- Changes in key odorants of raw coffee beans during storage under defined conditions
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During storage of raw coffee beans (green coffee) atypical odors may develop, which are suggested to influence the aroma of particularly the coffee beverage. To gain insight into the aroma compounds responsible for such odor changes, a comparative aroma e
- Scheidig, Claudia,Czerny, Michael,Schieberle, Peter
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Read Online
- Cross-Coupling Reactions with 2-Amino-/Acetylamino-Substituted 3-Iodo-1,4-naphthoquinones: Convenient Synthesis of Novel Alkenyl- And Alkynylnaphthoquinones and Derivatives
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Functionalized 1,4-naphthoquinones have been employed as versatile synthons in organic synthesis, in addition to presenting a large array of biological activities. Herein, the applications of 2-amino-/ acetylamino-substituted 3-iodo-1,4-naphthoquinones in cross-coupling reactions are described to successfully afford sixteen novel 3-styryl-1,4-naphthoquinones (amino-stilbene-quinone hybrids) and four 3-alkynyl-1,4-naphthoquinone in overall good yields. Interestingly, the alkynylated derivatives could be obtained from ligand- and Pd-free Cu I -mediated cross-coupling reactions, after extensive investigations to exclude Pd as a co-catalyst. Lastly, the desilanized terminal alkyne was subjected to click chemistry reactions to give two novel triazole-1,4-naphthoquinone hybrids.
- Demidoff, Felipe C.,Rodrigues Filho, Eduardo José P.,De Souza, Andréa Luzia F.,Netto, Chaquip D.,De Carvalho, Leandro L.
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supporting information
p. 4097 - 4109
(2021/08/31)
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- Synthesis method of piceatannol
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The invention provides piceatannol. A target product piceatannol is prepared through the steps of taking 3-hydroxyl-4-methoxybenzaldehyde as a starting raw material, carrying out wittig reaction to generate 3-hydroxyl-4-methoxystyrene, carrying out Heck r
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Paragraph 0011; 0025-0027
(2018/11/03)
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- Synthesis of Stilbene-Quinone Hybrids through Heck Reactions in PEG-400
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Styrenes were coupled with 3-iodolawsone in PEG-400 at 90 °C, leading stereoselectively to (E)-stilbene-quinone hybrids through Heck reactions. The best reaction conditions were found to be the use of NaOH (3 equiv) and 10 mol% of palladium acetate at 90 °C for 15 minutes. The chemical yields of the Heck reactions using styrenes with electron-withdrawing groups (65-98%) were greater than styrenes bearing electron-donating groups (7-32%) on the aromatic ring. In particular, the chemical yields of Heck reactions involving nitrostyrenes were the best ones observed.
- Demidoff, Felipe C.,De Souza, Fabrícia P.,Netto, Chaquip D.
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supporting information
p. 5217 - 5223
(2017/11/28)
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- Regioselective enzymatic β-carboxylation of para-hydroxy-styrene derivatives catalyzed by phenolic acid decarboxylases
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Abstract We report on a 'green' method for the utilization of carbon dioxide as C1 unit for the regioselective synthesis of (E)-cinnamic acids via regioselective enzymatic carboxylation of para-hydroxystyrenes. Phenolic acid decarboxylases from bacterial sources catalyzed the β-carboxylation of para-hydroxystyrene derivatives with excellent regio- and (E/Z)-stereoselectivity by exclusively acting at the β-carbon atom of the C=C side chain to furnish the corresponding (E)-cinnamic acid derivatives in up to 40% conversion at the expense of bicarbonate as carbon dioxide source. Studies on the substrate scope of this strategy are presented and a catalytic mechanism is proposed based on molecular modelling studies supported by mutagenesis of amino acid residues in the active site.
- Wuensch, Christiane,Pavkov-Keller, Tea,Steinkellner, Georg,Gross, Johannes,Fuchs, Michael,Hromic, Altijana,Lyskowski, Andrzej,Fauland, Kerstin,Gruber, Karl,Glueck, Silvia M.,Faber, Kurt
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p. 1909 - 1918
(2015/06/02)
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- Resveratrol derived butyrylcholinesterase inhibitors
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Novel polyhydroxylated (E)-stilbenes were synthesized by Mizoroki-Heck reactions and tested for their ability to inhibit the enzymes acetyl- and butyrylcholinesterase. Several of them are good inhibitors of butyrylcholinesterase; one of them carrying an extra fluorine substituent is a 94-fold stronger inhibitor of butyrylcholinesterase than of acetylcholinesterase. Novel polyhydroxylated (E)-stilbenes synthesized by Mizoroki-Heck reactions were tested for their ability to inhibit the enzymes acetyl- and butyrylcholinesterase. Several of them were found to be good inhibitors of butyrylcholinesterase. One of them carrying an extra fluorine substituent is a 94-fold stronger inhibitor of butyrylcholinesterase than of acetylcholinesterase.
- Csuk, Rene,Albert, Sabrina,Kluge, Ralph,Stroehl, Dieter
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p. 499 - 503
(2013/07/26)
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- Synthesis and radical scavenging activities of resveratrol analogs
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Highly substituted polyhydroxylated (E)-stilbenes were synthesized by Mizoroki-Heck reactions and tested for their ability to act as radical scavenger. One of the 56 stilbenes included in this study and investigated in DPPH assays gave an SC50 value of 11.0 μM, hence exhibiting an about 9.3 times higher activity than resveratrol. As shown in a photometric SRB assay using mouse NiH 3T3 fibroblasts, this compound is not cytotoxic up to concentrations of 30 μM. Highly substituted polyhydroxylated (E)-stilbenes synthesized by Mizoroki-Heck reactions were tested for their ability to act as radical scavengers. One of the 56 stilbenes included exhibited about 9.3 times higher activity than resveratrol. At concentrations 30 μM, this compound was not cytotoxic.
- Csuk, Rene,Albert, Sabrina,Siewert, Bianka
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p. 504 - 510
(2013/07/26)
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- A short synthesis of rhaponticin and its 3''-fluoroanalog via a wittig/heck-mizoroki route
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Rhaponticin and its 3''-fluoroanalog have been prepared from easily accessible starting materials. The key step of these syntheses is the silver carbonate-mediated glycosidation reaction employed for the selective formation of a β -glycosidic bond. A palladium acetate-catalyzed Heck-Mizoroki reaction in triethanolamine established an (E) configuration in the stilbene with simultaneous deprotection of the carbohydrate.
- Csuk, Rene,Albert, Sabrina
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experimental part
p. 311 - 316
(2011/05/07)
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- Synthesis and antimicrobial activity of (E) stilbene derivatives
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Plants use multiple defence mechanisms comprising both constitutive and inducible barriers to prevent entering of phytopathogenic micro-organisms. In many plant species one of the most efficient responses to combat attacking microbes is the rapid synthesis of antimicrobial low molecular weight phytoalexins, for example, resveratrol, 3,5,4′-trihydroxystilbene (1). Resveratrol and its natural derivatives, however, display only moderate antimicrobial effects. Nevertheless, resveratrol may be a useful lead structure for the chemical synthesis of antimicrobials. In this study, several series of stilbenes have been synthesized, starting from the aldehydes using Wittig reactions to access the corresponding styrenes that were subjected to Mizoroki-Heck reactions to yield the stilbenes in good yields. The stilbenes were tested in an agar diffusion assay against several bacteria and fungi. For some of these compounds the inhibiting zones for bacteria and fungi were comparable with those of the antibiotics tetracycline, streptomycin, ampicillin, or kanamycin, directed against prokaryotes, and nourseothricin or hygromycin controlling fungi, respectively.
- Albert, Sabrina,Horbach, Ralf,Deising, Holger B.,Siewert, Bianka,Csuk, René
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experimental part
p. 5155 - 5166
(2011/10/04)
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- Total synthesis of ovalifoliolatin B, acerogenins A and C
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A short and concise route for the synthesis of ovalifoliolatin B, a highly strained macrocyclic diaryl ether heptanoid natural product that also provides quick access to acerogenins A and C natural products has been reported.
- Kishore Kumar,Natarajan, Amarnath
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p. 2103 - 2105
(2008/09/18)
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- Pinacolboratamethyl-enetriphenylphosphonium iodide, a new methylene transfer reagent
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The title compound is easily prepared and reacts with various aldehydes and ketone. The reagent is compatible with free hydroxy groups. Yields with various aldehydes and ketones are in 50- > 99% range. Both aliphatic, aromatic and unsaturated carbonyls react.
- Al-Aziz Quntar, Abed,Srebnik, Morris
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p. 2575 - 2579
(2007/10/03)
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- A new convenient synthesis of 1-(3-hydroxy-4-methoxyphenyl)ethane-1,2- diol (iso-MHPG) and its enantiomers
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A safe and efficient process has been developed for the multigram synthesis of 1-(3-hydroxy-4-methoxyphenyl)ethane-1,2-diol (iso-MHPG) 2, via osmium-catalysed dihydroxylation of 3-benzyloxy-4-methoxystyrene 5, and subsequent debenzylation. The methodology
- Fisher, Adrian J.,Kerrigan, Frank
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p. 2959 - 2968
(2007/10/03)
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- Phenol nitration from a 2-(nitrooxy)ethyl side chain
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A novel nitration of phenols is described on 2-(3-hydroxy-4-methoxyphenyl)ethyl nitrate (2), which is synthesized by three alternative routes.
- Castedo,Borges,Marcos,Tojo
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p. 1717 - 1727
(2007/10/02)
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