

Investigation of a further 27 Euryops species affords, besides known compounds, 55 new furanoeremophilanes together with several other compounds. The configuration of six furanoeremophilanes earlier given as 10β-H has to be changed to 10α-H. Furthermore 9 new eremophilenes were isolated; the configurations of four compounds of this type isolated before have had to be changed. One of the eremophilenes is esterified with 3-methylpent-3(E)-enoic acid, not found before in nature. Two hemiacetals, which are probable precursors of the furanoerephilanes, and a corresponding lactone are also present. Furthermore two benzylic esters, cis-caryophyllene, a bicyclo-germacrene derivative, and a new oplopanone derivative have been found. The structures are elucidated mainly by spectroscopic methods together with some chemical transformations. From the chemotaxonomic viewpoint, the high concentration of very variable furanoeremophilanes may be important. The proposed differentiation into sections however can not be clearly correlated with the chemical constituents, though some taxonomic conclusions seem to be supported by the chemical evidence.     

Neue furanoeremophilane und weitere inhaltsstoffe aus südafrikanischen Senecio-arten

The investigation of further 27 South African and a few other Senecio species afforded in addition to known compounds 18 new furanoeremophilanes, most of them being cacalol derivatives, two new lactones, a new eudesmane derivative and four acyl pyrrole derivatives. The structures are elucidated by spectroscopic methods mainly. The chemical results on more than 140 species now available indicate much of chemotaxonomic interest. Together with the chemical data on related genera, the taxonomic situation of the subtribe Senecioninae is discussed in connection with the proposed new classification. The chemical data are in good agreement with this new arrangement.     

Neue eremophilan-derivate aus Lopholaena-arten

The genus Lopholaena contains several eremophilane derivatives. The structures of four new furanoeremophilanes and one eremophilone derivative were elucidated using spectroscopic methods. The chemical relationship of Lopholaena to other genera is discussed.     

Inhaltsstoffe aus Gynoxys- und Pseudogynoxys-arten

Five new furanoeremophilanes have been isolated from Gynoxys sancto antonii, while two Pseudogynoxys species yield three new polyenes. The chemotaxonomic aspects are discussed.     

Neue labdan- und pimaren-derivate aus Palafoxia rosea

The investigation ofPalafoxia rosea afforded in addition to known compounds five new labdane derivatives and five pimarene derivatives. The structures are elucidated by spectroscopic methods and some chemical transformations. The chemotaxonomic situation of the genus is discussed briefly.     

Neuartige sesquiterpenlactone und neue acetylenverbingen aus Athanasia-arten

The investigation of two further South African Athanasia-species afforded, in addition to known compounds, sixteen new ones, ten guaianolides, an eudesmanolide, three sesquiterpenes, a new enediynene and a phenylpropane derivative. The structures were elucidated by extensive NMR-studies. Three of the lactones are very unusual in having an endoperoxide bridge; their structures, however, were elucidated only indirectly. These further chemical results on Athanasia again add support to the idea that these species might be better placed in the genus Pentzia.     

8-Oxo-α-selinen und neue scopoletin-derivate aus Conyza-arten

The investigation of three South African and a North American Conyza species afforded, in addition to known compounds, a new eudesmane ketone and five new scopoletin derivatives. The structures are elucidated by spectroscopic methods and by some chemical transformations. Two of the scopoletin enol ethers have very unusual structures. While most of the Conyza species investigated so far contain typical C₁₀-acetylenes, also present in related genera, there are some with different chemistry. The relationship of the genus to Aster and Erigeron, however, is clearly indicated.