- Behaviour of monocomplexed 1,4-diynes in the Khand reaction and use of ethylene equivalent techniques in a convenient route to tritium-labelled methyl jasmonate
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1,2-Complexed hexacarbonyl(hepta-1,4-diyne)dicobalt, obtained from hexacarbonyl(propargyl acetate)dicobalt with tri-1-butynylaluminium, has been converted, by selective Khand annulation of the complexed triple bond with vinyl benzoate, to 2-pent-2-yn-1-ylcyclopent-2-en-1-one. By use of standard procedures this alkynyl cyclopentenone has been transformed into methyl jasmonate, allowing replacement of the final hydrogenation step by tritiation to produce the labelled analogue. Two alternative approaches to the intermediate pentynylcyclopentenone were examined and shown to be unsuccessful.
- Kerr, William J.,McLaughlin, Mark,Pauson, Peter L.
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p. 118 - 124
(2007/10/03)
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- Synthesis of (±)-methyl epijasmonate and (±)-methyl dihydroepijasmonate by diastereoselective protonation
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The synthesis of (±)-methyl epijasmonate (1) was carried out by Michael addition of lithium diallylcuprate to enone 3 and diastereoselective enolate protonation with the chelating proton source 2-(methyliminomethyl)phenol (4; 85% ds), followed by ozonolysis, oxidation, esterification, and Lindlar hydrogenation. During the ozonisation, epimerization to the thermodynamically more stable trans-isomer takes place to some extent, so that 1 was isolated with a cis:trans ratio of 72:28. The analogous transformation of enone 7 with lithium diallylcuprate and 2-(methyliminomethyl)phenol (4) furnished ketone 8 with 94% ds; this was then transformed into (±)-methyl dihydroepijasmonate (2) with a cis:trans ratio of 91:9. The olfactory properties of this product are superior to those available from commercial sources.
- Krause, Norbert,Ebert, Sophia
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p. 3837 - 3841
(2007/10/03)
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- Structural separation of biological activities of jasmonates and related compounds
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A wide range of compounds derived from the basic structure of jasmonic acid, when tested for biological activity in different bioassays (Eschscholzia californica elicitation, Bryonia dioica tendril coiling, tomato transpiration and senescence and barley senescence assays) display, in each of the assays, an activity profile that is distinctly characteristic and different between assays. While differences in uptake, metabolism and/or sequestration of the compounds may account for some of the effects observed, the data allow the conclusion that structural requirements are also different for different physiological responses regulated by jasmonates. While jasmonic acid itself is active in all assays employed, some of the compounds tested in our study display a much narrower range of biological effects. Thus, tailoring of jasmonate analogues for specific applications and lacking undesirable side effects should be possible.
- Blechert, Siegfried,Bockelmann, Christian,Bruemmer, Oliver,Fuesslein, Martin,Gundlach, Heidrun,Haider, Georg,Hoelder, Swen,Kutchan, Toni M.,Weiler, Elmar W.,Zenk, Meinhart H.
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p. 3549 - 3559
(2007/10/03)
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- Preparation of (±)-2-(2,3-2H2) jasmonic acid and its methyl ester, methyl (±)-2-(2,3-2H2)jasmonate
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For use as the internal standards in a quantitative analysis of natural jasmonic acid (JA) and methyl jasmonate (JAMe) by gas chromatography-mass spectrometry-selected ion monitoring, (±)-2-(2,3-2H2)JA and its methyl ester, (±)-2-(2,3-2H2)JAMe, were efficiently prepared from 2-(2-pentyl)- 2-cyclopentenone through catalytic semi-deuteriogenation of acetylenic intermediates with deuterium gas in pyridine.
- Seto,Fujioka,Fujisawa,Goto,Nojiri,Yamane,Yoshida
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p. 1709 - 1711
(2007/10/03)
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- CONJUGATE ADDITION OF LITHIOTRIMETHYLSILYLACETATE. A SIMPLE SYNTHESIS OF METHYL JASMONATE VIA VICINAL DOUBLE ALKYLATION
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Exceptional conjugate addition of methyl lithiotrimethylsilylacetate to cyclopentenone has been found and can be applied to a convenient synthesis of methyl jasmonate by sequential vicinal double alkylation via succesful stannyl enolate trapping.
- Nishiyama, Hisao,Sakuta, Koji,Itoh, Kenji
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p. 2487 - 2488
(2007/10/02)
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- Keten Silyl Acetal Chemistry; Simple Synthesis of Methyl Jasmonate and Related Compounds by Utilising Keten Methyl Dimethyl-t-butylsilyl Acetal
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Conjugate addition of keten silyl acetals to α,β-unsaturated carbonyl compounds in acetonitrile gave a quantitative yield of the corresponding methyl (3-trialkylsiloxyalk-2-enyl)acetates; subsequent site-specific electrophilic substitution yielded the corresponding 2-substituted 3-(alkoxycarbonylmethyl)alkanones.These novel addition and sequential alkylation reactions could be applied to a simple synthesis of methyl jasmonate, methyl didehydrojasmonate, and methyl dihydrojasmonate.
- Kita, Yasuyuki,Segawa, Jun,Haruta, Jun-ichi,Yasuda, Hitoshi,Tamura, Yasumitsu
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p. 1099 - 1104
(2007/10/02)
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- An Efficient Synthesis of Methyl Jasmonate and Methyl Dihydrojasmonate
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A simple and an efficient synthesis of methyl jasmonate (1) and methyl dihydrojasmonate (5) is described.Starting from alkyl acetoacetate or acetonedicarboxylate, 1 and 5 were obtained in only a few steps via intramolecular Michael addition.
- Kitahara, Takeshi,Mori, Kenji,Matsui, Masanao,Iwamoto, Minoru,Takagi, Yoshikazu,Warita, Yasuhiro
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p. 1369 - 1376
(2007/10/02)
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- An Efficient Synthesis of Methyl dl-cis-Jasmonate
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An efficient synthesis of methyl dl-cis-jasmonate is described, starting from the previously described 2-(methoxycarbonyl)-3-cyclopentanone (3), itself easily prepared from succinyl chloride and methyl potassium malonate.Alkylation of 3 with 1-bromo-2-pentyne followed by selective removal of the 2-carbomethoxy group gave dehydrojasmonic acid.On esterification and reduction (H2/Pd/C/pyridine) of the triple bond to the cis olefin, dehydrojasmonic acid afforded methyl dl-cis-jasmonate in 40percent overall yield from succinyl chloride.
- Johnson, Francis,Paul, Kenneth G.,Favara, D.
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p. 4254 - 4255
(2007/10/02)
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