Robert M. King

Pseudoguaianolides and other sesquiterpene lactones from Gaillardia species

Abstract The aerial parts of two Gaillardia species afforded in addition to known sesquiterpene lactones 23 new pseudoguaianolides, two dugaldiolide derivatives and two seco-neopulchellin derivatives. The structures were elucidated by spectroscopic methods. Biogenetic relationships are discussed briefly.

Diterpene glycosides and other constituents from argentinian baccharis species

Abstract 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 1 H NMR determination of the configuration of the main phenylbutyrate obtained. The chemotaxonomy is discussed.

A dimeric germacranolide and other sesquiterpene lactones from Mikania species

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

Eudesmane derivatives from Verbesina species

Abstract The investigation of seven Verbesina species afforded, in addition to known compounds, several new eudesmane and germacrane derivatives, all bearing a cinnamate or derivatives as residue. Furthermore, a new bisabolene aldehyde and two acetophenone derivatives were isolated. The structures were elucidated mainly by spectroscopic methods and some chemical transformations. The chemotaxonomic situation is discussed briefly.

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.

ent-clerodanes and other constituents from bolivian Baccharis species

Abstract Investigation of seven Bolivian Baccharis species afforded in addition to known compounds 17 ent -clerodane, 10 ent -labdane, two bisabolene, a germacrane, a cadinane, a guaiane and a p -coumaric acid derivative. In one case the ent -labdane was linked with a bisabolene derivative via a malonate group. The structures were elucidated mainly by high field NMR techniques.

Further 5-methyl coumarins and other constituents from the subtribe mutisiinae

Abstract The investigation of four species from the subtribe Mutisiinae afforded eight new monoterpenes, seven 5-methyl coumarins, two closely related 5-methyl chromones, two coumarane derivatives, a p-hydroxy acetophenone derivative and a new C14-acetylene. The structures were elucidated by spectroscopic methods and a few chemical transformations. The chemotaxonomy of the Mutisiinae is discussed.

Caryophyllene derivatives and a heliangolide from Lychnophora species

Abstract The investigation of three Lychnophora species afforded three new caryophyllenic acids and a new heliangolide closely related to 15-desoxygoyazensiolide. All three species contain lupeol, lupeyl acetate and eremanthine. The chemotaxonomic situation is discussed briefly.

Hirsutinolides, glaucolides and sesquiterpene lactone from Vernonia species

Abstract The investigation of nine Vernonia species afforded in addition to known sesquiterpenes 28 new ones. The structures were elucidated by high field 1 H NMR spectroscopy and the configurations were determined by NOE difference spectroscopy and, in one case, by X-ray analysis. The results indicated that configurations of several previously reported sesquiterpene lactones have had to be revised. In addition to known types two new ones, the jalcaguaianolides and the vernojalcanolides, are described. Furthermore some unusual reaction products are presented which, in part, led to some natural occurring lactones.

Five diterpenes and other constituents from nine Baccharis species

Abstract The investigation of nine Baccharis species afforded, in addition to known compounds, three new clerodane derivatives related to bacchotricuneatin B, two ent -labdane derivatives, two 3-acetoxyflavanones, a benzofuran derivative and a chromene. The overall picture of the chemistry of this large genus is still not very clear.