- The role of germacrene D as a precursor in sesquiterpene biosynthesis: Investigations of acid catalyzed, photochemically and thermally induced rearrangements
-
Germacrene D is considered as a precursor of many sesquiterpene hydrocarbons. We have investigated the acid catalyzed as well as the photochemically and thermally induced rearrangement processes of germacrene D isolated from several Solidago species, which contain both enantiomers of germacrene D. Enantiomeric mixtures of sesquiterpenes of the cadinane, eudesmane (selinane), oppositane, axane, isodaucane, and bourbonane group as well as isogermacrene D were identified as main products and made available as reference compounds for structure investigations and stereochemical assignments of plant constituents. δ-Amorphene, one of the rearrangement products, was identified as a natural product for the first time. The absolute configuration of γ-amorphene was revised by correlation with the absolute configuration of germacrene D. The mechanisms of the rearrangement reactions are discussed. (C) 2000 Elsevier Science Ltd.
- Buelow, Nils,Koenig, Wilfried A
-
p. 141 - 168
(2007/10/03)
-
- Annulation by Sequential Doubla Michael Reaction; Synthesis of Decalones and Its Application to the Syntheses of ε-Cadinene, Khusitone and Khusilal
-
Reaction of kinetic enolates or the trimethylsilyl enol ethers of 1-acetylcyclohexenes with α,β-unsaturated carbonyl compounds affords 4-substituted 1-decalone derivatives under basic or Lewis acidic conditions.The reaction with acrylates of chiral alcohols has achieved 70percent diastereoselection.Application of these reactions has enabled syntheses of ε-cadinene, khusitone and khusial to be accomplished.
- Hagiwara, Hisahiro,Akama, Tsutomu,Okano, Akihiro,Uda, Hisashi
-
p. 2173 - 2184
(2007/10/02)
-
- Lewis Acid Assisted Annelation of Trimethylsilyl Enol Ethers of 1-Acetylcyclohexenes with α,β-Unsaturated Carbonyl Compounds to give Substituted 2-Decalones; Synthesis of (+/-)-ε-Cadinene
-
The trimethylsilyl enol ethers of 1-acetylcyclohexenes undergo a Lewis-acid-assisted one-pot annelation reaction with α,β-unsaturated carbonyl compounds to produce 5-substituted 2-decalones; the application of this reaction has enabled a synthesis of (+/-)-ε-cadinene (12).
- Hagiwara, Hisahiro,Okano, Akihiro,Akama, Tsutomu,Uda, Hisashi
-
p. 1333 - 1335
(2007/10/02)
-
- Stereoisomeric ε-Dienes of the Cadalane Series: Synthesis and Configurational Correlation
-
rac-ε-Cadinene (1) and rac-ε-amorphene (4) were prepared by Wittig reaction of the diketones 9 and 10, obtained by ?-cyclization (7->8), and alternatively from the keto alcohols 11b and 12b. rac-ε-bulgarene (3) was prepared from the ene-ol 15b, available from 11b by Wittig reaction via epimerization.The ketones 10 and 12b are not epimerizable, so rac-ε-muurolene (2) was obtained from the enone 24, accessible by Diels-Alder reaction (21 + 22 ->23). - Configurational assignments of 1 - 4 and of the bicyclic precursors are confirmed by the 13C-NMR spectra supported by 2D-INADEQUATE experiments.
- Koester, Frank-Hinrich,Wolf, Herbert,Kluge, Heinz
-
-
- CHEMISTRY OF THE ORGANOSILICON COMPOUNDS-165 2-TRIMETHYLSILYL-METHYL-1, 3-BUTADIENE-A VERSATILE BUILDING BLOCK FOR TERPENE SYNTHESIS
-
Two types of synthetically useful reactions of 2-trimethylsilylmethyl-1,3-butadiene (7) are discussed.Reactions of 7 with acid chlorides, aldehydes, ketones and acetals activated by a Lewis acid give isoprenylated compounds, while 7 undergoes the Diels-Alder reaction whit dienophiles.High regiospecificity of the reaction qualifies 7 for a versatile building block of terpene synthesis.
- Sakurai, Hideki,Hosomi, Akira,Saito, Masaki,Sasaki, Koshi,Iguchi, Hirokazu,et al.
-
p. 883 - 894
(2007/10/02)
-