- Stereodivergent Synthesis of Chiral Paraconic Acids via Dynamic Kinetic Resolution of 3-Acylsuccinimides
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A direct N-heterocyclic carbene (NHC) catalysis of maleimides with alkyl aldehydes is established for the synthesis of 3-acylsuccinimides. The first dynamic kinetic resolution of 3-acylsuccinimides is accomplished through asymmetric transfer hydrogenation. These two catalytic methodologies are utilized for the synthesis of each enantiomer of trans-paraconic acids in three steps and cis-paraconic acids in four steps with good yields and high stereoselectivities. This stereodivergent synthetic methodology is applied for the synthesis of seven bioactive paraconic acid natural products.
- Sarkale, Abhijeet M.,Maurya, Vidyasagar,Giri, Sachin,Appayee, Chandrakumar
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p. 4266 - 4270
(2019/06/18)
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- A protecting-group-free synthesis of (+)-nephrosteranic, (+)-protolichesterinic, (+)-nephrosterinic, (+)-phaseolinic, (+)-rocellaric acids and (+)-methylenolactocin
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A collective synthesis of a γ-butyrolactone class of paraconic acids such as (+)-methylenolactocin, (+)-phaseolinic acid, (+)-nephrosteranic acid, (+)-nephrosterinic acid, (+)-rocellaric acid and (+)-protolichesterinic acid is described. The strategy adopted is protecting-group-free based on efficient Pd-catalyzed Suzuki-Miyaura coupling and Ru-catalyzed Sharpless oxidation to construct the core β-CO2H-γ-butyrolactone unit to accomplish the synthesis of various paraconic acids.
- Nallasivam, Jothi L.,Fernandes, Rodney A.
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p. 708 - 716
(2017/01/25)
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- Design, synthesis and biological evaluation of potential antibacterial butyrolactones
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Novel butyrolactone analogues were designed and synthesized based on the known lichen antibacterial compounds, lichesterinic acids (B-10 and B-11), by substituting different functional groups on the butyrolactone ring trying to enhance its activity. All synthesized butyrolactone analogues were evaluated for their in vitro antibacterial activity against Streptococcus gordonii. Among the derivatives, B-12 and B-13 had the lowest MIC of 9.38 μg/mL where they have shown to be stronger bactericidals, by 2–3 times, than the reference antibiotic, doxycycline. These two compounds were then checked for their cytotoxicity against human gingival epithelial cell lines, Ca9–22, and macrophages, THP-1, by MTT and LDH assays which confirmed their safety against the tested cell lines. A preliminary study of the structure–activity relationships unveiled that the functional groups at the C4position had an important influence on the antibacterial activity. An optimum length of the alkyl chain at the C5position registered the best antibacterial inhibitory activity however as its length increased the bactericidal effect increased as well. This efficiency was attained by a carboxyl group substitution at the C4position indicating the important dual role contributed by these two substituents which might be involved in their mechanism of action.
- Sweidan, Alaa,Chollet-Krugler, Marylene,van de Weghe, Pierre,Chokr, Ali,Tomasi, Sophie,Bonnaure-Mallet, Martine,Bousarghin, Latifa
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p. 5823 - 5833
(2016/10/30)
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- Butyrolactone synthesis via polar radical crossover cycloaddition reactions: Diastereoselective syntheses of methylenolactocin and protolichesterinic acid
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A direct catalytic synthesis of γ-butyrolactones from simple alkene and unsaturated acid starting materials is reported. The catalytic system consists of the Fukuzumi acridinium photooxidant and substoichiometric quantities of a redox-active cocatalyst. Oxidizable alkenes such as styrenes and trisubstituted aliphatic alkenes are cyclized with unsaturated acids via polar radical crossover cycloaddition (PRCC) reactions. This method has been applied to the diastereoselective total synthesis of methylenolactocin and protolichesterinic acid.
- Zeller, Mary A.,Riener, Michelle,Nicewicz, David A.
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supporting information
p. 4810 - 4813
(2015/04/27)
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- Diastereoselective synthesis of (+)-nephrosterinic acid and (+)-protolichesterinic acid
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A diastereoselective synthesis of (+)-nephrosterinic acid and (+)-protolichesterinic acid, common members of the paraconic acids is described. The synthesis is based on a diastereoselective orthoester Johnson-Claisen rearrangement of a (Z)-allyl alcohol with a vicinal dioxolane moiety as key steps. The synthesis is completed in 10 steps and with overall yields of 15.9% for (+)-nephrosterinic acid and 16.4% for (+)-protolichesterinic acid.
- Fernandes, Rodney A.,Halle, Mahesh B.,Chowdhury, Asim K.,Ingle, Arun B.
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experimental part
p. 60 - 66
(2012/05/07)
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- Separation of a mixture of paraconic acids from Cetraria islandica (L.) Ach. employing a fluorous tag-catch and release strategy
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A light-fluorous catch and release approach application has been designed to the separation of a mixture of three paraconic acids extracted from the Island moss (Cetraria islandica (L.) Ach.). The (+)-protolichesterinic acid was caught and released via a Micha?l/retro-Micha?l addition sequence with a fluorous thiol, while the resulting two other compounds were classically separated, allowing the isolation of (+)-roccellaric acid for the first time in this lichen.
- Horhant, David,Lamer, Anne-Cécile Le,Boustie, Jo?l,Uriac, Philippe,Gouault, Nicolas
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p. 6031 - 6033
(2008/02/10)
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- Enantioselective butenolide preparation for straightforward asymmetric syntheses of γ-lactones - Paraconic acids, avenaciolide, and hydroxylated eleutherol
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The naturally occurring γ-lactones (+)-methylenolactocin (13) and its enantiomer, (+)-protolichesterinic acid (14) and its enantiomer, (+)-rocellaric acid (15), and the methylene bis(γ-lactone) (-)-avenaciolide (16) were synthesized with 95-98 % ees in very few steps. Enantiocontrol was imposed by the asymmetric dihydroxylation of trans-configured β,γ-unsaturated carboxylic esters (namely compounds 1i, 1j, and 1n) with AD mix-α [for the levorotatory target structures, except for (-)-avenaciolide] or AD mix-β [for the dextrorotatory target structures plus (-)-avenaciolide]. β,γ-Unsaturated carboxylic ester 1e required increased amounts of the oxidant and auxiliary to produce the hydroxy lactone R,R-3e, a precursor of the naphtho-γ-lactone (+)-9-hydroxyeleutherol (12; 96 % ee). Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Braukmueller, Stefan,Brueckner, Reinhard
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p. 2110 - 2118
(2007/10/03)
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- INHIBITION OF FATTY ACID SYNTHASE AS A MEANS TO REDUCE ADIPOCYTE MASS
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Weight loss was noted in nude mice treated with cerulenin, a non-competitive inhibitor of FAS. Sustained reduction of adipocyte mass in humans without toxicity would significantly impact disease prevention worldwide. Aside from psychological and self-este
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Page/Page column 13
(2010/02/13)
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- Synthesis of both enantiomers of methylenolactocin, nephrosterinic acid and protolichesterinic acid via tandem aldol-lactonization reactions
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Both forms of the enantiomerically pure methylenolactocin, nephrosterinic and protolichesterinic acid have been synthesized via tandem aldol-lactonization reactions from corresponding optically active itaconate-anthracene adducts.
- Kongsaeree, Palangpon,Meepowpan, Puttinan,Thebtaranonth, Yodhathai
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p. 1913 - 1922
(2007/10/03)
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- Efficient total syntheses of (±)protolichesterinic acid and (±)rocellaric acid via tungsten-π-allyl complexes
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Total syntheses of racemic protolichesterinic acid (1) and rocellaric acid (2) were achieved with the use of tungsten-π-allyl complex in the key step. In this synthetic route, compounds 1 and 2 were prepared in four and six steps respectively starting from readily available chloropropargyl derivatives.
- Chen, Ming-Jung,Liu, Rai-Shung
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p. 9465 - 9468
(2007/10/03)
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- An aldol - Bislactonization route to α-methylene bis-γ-butyrolactones
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The syntheses of α-methylene γ-butyrolactones and α-methylene bis- γ-butyrolactones are made simple through the use of the versatile dimethyl itaconate - anthracene adduct, 1.
- Lertvorachon, Jittiwud,Meepowpan, Puttinan,Thebtaranonth, Yodhathai
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p. 14341 - 14358
(2007/10/03)
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- Stereoselective synthesis of polysubstituted tetrahydrofurans by radical cyclization of epoxides using a transition-metal radical source. Application to the total synthesis of (±)-methylenolactocin and (±)-protolichesterinic acid
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Radical cyclization reactions of substituted α-(prop-2-ynyloxy) epoxides using bis(cyclopentadienyl)-titanium(III) chloride as the radical source resulted in polysubstituted tetrahydrofurans. Titanium(III) species were prepared in situ from commercially available titanocene dichloride and zinc dust in tetrahydrofuran. Upon radical cyclization, 2-aryl epoxides 3a-e afforded only trans products 4a-e whereas the 2-alkyl epoxides 3f-h formed a mixture of isomeric products 4f-h in a ratio of 5:1. Some of the aryl tetrahydrofuran derivatives have already been used for the synthesis of bioactive furofuran lignans. 2-Pentyl-3-(hydroxymethyl)-4- methylenetetrahydrofuran (4f) and 2-tridecyl-3-(hydroxymethyl)-4- methylenetetrahydrofuran (4g) have been transformed to two antitumor antibiotics (±)-methylenolactocin (1f) and (±)-protolichesterinic acid (1g), respectively, in good overall yield.
- Mandal,Maiti,Roy
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p. 2829 - 2834
(2007/10/03)
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- Strategic use of retro Diels-Alder reaction in the construction of β-carboxy-α-methylene-γ-lactones. Total synthesis of methylenolactocin and protolichesterinic acid
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A facile route for the construction of β-carboxy-α-methylene-γ-lactone unit is described using retro Diels-Alder reaction as the key step. Using this protocol, total synthesis of (±)-methylenolactocin and (±)-protolichesterinic acid has been achieved.
- Ghatak, Anjan,Sarkar, Subrata,Ghosh, Subrata
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p. 17335 - 17342
(2007/10/03)
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- FACILE SYNTHESIS OF 2-METHYLENE-4-BUTYROLACTONES
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2-Methylene-4-butyrolactones were conveniently synthesized by treatment of an aldehyde with 2-carboethoxyallyl(-ic) bromide and metallic tin (and aluminium) in good yields.Protolichesterinic acid was synthesized by employing the method.
- Nokami, Junzo,Tamaoka, Takashi,Ogawa, Hideki,Wakabayashi, Shoji
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p. 541 - 544
(2007/10/02)
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