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Boronic-Acids.Pdf V Table of Contents Preface XV List of Authors XIX List of Abbreviations XXI 1 Structure, Properties, and Preparation Of Boronic Acid Derivatives. Overview of Their Reactions and Applications 1 D. G. Hall 1.1 Introduction 1 1.2 Structure and Properties of Boronic Acid Derivatives 2 1.2.1 General Types and Nomenclature of Boronic Acid Derivatives 2 1.2.2 Boronic Acids 3 1.2.2.1 Structure and Bonding 3 1.2.2.2 Physical Properties and Handling 7 1.2.2.3 Safety Considerations 8 1.2.2.4 Acidic Character 8 1.2.2.5 Chemical Stability 13 1.2.3 Boronic Acid Derivatives 14 1.2.3.1 Boroxines 14 1.2.3.2 Boronic Esters 15 1.2.3.3 Dialkoxyboranes and other Heterocyclic Boranes 23 1.2.3.4 Diboronyl Esters 24 1.2.3.5 Azaborolidines and other Boron Heterocycles 24 1.2.3.6 Dihaloboranes and Monoalkylboranes 26 1.2.3.7 Trif luoroborate Salts 27 1.3 Synthesis of Boronic Acids and their Esters 28 1.3.1 Arylboronic Acids 28 1.3.1.1 Electrophilic Trapping of Arylmetal Intermediates with Borates 28 1.3.1.2 Transmetallation of Aryl Silanes and Stannanes 34 1.3.1.3 Coupling of Aryl Halides with Diboronyl Reagents 35 1.3.1.4 Direct Boronylation by Transition Metal-catalyzed Aromatic C–H Functionalization 35 Boronic Acids. Edited by Dennis G. Hall Copyright © 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ISBN 3-527-30991-8 VI Table of Contents 1.3.1.5 Other Methods 36 1.3.2 Diboronic Acids 36 1.3.3 Heterocyclic Boronic Acids 37 1.3.4 Alkenylboronic Acids 37 1.3.4.1 Electrophilic Trapping of Alkenymetal Intermediates with Borates 37 1.3.4.2 Transmetallation Methods 37 1.3.4.3 Transition-metal Catalyzed Coupling between Alkenyl Halides/Trif lates and Diboronyl Reagents 42 1.3.4.4 Hydroboration of Alkynes 43 1.3.4.5 Alkene Metathesis 46 1.3.4.6 Other Methods 46 1.3.5 Alkynylboronic Acids 48 1.3.6 Alkylboronic Acids 48 1.3.7 Allylic Boronic Acids 49 1.3.8 Chemoselective Transformations of Compounds containing a Boronic Acid (Ester) Substituent 49 1.3.8.1 Oxidative Methods 50 1.3.8.2 Reductive Methods 51 1.3.8.3 Generation and Reactions of α-Boronyl-substituted Carbanions and Radicals 51 1.3.8.4 Reactions of (α-Haloalkyl)boronic Esters 54 1.3.8.5 Other Transformations 55 1.4 Isolation and Characterization 57 1.4.1 Chromatography and Recrystallization 57 1.4.2 Solid Supports for Boronic Acid Immobilization and Purification 58 1.4.2.1 Diethanolaminomethyl Polystyrene 59 1.4.2.2 Other Solid-supported Diol Resins 60 1.4.2.3 Soluble Diol Approaches 60 1.4.3 Analytical and Spectroscopic Methods for Boronic Acid Derivatives 61 1.4.3.1 Melting Points and Combustion Analysis 61 1.4.3.2 Mass Spectrometry 61 1.4.3.3 Nuclear Magnetic Resonance Spectroscopy 61 1.4.3.4 Other Spectroscopic Methods 62 1.5 Overview of the Reactions of Boronic Acid Derivatives 62 1.5.1 Metallation and Metal-catalyzed Protodeboronation 62 1.5.2 Oxidative Replacement of Boron 63 1.5.2.1 Oxygenation 63 1.5.2.2 Amination 65 1.5.2.3 Halogenation 66 1.5.3 Carbon–Carbon Bond forming Processes 68 1.5.3.1 Palladium-catalyzed Cross-coupling with Carbon Halides (Suzuki Coupling) 69 1.5.3.2 Allylation of Carbonyl Compounds 71 1.5.3.3 Uncatalyzed Additions to Imines and Iminiums 73 1.5.3.4 Rhodium-catalyzed Additions to Aldehydes and Alkenes 73 Table of Contents VII 1.5.3.5 Heck-type Coupling to Alkenes and Alkynes 73 1.5.4 Carbon–Heteroatom Bond forming Processes 73 1.5.4.1 Copper-catalyzed Coupling with Nucleophilic Oxygen and Nitrogen- containing Compounds 73 1.5.5 Other Reactions 74 1.6 Overview of other Applications of Boronic Acid Derivatives 76 1.6.1 Use as Reaction Promoters and Catalysts 76 1.6.2 Use as Protecting Groups for Diols and Diamines 78 1.6.3 Use as Supports for Derivatization and Affinity Purification of Diols, Sugars, and Glycosylated Proteins 79 1.6.4 Use as Receptors and Sensors for Carbohydrates and other Small Molecules 81 1.6.5 Use as Antimicrobial Agents and Enzyme Inhibitors 81 1.6.6 Use in Neutron Capture Therapy for Cancer 82 1.6.7 Use in Transmembrane Transport 83 1.6.8 Use in Bioconjugation and Labeling of Proteins and Cell Surface 84 1.7 References 85 2Metal-catalyzed Borylation of Alkanes and Arenes via C–H Activation for Synthesis of Boronic Esters 101 T. Ishiyama and N. Miyaura 2.1 Introduction 101 2.2 Borylation of Aromatic Halides and Trif lates 102 2.2.1 Cross-coupling Reaction of Diborons 102 2.2.2 Cross-coupling Reaction of Pinacolborane 104 2.3 Aliphatic C–H Borylation 105 2.3.1 Rhenium-catalyzed Photochemical Reaction 106 2.3.2 Rhodium-catalyzed Reaction 107 2.4 Aromatic C–H Borylation 109 2.4.1 Rhenium-catalyzed Photochemical Reaction 109 2.4.2 Rhodium-catalyzed Reactions 109 2.4.3 Iridium-catalyzed Reactions 110 2.4.4 Catalytic Cycle 116 2.5 Benzylic C–H Borylation 118 Acknowledgments 119 2.6 References 119 3 Coupling Reactions of Areneboronic Acids or Esters with Aromatic Electrophiles 123 A. Suzuki 3.1 Introduction 123 3.2 Coupling Reactions of Areneboronic Acid Derivatives 124 3.2.1 With Aryl Halides. Synthesis of Biaryls 124 3.2.1.1 Aromatic–Aromatic Coupling 124 3.2.1.2 Aromatic–Heteroaromatic and Heteroaromatic–Heteroaromatic Couplings 131 VIII Table of Contents 3.2.1.3 Coupling of Sterically Hindered Arylboronic Acids or ones Possessing Electron-attracting Substituents 141 3.2.1.4 Modified Catalysts and Ligands 144 3.2.1.5 Solid-phase Synthesis (Combinatorial Methodology) 153 3.2.2 With Other Organic Halides, including Aryl Chlorides and Electrophiles 156 3.2.3 Miscellaneous 160 3.3 Conclusion 166 3.4 References 167 4 Rhodium-catalyzed Additions of Boronic Acids to Alkenes and Carbonyl Compounds 171 K. Yoshida and T. Hayashi 4.1 Introduction 171 4.2 Addition of Organoboronic Acids to α,β-Unsaturated Ketones 171 4.3 Mechanism 176 4.4 Addition of Organoboronic Acids to Other Alkenes 181 4.5 Addition of Organoboronic Acids to Alkynes 192 4.6 Addition of Organoboronic Acids to Aldehydes and Imines 195 4.7 Addition of Organoboronic Acids to Anhydrides 200 4.8 Outlook 201 4.9 References 201 5 Recent Advances in Copper-promoted C–Heteroatom Bond Cross-coupling Reactions with Boronic Acids and Derivatives 205 D. M. T. Chan and P. Y. S. Lam 5.1 General Introduction 205 5.2 Copper-mediated Boronic Acid C–O and C–N Cross-coupling – Historical Background 206 5.3 C(aryl)–O Cross-coupling 207 5.3.1 Intermolecular C–O Cross-coupling 207 5.3.2 Intramolecular C–O Cross-coupling 210 5.4 C–N Cross-coupling 212 5.4.1 C–N (Non-heteroarene NH) Cross-coupling 212 5.4.1.1 Application in Solid-phase Synthesis 214 5.4.2 C–N (Heteroarene) Cross-coupling 215 5.4.2.1 Factor Xa Inhibitors 217 5.4.2.2 Purines 219 5.4.2.3 Heteroarene–Heteroarene Cross-coupling 220 5.5 C–O vs. C–N Cross-couplings 221 5.6 C–N and C–O Cross-coupling with Alkenylboronic Acids 222 5.7 C–S Cross-coupling 224 5.8 C–N and C–O Cross-coupling with Boronic Acid Derivatives 224 5.8.1 Boroxines, Boronic Esters and Trif luoroborate Salts 224 5.8.2 Alkylboronic Acids 227 Table of Contents IX 5.9 Mechanistic Considerations 227 5.9.1 Electronic Effects 227 5.9.2 Solvent Effects 228 5.9.3 Ligand or Base Effects 229 5.9.4 Mechanism 230 5.9.5 Side-products 231 5.10 Other Organometalloids 233 5.11 Conclusion 233 5.12 Appendix 235 5.13 References 238 6 Recent Advances in the Preparation of Allylboronates and Their Use in Tandem Reactions with Carbonyl Compounds 241 J. W. J. Kennedy and D. G. Hall 6.1 Introduction 241 6.2 Preparation of Allylboronates 243 6.2.1 Direct Methods 243 6.2.1.1 Allylboronates from Allylmetal Intermediates 243 6.2.1.2 Allylboronates from Alkenylmetal Intermediates 244 6.2.1.3 Allylboronates from the Hydroboration of 1,3-Butadienes and Allenes 246 6.2.1.4 Allylboronates from the Transition-metal Catalyzed Diboration and Silaboration of Dienes and Allenes 247 6.2.1.5 Allylboronates from Palladium-catalyzed Cross-coupling Reactions with Alkenyl Fragments 249 6.2.1.6 Allylboronates from Palladium-catalyzed Cross-coupling Reactions with Allyl Electrophiles 249 6.2.2 Indirect Methods 250 6.2.2.1 Allylboronates from Alcoholysis of Triallylboranes 250 6.2.2.2 Allylboronates from Homologation of Alkenylboronates 250 6.2.2.3 Allylboronates from Allylic Rearrangement of Alkenylboronates 251 6.2.2.4 Allylboronates from Isomerization of Alkenylboronates 252 6.2.2.5 Allylboronates by Cycloadditions of Dienylboronates 253 6.2.2.6 Allylboronates by Olefin Metathesis 254 6.3 Reactions of Allylboronates 256 6.3.1 Additions to Aldehydes – Formation of Homoallylic Alcohols 256 6.3.1.1 Stereoselectivity and Mechanism of Non-catalyzed Additions 256 6.3.1.2 Lewis Acid-catalyzed Additions 257 6.3.1.3 Stereoselective Additions with Chiral Allylboronates 259 6.3.2 Additions to Ketones 263 6.3.3 Additions to Imine Derivatives 264 6.4 Applications of Allylboronates in Tandem Reactions with Carbonyl Compounds 266 6.4.1 Allylboration as the Terminal Process 266 6.4.1.1 Tandem [4+2] Cycloaddition/Allylation 266 X Table of Contents 6.4.1.2 Tandem Hydroformylation/Intramolecular Allylation 267 6.4.1.3 Tandem Alkene Cross-metathesis/Allylation 268 6.4.1.4 Tandem Diene Hydroboration/Allylation 269 6.4.1.5 Tandem Diene Diborylation (Silaboration)/Allylboration 270 6.4.1.6 Tandem Allylic Borylation/Intramolecular Allylation 271 6.4.2 Allylboration as the Initiating Process 271 6.4.2.1 Tandem Allylation/Allylation 271 6.4.2.2 Tandem Allylation/Lactonization 272 6.4.2.3 Tandem Allylation/Dioxene Thermolysis 273 6.5 Conclusion 274 6.6 References 274 7 Nucleophilic Addition Reactions of Aryl and Alkenylboronic Acids and Their Derivatives to Imines and Iminium Ions 279 R.
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