Organic Reaction Mechanisms 2010 E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Serie: Organic Reaction Mechanisms
• Sprache: Englisch

Seitenzahl: 1013

Veröffentlichungsjahr: 2012

Beschreibung

Organic Reaction Mechanisms 2010, the 46th annual volume in this highly successful and unique series, surveys research on organic reaction mechanisms described in the available literature dated 2010. It details the latest progress in a wide range of classes of organic reaction mechanisms, including reactions of different compounds and acids and their derivatives, oxidation and reduction, aliphatic substitutions, elimination reactions, and molecular rearrangements, to name a few. An experienced team of authors compiled these reviews, ensuring the quality of selection and presentation.

Leseprobe

Table of Contents

Title Page

Copyright

Contributors

Preface

Chapter 1: Reactions of Aldehydes and Ketones and their Derivatives

Formation and Reactions of Acetals and Related Species

Reactions of Glucosides

Reactions of Ketenes

Formation and Reactions of Nitrogen Derivatives

C–C Bond Formation and Fission: Aldol and Related Reactions

Other Addition Reactions

Enolization and Related Reactions

Oxidation and Reduction of Carbonyl Compounds

Atmospheric Reactions

Other Reactions

References

Chapter 2: Reactions of Carboxylic, Phosphoric, and Sulfonic Acids and their Derivatives

INTERMOLECULAR CATALYSIS AND REACTIONS

Carboxylic Acids and their Derivatives

Phosphoric Acids and their Derivatives

Sulfonic Acids and their Derivatives

INTRAMOLECULAR CATALYSIS AND NEIGHBOURING GROUP PARTICIPATION

ASSOCIATION-PREFACED CATALYSIS

BIOLOGICALLY SIGNIFICANT REACTIONS

Carboxylic Acids and their Derivatives

Phosphoric Acids and their Derivatives

References

Chapter 3: Oxidation and Reduction

Oxidation by Metal Ions and Related Species

Oxidation by Compounds of Non-metallic Elements

Ozonolysis and Ozonation

Peracids and Peroxides

Photo-oxygenation and Singlet Oxygen

Triplet Oxygen and Autoxidation

Other Oxidations

Reduction by Complex Metal Hydrides

Hydrogenation

Transfer Hydrogenation

Other Reductions

References

Chapter 4: Carbenes and Nitrenes

Reviews

Generation, Structure, and Reactivity

Carbenes in Coordination Chemistry

Addition—Fragmentations

Insertion—Abstraction

Rearrangements

Nucleophilic Carbenes—Carbenes as Organocatalysts

Nitrenes

Heavy-atom Carbene Analogues

References

Chapter 5: Nucleophilic Aromatic Substitution

General

The SNAr Mechanism

Heterocyclic Systems

Meisenheimer and Related Complexes

References

Chapter 6: Electrophilic Aromatic Substitution

General

Halogenation

Nitration

Alkylation, Acylation, and Arylation Reactions

Substitutions on Heterocyclic Rings

Other Reactions

References

Chapter 7: Carbocations

Introduction

Alkyl and Cycloalkyl Carbenium Ions

Benzyl Cations and Quinone Methides

Benzhydryl, Trityl, and Fluorenyl Cations

Carbocation Reactivity—Quantitative Studies

Oxygen- and Sulfur-stabilized Cations

Carbocations Containing Silicon and Other Group 14 Elements

Halogenated Carbocations

Allyl and Vinyl Cations

Aryl Cations

Arenium Ions

Nitrenium Ions

Aromatic Systems

Dications

Polycyclic Systems

Carbonium (Bridged) Ions

Carbocations in Biosynthesis

References

Chapter 8: Nucleophilic Aliphatic Substitution

Allylic and Vinylic Substitutions

Reactions of Cyclic Ethers

Aziridines and Other Small Ring Substitutions

Studies Using Kinetic Isotope Effects

Nucleophilic Substitution on Elements Other than Carbon

Medium Effects/Solvent Effects

Micelles and Ion Pair Aggregates in Substitution Reactions

Structural Effects

Theoretical Studies

Gas-phase Substitution Reactions

Miscellaneous Kinetic and Product Studies

Acknowledgement

References

Chapter 9: Carbanions and Electrophilic Aliphatic Substitution

Carbanion Structure and Stability

Carbanion Reactions

Proton-transfer Reactions

Miscellaneous

Electrophilic Aliphatic Substitution

References

Chapter 10: Elimination Reactions

E1cB and E2 Mechanisms

Pyrolytic Reactions

Elimination Reactions in Synthesis

Other Reactions

References

Chapter 11: Addition Reactions: Polar Addition

Reviews

Electrophilic Additions

Nucleophilic Additions

References

Chapter 12: Addition Reactions: Cycloaddition

2 + 2-Cycloaddition

2 + 3-Cycloaddition

2 + 4-Cycloaddition

Miscellaneous Cycloadditions

References

Chapter 13: Molecular Rearrangements: Part 1. Pericyclic Reactions

[3,3]-Sigmatropic, Claisen, and Cope Rearrangements

[2,3]-Reactions

Vinyl Cyclobutane and Vinyl Cyclopropane Rearrangement

1,2-Migration

Ene Reaction

Bergman Reaction

Electrocyclic Reactions

Cyclization

4 + 2-Cycloadditions

3 + 2-Cycloadditions

Metathesis

Metal-catalysed Reactions

Miscellaneous

References

Chapter 14: Molecular Rearrangements: Part 2. Other Reactions

Aromatic Rearrangement

Ionic Rearrangements

Rearrangements Catalysed by Metals

Organo-catalysed Rearrangements

Rearrangements Involving Ring Opening

Isomerizations

Tautomerism

Radical Rearrangements

References

Author Index

Subject Index

This edition first published 2012

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Print ISBN: 978-0-470-97081-2

Contributors

K. K. BANERJI

    Faculty of Science, National Law University, Mandore, Jodhpur 342304, India

C. T. BEDFORD

    Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK

M. L. BIRSA

    Faculty of Chemistry, “Al. I. Cuza” University of Iasi, Bd. Carol I, 11, Iasi 700506, Romania

A. BRANDI

    Dipartimento di Chimica Organica “U. Schiff”, Universita' degli Studi di Firenze-Polo Scientifico, Via della Lastruccia 13 1-50019 Sesto Fiorentino (Fl), Italy

J. M. COXON

    Department of Chemistry, University of Canterbury, Christchurch, New Zealand

M. R. CRAMPTON

    Department of Chemistry, University of Durham, South Road, Durham, DH1 3LE, UK

N. DENNIS

    3 Camphor Laurel Court, Stretton, Brisbane, Queensland 4116, Australia

M. GENSINI

    Department of Chemistry, Menarini Ricerche S.p.A., Via Sette Santi, 3, 50131 Florence, Italy

E. GRAS

    Laboratoire de Chimie de Coordination, CNRS, 205 Route de Narbonne, 31077 Toulouse Cedex 4, France

A. C. KNIPE

    Faculty of Life and Health Sciences, University of Ulster, Coleraine, Northern Ireland

P. KOOVSKÝ

    Department of Chemistry, The Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK

R. A. McCLELLAND

    Department of Chemistry, University of Toronto, 80 St George Street, Toronto, Ontario M5S 1A1, Canada

B. A. MURRAY

    Department of Science, Institute of Technology Tallaght (ITT Dublin), Dublin 24, Ireland

K. C. WESTAWAY

    Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario P3E 2C6, Canada

Preface

The present volume, the forty-sixth in the series, surveys research on organic reaction mechanisms described in the available literature dated 2010. In order to limit the size of the volume, it is necessary to exclude or restrict overlap with other publications which review specialist areas (e.g. photochemical reactions, biosynthesis, enzymology, electrochemistry, organometallic chemistry, surface chemistry and heterogeneous catalysis). In order to minimize duplication, while ensuring a comprehensive coverage, the editor conducts a survey of all relevant literature and allocates publications to appropriate chapters. While a particular reference may be allocated to more than one chapter, it is assumed that readers will be aware of the alternative chapters to which a borderline topic of interest may have been preferentially assigned.

In view of the considerable interest in application of stereoselective reactions to organic synthesis, we now provide indication, in the margin, of reactions which occur with significant diastereomeric or enantiomeric excess (de or ee).

Some changes of authorship will be apparent as Sue Armstrong (Molecular Rearrangements: Pericyclic) and Bob Coombes (Electrophilic Aromatic Substitution) have found it necessary to step down, having previously made excellent contributions to ORM for eight and twenty years respectively. Hopefully they will be reassured to find that their chapters are now in the safe hands of continuing members of the team.

Steps taken to reduce progressively the delay between title year and publication date have continued to bear fruit, as evidenced by the publication of recent annual ORM volumes at nine-month intervals. Consequently we hope to regain our optimum production schedule soon.

I wish to thank the staff of John Wiley & Sons and our expert contributors for their efforts to ensure that the review standards of this series are sustained, particularly during a period of substantial reorganization of production procedures.

A. C. K.

Chapter 1

Reactions of Aldehydes and Ketones and their Derivatives

B. A. Murray

Department of Science, Institute of Technology Tallaght (ITT Dublin), Dublin, Ireland

Formation and Reactions of Acetals and Related Species

Reactions of Glucosides

Reactions of Ketenes

Formation and Reactions of Nitrogen Derivatives

Synthesis of Imines

The Mannich Reaction

Addition of Organometallics

Other Arylations, Alkenylations, and Allylations of Imines

Reduction of Imines

Iminium Species

Other Reactions of Imines

Oximes, Hydrazones, and Related Species

C–C Bond Formation and Fission: Aldol and Related Reactions

Reviews of Organocatalysts

Asymmetric Aldols Catalysed by Proline and its Derivatives

Other Asymmetric Aldols

Mukaiyama and Vinylogous Aldols

Other Aldol and Aldol-type Reactions

The Henry (Nitroaldol) Reaction

The Baylis–Hillman Reaction and its Morita-variant

Allylation and Related Reactions

The Horner–Wadsworth–Emmons Reaction and Other Olefinations

Alkynylations

Benzoin Condensation and Pinacol Coupling

Michael Additions

Miscellaneous Condensations

Other Addition Reactions

Addition of Organozincs

Arylations

Addition of Other Organometallics, Including Grignards

The Wittig Reaction

Hydrocyanation, Cyanosilylation, and Related Additions

Hydrosilylation, Hydrophosphonylation, and Related Reactions

Enolization and Related Reactions

α-Halogenation, α-Alkylation, and Other α-Substitutions

Oxidation and Reduction of Carbonyl Compounds

Regio-, Enantio-, and Diastereo-selective Reduction Reactions

Other Reduction Reactions

Oxidation Reactions

Atmospheric Reactions

Other Reactions

References

Formation and Reactions of Acetals and Related Species

A series of pyridinium cations with electron-withdrawing substituents on the ring catalyse acetalization of aldehydes and other protection reactions, such as the formation of dithianes, dithiolanes, dioxanes, and dioxolanes.1 The best catalyst works at 0.1mol%, outperforming a Brønsted acid with a pKa of 2.2.

Cyclic hemiacetals (2) have been prepared stereoselectively in a 2:1 reaction of 4-formylbenzoates and aromatic enals (trans-Ar–CHCHCHO), using catalysis by N-heterocyclic carbenes (NHCs).4

A dual acid-catalyst system has been employed for enantioselective addition of alkenyl and aryl boronates to chromene acetals (3).5 The Lewis–Brønsted combination of a lanthanide triflate and a tartaric acid monoamide gives ee up to 97%.

The gas-phase elimination kinetics of several β-substituted acetals have been measured in the range 370–441°C and in the presence of a radical inhibitor.6 Two different concerted four-membered transition states are proposed, leading to either the alcohol and vinyl ether (the latter decomposing to alkene and aldehyde) or alkane and alkyl ester.

Methylenecyclopropylcarbinols such as (4) react with acetals to give 3-oxabicyclo[3.1.0]hexanes (5); an intramolecular Prins-type mechanism is proposed.7

Iron(III) chloride or bromide has been used to catalyse Prins cyclization/halogenation of alkynyl acetals, using an acetyl halide as halogen source.8

Deacetalization of acetals, R1CH(OR2)2, in the presence of trifluoroacetic acid has been shown to be viable without water.9 Although water is a by-product, alcohols are not, and a hemiacetal is not an intermediate. Rather, a hemiacetal TFA ester [R1–CH(OR2)–OCOCF3] is formed, followed by carbonyl production with two TFA ester byproducts, F3CCO2R2. The latter process renders the reaction irreversible. The two esters are produced at separate points in what is essentially a cascade mechanism. All intermediates have been identified by NMR. The new reaction has been dubbed ‘acidolysis’ to distinguish it from the more familiar acid-catalysed hydrolysis.

Reactions of Glucosides

4,6-O-Benzylidene acetals of glycopyranosides (6) have been oxidatively cleaved to the corresponding hydroxy-benzoates (7a/b) using dimethyldioxirane under mild conditions, and in high yield.10 Appropriate choice of the neighbouring protecting group gives regioselectivity, with a preponderance of (7a) or (7b) of >99%, as desired. The balance of electronic and steric effects in the best groups—chloroacetyl and TBS (t-butyldimethylsilyl)—is discussed.

The stereo- and regio-selectivity of Lewis-acid-catalysed reductive ring-opening of 4,6-O-benzylidene acetals have been studied by kinetics, including primary and secondary isotope effects, leading to identification of a range of mechanisms in solvents of varying polarity, and in protocols with Brønsted acid additives.11 It is hoped that this will lead to new reducing agents, where reactivity and selectivity can be fine-tuned by choice of borane, solvent, Lewis acid, and temperature.

Glycoside hydrolases can give 1017-fold rate enhancements, and estimates of their dissociation constants from their transition states are as low as 10−22moldm−3. Such affinity has encouraged mimicry, and a number of criteria have now been advanced to assess whether a natural or man-made glycosidase inhibitor is a true TS mimic.12

A new dicyanohydrin-β-cyclodextrin acts as an artificial glycosidase, hydrolyzing aryl glycosides up to 5500 times faster than the uncatalysed reaction.13 Michaelis–Menten parameters are reported and compared with other modified cyclodextrins.

An investigation of nucleophilic substitutions of 2-deoxyglycosyl donors indicates that the more nucleophilic the oxygen nucleophile used, the less stereo-selective the reaction becomes. This erosion of stereo-chemical control is attributed to the rate of the stereochemistry-determining step approaching the diffusion limit, when the two faces of the prochiral oxocarbenium ion are subject to nucleophilic addition to afford a statistical mixture of diastereomers.