39924-52-2Relevant articles and documents
Synthesis of cis-Hedione and methyl jasmonate via cascade Baylis-Hillman reaction and Claisen ortho ester rearrangement
Chapuis, Christian,Buechi, George H.,Wueest, Hans
, p. 3069 - 3088 (2007/10/03)
The exocyclically unsaturated conjugated keto esters 10, obtained via a Claisen ortho ester rearrangement of the allylic hydroxy ketones 9, were either directly hydrogenated or partially isomerized into the endocyclically unsaturated tetrasubstituted didehydrojasmonoid intermediates 14, prior to a more selective hydrogenation with Pd/C in cyclohexane to the disubstituted oxocyclopentaneacetates 15 (Scheme 2). The key intermediates 9 were obtained either by a four-step sequence, including acetal protection/deprotection from enone 1, in the specific case of hydroxy ketone 9a (Scheme 1), or more directly and generally by a Baylis-Hillman reaction from cyclopent-2-en-1-one (16) and the appropriate aldehydes 17 (Scheme 2). The judicious choice of these aldehydes opens versatile modifications for the stereoselective introduction of the partially cis- or epimerized trans-C(2) jasmonoid side chain, while the Baylis-Hillman reaction, catalyzed by chiral [1,1′-binaphthalene]-2, 2′-diols (BINOLs) 19 (Scheme 3), may be efficiently conducted in a one-pot cascade fashion including the ortho ester Claisen rearrangement.
Synthesis of (±)-methyl epijasmonate and (±)-methyl dihydroepijasmonate by diastereoselective protonation
Krause, Norbert,Ebert, Sophia
, p. 3837 - 3841 (2007/10/03)
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.
Synthesis of methyl epijasmonate and cis-3-(2-oxopropyl)-2-(pent-2Z-enyl)-cyclopentan-1-one
Hailes, Helen C,Isaac, Ben,Hashim Javaid
, p. 10329 - 10333 (2007/10/03)
A novel and efficient synthesis of both (±)-methyl epijasmonate and (±)-cis-3-(2-oxopropyl)-2-(pent-2Z-enyl)-cyclopentan-1-one is described. The key step to establish the cis-stereochemistry on the 5-membered ring is an ionic Diels-Alder reaction, which is high yielding and highly regioselective. Subsequent key steps include oxidative cleavage of the six-membered ring, Wittig coupling and for the synthesis of epijasmonate, the haloform reaction.
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
Kerr, William J.,McLaughlin, Mark,Pauson, Peter L.
, p. 118 - 124 (2007/10/03)
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.
Stereochemical Control over Three Contiguous Stereogenic Centers in the Intramolecular Ene Reaction of Activated 1,6-Dienes. Application to the Synthesis of (±)-Methyl Cucurbate and (±)-Methyl Epijasmonate
Sarkar, Tarun K.,Ghorai, Binay K.,Nandy, Sandip K.,Mukherjee, Bireswar,Banerji, Asoke
, p. 6006 - 6011 (2007/10/03)
The influence of a protected alcohol group adjacent to the ene or enophile component on diastereoselectivity in both thermal and Lewis acid-catalyzed 5-(3,4) ene reactions of a series of 1,6-dienes 1-7 has been studied. The results indicate that its effect can be considerable, and in one example, with a gem-dimethyl group on the connecting chain and a large silyl protecting group on the hydroxyl, the diastereocontrol was almost perfect, with three stereogenic centers and one double bond geometry set up in one step, e.g., 4 → 10. This new finding was exploited in a synthesis of epijasmonoid natural products, (±)-methyl cucurbate (19) and (±)-methyl epijasmonate (18) starting from aldehyde 24, where the key step was a highly diastereocontrolled 5-(3,4) ene cyclization 23 → 22. 1 Indian Institute of Technology 2 BARC.
Vitamin-B12-catalyzed C,C-bond formation: Synthesis of jasmonates via sequential radical reaction
Busato,Scheffold
, p. 92 - 99 (2007/10/02)
The Cbl-catalyzed electroreduction of 3-(2'-bromo-1'-ethoxyethoxy)cyclopenten (1a) in presence of 1-cyanovinyl-acetate (8) gave, in a sequential radical reaction (5-exo-trig-cyclization of 1a following by addition to 8), 1-cyano-2-(2'-ethoxy-hexahydro-2'H-cyclopenta[b]furan-4'-yl)ethyl acetate (10a). This intermediate was transformed to methyl jasmonate (7; four steps) and epituberolide (9; three steps) in 20 and 31% yield, respectively, from cyclopent-2-en-1-ol.
Intramolecular Alder ene approach to stereochemical control over three contiguous stereogenic centres: Synthesis of (±)-methyl cucurbate and (±)-methyl epijasmonate
Sarkar, Tarun K.,Ghorai, Binay K.,Banerji, Asoke
, p. 6907 - 6908 (2007/10/02)
The total synthesis of epijasmonoids, (±)-methyl cucurbate and (±)-methyl epijasmonate is described starting from aldehyde 14, where the key step is a highly stereocontrolled 5-(3,4) ene cyclization 17→18.
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
Crombie, Leslie,Mistry, Kamlesh M.
, p. 1981 - 1991 (2007/10/02)
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.
Stereoselective Synthesis of Methyl Epijasmonate
Kitahara, Takeshi,Warita, Yasuhiro,Abe, Masaki,Seya, Motohide,Takagi, Yoshikazu,Mori, Kenji
, p. 1013 - 1017 (2007/10/02)
Methyl epijasmonate (1) was stereoselectively synthesized from 3-hydroxymethylcyclopentanone (7).The intramolecular alkylation of bromoketone (8) or (9) was the key step to exclusively afford thermodynamically more stable oxahydrindanone (10) or (11).Synthesis was achieved in a 6percent overall yield in 12 steps from (7).
An Efficient and Stereocontrolled Synthesis of (+/-)-Methyl Epijasmonate and (+/-)-Cucurbic Acid
Seto, Hideharu,Yoshioka, Hirosuke
, p. 1797 - 1800 (2007/10/02)
The total synthesis of epijasmonoids, (+/-)-methyl epijasmonate and (+/-)-cucurbic acid, starting from norbornene was described, where a key intermediate, 5β-hydroxy-2β-methoxycarbonylmethylcyclopentane 1β-acetic acid γ-lactone was efficiently prepared via a highly regioselective Baeyer-Villiger oxidation of 7-syn-substituted norbornanone based on remote substituent control.