Neue ent-atisiren- und ent-kaurensäure-derivate aus Helianthus-arten

The investigation of four Helianthus species afforded, in addition to known compounds, four new atisirenic acid derivatives, a new ent-kaurenic acid derivative, three new labdane derivatives and an unknown C₁₅-acetylenic compound. The structures of the diterpenes were elucidated by intensive NMR studies and some chemical transformations. An unusual fragmentation in the mass spectra of the atisirenes is discussed briefly.     

Neue labdan-derivate aus Carterothamnus anomalochaeta

The investigation of a Carterothamnus species afforded in addition to known euparine derivatives four new diterpenes, all being labdane derivatives. The structures are elucidated by ¹H-NMR-studies and by some chemical transformations. The chemotaxonomic situation is briefly discussed. The constituents of the Carterothamnus species show a distinct differentiation to those of the neighbouring groups; however, in addition they also indicate some relationships.     

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.     

Montafrusin,a new germacrolide from Montanoa frutescens

The investigation of Montanoa frutescens afforded a new sesquiterpene lactone of the germacrolide type, montafrusin, besides the known diterpenes kaurenic acid and its 15α-isovalerate.     

Neue diterpene aus Schkuhria-arten

The investigation of two further Schkuhria species afforded, in addition to several known compounds, three new diterpenes from the labdane series of the manoyl oxide type. The structures were elucidated by spectroscopic methods and by some chemical transformations, although the absolute configuration and that at C-13 could not be established with certainty. Furthermore a new thymol derivative was obtained. The chemotaxomonic situation is discussed briefly.     

Neue labdan-derivate aus Aristeguietia buddleaefolia

The aerial parts of Aristeguietia buddleaefolia afforded, in addition to known compounds, three new diterpenes, all being 12, 13-E-abienol derivatives. A further diterpene turned out to be jhanidiol-18-O-acetate, isolated earlier from an Ageratina species. Furthermore two derivatives of hydroxy dihydroconiferyl alcohol are present. The structures were elucidated by spectroscopic methods and by some chemical transformations.     

Neue diterpene aus der subtribus espeletiinae

The investigation of several species from the newly created subtribe Espeletiinae afforded in addition to known compounds seven new diterpenes and two norditerpenes. The structures were elucidated by intensive ¹H-NMR studies. The chemotaxonomic situation is discussed briefly.     

Labdane derivatives from hemizonia species

The investigation of three Hemizonia species afforded in addition to known compounds seven new labdane derivatives, all derived from labd-13-en-15-ol. The absolute configuration of these diterpenes was determined by degradation of the triol by periodate cleavage, which afforded a known norditerpene ketone. From H. fitchii two new chromene esters and the cis-isomer of a known coumarate were isolated. H. congesta afforded in addition to labdane derivatives a hydroxycubebol.     

Sesquiterpenlactone und polyine aus der gattung Arctotis

The South African genus Arctotis contains two polyynes sometimes together with diterpenes and sesquiterpene lactones, four of which are new. The structures have been elucidated by spectroscopic methods.     

Eudesmane derivatives from Verbesina species

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.     

Diterpenoids from Baccharis tola

Erythroxylol-A, oleanolic acid, erythroxylol-A oxide, scopolatine, 4-hydroxy-3-methoxyacetophenone and two new diterpenes, ent-beyer-14-en-18-ol and 19-hydroxy-13-epimanoyl oxide, were isolated from B. tola.     

Weitere diterpene mit helifulvan-gerüst und andere inhaltsstoffe aus Helichrysum chionosphaerum

The aerial parts of Helichrysum chionosphaerum afforded, in addition to known compounds, a humulene alcohol, an abietane derivative, atisirenic acid and two further representatives of a new class of diterpenes. The structure of the basic acid, named helifulvanic acid, was elucidated by NMR studies and by X-ray analysis. The chemotaxonomic importance of these diterpenes is discussed briefly.     

Gutierrezial and further diterpenes from Gutierrezia sarothrae

The aerial parts of Gutierrezia sarothrae afforded in addition to polyalthic acid, daniellic acid and nivenolide, 14 new diterpenes, most of them closely related to polyalthic acid. One of these compounds has a new carbon skeleton. The structures were elucidated by spectroscopic methods and by some chemical transformations.     

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.     

Chromones and flavans from Marshallia obovata

An investigation of Marshallia obovata afforded, in addition to known thymol derivatives, one new ester. Furthermore six new chromone derivatives, all prenylated, were present together with the known spathelia chromene. The main constituent was a flavan already isolated from M. grandiflora but five new flavans were also isolated. Besides other widespread compounds a tetraester of inositol was isolated in minute amounts. All the structures were elucidated by spectroscopic methods or chemical transformations. Surprisingly, even the main 4-methoxyflavan could be split by periodic acid.     

Diterpene glycosides and other constituents from argentinian baccharis species

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

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.     

Four new cassane diterpenes from the seeds of Caesalpinia minax

In our survey on the chemical composition of traditional Chinese medicines to further elucidate their chemical substances for the treatment of diseases, we investigated the chemical constituents of the seeds of plants Caesalpinia minax. The investigation led to the isolation and identification of four new cassane diterpenes, caesalpines A–D (1–4). Their structures were elucidated on the basis of extensive 1D and 2D NMR (COSY, HMQC, HMBC, and NOESY) and mass (ESIMS and HR-ESIMS) spectroscopic data analyses. The phytochemical results imply that cassane diterpenes are maybe regarded as the characteristic constituents of C. minax.     

Ein neues germacran-8.12-olid und neue diterpene aus Polymnia canadensis

The aerial parts of P. canadensis afforded a new germacran-8,12-olide and several diterpenic acids. The stereochemistry of the lactone could be established only by careful ¹H NMR investigations of the corresponding pyrazolines formed by addition of diazomethane, while the natural compound and its acetate only show very uncharacteristic NMR spectra. The diterpenes all belong to the rare isokaurene type. The chemotaxonomic aspects are 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.