- Sesquiterpenes from the essential oil of the liverwort Conocephalum conicum
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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.
- Melching, Stephanie,Koenig, Wilfried A.
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- Ene-Ene-Retroene Conversion of (-)-β-Pinene to (+)-β-Selinene
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(-)-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.
- Moore, Lionel,Gooding, David,Wolinsky, Joseph
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- Absolute configuration of helminthogermacrene
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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.
- Adio, Adewale Martins,Paul, Claudia,Tesso, Hailemichael,Kloth, Petra,Koenig, Wilfried A.
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- Antimutagenic activity of (+)-β-eudesmol and paeonol from Dioscorea japonica
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A methanol extract from Dioscorea japonica showed a suppressive effect on umu gene expression of the SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (furylfuramide). The methanol extract from D. japonica was reextracted with dichloromethane, n-butanol, and water, respectively. The suppressive compounds in the dichloromethane extract fraction were isolated by SiO2 column chromatography and identified as (+)-β-eudesmol and 2-hydroxy-4-methoxyacetophenone (paeonol) by EI-MS and 1H and 13C NMR spectroscopy. (+)-β-Eudesmol suppressed the SOS-inducing activity of furylfuramide in the umu test. Gene expression was suppressed 80% at 50 value was 0.09 μmol/ mL. Paeonol also suppressed the SOS-inducing activity of furylfuramide in the umu test. Gene expression was suppressed 60% at 50 value was 0.99 μmol/mL. (+)-β-Eudesmol and paeonol were assayed with the mutagen 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), which requires liver metabolizing enzymes, and showed suppressive effects on the SOS induction of the mutagen. (+)-β-Eudesmol suppressed gene expression 48% at 50 was 0.41 μmol/mL. The antimutagenic activities of these compounds against furylfuramide and Trp-P-1 were tested by an Ames test using S. typhimurium TA100, which indicated that these compounds showed antimutagenic activity.
- Miyazawa, Mitsuo,Shimamura, Hideo,Nakamura, Sei-Ichi,Kameoka, Hiromu
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- Germacrenes from fresh costus roots
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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.
- De Kraker, Jan-Willem,Franssen, Maurice C.R,De Groot, Aede,Shibata, Toshiro,Bouwmeester, Harro J
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p. 481 - 487
(2007/10/03)
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- Structures and spasmolytic activities of derivatives from sesquiterpenes of Alpinia speciosa and Alpinia japonica
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Sesquiterpenes isolated from Alpinia speciosa and Alpinia japonica, and their derivatives were found to inhibit histamine- or barium chloride- induced contraction of excised guinea pig ileum when tested by the Magnus method. Major spasmolytic principles contained in those extracts were the sesquiterpenes, β-eudesmol, nerolidol, humulene epoxide II and 4α- hydroxydihydroagarofuran. Relationships between the chemical structures of the sesquiterpenes and their derivatives, and their spasmolytic activities were discussed.
- Morita, Makoto,Nakanishi, Hiroshi,Morita, Hiroshi,Mihashi, Susumu,Itokawa, Hideji
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p. 1603 - 1606
(2007/10/03)
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- Identification of the Bicyclic Sesquiterpenes Drimane and Eudesmane in Petroleum
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Drimane and Eudesmane have been identified in Petroleum; eudesmane is formed from higher plant precursors while drimane is probably derived from microbial source.
- Alexander, Robert,Kagi, Robert,Noble, Rohinton
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p. 226 - 228
(2007/10/02)
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- BIOMIMETIC CYCLIZATION OF HEDYCARYOL DERIVATIVES. UNEXPECTED CYCLIZATION OF PHENYL SULFIDES WITH METHYL IODIDE
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Four isomeric hedycaryol phenyl sulfides, when reacted with MeI, yielded eudesmol derivatives with different stereochemistry from that of the acid cyclization products of the corresponding hedycaryols.New stereoisomers of α- and β-eudesmols, β-dehydroparadisiol and a defensive substance of termite were synthesized.Nephthenol phenyl sulfide yielded a 14-membered tetraene.
- Kodama, Mitsuaki,Shimada, Kazuaki,Ito, Sho
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p. 1523 - 1526
(2007/10/02)
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