- Further explorations into the synthesis of Dehydro-Hedione
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Dehydrohedione (DHH) 1 may be obtained in 20% overall yield by a Reformatsky reaction with enone methyl ether 3b, followed by acidic workup of the crude reaction mixture. Alternatively, epoxidation (3-chloroperbenzoic acid, CH2Cl2, 84% yield) of the tertiary allyl alcohol derivative 4 affords a 1: 2 mixture of 8a and 8b. The latter epoxy ester 8b may also be obtained stereoselectively either from 4 (tBuO2H, [Mo(CO)6], 1,2-dichloroethane, 70°, 62% yield; or tBuO2H, [VO(acac)2], decane, 20°, 92% yield), or from 5 (AcOMe, LiN(SiMe3)2, THF, -78°, 84-87%). BF3×Et2O-Catalyzed cascade rearrangement and OH elimination of 8a afford selectively DHH 1 in 88% yield. The cis disposition of the side chains of the weakly odoriferous hedione-like analogues 2b and 2c was maintained by means of either an epoxy or a cyclopropane moiety. Copyright
- Winter, Béat,Chapuis, Christian,Brauchli, Robert,De Saint Laumer, Jean-Yves
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p. 246 - 258
(2013/03/28)
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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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- Electroorganic Chemistry. 140. Electroreductively Intra- and Intermolecular Couplings of Ketones with Nitriles
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Electroreduction of γ- and δ-cyano ketones in i-PrOH with Sn cathode gave α-hydroxy ketones and their dehydroxylated ketones as the intramolecularly coupled products.Guaiazulene, (-)-valeranone, polyquinanes, dihydrojasmone, methyl dihydrojasmonate, and rosaprostol have been synthesized by utilizing this electroreductive intramolecular coupling of γ- and δ-cyano ketones in one of the key steps.Similarly, electroreduction of a mixture of ketone and nitrile gave the corresponding intermolecularly coupled product.The product obtained by the electroreductive intermolecular coupling of (+)-dihydrocarvone with acetonitrile has been found to be the precursor of an effective chiral ligand for the enantioselective addition of diethylzinc to aldehydes.
- Shono, Tatsuya,Kise, Naoki,Fujimoto, Taku,Tominaga, Naoto,Morita, Hiroshi
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p. 7175 - 7187
(2007/10/02)
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- Synthesis of 12-Oxophytodienoic Acid (12-OxoPDA) and the Compounds of its Enzymic Degradation Cascade in Plants, OPC-8:0, -6:0, -4:0 and -2:0 (epi-Jasmonic Acid), as their Methyl Esters
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The synthesis of 12-Oxophytodienoic acid, and the compounds of its enzymatic degradation sequence, OPC-8:0, -6:0, -4:0 and -2:0, important plant metabolites derived from linolenic acid, is reported.The syntheses use the known cyclopent-3-ene-1,2-diacetic acid as an early intermediate, and this is derived from the Cope rearrangement of 5-vinyltrinorborn-2-ene via bicyclonona-3,7-diene.Iodolactonisation and tributyltin hydride reduction provides the key intermediate (3-oxo-2-oxabicyclooctan-6-yl)acetic acid for the OPC series, whilstphenylselenolactonisation and elimination provides the necessary unsaturated lactone (7-oxo-8-oxabicyclooct-2-en-4-yl)acetic acid for 12-oxoPDA.Members of the OPC-series were made by chain extending the saturated oxabicyclooctane acid: that for the OPC-4:0 involved double Arndt-Eistert reaction, whilst the intermediates for OPC-6:0 and -8:0 were made by Kolbe anodic crossed coupling.The lactones were than converted via their lactols, Wittig reaction, esterfication and oxidation, into the compounds of the OPC ester series, including OPC-2:0 (methyl epi-jasmonate).The unsaturate lactone 8-(7-oxo-8-oxabicyclooct-2-en-4-yl)octanoic acid required for 12-oxoPDA synthesis could also be prepared by anodic synthesis either from (7-oxo-8-oxa-bicyclooct-2-en-4-yl)acetic acid, or from its 2-phenylseleno-2,3-dihydro precursor as elimination occurred concomitantly during the reaction.Since yields were low, the unsaturated acid lactone was converted into its lactol and the (Z)-pent-2-enyl side-chain was inserted first.After TBDMS blocking of the cyclopentene hydroxy group, the side-chain was elaborated to give5-(pent-2-enyl)cyclopent-2-enylacetaldehyde and chain extension carried out by a Grignard-demesylation procedure.Sequential desilylation and depyranylation, followed by oxidation of the diol, gave 12-oxoPDA, isolated as its methyl ester.
- Crombie, Leslie,Mistry, Kamlesh M.
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p. 1981 - 1991
(2007/10/02)
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- ELECTROREDUCTIVE INTRAMOLECULAR COUPLING OF γ- AND δ-CYANOKETONES
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Electroreduction of γ- and δ-cyanoketones in i-PrOH gave cyclized products α-hydroxyketones and their dehydroxylated ketones, and this reaction was applied to the synthesis of dihydrojasmone, methyl dihydrojasmonate, and Rosaprostol.
- Shono, Tatsuya,Kise, Naoki
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p. 1303 - 1306
(2007/10/02)
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- METABOLISM OF THE PLANT GROWTH REGULATOR DIHYDROJASMONIC ACID IN BARLEY SHOOTS
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Key Word Index--Hordeum vulgare; Gramineae; barley; (+/-)-9,10-dihydrojasmonic acid metabolism; (-)-9,10-dihydro-11ξ-hydroxyjasmonic acid; (-)-9,10-dihydro-12-hydroxyjasmonic acid; (-)-9,10-dihydro-11-ξ-hydroxyjasmonic acid O(11)-β-D glucopyranoside.Abstract--The biotransformation of (+/-)-9,10-dihydrojasmonic acid (DJA) was studied in six-day-old barley seedlings.Both and DJA were fed to excised shoots and the formed metabolites analysed after 72 hr.DJA was converted into two major and some minor metabolites, purified by chromatographic methods.The major metabolites were identified mainly by spectroscopic investigations as (-)-9,10-dihidro-11ξ-hydroxyjasmonic acid and its O(11)-β-D-glucopyranoside.To a lesser extent (-)-9,10-dihydro-12-hydroxyjasmonic acid was also found.
- Meyer, Angelika,Gross, Dieter,Vorkefeld, Sabine,Kummer, Monika,Schmidt, Juergen,et al.
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p. 1007 - 1012
(2007/10/02)
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- Syntheses of Jasmone, Jasmonic Acid and some Analogues from Alkyne-cobalt Complexes via the Khand Reaction.
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The Khand reactions of the hexacarbonyldicobalt complexes of 2-octyne and of Z-oct-5-en-2-yne with ethylene lead directly to jasmone and dihydrojasmone. 2-Pentyl- and Z-2-pentenylcyclopent-2-en-1-one, known intermediates in the synthesis of jasmonic and dihydrojasmonic acid or their esters, have been obtained similarly from 1-heptyne and hept-4-en-1-yne respectively.These and related cyclopentenones have been converted into new analogues of methyl jasmonate, of interest as potential plant growth regulators.
- Billington, David C.,Bladon, Peter,Helps, I. Malcolm,Pauson, Peter L.,Thomson, William,Willison, Debra
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p. 2601 - 2623
(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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- Convenient Synthesis of Jasmonoid Compounds from γ-(Trimethylsiloxy)butyronitrile
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1,4-Dioxygenated compounds 4 are constructed by the addition of a Grignard reagent to γ-(trimethylsiloxy)nitriles 1,2, and 3 and subsequent hydrolysis.Oxidation of 4 with pyridinium chlorochromate or Jones reagent yields compounds 5 which are used to produce cyclopentenones 6.Methyl jasmonate and methyl dihydrojasmonate are made by the conjugate addition of silylated ketene acetal 9 to 6a and 6b, respectively, and subsequent protodesilylation. γ-Jasmolactone is also derived from 4a by oxidation with pyridinium dichromate in DMF followed by reduction with NaBH4 in ethanol.
- Matsuda, Isamu,Murata, Shizuaki,Izumi, Yusuke
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p. 237 - 240
(2007/10/02)
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