Academic literature on the topic 'A -hydroxy ketones'

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Dissertations / Theses on the topic "A -hydroxy ketones"

1

Lively, Sarah Elizabeth. "Catalytic asymmetric synthesis of #alpha#-hydroxy ketones." Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388709.

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2

Aybey, Ayse. "Oxidative Ring Opening Reactions Of A-hydroxy Ketones." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609279/index.pdf.

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Chiral polyfunctionalized 1,5-dicarbonyl compounds are important synthetic intermediates and starting materials for many biologically active compounds so their synthesis has a great importance in the literature. In the first step, 1,3-cyclohexandione and other b-diketone derivatives are protected under acid catalyzation and their corresponding b-keto enol ether derivatives are obtained. These b-keto enol ethers are then converted to a-acetoxy enones in racemic form by Mn(OAc)3 mediated oxidation. Enzymatic kinetic resolution is applied to the racemic acetoxy enones by using different lipases and enantiomerically pure a-acetoxy and hydroxy enones are obtained. Then, dicarbonyl derivatives are obtained by hydrolizing racemic a-acetoxy enones. Oxidative cleavage of racemic a-acetoxy diketones in the presence of oxone gives corresponding racemic 1,5-dimethyl ester derivatives. By using this reaction as a reference, same reactions are applied to the chiral a-acetoxy and hydroxy diketones in order to synthesize chiral a-acetoxy and hydroxy 1,5-diester derivatives.
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3

Ayhan, Peruze. "Novel Bioconversion Reactions For The Syntheses Of A-hydroxy Ketones." Phd thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610354/index.pdf.

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The objective of the study presented here was to develop either enzymatic or whole cell mediated green procedures for the syntheses of a-hydroxy ketones. Production of optically active synthons is crucial for the preparation of fine chemicals. Enzymes and whole-cell biocatalysts have proven to be excellent vehicles with their chiral nature for the biotransformations. Under the light of this discussion, firstly benzaldehyde lyase [BAL, (EC 4.1.2.38)] was used in novel C-C bond formation reactions to obtain interesting and biologically important precursors<br>2-Hydroxy-1-arylethan-1-ones and functionalized aliphatic acyloin derivatives. All the compounds were obtained with high yields and in the case of aliphatic acyloin derivatives with high enantiomeric excesses (ee&rsquo<br>s). Another strategy was to use whole cell biocatalysis. A.flavus 200120 was found to be a promising biocatalyst with the ability to catalyze a broad range of reactions<br>reduction, hydrolysis and deracemization, while another fungus<br>A. oryzae 5048 was utilized in bioreduction reactions of benzil and its derivatives. Each reaction was investigated, optimized and thus enhanced via medium design. Products were obtained with high yields and ee&rsquo<br>s. To sum up, in this study novel efficient green procedures were developed to synthesize various ahydroxy ketones with high yield and stereoselectivity. These newly established methods present promising alternatives to classical chemical methodologies.
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4

Vaismaa, M. (Matti). "Development of benign synthesis of some terminal α-hydroxy ketones and aldehydes". Doctoral thesis, University of Oulu, 2009. http://urn.fi/urn:isbn:9789514291753.

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Abstract The synthesis of α-hydroxy aldehydes and hydroxymethyl ketones as well as their interconversion to each other are discussed in this thesis. The literature survey of the monograph reviews the synthetic methods for the preparation of 1,2-bifunctionalized hydroxy aldehydes and ketones. The keto-aldehyde isomerisation reaction catalyzed by Triosephosphate isomerase enzyme (TIM) and organic compounds that interact with the TIM are also introduced. In addition, the microwave heating techniques in organic syntheses are reviewed. The practical work consists of two entities: The synthesis of new substrate candidates and transition state analogues for a mutated monomeric TIM. These compounds are model compounds for the catalytic activity and the structural studies of the mutated monomeric TIM. The synthesis of the sulphonyl α-hydroxy ketone-based substrate candidates consists of four successive syntheses. The microwave-activation was utilized in the preparation of a carbon-sulphur bond and the synthesis of hydroxymethyl ketones. The improved synthesis of the terminal α-hydroxy ketone functionality with microwave activation is presented. The formation of charged compounds was utilized to improve the absorption of microwave energy of reaction mixtures. The design and the synthetic work were carried out in accordance to principles of green chemistry. The second part of the practical work is the development of an organocatalytic α-oxybenzoylation reaction of aldehydes with high enantiomeric selectivity. This novel method generated enantiomerically pure α-hydroxy aldehydes in the stable benzoate-protected form from achiral starting materials under mild conditions at the presence of air and moisture.
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5

Whitworth, S. M. "The chemistry of some polycyclic hydroxy-ketones under very strong acid conditions." Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377485.

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6

Karabacak, Elife Ozlem. "Aspergillus Niger Mediated A-hydroxylation Of Cyclic Ketones." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/3/12608088/index.pdf.

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Chiral a -hydroxy ketones are important structural units in many natural products, biologically active compounds and the hydroxyl group has frequently been used as a reagent directing group, such as for the selective elaboration of aldol products. In this work, enzymatic synthesis of both enantiomers of the a -hydroxy ketones (2-hydroxy indanone, 2-hydroxy tetralone) using Aspergillus niger by selective &amp<br>#945<br>-oxidation of ketones (1-indanone, 1-tetralone) was studied. The &amp<br>#945<br>-oxidation of ketones was carried out by using whole cells of Aspergillus niger in different growth media. A. niger whole cell catalyzed reactions afforded (S)-configurated 2- hydroxy-1-tetralone with %87 e.e. in DMSO at pH 5.0. In addition to this,while (S)-configurated 2-hydroxy-1-indanone with %33 e.e. in pH 8.0 (in DMSO) was synthesized, (R)-configurated-2-hyroxy-1-indanone with %32 e.e. in pH 7.0 ( in DMSO) was synthesized.
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7

Baraibar, Alvaro Gomez [Verfasser]. "Development of a biocatalytic production process for (S)-a-hydroxy ketones / Alvaro Gomez Baraibar." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2014. http://d-nb.info/1048428583/34.

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8

Hosrik, Birsu Semra. "Benzaldehyde Lyase From Pseudomonas Fluorescens Biovar I Mediated Biotransformation For The Synthesis Of Chiral Alpha Hydroxy Ketones." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611456/index.pdf.

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Optically active &amp<br>#945<br>-hydroxy ketones are important subunits of many biologically active compounds and indispensable synthons for asymmetric synthesis. Benzaldehyde Lyase from Pseudomonas fluorescens Biovar I is a novel ThDP-dependent enzyme that catalyzes the synthesis of benzoin type chiral &amp<br>#945<br>-hydroxy ketones starting from both benzaldehyde and racemic benzoin derivatives. Benzaldehyde Lyase is the first example of enzymes in the literature which leads to a chemical resolution of enantiomers of benzoin derivatives through a C-C bond cleavage reaction. Chiral 2-hydroxypropiophenone derivatives are formed by benzaldehyde lyase (BAL), catalyzing C-C bond formation after a selective C-C bond cleavage of a benzoin derivative accepted as a substrate. The enzyme uses only the (R)-benzoin derivatives as substrate for the formation of (R)-HPP derivatives and it is highly stereoselective. Thus, in the presence of the acetaldehyde as the acceptor aldehyde, the C-C bond cleavage of the benzoin molecule followed by the carboligation of the acetaldehyde to yield chiral 2-hydroxy propiophenone derivatives. Given the racemic benzoin to the enzyme as the substrate in the presence of acetaldehyde, both the racemic resolution of the substrate, revealing the unreacted (S)-Benzoin and the formation of the corresponding R-HPP occur.
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9

Kose, Elif. "Chemoenzymatic Synthesis Of 4-hydroxy Enones." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/1252519/index.pdf.

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Chiral cyclic polyoxo-ketones are important structural units in many natural products, biologically active compouds, such as prostaglandins, didemnenones, sarkomycin, punaglandin, clavulone, etc. In this work, a chemoenzymatic synthesis of both enantiomers of the &amp<br>#945<br>&rsquo<br>-acetoxy-&amp<br>#945<br>-methyl and &amp<br>#947<br>-hydroxy-&amp<br>#945<br>-methyl cyclic enones starting from &amp<br>#945<br>-methyl-&amp<br>#946<br>-methoxy cyclic enone is described. Manganese (III) acetate-mediated acetoxylation followed by the enzyme-mediated hydrolysis of &amp<br>#945<br>&rsquo<br>-acetoxy enone provides acetoxy enones. The reduction of the hydroxy enone, obtained from hydrolysis, furnished both enantiomers of 4-hydroxy enone or &amp<br>#947<br>-hydroxy enone by using LiAlH4. This study is a model for the synthesis of these type compounds
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10

Simsek, Ilke. "Benzaldehyde Lyase Catalyzed Synthesis Of Novel Acyloins." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610901/index.pdf.

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&amp<br>#945<br>-Hydroxy phosphonates are versatile building blocks for the synthesis of many biologically active compounds that display antiviral, antibacterial, anticancer, pesticide activities beside their enzyme inhibitory activities such as they are the inhibitors of rennin or human immunodeficiency virus (HIV) protease and polymerase. Benzaldehyde lyase is able to catalyze not only C-C bond formation reactions but also C-C bond breaking reactions with high enantioselectivity that brings about the development of new synthetic methodologies for the synthesis of hydroxy ketones which are the key intermediates in the synthesis of many biologically active compounds due to the versatility of stereogenic center for developing structural diversity. There are several synthetic methodologies for the synthesis of hydroxy phoshonates however, in this work we have achieved the synthesis of hydroxy phoshonates through C-C bond forming reactions catalyzed by Benzaldehyde lyase that offers the use of green methodologies. Moreover, we have achieved the synthesis of hydroxy ketones which are versatile building blocks in the synthesis of many biologically active compounds via the immobilization of BAL enzyme on superparamagnetic solid support with high yield and high enantioselectivity.
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