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Author: Jan-E Bäckvall
Publisher: Thieme Chemistry
ISBN: 9783132453777
Category :
Languages : en
Pages : 0
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Book Description
DKR and DYKAT are of ever increasing importance in the synthesis of enantiomerically enriched compounds. The preparation of enantiomerically pure compounds is of great importance in society today, in particular in pharmaceutical chemistry and in the agrochemical sector. Kinetic resolution is a popular method for differentiating two enantiomers in a racemic mixture that react at different rates with a chiral catalyst or reagent. The drawback of kinetic resolution is that the yield of one pure enantiomer is limited to a maximum of 50%. To overcome this limitation, an in situ racemization of the starting material can be combined with a kinetic resolution. This combination leads to a so called dynamic kinetic resolution (DKR), where the two enantiomers are in equilibrium with one another. The slow-reacting enantiomer will continuously be converted into the fast-reacting one, when the latter is transformed into the enantiomerically pure product. Thus, a racemic starting material can be transformed in catalytic processes into a single isomer of a chiral compound in up to 100% yield. DKR only applies to the resolution of racemic mixtures and the involvement of enantiomers leads to simple kinetics. When diastereomers, either as starting materials or as diastereomeric intermediates, are involved in the resolution process under dynamic conditions (via equilibria between diastereomers), the kinetics is different from DKR. These reactions are classified as dynamic kinetic asymmetric transformations (DYKAT). This volume covers the principles of DKR and DYKAT and presents examples of organocatalytic, chemoenzymatic, and transition-metal catalyzed approaches, including applications in the synthesis of complex, biologically active compounds.
Author: Jan-E Bäckvall
Publisher: Thieme Chemistry
ISBN: 9783132453777
Category :
Languages : en
Pages : 0
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Book Description
DKR and DYKAT are of ever increasing importance in the synthesis of enantiomerically enriched compounds. The preparation of enantiomerically pure compounds is of great importance in society today, in particular in pharmaceutical chemistry and in the agrochemical sector. Kinetic resolution is a popular method for differentiating two enantiomers in a racemic mixture that react at different rates with a chiral catalyst or reagent. The drawback of kinetic resolution is that the yield of one pure enantiomer is limited to a maximum of 50%. To overcome this limitation, an in situ racemization of the starting material can be combined with a kinetic resolution. This combination leads to a so called dynamic kinetic resolution (DKR), where the two enantiomers are in equilibrium with one another. The slow-reacting enantiomer will continuously be converted into the fast-reacting one, when the latter is transformed into the enantiomerically pure product. Thus, a racemic starting material can be transformed in catalytic processes into a single isomer of a chiral compound in up to 100% yield. DKR only applies to the resolution of racemic mixtures and the involvement of enantiomers leads to simple kinetics. When diastereomers, either as starting materials or as diastereomeric intermediates, are involved in the resolution process under dynamic conditions (via equilibria between diastereomers), the kinetics is different from DKR. These reactions are classified as dynamic kinetic asymmetric transformations (DYKAT). This volume covers the principles of DKR and DYKAT and presents examples of organocatalytic, chemoenzymatic, and transition-metal catalyzed approaches, including applications in the synthesis of complex, biologically active compounds.
Author: Patrick J. Walsh
Publisher: University Science Books
ISBN: 9781891389542
Category : Science
Languages : en
Pages : 692
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Book Description
This work describes the essential aspects of enantioselective catalysis, with chapters organised by concept rather than by reaction type. Each concept is supported by examples to give the reader broad exposure to a wide range of catalysts, reactions and reaction mechanisms.
Author: Daniel Robert Fandrick
Publisher:
ISBN:
Category :
Languages : en
Pages : 546
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Book Description
Author: Ari M. P. Koskinen
Publisher: John Wiley & Sons
ISBN: 1118347331
Category : Science
Languages : en
Pages : 415
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Book Description
Asymmetric Synthesis of Natural Products, 2nd Edition introduces students to this rapidly growing field of organic chemistry. The initial chapters present the foundations of asymmetric synthesis, including the theory and applications of individual asymmetric reactions. This is followed by chapters on each of the major individual classes of natural products; their structures, biosynthesis and interrelationships as well as examples of asymmetric syntheses and the practical value of these compounds. Natural product classes covered include carbohydrates, amino acids, peptides, proteins, nucleosides, nucleotides, nucleic acids, polyketides, isoprenoids, shikamic acid derivatives and alkaloids. For this second edition the text has been thoroughly updated and expanded, and includes new discussions and examples covering atom and redox economies, practical aspects and environmental awareness. Organocatalysis has emerged completely in the last ten years, and has been fully integrated into this new edition.
Author: A. C. Knipe
Publisher: John Wiley & Sons
ISBN: 1118941799
Category : Science
Languages : en
Pages : 1023
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Book Description
Organic Reaction Mechanisms 2014, the 50th annual volume in this highly successful and unique series, surveys research on organic reaction mechanisms described in the available literature dated 2014. The following classes of organic reaction mechanisms are comprehensively reviewed: Reaction of Aldehydes and Ketones and their Derivatives Reactions of Carboxylic, Phosphoric, and Sulfonic Acids and their Derivatives Oxidation and Reduction Carbenes and Nitrenes Nucleophilic Aromatic Substitution Electrophilic Aromatic Substitution Carbocations Nucleophilic Aliphatic Substitution Carbanions and Electrophilic Aliphatic Substitution Elimination Reactions Polar Addition Reactions Cycloaddition Reactions Molecular Rearrangements An experienced team of authors compile these reviews every year, so that the reader can rely on a continuing quality of selection and presentation. This volume includes a 5-year cumulative index.
Author: Alexandre Alexakis
Publisher: John Wiley & Sons
ISBN: 3527664599
Category : Science
Languages : en
Pages : 467
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Book Description
This book reflects the increasing interest among the chemical synthetic community in the area of asymmetric copper-catalyzed reactions, and introduces readers to the latest, most significant developments in the field. The contents are organized according to reaction type and cover mechanistic and spectroscopic aspects as well as applications in the synthesis of natural products. A whole chapter is devoted to understanding how primary organometallics interact with copper to provide selective catalysts for allylic substitution and conjugate addition, both of which are treated in separate chapters. Another is devoted to the variety of substrates and experimental protocols, while an entire chapter covers the use on non-carbon nucleophiles. Other chapters deal with less-known reactions, such as carbometallation or the additions to imines and related systems, while the more established reactions cyclopropanation and aziridination as well as the use of copper (II) Lewis acids are warranted their own special chapters. Two further chapters concern the processes involved, as determined by mechanistic studies. Finally, a whole chapter is devoted to the synthetic applications. This is essential reading for researchers at academic institutions and professionals at pharmaceutical or agrochemical companies.
Author: Florian de Nanteuil
Publisher: Springer
ISBN: 3319230069
Category : Science
Languages : en
Pages : 329
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Book Description
This thesis presents a general approach to accessing nitrogen-substituted hetero- and carbocycles. In short, the annulation reactions developed in the thesis make it possible to access nitrogen-substituted four-, five- and six-membered rings, all essential building blocks for the synthesis of bioactive molecules. Many natural products display a saturated polycyclic core allowing a well-defined arrangement of functional groups in space. As such, they can interact with biological targets with a high degree of affinity and selectivity, surpassing many synthetic drugs. Nevertheless, the efficient synthesis of such complex ring systems poses a challenge for organic chemistry. Through careful tuning of the electronic properties of a nitrogen donor group and a diester acceptor group, the first [3+2] annulation reaction between aminocyclopropanes and enol ethers or carbonyl compounds is now possible. The reaction proceeded under mild catalytic conditions, and the building blocks obtained can be found at the core of bioactive alkaloids, drugs such as Ramipril and biomolecules such as DNA and RNA. Thanks to the dynamic kinetic asymmetric annulation of aminocyclopropanes with enol ethers and aldehydes, access to enantioenriched compounds is also now possible. Lastly, a synthesis of donor-acceptor aminocyclobutanes via [2+2] cycloaddition using a cheap iron catalyst was developed, allowing them to be used in [4+2] annulations to access cyclohexylamines.
Author: A. C. Knipe
Publisher: John Wiley & Sons
ISBN: 1119125065
Category : Science
Languages : en
Pages : 717
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Book Description
Organic Reaction Mechanisms 2015, the 51st annual volume in this highly successful and unique series, surveys research on organic reaction mechanisms described in the available literature dated 2015. The following classes of organic reaction mechanisms are comprehensively reviewed: Reaction of Aldehydes and Ketones and their Derivatives Reactions of Carboxylic, Phosphoric, and Sulfonic Acids and their Derivatives Oxidation and Reduction Carbenes and Nitrenes Nucleophilic Aromatic Substitution Electrophilic Aromatic Substitution Carbocations Nucleophilic Aliphatic Substitution Carbanions and Electrophilic Aliphatic Substitution Elimination Reactions Polar Addition Reactions Cycloaddition Reactions Molecular Rearrangements An experienced team of authors compile these reviews every year, so that the reader can rely on a continuing quality of selection and presentation.
Author: Karlheinz Drauz
Publisher: John Wiley & Sons
ISBN: 3527325476
Category : Science
Languages : en
Pages : 2143
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Book Description
This comprehensive three-volume set is the standard reference in the field of organic synthesis, catalysis and biocatalysis. Edited by a highly experienced and highly knowledgeable team with a tremendous amount of experience in this field and its applications, this edition retains the successful concept of past editions, while the contents are very much focused on new developments in the field. All the techniques described are directly transferable from the lab to the industrial scale, making for a very application-oriented approach. A must for all chemists and biotechnologists.
Author: Peter Grunwald
Publisher: CRC Press
ISBN: 1000707571
Category : Business & Economics
Languages : en
Pages : 567
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Book Description
This volume provides an insight into the future strategies for commercial biocatalysis with a focus on sustainable technologies, together with chemoenzymatic and biotechnological approaches to synthesize various types of approved and new active pharmaceutical ingredients (APIs) via proven and latest synthetic routes using single-step biocatalytic or enzyme cascade reactions. Many of these drugs act as enzyme inhibitors, as discussed in a chapter with a variety of examples. The targeted enzymes are involved in diseases such as different cancers, metastatic and infectious diseases, osteoporosis, and cardiovascular disorders. The biocatalysts employed for API synthesis include hydrolytic enzymes, alcohol dehydrogenases, laccases, imine reductases, reductive aminases, peroxygenases, cytochrome P450 enzymes, polyketide synthases, transaminases, and halogenases. Many of them have been improved with respect to their properties by engineering methods. The book discusses the syntheses of drugs, including alkaloids and antibiotics, non-ribosomal peptides, antimalarial and antidiabetic drugs, prenylated xanthones, antioxidants, and many important (chiral) intermediates required for the synthesis of pharmaceuticals.
