17066-67-0Relevant articles and documents
Sesquiterpenes from the essential oil of the liverwort Conocephalum conicum
Melching, Stephanie,Koenig, Wilfried A.
, p. 517 - 523 (1999)
Three new brasilane type sesquiterpenes related to the known alcohol conocephalenol and the sesquiterpene alcohol presilphiperfolan-1-ol were isolated from a chemotype of the liverwort Conocephalum conicum collected in southern Germany and identified by NMR investigations, enantioselective gas chromatography and chemical correlations. In addition ent-(-)-dactylol, the enantiomer of a compound so far only found as a constituent of the Caribbean sea hare Aplysia dactylomela, was identified.
Ene-Ene-Retroene Conversion of (-)-β-Pinene to (+)-β-Selinene
Moore, Lionel,Gooding, David,Wolinsky, Joseph
, p. 3750 - 3754 (1983)
(-)-β-Pinene undergoes an ene reaction with acryloyl chloride at 70 deg C to afford 6,6-dimethylbicyclohept-2-ene-2-butanoyl chloride (2) in better than 80percent yield.Cyclization of 2 to 10,10-dimethyltricyclo2,7>undec-2(7)-en-6-one (4) by way of an intramolecular ene reaction involving a ketene intermediate occurs on heating with tributylamine at 150 deg C.Unsaturated ketone 4 undergoes a clean retroene reaction to yield (+)-7-(2-propenyl)-Δ9-decal-1-one (11) on brief heating at 265 deg C.Lithium dimethylcuprate addition to 11 yields a mixture of four isomeric 7-(2-propenyl)-10-methyl-1-decalones (15-18) where the isomers having the desired cis relationship between the angular methyl and the 2-propenyl groups comprise ca. 75percent of the product.Treatment of the ketone mixture with methylenetriphenylphosphorane completes the synthesis of (+)-β-selinene.
Absolute configuration of helminthogermacrene
Adio, Adewale Martins,Paul, Claudia,Tesso, Hailemichael,Kloth, Petra,Koenig, Wilfried A.
, p. 1631 - 1635 (2004)
The absolute configuration of the sesquiterpene hydrocarbon helminthogermacrene is established. Helminthogermacrene is an (E,Z)-configurational isomer of germacrene A and thus undergoes similar transformations forming elemenes via Cope rearrangement and yielding bicyclic systems via acid catalyzed reactions. The reaction products are investigated using enantioselective GC and extensive NMR measurements (1H-; 1H1H-COSY; HSQC; HMBC and NOE-experiments). In addition, NMR data of related compounds isolated during the course of this investigation not yet reported in literature are given.
Germacrenes from fresh costus roots
De Kraker, Jan-Willem,Franssen, Maurice C.R,De Groot, Aede,Shibata, Toshiro,Bouwmeester, Harro J
, p. 481 - 487 (2007/10/03)
Four germacrenes, previously shown to be intermediates in sesquiterpene lactone biosynthesis, were isolated from fresh costus roots (Saussurea lappa). The structures of (+)-germacrene A, germacra-1(10),4,11(13)-trien-12-ol, germacra-1(10),4,11(13)-trien-12-al, and germacra-1(10),4,11(13)-trien-12-oic acid were deduced by a combination of spectral data and chemical transformations. Heating of these compounds yields (-)-β-elemene, (-)-elema-1,3,11(13)-trien-12-ol, (-)-elema-1,3,11(13)-trien-12-al, and elema-1,3,11(13)-trien12-oic acid respectively, in addition to small amounts of their diastereomers. Acid induced cyclisation of the germacrenes yields selinene, costol, costal, and costic acid respectively. It is highly probable that the elemenes reported in literature for costus root oil are artefacts.
