Neue sesquiterpene und acetylenverbindungen aus Cineraria-arten

The investigation of several members of the South African genus Cineraria affords, in addition to known compounds, several new eremophilene derivatives together with modified types all derived from a carbon skeleton where the 5-methyl has migrated to C-6. Some of these compounds are transformed to unusual enol lactones. Furthermore some derivatives of himachalene are present. All species also contain C₁₁-acetylenes, most of which are new. Senecio deltoideus also contains some of these compounds. The chemotaxonomic situation is discussed.     

Neue sesquiterpene aus Artemisia koidzumii

The roots of A. koidzumii afforded, in addition to known compounds, a new sesquiterpene with an anomalous carbon skeleton, while the aerial parts yielded a new nerolidol and a new farnesol derivative. The structures were elucidated by spectroscopic methods and some chemical transformations.     

Neue sesquiterpene aus Liabum-arten

The reinvestigation of the roots of Liabum eggersii afforded, in addition to compounds reported before, several sesquiterpene hydrocarbons with unusual carbon skeletons and the first derivative of the propellane modhephene which itself is also present. The roots of L. floribundum contain a tricyclic sesquiterpene with three five-membered rings. This ketone most probably is a derivative of the sesquiterpene silphiperfolene. The structures of the new compounds were elucidated by extensive NMR studies and by some chemical transformations. Two further species only afforded known compounds. The chemotaxonomic situation is 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 labdan-derivate aus Chrysothamnus nauseusus

The South American Chrysothamnus species afforded in addition to known compounds six new labdanetype acids, a bisabolene and a germacrene derivative as well as a new flavanone. The structures were elucidated by spectroscopic methods.     

Neue germacranolide aus Calea urticifolia

The investigation of Calea urticifolia afforded eight new germacranolides. While five are heliangolides, three are of a new type and have some unusual structural features. The structures are elucidated by extensive ¹H-NMR studies and some chemical transformations. In addition, a new isoeugenol and an unusual phloroglucinol derivative were isolated; the structure of the latter could only be established after some chemical transformations. Other Calea species contain typical C₁₇ acetylenes only, also present in other species of the subtribe Galinsoginae. So far, the results on Calea indicate that the genus is chemically heterogenous.     

Neue sesquiterpene,triterpene, flavanone und andere aromatische verbindungen aus Flourensia heterolepis

The investigation of a further Flourensia species afforded in addition to already known compounds 12 new sesquiterpene acids isolated as their methyl esters, a new eudesmane diol, four lupane derivatives and two flavanones, two cinnamic acid derivatives, also isolated as methyl esters and a ketone. The structures are elucidated mainly by spectroscopic methods and by some chemical transformations. Several of the compounds isolated are more or less similar to those isolated from other Flourensia species; the considerable amounts of eudesmanes, however, are unusual. The overall picture of the genus is still relatively uniform. Close relationships to Helianthella are obvious, while to Helianthus, placed in the same subtribe, no clear relations are visible.     

Neue Guajanolide aus Podachaenium eminens

The airial parts of Podachaenium eminens contain, besides known compounds, four new guaianolides. The roots afford known acetylenes together with a new euparine-derivative. The structures are elucidated using spectroscopic methods.     

Neue diterpene und sesquiterpene aus südafrikanischen Helichrysum-arten

The investigation of several South African Helichrysum species afforded in addition to known compounds two new kaurenic acid derivatives, three new labdane derivatives, three aromadendrene derivatives and geranylterpinene. The structures are elucidated mainly by extensive ¹H NMR-studies. The chemotaxonomic importance of these findings is discussed briefly.     

Neue sesquiterpene und norditerpene aus vertretern der gattung Libanothamnus

The aerial parts of L. granatesianus afforded in addition to known compounds two nor- ent-kaurenes, while those of L. occultus yielded in addition to several diterpenes, two new dialdehydes derived from silinene. The chemotaxonomic situation is discussed briefly.     

Neue melampolide und cis,cis-germacranolide aus vertretern der subtribus melampodiinae

The investigation of four South American species of the tribe Heliantheae afforded in addition to known compounds 14 new sesquiterpene lactones, mostly belonging to the melampolides, but four being further examples of cis,cis-germacranolides. The stereochemistry is established by intensive ¹H-NMR studies and some chemical transformations. Some of the new lactones were only obtainable as inseparable mixtures of 2-methylbutyric and isovaleric esters. Furthermore a new acetylenic aldehyde was isolated. The chemotaxonomic situation is discussed especially with regard to the position of the genus Smallanthus.