New germacranolides and other sesquiterpene lactones from Dicoma species

Two subspecies of Dicoma anomala afforded, in addition to known compounds, an eudesmanolide, a guaianolide and four germacranolides, the latter being closely related 8, 12-lactones. D. schinzii gave three new germacranolides and D. zeyheri a pair of isomeric acetylenic compounds. The structures were elucidated by highfield ¹H NMR spectroscopy. The chemotaxonomic situation of this genus is discussed briefly.     

Seven germacranolides and four eudesmanolides from Tithonia rotundifolia

The aerial parts of Tithionia rotundifolia afforded, in addition to two known sesquiterpene lactones, eleven new ones, seven germacranolides and four eudesmanolides. The structures were determined by ¹H NMR spectroscopy.     

A dimeric germacranolide and other sesquiterpene lactones from Mikania species

The investigation of two Mikania species, both previously placed in the genus Kanimia, afforded in addition to known compounds several new germ     

Ineupatorolide-like sesquiterpene lactones from Dittrichia viscosa

Dittrichia viscosa afforded, in addition to known compounds, minute amounts of nine sesquiterpene lactones, all closely related to ineupatorolide B     

Two eudesmanolides from Sonchus macrocarpus

The aerial parts of Sonchus macrocarpus afforded, in addition to known triterpenes, two new eudesmanolides.     

Three eudesmanolides from Pluchea rosea

Three eudesmanolides of Pluchea rosea were found to be structurally related to the eudesmane, cuauthemone, earlier reported from plants of the same genus.     

Sesquiterpene lactones and other constituents from Schistostephium species

From four Schistostephium species, in addition to known compounds, 43 new ones were isolated, three isocomene, two bisabolene, two eudesmane, two allo-himachalene and two nerolidol derivatives, two sesquiterpenes with a new carbon skeleton derived from isocomene, nine eudesmanolides, 20 6,12- and 8,12-germacranolides respectively, and a prostaglandin-like acid. The structures were elucidated by spectroscopic methods, especially high field ¹H NMR and some chemical transformations. The stereochemistry of some 8,12-germacranolides was established by partial synthesis which required revision of the previous assignments of the configuration of inunolide, its 4,5- and 1,10-epoxide, vernudifloride, simsiolide, 6-hydroxy-1,10-epoxyinunolide and perhaps also of tanachin. The chemotaxonomic situation is discussed briefly.     

Seven sesquiterpene lactones from Ferreyanthus species

The investigation of two Ferreyanthus species afforded seven germacranolides which have not been isolated previously. Two derivatives of linalol were also present. The structures were elucidated by spectroscopic methods. Chemotaxonomic relationships are briefly discussed.     

Further eudesmanolides and xanthanolides from Telekia speciosa

The re-investigation of the aerial parts of Telekia speciosa afforded five new sesquiterpene lactones, two eudesmanolides and three xanthanolides, all closely related to those isolated before from this species or from related genera. The structures were elucidated by ¹H NMR spectroscopy.     

Glaucolide-like sesquiterpene lactones from Cotula cinerea

The aerial parts of Cotula cinerea gave, in addition to widespread compounds, a characteristic diacetylenic spiroketal enolether and several sesquiterpene lactones, three of them being glaucolide-like lactones. The structures were elucidated by highfield ¹H NMR spectroscopy.     

Sesquiterpene lactones from Brachylaena species

The investigation of two Brachylaena species afforded in addition to known sesquiterpene lactones and other constituents five new lactones, a germacranolide, a guaianolide and three eudesmanolides. The structures were elucidated by spectroscopic methods. The chemotaxonomy of this complex genus is discussed.     

Eriolanolides,eudesmanolides and a rearranged sesquiterpene from Eriophyllum species

The investigation of two Eriophyllum species afforded, in addition to numerous known compounds, eight new sesquiterpene lactones related to eriolanin, two eudesmanolides and a new type of sesquiterpene alcohol. The structures were elucidated by spectroscopic methods and a few chemical transformations. The chemotaxonomic situation of this genus, the placement of which is still in doubt, is discussed briefly.     

Five eudesmanolides from Calostephane divaricata

The investigation of Calostephane divaricata afforded in addition to known compounds five new eudesmanolides, all being tri-substituted derivatives of 6-epi- α-cyclocostunolides. The structures were eluciated by highfield ¹H NMR spectroscopy. The relative positions of the oxygen functions could not be stablished with certainty. The observed shift differences agreed well with the proposed structures.     

New sesquiterpene lactones and other constituents from Fitchia speciosa

The investigation of Fitchia speciosa afforded, in addition to known compounds, three new sesquiterpene lactones, iso-β-costal, two p-hydroxyacetophenone derivatives and an isoeugenol derivative. The structures were elucidated by spectroscopic methods. The chemotaxonomic situation in this complicated genus is discussed.     

Further eudesmanolides from Dimerostemma species

The aerial parts of a new Dimerostemma species afforded four eudesmanolides which are all derivatives of arbusculin B and an aldehyde, obviously a degradation product of syringenin. A reinvestigation of Dimerostemma asperatum gave a further dimerostemmolide.     

Further sesquiterpene lactones from Calea and Viguiera species

The aerial parts of Calea clematidea gave three new germacranolides, those of Viguiera procumbens two orizabin derivatives and those of V. linearis dihydrobudlein A. In addition to these lactones, several known ones were isolated.     

Sesquiterpene lactones from Inezia integrifolia

Inezia integrifolia afforded, in addition to known compounds, three new eudesmanolides and a guaianolide. Two of the eudesmanolides were obtained as a mixture. The relative position of the ester groups could not be determined with certainty. The chemotaxonomy is discussed briefly.     

Five germacranolides from Gochnatia discoidea

The investigation of two further Gochnatia species afforded five new germacranolides, all being 8,12-lactones. The structures were elucidated by intensive ¹H NMR studies and by some chemical transformations. The chemotaxonomic aspects are discussed briefly.     

Germacranolides from Dicoma tomentosa

An investigation of the aerial parts of Dicoma tomentosa afforded four new germacranolides and four melampolides together with urospermal A and its 11β,13-dihydroderivative. The structures were elucidated by spectroscopic methods. The chemotaxonomic situation is discussed briefly.