- Tertiary amines as vinyl source for the formations of aryl or pyrrole ring on amido-substitued 1,4-quinone with the assistance of palladium salt
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The one-pot synthesis of 3-isopropyl-6-methyl-1H-benzo[f]indole-4,9-dione (3e), N-(4-[isopentylamino]-3,6-dioxocyclohexa-1,4-dien-1-yl)acetamide (4d), 2-(isopentylamino)-6-methylnaphthalene-1,4-dione (5b), and 2-(4-acetamido-3,6-dioxocyclohexa-1,4-dien-1-
- Jhou, Jia-Nan,Cheng, Chiu-Wen,Hong, Fung-E
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p. 2118 - 2128
(2020/06/17)
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- Natural Abenquines and Their Synthetic Analogues Exert Algicidal Activity against Bloom-Forming Cyanobacteria
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Abenquines are natural quinones, produced by some Streptomycetes, showing the ability to inhibit cyanobacterial growth in the 1 to 100 μM range. To further elucidate their biological significance, the synthesis of several analogues (4f-h, 5a-h) allowed us to identify some steric and electronic requirements for bioactivity. Replacing the acetyl by a benzoyl group in the quinone core and also changing the amino acid moiety with ethylpyrimidinyl or ethylpyrrolidinyl groups resulted in analogues 25-fold more potent than the natural abenquines. The two most effective analogues inhibited the proliferation of five cyanobacterial strains tested, with IC50 values ranging from 0.3 to 3 μM. These compounds may be useful leads for the development of an effective strategy for the control of cyanobacterial blooms.
- Nain-Perez, Amalyn,Barbosa, Luiz Cláudio Almeida,Maltha, Célia Regina álvares,Forlani, Giuseppe
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p. 813 - 818
(2017/05/05)
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- Natural abenquines and synthetic analogues: Preliminary exploration of their cytotoxic activity
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In this study, we explore the cytotoxic activity of four natural abenquines (2a–d) and fourteen synthetic analogues (2e–j and 3a–h) against a panel of six human cancer cell lines using a SRB assay. It was found that most of the compounds revealed higher levels of cytotoxic activities than naturally occurring abenquines. The analogues carrying ethylpyrrolidinyl and ethylpyrimidinyl with either an acetyl group (2?h–i) or a benzoyl group (3f–g), were the most potent against all human cancer cell lines and displayed EC50 between a range of 0.6–3.4?μM. Notably, of the compounds tested, compound 2i proved the most cytotoxic against both ovarian (A2780) and breast (MCF7) cells, showing EC50?=?0.6 and 0.8?μM respectively. Likewise, the analogues 2i, 3f and 3?g showed strong activity against cell HT29 with EC50?=?0.9?μM for these compounds.
- Nain-Perez, Amalyn,Barbosa, Luiz C.A.,Rodríguez-Hernández, Diego,Kramell, Annemarie E.,Heller, Lucie,Csuk, René
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p. 1141 - 1144
(2017/06/19)
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- Tailoring Natural Abenquines to Inhibit the Photosynthetic Electron Transport through Interaction with the D1 Protein in Photosystem II
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Abenquines are natural N-acetylaminobenzoquinones bearing amino acid residues, which act as weak inhibitors of the photosynthetic electron transport chain. Aiming to exploit the abenquine scaffold as a model for the synthesis of new herbicides targeting photosynthesis, 14 new analogues were prepared by replacing the amino acid residue with benzylamines and the acetyl with different acyl groups. The synthesis was accomplished in three steps with a 68-95% overall yield from readily available 2,5-dimethoxyaniline, acyl chlorides, and benzyl amines. Key steps include (i) acylation of the aniline, (ii) oxidation, and (iii) oxidative addition of the benzylamino moiety. The compounds were assayed for their activity as Hill inhibitors, under basal, uncoupled, or phosphorylating conditions, or excluding photosystem I. Four analogues showed high effectiveness (IC50 = 0.1-0.4 μM), comparable with the commercial herbicide diuron (IC50 = 0.3 μM). The data suggest that this class of compounds interfere at the reducing side of photosystem II, having protein D1 as the most probable target. Molecular docking studies with the plastoquinone binding site of Spinacia oleracea further strengthened this proposal.
- Nain-Perez, Amalyn,Barbosa, Luiz C.A.,Maltha, Celia R. A.,Giberti, Samuele,Forlani, Giuseppe
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p. 11304 - 11311
(2018/01/10)
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- First total synthesis and phytotoxic activity of Streptomyces sp. metabolites abenquines
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The first total synthesis of abenquines A, B2, C and D has been achieved in three steps starting from commercially available 2,5-dimethoxyaniline, with overall yields of 41-61%. Four analogues bearing the amino acids d-valine (17), l-methionine (18), and glycine (19), and benzylamine (20), were also prepared in 45-72% yield. The inhibitory properties of these compounds were evaluated against the photoautotrophic growth of a model Synechococcus sp. strain. Abenquine C and its enantiomer were substantially ineffective, whereas all other abenquines significantly inhibited cell proliferation, with concentrations causing 50%-inhibition of algal growth ranging from 10-5 to 10-6 M.
- Nain-Perez, Amalyn,Barbosa, Luiz C.A.,Maltha, Celia R.A.,Forlani, Giuseppe
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p. 1811 - 1814
(2016/04/05)
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- Synthesis of amino-1,4-benzoquinones and their use in Diels - Alder approaches to the aminonaphthoquinone antibiotics
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A new protocol for the synthesis of protected amino-1,4-benzoquinones by oxidation of the corresponding 2,5-dimethoxyaniline derivatives using PhI(OAc)2 or PhI- (OCOCF3)2 in water containing 2.5% methanol is reported. The process represents an improvement over previously reported methods, both in terms of yield and number of steps, and in the range of nitrogen protecting groups that it tolerates. A number of novel aminobenzoquinones were prepared and subsequently used as dienophiles in Diels - Alder reactions to (Figure presented) form building blocks for the synthesis of the aminonaphthoquinone antibiotics such as salinisporamycin.
- Nawrat, Christopher C.,Lewis, William,Moody, Christopher J.
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p. 7872 - 7881
(2011/12/14)
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- Mechanistic diversity of the selective oxidations mediated by supported iron phthalocyanine complexes
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Selective oxidations of (i) phenols and condensed aromatics to quinones and (ii) alkynes to α,β-acetylenic ketones mediated by supported iron phthalocyanine complexes exhibit very different mechanistic features as evidenced by 18O labelling and kinetic isotope effect studies. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2005.
- Perollier, Celine,Pergrale-Mejean, Corinne,Sorokin, Alexander B.
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p. 1400 - 1403
(2007/10/03)
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- Oxidation of anisoles to p-benzoquinone monoketals catalyzed by a ruthenium complex of 1,4,7-trimethyl-1,4,7-triazacyclononane with tert-butyl hydroperoxide
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A protocol based on [RuIII(Me3tacn)(CF 3CO2)2(H2O)]CF3CO 2 (1, Me3tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane) as catalyst and tert-butyl hydroperoxide (TBHP) as oxidant was developed for oxidation of anisoles to p-benzoquinone monoketals. This reaction can be formally considered as regioselective aromatic C-H oxidation. With 2-methoxyanisole as substrate, 3,4-dimethoxy-4-tert-butoxy-2,5-cyclohexadienone can be obtained in up to 82% yield based on 84% substrate conversion.
- Cheung, Wai-Hung,Yip, Wing-Ping,Yu, Wing-Yiu,Che, Chi-Ming
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p. 521 - 526
(2007/10/03)
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- Acetamidoquinone and acetamidohydroxy derivatives as inhibitors for both dihydroxyacetamido epoxidase and dehydrogenase
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A series of monohydroxy and dihydroxyacetanilides, acetamidoquinones and bromoacetamidoquinones have been synthesised and tested as substrates and/or inhibitors of highly purified dihydroxyacetamido epoxidase (DHAE) and dihydroxy acetamido dehydrogenase (DHADH) from Streptomyces LL-C10337. None was found to act as substrates but many selectively inhibit the enzymes. Kinetic analysis has shown that all the compounds act as reversible competitive inhibitors with respect to the substrates 2,5-dihydroxyacetanilide and 2,3-epoxy-1,4-benzoquinone-5-acetanilide. Monohydroxy acetanilides showed weak inhibition to these enzymes compared to the dihydroxy derivatives while the more powerful inhibitors were the benzoquinoneacetanilide and its 5-bromo equivalent.
- Whiteley, Chris G.
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p. 1221 - 1227
(2007/10/03)
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- Iodine(V) reagents in organic synthesis. Part 2. Access to complex molecular architectures via Dess-Martin periodinane-generated o-imidoquinones
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o-Imidoquinones, a rather rare class of compounds, are prepared from anilides by the action of Dess-Martin pedodinane (DMP) and water. Their chemistry has been extensively investigated and found to lead to p-quinones and polycyclic systems of diverse mole
- Nicolaou,Sugita,Baran,Zhong
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p. 2221 - 2232
(2007/10/03)
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- Polymer-supported hypervalent iodine reagents in 'clean' organic synthesis with potential application in combinatorial chemistry
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A clean oxidation reaction of a variety of substrates using polymer-supported (diacetoxyiodo)benzene (PSDIB) which proceeds in high to excellent yield with maximum purity is described including isolation and regeneration of the polymer reagent.
- Ley, Steven V.,Thomas, Andrew W.,Finch, Harry
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p. 669 - 671
(2007/10/03)
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- The synthesis of alisamycin, nisamycin, LL-C10037α and novel epoxyquinol and epoxyquinone analogues of manumycin A
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Versatile synthetic routes are described for the preparation of a range of epoxyquinol and epoxyquinone analogues of the antitumour antibiotic manumycin A lacking the lower side chain, and these procedures have also been applied to prepare the bioactive natural product LL-C10037α. The extension of this methodology to provide a general synthetic route to the manumycin family of antibiotics is discussed and exemplified by the first total synthesis of alisamycin and ent-alisamycin. This route includes the novel, stereoselective organometallic addition of the Corey-Wollenberg reagent (E- 2-tributylstannylethenyllithium) to the manumycin nucleus and palladium catalysed Stille coupling technology for the introduction of the polyunsaturated 2-amino-3-hydroxycyclopentenone derived amide. Similar methodology has also been employed to complete the first total synthesis of the antibiotic nisamycin.
- Taylor, Richard J. K.,Alcaraz, Lilian,Kapfer-Eyer, Isabelle,Macdonald, Gregor,Wei, Xudong,Lewis, Norman
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p. 775 - 790
(2007/10/03)
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- Synthesis of (-)-LL-C10037α and related manumycin-type epoxyquinols
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Starting with N-allyloxycarbonyl-protected 2,5-dimethoxyaniline, hypervalent iodine oxidation protocols and selective enone epoxidation provides the Streptomyces metabolite LL-C10037α in nine steps and 7-10% overall yield. In an asymmetric variant of this strategy, (R,R)-pentane-2,4-diol is used as a chiral acetalization agent. The resulting semiquinone spiroacetal, due to an ortho-acylamino substituent that restricts the 1,3-dioxane ring conformation, undergoes face-selective epoxidation and is further functionalized to give (-)-LL-C10037α in 94% ee. These pathways represent the first syntheses of the highly functionalized mC7N core of the manumycins and have been further extended toward the preparation of analogs for SAR studies of this class of antitumor antibiotics. Manumycins inhibit the farnesylation of Ras-protein by PFTase (protein farnesyltransferase).
- Wipf,Kim,Jahn
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p. 1549 - 1561
(2007/10/02)
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- Method for dyeing keratinous fibres using an aminoindole in combination with a quinone derivative
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Method for dyeing keratinous fibres, characterized in that at least one composition (A) containing at least one aminoindole in a medium appropriate for dyeing is applied to these fibres, the application of the composition (A) being preceded or followed by the application of a composition (B) containing, in a medium appropriate for dyeing, at least one quinone derivative chosen from ortho- or para-benzoquinones, ortho- or para-benzoquinone monoimines or diimines, 1,2- or 1,4-naphthoquinones, ortho- or para-benzoquinone sulphonimides, α,ω-alkylene-bis-1,4-benzoquinones, or 1,2- or 1,4-naphthoquinone monoimines or diimines, the aminoindoles and the quinone derivatives being chosen such that the difference in redox potential ΔE between the redox potential Ei of the aminoindoles, determined at pH 7 in a phosphate medium on a vitreous carbon electrode by voltametry, and the redox potential Eq of the quinone derivative, determined at pH 7 in a phosphate medium by polarography on a mercury electrode relative to the saturated calomel electrode, in such that
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- Process for dyeing keratinous fibres with a hydroxyindole in combination with a quinone derivative; and novel 1,4-benzoquinones
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Process for dyeing keratinous fibres, comprising the step of applying to these fibres at least one composition A containing, in a medium appropriate for dyeing, at least one mono- or di-hydroxyindole the application of the composition A being preceded or followed by the application of a composition B containing, in a medium appropriate for dyeing, at least one quinone derivative chosen from ortho- or para-benzoquinones, monoimines or diimines of ortho- or para-benzoquinones, 1,2- or 1,4-naphthoquinones, sulphonimides of ortho- or para-benzoquinones, α, ω-alkylene-bis-1,4-benzoquinones, or 1,2- or 1,4-naphthoquinone-monoimines or -diimines; the mono- or di-hydroxyindoles and the quinone derivatives being chosen such that the oxidation-reduction potential difference ΔE between the oxidation-reduction potential Ei of the mono- or di-hydroxyindoles, determined at pH 7 in a phosphate medium on a vitreous carbon electrode by voltametry, and the oxidation-reduction potential Eq of the quinone derivative determined at pH 7 in a phosphate medium by polarography on a mercury electrode and relative to a saturated calomel electrode is such that
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- Biosynthesis of Antibiotic LL-C10037α: The Steps beyond 3-Hydroxyanthranilic Acid
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The six steps from 3-hydroxyanthranilic acid to the epoxyquinol LL-C10037α, 1, produced by Streptomyces LL-C10037 have been determined by whole-cell feedings with deuterated substrates and by cell-free studies. 3-Hydroxyanthranilic acid, 2, is decarboxylated to 2-hydroxyaniline, 11, and then oxidized to 2,5-dihydroxyaniline, 8.Acetylation at nitrogen and oxidation afford acetamido-1,4-benzoquinone, 4.A crude cell-free preparation has been found to epoxidize 4 to the epoxyquinone 16 in the presence of O2 and either NaDH or NADPH.Reduction of 16 yields 1.Therelationship of this pathway to that of fungi that produce patulin via analogous intermediates from 6-methylsalicylic acid is discussed.
- Gould, Steven J.,Shen, Ben,Whittle, Yvonne G.
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p. 7932 - 7938
(2007/10/02)
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- Synthesis of Substituted Dibenzophospholes. Part 5. Synthesis of Intermediates for 4- and 6-Aryl Substituents
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6-Iodo-5-methoxy-8-methyl-1,2,3,4-tetrahydro-1,4-ethanonaphthalene was prepared from the Diels-Alder adduct of benzoquinone and cyclohexadiene.Diels-Alder condensation of 2-acetamimido-benzoquinone and 2-iodobenzoquinone (convenient, new syntheses of both quinones are described) with 2-methylcyclohexa-1,3-diene led to mixtures of adducts; the major adduct from the iodoquinone was isolated and found by X-ray analysis to have the methyl and iodo substituents at the 2- and 7-positions, respectively, of the 1,4-ethanonaphthalene skeleton.Addition of 2-acetamidobenzoquinone to mentha-2,6,8(9)-triene derived from (-)-carvone gave two regioisomers (structures determined by n.m.r. spectroscopy).In a smooth 4-step synthesis from 6,6-dimethylfulvene and benzoquinone, 6-iodo-9-syn-isopropyl-5,8-dimethoxy-1,2,3,4-tetrahydro-1,4-methanonaphthalene was prepared and its stucture confirmed by X-ray analysis.
- Buttrus, Nabeel H.,Cornforth, Sir John,Hitchcock, Peter B.,Kumar, Ashok,Stuart, Alan S.
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p. 851 - 858
(2007/10/02)
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- Lewis Acid Catalyzed Cycloreversion Reaction of Strained Cage Ketones to Triquinane Skeletons: Kinetic Evidence for a Large Acceleration of the Reaction Owing to Stereoelectronic Requirement
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Cookson's pentacyclic cage diketones substituted with an electron-donating group (1b-e) underwent a remarkably fast cycloreversion reaction under various Lewis acid catalyzed conditions.The high reactivity of these cage ketones is discussed in terms of push-pull type interactions on the basis of large substituent effects and kinetic measurements.Keywords - cycloreversion reaction; Cookson's pentacyclic cage diketone; Lewis acid catalyst; electron-donating group; stereoelectronic effect
- Okamoto, Yasushi,Senokuchi, Kazuhiko,Kanematsu, Ken
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p. 4593 - 4599
(2007/10/02)
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- OXYDATION SELECTIVE EN PARA DES PHENOLS PAR UN COMPLEXE CUIVRIQUE OXYDANT
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Oxidation of phenols by molecular oxygen in the presence of the μ-oxo cupric catalyst Cu4Cl4O2 (CH3CN)3 (A), can be selectively directed to give either oxidative coupling or para-hydroxylation (p-quinols or p-quinones) products by the choice of the (A)/(phenol) ratio.The mechanism is discussed and a -OH ligand transfer from CuII to the phenolic para position is proposed.
- Capdevielle, Patrice,Maumy, Michel
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p. 5611 - 5614
(2007/10/02)
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