- Intramolecular 1,6-conjugate addition approach for construction of the hydrindane framework: Total synthesis of (±)-coronafacic acid
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A new approach for the construction of the hydrindane framework has been achieved by intramolecular 1,6-conjugate addition under some basic conditions. The precursors, α, β, γ, δ-unsaturated esters (11a-11d) were synthesized from the ester 8 and acrolein derivatives (6a-6d) via aldol condensation. This methodology was applied to the total synthesis of (±)-coronafacic acid and its analogues.
- Nara, Shinji,Toshima, Hiroaki,Ichihara, Akitami
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- Syntheses and Potato Tuber-inducing Activity of Coronafacic Acid Analogues
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Coronafacic acid (1) is an acid component of coronatine, and has been isolated from several pathovars of Pseudomonas syringae. Syntheses of C6-non- and C6-alkyl-substituted analogues of 1 were accomplished via intramolecular 1,6-conjugate addition as the key step. Among them, 1 and four C6-alkyl-substituted analogues exhibited potato tuber-inducing activity, but the C6-non-substituted analogue did not. It was revealed that a certain length of the C6-alkyl group was necessary to exhibit activity.
- Toshima, Hiroaki,Nara, Shinji,Ichihara, Akitami,Koda, Yasunori,Kikuta, Yoshio
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- Stereoselective Route to Functionalized cis-Hydrindanes from Tricyclo2,6>decan-10-ones. A Total Synthesis of (+/-)-Coronafacic Acid
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A flexible approach to functionalized cis-hydrindanes via Haller-Bauer type cleavage of endo-tricyclo2,6>decan-10-ones is delineated and its efficacy demonstrated through a concise synthesis of (+/-)-coronafacic acid.
- Mehta, Goverdhan,Praveen, Marapaka
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- Stereoselective Syntheses of all the Possible Stereoisomers of Coronafacic Acid
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An efficient and stereoselective syntheses of all the possible stereoisomers of coronafacic acid (CFA) has been developed. The stereochemistries of C3a and C7a were controlled in a diastereoselective Diels-Alder type cycloaddition using a chiral auxiliary. CFA and 6-epi-CFA were synthesized by hydrogenation of a common intermediate. During the synthesis of 6-epi-CFA, we established that its cis-fused configuration is important for the introduction of C4-C5 double bond by dehydration. This report is the first practical synthesis of both 6-epi-CFA, and its enantiomer.
- Hayashi, Kengo,Kato, Nobuki,Kuwahara, Shigefumi,Ogura, Yusuke,Tozawa, Sho,Ueda, Minoru,Watanabe, Raku
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- An enantioselective ambimodal cross-Diels–Alder reaction and applications in synthesis
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Compared with the conventional Diels–Alder reaction, the development of selective cross-Diels–Alder reactions between two different conjugated dienes, especially in a catalytic asymmetric manner, has been neglected. We now report a peri- and enantioselective cross-Diels–Alder reaction of 3-alkoxycarbonyl-2-pyrones with unactivated conjugated dienes catalysed by a copper(II)–bis(oxazoline) complex, leading to formal inverse-electron-demand adducts with high enantioselectivity under mild reaction conditions. Computational studies showed that this reaction proceeds through an ambimodal transition state: post-transition-state bifurcation leads to [2+4] and [4+2] adducts with the same enantioselectivity, followed by a facile Cope rearrangement to provide a single observed thermodynamic [2+4] product. This reaction occurs with a wide variety of cyclopentadienes, fulvenes and cyclohexadienes, providing a highly efficient and enantioselective approach to densely functionalized cis-bicyclic scaffolds. The synthetic value of this reaction is demonstrated by the asymmetric synthesis of two biologically important natural products, artemisinic acid and coronafacic acid. [Figure not available: see fulltext.].
- Cai, Quan,Chen, Xiangyang,Houk, K. N.,Lu, Qi-Tao,Tan, Kui,Xu, Meng-Meng,Yang, Limin
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p. 892 - 900
(2021/10/20)
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- A scalable synthesis of (+)-coronafacic acid
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A facile, efficient, and scalable synthesis of optically pure coronafacic acid by resolution of racemic coronafacic acid obtained using an improved version of Watson's method has been developed. By optimizing the boron-mediated aldol reaction of Watson, we were able to prepare 2.1 g of racemic coronafacic acid. This was coupled with (S)-4-isopropyl-2-oxazolidinone to give a mixture of diastereomeric coronafacyl oxazolidinones, which were readily separable by silica-gel column chromatography to give 630 mg of optically pure (+)-coronafacic acid.
- Kato, Nobuki,Miyagawa, Saki,Nomoto, Haruna,Nakayama, Misuzu,Iwashita, Makoto,Ueda, Minoru
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p. 423 - 430
(2020/02/11)
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- Synthesis of coronafacic acid via TBAF-assisted elimination of the mesylate and its conversion to the isoleucine conjugate
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An aldol reaction followed by elimination of the derived mesylate was used to construct the side chain that was designed to afford the cyclohexene ring of coronafacic acid via intramolecular alkylation. Elimination of the mesylate proceeded with TBAF. The
- Kosaki, Yusuke,Ogawa, Narihito,Wang, Qian,Kobayashi, Yuichi
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supporting information; experimental part
p. 4232 - 4235
(2011/10/09)
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- Azido-coronatine: A useful platform for "click chemistry"- mediated probe synthesis for bioorganic studies
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We report on the development of azide-coronatine as a useful platform for azide alkyne cycloaddition ("click chemistry")-mediated synthesis of molecular probes. (p)-Azido-coronatine was synthesized in 10 steps with 11% yield using improved synthesis of coronafacic acid, in which the highly exo-selective Diels-Alder reaction (endo:exo > 1:25) is the key step. Azido coronatine was as effective as the original coronatine in a stomatal opening assay, and was easily modified to a fluorescein isothiocyanate (FITC)-labeled probe with high yield.
- Okada, Masahiro,Egoshi, Syuusuke,Ueda, Minoru
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p. 2092 - 2095
(2011/06/19)
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- Total syntheses of coronatines by exo-selective Diels-Alder reaction and their biological activities on stomatal opening
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The natural phytotoxin coronatine, which is composed of two individual parts, coronafacic acid and coronamic acid, exhibits various promising biological activities similar to jasmonic acid. Interestingly, coronatine induces stomatal opening involving the swelling of guard cells in which jasmonic acid is not involved as an endogenous regulator. We established syntheses of four stereoisomers of coronatine employing the exo-selective Diels-Alder reaction as a key step. Remarkable differences in stomatal opening activity were observed between enantiomers of coronatine. This result strongly suggests that the stereo structure of coronatine is very important for its stomatal opening activity. In addition, SAR studies suggested that coronatine operates as a molecular mimic of jasmonyl-l-isoleucine in plant guard cells.
- Okada, Masahiro,Ito, Satoko,Matsubara, Akira,Iwakura, Izumi,Egoshi, Syusuke,Ueda, Minoru
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experimental part
p. 3065 - 3073
(2011/02/25)
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- Expedient stereoselective synthesis of coronafacic acid through intramolecular Diels-Alder cyclization
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(Chemical Equation Presented) A stereoselective synthesis of coronafacic acid, a natural component of the phytotoxin coronatin, was achieved using an intramolecular Diels-Alder reaction as the key step. The triene precursor bearing a substituted diene and a vinylketone as dienophile was synthesized and then tested in the thermal intramolecular cyclization. We have devised a new strategy to assemble the E,Z-diene through the stereoselective aldol reaction of an ester enolate followed by a stereoselective dehydration. Following the thermal cyclization, the corresponding hydrindanone thereby obtained with the desired relative stereochemistry could easily be converted into the natural product. The synthesis of the coronafacic acid was accomplished in six steps in 29% overall yield.
- Moreau, Benoit,Ginisty, Maryon,Alberico, Dino,Charette, Andre B.
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p. 1235 - 1240
(2007/10/03)
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- A simple entry into enantiopure hydrindanes, hydroisoquinolones and diquinanes from 3,10-dioxygenated dicyclopentadienes: Application to the synthesis of (+)-coronafacic acid and a formal synthesis of (+)-coriolin
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A ready access to enantiopure 3,10-dioxygenated tricyclo[5.2.1.02,6]decane derivatives is reported. An efficient enzymatic kinetic resolution is employed through transesterification in the presence of lipase PS immobilized on Celite. Absolute configuration of the tricyclo[5.2.1.02,6]decan-10-one derivatives has been secured through correlation with (1R,2S)-1-aminoindan-2-ol. The promising utility of these enantiopure tricyclo[5.2.1.02,6]decane derivatives in synthesis has been demonstrated through the preparation of several optically pure cis-hydrindanes 15-18, employing the Haller-Bauer reaction as the key step for unbridging the trinorbornyl system. The cis-hydrindane (-)-16 has been further elaborated to the natural product (+)-coronafacic acid (+)-24. In an interesting sequence, cis-hydrindanone (+)-18 has been transformed into cis-hydroisoquinolones (+)-30 and (+)-33 via photorearrangement of the derived oxaziridines 29 and 32, respectively. The hydroisoquinolones (+)-30 and (+)-33 can serve as useful enantiopure building blocks for the synthesis of complex indole alkaloids. Oxidative cleavage of the trinorbornene double bond in the tricyclo[5.2.1.02,6]decan-10-one derivative (-)-37 and functional-group adjustments leads to the optically pure diquinane (+)-38, an advanced intermediate in the total synthesis of (+)-coriolin (+)-34.
- Mehta, Goverdhan,Reddy, D. Srinivasa
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p. 1153 - 1161
(2007/10/03)
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- Total synthesis of coronafacic acid through 6-endo-trig mode intramolecular cyclization of an enone-aldehyde to a hydrindanone using samarium(II) iodide
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Coronafacic acid has been synthesized from a hydrindanone prepared by a 6-endo-trig mode cyclization reaction of the enone-aldehyde with samarium(II) iodide. The stereochemistry of the hydrindanone was controlled by the coordinated samarium species resulting in cis in respect of the hydroxyl group at C-4 and the juncture proton at C-3a. (C) 2000 Elsevier Science Ltd.
- Sono, Masakazu,Hashimoto, Atsuko,Nakashima, Katsuyuki,Tori, Motoo
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p. 5115 - 5118
(2007/10/03)
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- Asymmetric total syntheses of (+)-coronafacic acid and (+)-coronatine
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An asymmetric total synthesis of (+)-coronafacic acid, starting from (R)-(+)-4-acetoxy-2-cyclopen-1-one as a chiral source, was accomplished. Construction of the 1-hydrindanone framework was carried out by using intramolecular 1,6-conjugate addition as the key step. Coupling between (+)-coronafacic acid and protected coronamic acid, and subsequent deprotection provided (+)-coronatine. This is the first asymmetric total synthesis of (+)-coronatine.
- Toshima, Hiroaki,Nara, Shinji,Ichihara, Akitami
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p. 752 - 753
(2007/10/03)
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- Asymmetric total syntheses of (+)-coronafacic acid and (+)-coronatine, phytotoxins isolated from Pseudomonas Syringae pathovars
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Asymmetric total synthesis of (+)-coronafacic acid (2), was accomplished via intramolecular 1, 6-conjugate addition as the key step. The chiral ester (+)-7 was prepared via two approaches: starting from (R)-(+)-4-acetoxy-2- cyclopenten-1-one (12), and using catalytic asymmetric Michael reactions promoted by heterobimetallic BINOL complexes. Coupling between (+)-2 and the protected coronamic acid 8 and subsequent deprotection by hydrogenolysis provided (+)-coronatine (1). This is the first asymmetric total synthesis of(+)-1.
- Nara, Shinji,Toshima, Hiroaki,Ichihara, Akitami
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p. 9509 - 9524
(2007/10/03)
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- Tandem Wessely oxidation and intramolecular Diels-Alder reactions. IV. The synthesis of (+/-)-coronafacic acid
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Ethyl E-5-(4-ethyl-2-hydroxyphenyl)-2-pentenoate (7), prepared in four steps from m-ethylphenol (9), was converted via Wessely oxidation with lead tetraacetate followed by intramolecular Diels-Alder reaction in boiling xylene to ethyl 1-acetyloxy-6-ethyl-2,3,3a,4,5,7a-hexahydro-8-oxo-1,5-methano-1H-indene-anti-4-carboxylate (16).Hydrogenation of 16 followed by mild hydrolysis gave ethyl 6-ethyloctahydro-1-hydroxy-8-oxo-1,5-methano-1H-indene-anti-4-carboxylate (24), which on oxidation with periodate gave 4-(ethoxycarbonyl)-6-ethyloctahydro-1-oxo-1H-indene-5-carboxylic acid (26).Oxidative decarboxylation of this gave a mixture of ethyl 6-ethyl-2,3,3a,6,7,7a-hexahydro-1-oxo-1H-indene-4-carboxylate (31) and ethyl 6-ethyl-2,3,3a,4,7,7a-hexahydro-1-oxo-1H-indene-4-carboxylate (32); the latter was converted to the former by ethanolic sodium ethoxide.Hydrolysis of 31 with hot hydrochloric acid gave (+/-)-coronafacic acid (4).
- Yates, Peter,Bhamare, N. K.,Granger, Thierry,Macas, T. S.
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p. 995 - 1001
(2007/10/02)
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- The Synthesis of (+/-)-Coronafacic Acid by a Tandem Wessely Oxidation-Diels-Alder Reaction Sequence
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(+/-)-Coronafacic acid (9) has been synthesized from ethyl 5-(4-ethyl-2-hydroxyphenyl)pent-2-enoate (4) via a tandem Wessely oxidation-Diels-Alder reaction sequence.
- Bhamare, N. K.,Granger, Thierry,Macas, T. S.,Yates, Peter
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p. 739 - 740
(2007/10/02)
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- NORCORONATINE AND N-CORONAFACOYL-L-VALINE, PHYTOTOXIC ANALOGUES OF CORONATINE PRODUCED BY A STRAIN OF PSEUDOMONAS SYRINGAE PV. GLYCINEA
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Key Word Index - Pseudomonas syringae pv. glycinea; toxin; leaf chlorosis; coronatine; norcoronatine; N-coronafacoyl-L-valine; biosynthesis; coronafacic acid; 1-amino-2-methylcyclopropane-1-carboxylic acid.Abstract - Compounds in liquid cultures of the phytopatogenic bacterium Pseudomonas syringae pv. glycinea that cause chlorosis after application to young bean leaves have been investigated.Known compounds that were isolated and identified were coronatine, the major component, and N-coronafacoyl-L-valine, which are both biologically active, and cornafacic acid which is inactive.In addition a new minor component was isolated and purified.Mass spectrometry indicated that this was an amide of coronafacic acid, bearing one less methylene group than coronatine.Mass spectral and NMR data, together with a study of the products from acid hydrolysis of the new compound, established its structure to be norcoronatine (i.e. a methyl substituent in place of the 2-ethyl substituent on the cyclopropyl moiety of coronatine).The probable biosynthetic derivation of norcoronatine is discussed.
- Mitchell, Robin E.
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p. 1485 - 1488
(2007/10/02)
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- Total Synthesis of Racemic and Optically Active Coronafacic Acids
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(+/-)-Methyl 3-ethyl-4-oxotricyclo1,5>nonane-5-carboxylate (4), prepared by the stereoselective alkylation of methyl 4-oxotricyclo1,5>nonane-5-carboxylate, was reduced with zinc borohydride, and the resultant hydroxy
- Ohira, Susumu
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p. 1903 - 1907
(2007/10/02)
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- TOTAL SYNTHESIS OF (+/-)-CORONAFACIC ACID
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Coronafacic acid, the acidic component of coronatine, was synthesized via the stereospecific alkylation of the tricyclo1.5>nonane derivative, followed by the fission of cyclopropane ring.
- Nakayama, Mitsuru,Ohira, Susumu,Okamura, Yuichi,Soga, Shinji
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p. 731 - 732
(2007/10/02)
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- INTRAMOLECULAR LEWIS-ACID PROMOTED (2+2) CYCLOADDITIONS: AN EFFICIENT TOTAL SYNTHESIS OF (+/-)-CORONAFACIC ACID VIA AN INTERNAL DIELS-ALDER REACTION.
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Internal (2+2) cycloaddition of the ester 7 gave the cyclobutene 8 in fair yield; cyclization of the readily derived trienone 4 and hydrolysis produced coronafacic acid in 7percent overall yield.
- Jung, Michael E.,Halweg, Kim M.
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p. 2735 - 2738
(2007/10/02)
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