- First enantioselective total syntheses and absolute configurations of 4,5-dioxo-seco-γ-eudesmol and 5β,11-dihydroxyiphionan-4-one, two aglycones of naturally occurring sesquiterpenes with new skeletons
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A facile synthetic route to two new carbon skeleton sesquiterpenes 4,5-dioxo-seco-γ-eudesmol and 5β,11-dihydroxyiphionan-4-one from (+)-dihydrocarvone has been described. The configuration of the 5β,11-dihydroxyipbionan-4-one was confirmed by stereospecific synthesis.
- Gao,Xiong,Zhou,Li
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- Total synthesis of neohedycaryol. Its possible role in the biosynthesis of eudesmane sesquiterpenes
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The total synthesis of neohedycaryol (4), the C(9)-C(10) double bond regioisomer of the germacrane sesquiterpene hedycaryol, was accomplished in 10 steps from the known dione 6. A Marshall fragmentation of the intermediate mesylate 14 was used to prepare the trans,trans-cyclodeca-1,6-diene ring present in neohedycaryol. During the synthesis of 14, a pronounced example of through-bond interactions (TBI) was observed. The preferred elongated chair conformation of neohedycaryol was demonstrated spectroscopically and by chemical conversion into α-, β-, and γ-eudesmol. These findings indicate that the occurrence of neohedycaryol as a precursor in the biosynthesis of epi-eudesmanes as proposed in the literature is unlikely. The preference of neohedycaryol for the elongated chair conformation further shows that the compound occupies the meso form. This implies that neohedycaryol may act as a precursor in the biosynthesis of both ent- and usual eudesmanes.
- Minnaard, Adriaan J.,Stork, Gerrit A.,Wijnberg, Joannes B.P.A.,De Groot, Aede
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p. 2344 - 2349
(2007/10/03)
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- Biotransformation of (+/-)-4,8-dimethylcyclodeca-3(E),7(E)-dien-1β-ol and (+)-Hedycaryol by Cichorium intybus
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The biotransformation of the synthetic (E,E)-1,5-cyclodecadienol 5 and (+)-hedycaryol (11) by a root suspension of fresh chicory has been investigated.Incubation of 5 with a root suspension gave a 2:1 mixture of epimeric eudesmanediols 7a and 7b whereas 11 was selectively converted into cryptomeridiol (12).An explanation for the obtained results is proposed.
- Piet, Dennis P.,Minnaard, Adriaan J.,Heyden, Karel A. van der,Franssen, Maurice C. R.,Wijnberg, Joannes B. P. A.,Groot, Aede de
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p. 243 - 254
(2007/10/02)
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- The Synthesis of (+)-Hedycaryol, Starting from Natural (-)-Guaiol
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Starting from the readily available (-)-guaiol the germacrane sesquiterpene (+)-hedycaryol can be synthesized in a 7 steps reaction sequence in an overall yield of 16percent.Additionally, (+)-γ-eudesmol has been synthesized, also starting from (-)-guaiol. - Key Words: sesquiterpenes, germacrane, eudesmane, cadinane, γ-eudesmol.
- Minnaard, Adriaan J.,Wijnberg, Joannes B. P. A.,Groot, Aede de
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p. 4755 - 4764
(2007/10/02)
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- NEUROTROPHIC SESQUITERPENE-NEOLIGNANS FROM MAGNOLIA OBOVATA: STRUCTURE AND NEUROTROPHIC ACTIVITY
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Novel sesquiterpene-neolignans, eudesobovatols A (1) and B (2), eudesmagnolol (3), eudeshonokiols A (4) and B (5), clovanemagnolol (6), and caryolanemagnolol (7), have been isolated from the bark of Magnolia obovata.Their structures were elucidated to be sesquiterpenes (eudesmol, 4,4,8-trimethyltricyclo2,5>dodecane-1,9-diol, and clovanediol) combined through ether bond with neolignans such as obovatol, honokiol, and magnolol on the basis of spectral data, degradation, and/or synthesis.Compounds 1, 6, and 7 were found to exhibit interesting neurotrophic activity on a neuronal cell culture system derived from fetal rat hemisphere.
- Fukuyama, Yoshiyasu,Otoshi, Yukio,Miyoshi, Kumi,Nakamura, Kazuhiko,Kodama, Mitsuaki,et al.
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p. 377 - 392
(2007/10/02)
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- Acid-catalyzed Rearrangement of Hinesol and Related Compounds to Eudesmane Derivatives
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Acid-catalyzed rearrangement of hinesol α-epoxide (5a) gave 1α-hydroxyeudesmols (9, 10, 11) together with other spirane-type products (6, 8, 14).The same reaction of α- and β-epoxides of hinesol acetate also provided eudesmane derivatives.These results and mechanistic considerations led us to re-examine the formic acid dehydration reaction of hinesol and it was found that the main product does not have the structure 3 or 4 as assumed by Marshall et al., but is identical with (+)-δ-selinene (21).
- Itokawa, Hideji,Nakanishi, Hiroshi,Mihashi, Susumu
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p. 1991 - 1997
(2007/10/02)
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