Design Synthesis And Applications Of Biomimetic Flavin Based Organocatalysts
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Design Synthesis And Applications Of Biomimetic Flavin Based Organocatalysts
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Author : Mohammad Shawkat Hossain
language : en
Publisher:
Release Date : 2019
Design Synthesis And Applications Of Biomimetic Flavin Based Organocatalysts written by Mohammad Shawkat Hossain and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with Catalysis categories.
Oxidation reactions are one of the most important transformations in synthetic chemistry. Most commonly used oxidants are metal oxides, which are neither green nor selective towards multi-functional molecules. The efficiency of the reactions can be improved by the introduction of a catalyst by lowering the activation energy. In nature, oxidation reactions are highly specific and are controlled by enzymes, co-enzymes, and availability of a renewable terminal oxidant, molecular oxygen. Among the various enzymatic oxidative transformations, our research was inspired by the oxidations controlled by co-enzymes FMN or FAD in the presence of flavoproteins and molecular oxygen. Flavin mimics were often studied/used to oxidize heteroatoms; however, the goal of this research was initialy focused on mimicking other chemoselective oxidations of flavins, primarily at carbon centers. In chapter one, the function of natural flavins in nature and different approaches to perform nucleophilic and electrophilic oxidation using artificial flavin is described. In chapter two, flavin reactivity was extended to the Dakin oxidation of electron-rich benzaldehydes. This conversion of aryl aldehyde to phenol worked efficiently under mild conditions with either hydrogen peroxide or molecular oxygen as terminal oxidant. The mechanism was understood by various reaction rates studies. Substituent effects of catalysts and substrates aided in the identification of the rate determining step. The order of reagents and extensive pH studies reveal the various way flavin catalysts enable oxo-transfer under mild, more neutral conditions, by altering both the pKa of the active nucleophilic oxygen source, and by lowering the energy of the oxide leaving group, as previously hypothesized by Briuce and coworkers. In chapter three, pre-heteroaromatic compounds (initially investigated as possible reducing agents for flavin mimics) were transformed to their aromatic form aerobically using flavin catalyst in arguably the most mild methods described to date. Chapters four through six describe the preparation and function of various classes of flavins. Chapter four discussed the bioactivity of new flavin species against cancerous and normal breast cells. Chapter five details the preparation of water-soluble classes of flavins and their photochemical properties (O2 activation and Methyl Orange degredation). And Chapter six discusses the preparation of redox active flavins that were prepared for tethering to metal oxide photocatalyst and various electrode surfaces. Chapter seven describes a new preparation of 5-deazaflavin cofactors - deazariboflavin, 8-hydroxydeazariboflavin (an F420-precursor), and 10-methyl deazaflavin. An improved route to these species is described, and their redox activity were investigated in F420-dependent enzymes. Finally, chapter eight shows a new, concise and high yielding synthetic route explored for the synthesis of flavin catalysts, which includes the synthesis of different o-phenylenediamine derivatives and alloxan derivatives.
Design And Synthesis Of Flavin Based Organocatalysts For Biomimetic Aerobic Oxidation Reactions
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Author : Shuai Chen
language : en
Publisher:
Release Date : 2014
Design And Synthesis Of Flavin Based Organocatalysts For Biomimetic Aerobic Oxidation Reactions written by Shuai Chen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Catalysis categories.
Oxidation reactions are among the most costly and least selective transformations in synthetic chemistry. Catalytic methods that utilize O2 as a terminal oxidant strive to reduce the inefficiency in this large area of synthesis. Recent efforts have been aimed primarily at metal-/organometallic- or enzyme-catalyzed transformations. The goal of the research described in this dissertation was to develop organocatalytic systems based on natural biosynthetic catalysts in order to develop selective metal-free aerobic oxidations that function at room temperature. Prior to our work, riboflavin mimics were previously investigated to understand flavoenzyme function and to perform catalytic oxidations of primarily heteroatom systems. We set out to extend this relatively limited area of organocatalysis to the oxidation of more valuable carbon centers in a mild, chemoselective and stereoselective manner. In Chapter 1, a description of the development and application of biomimetic flavin organocatalysts thus far reported in the literature are summarized. In Chapter 2, the flavin-catalyzed Dakin oxidation is discussed. A range of riboflavin derivatives is used as catalysts to accelerate the transformation of o- or p- hydroxyl benzaldehydes into dihydroxybenzenes using H2O2 as the terminal oxidant. An aerobic version of this transformation is developed using the flavin catalysts and NAD(P)H mimics. In Chapter 3, an aerobic asymmetric Weitz-Scheffer epoxidation of enals using flavin and chiral, non-racemic pyrrolidines in a dual catalysis strategy is discussed. High enantioselectivity and diastereoselectivity are observed in the epoxides obtained using this method. A mechanical study is conducted to elucidate the characteristics of the reaction pathway. In Chapter 4, the flavin catalyzed aerobic aromatization of heterocycles is discussed. Riboflavin derivatives are used to convert substituted dihydropyridines and benzothiazolines to pyridines and benzothiazoles with molecular oxygen as terminal oxidant under mild reaction conditions.
Flavin Based Catalysis
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Author : Radek Cibulka
language : en
Publisher: John Wiley & Sons
Release Date : 2021-06-10
Flavin Based Catalysis written by Radek Cibulka and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-06-10 with Technology & Engineering categories.
The book gives a unique overview of this rapidly developing research field, presenting structures and properties of flavin derivatives as well as their proven application as bioinspired catalysts in various organocatalytic, biocatalytic, and photocatalytic reactions.
The Design Synthesis And Application Of Thio Urea Based Organocatalysts For A Range Of C C Bond Transformations
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Author : Eimear Fleming
language : en
Publisher:
Release Date : 2009
The Design Synthesis And Application Of Thio Urea Based Organocatalysts For A Range Of C C Bond Transformations written by Eimear Fleming and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
Design Synthesis And Study Of Biomimetic Catalysts
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Author : Robert S. Brown
language : en
Publisher:
Release Date : 1987
Design Synthesis And Study Of Biomimetic Catalysts written by Robert S. Brown and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1987 with categories.
Biomimetic catalysts modelled after the alkaline phosphatases and acid phosphatases were synthesized, and their catalysis of the hydrolysis of phosphate triesters was studied. The compounds fall into three classes: those that bind one divalent M2+-ion; those that bind two M2+ - ions; and those that contain an imidazole with a pendant guanidinium ion. The syntheses of the compounds in the former two classes is described along with the summary of in vitro assays. the Zn2+ and Co2+-chelates of these are respectable catalysts for hydrolysis of triesters. The guanidinium imidazoles are ineffective catalysts. Keywords: Biomimetic, Catalyst, Organophosphate ester, Alkaline phosphatase, Acid phosphatase, Chelates.
Design Synthesis And Evaluation Of New Organocatalysts
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Author : Samantha James
language : en
Publisher:
Release Date : 2009
Design Synthesis And Evaluation Of New Organocatalysts written by Samantha James and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Catalysts categories.
Design Synthesis And Applications Of Sulfur Ruthenium Based Catalysts For Light Directed Olefin Metathesis Reactions
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Author : Efrat Levin
language : en
Publisher:
Release Date : 2015
Design Synthesis And Applications Of Sulfur Ruthenium Based Catalysts For Light Directed Olefin Metathesis Reactions written by Efrat Levin and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Principles And Applications Of Asymmetric Synthesis
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Author : Guo-Qiang Lin
language : en
Publisher: John Wiley & Sons
Release Date : 2003-05-29
Principles And Applications Of Asymmetric Synthesis written by Guo-Qiang Lin and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003-05-29 with Science categories.
Asymmetric synthesis remains a challenge to practicing scientistsas the need for enantiomerically pure or enriched compoundscontinues to increase. Over the last decade, a large amount ofliterature has been published in this field. Principles andApplications of Asymmetric Synthesis consolidates and evaluates themost useful methodologies into a one-volume resource for theconvenience of practicing scientists and students. Authored by internationally renowned scientists in the field, thisreliable reference covers more than 450 reactions and includesimportant stoichiometric as well as catalytic asymmetric reactions.The first chapter reviews the basic principles, commonnomenclature, and analytical methods, and the remainder of the bookis organized according to reaction type. The text examines suchtopics as: Carbon-carbon bond formations involving carbonyls, enamines,imines, and enolates Asymmetric C-O bond formations including epoxidation,dihydroxylation, and aminohydroxylation Asymmetric synthesis using the Diels-Alder reaction and othercyclizations Applications to the total synthesis of natural products Use of enzymes in asymmetric synthesis Practicing chemists in the pharmaceutical, fine chemical, andagricultural professions as well as graduate students will findthat Principles and Applications of Asymmetric Synthesis affordscomprehensive and current coverage.
Computational Electrochemistry
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Author : S. Paddison
language : en
Publisher: The Electrochemical Society
Release Date : 2015-12-28
Computational Electrochemistry written by S. Paddison and has been published by The Electrochemical Society this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-12-28 with Science categories.
Polymeric Chiral Catalyst Design And Chiral Polymer Synthesis
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Author : Shinichi Itsuno
language : en
Publisher: John Wiley & Sons
Release Date : 2011-06-28
Polymeric Chiral Catalyst Design And Chiral Polymer Synthesis written by Shinichi Itsuno and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-06-28 with Technology & Engineering categories.
This book reviews chiral polymer synthesis and its application to asymmetric catalysis. It features the design and use of polymer-immobilized catalysts and methods for their design and synthesis. Chapters cover peptide-catalyzed and enantioselective synthesis, optically-active polymers, and continuous flow processes. It collects recent advances in an important field of polymer and organic chemistry, with leading researchers explaining applications in academic and industry R & D.