Alkynes in Cycloadditions

Acetylene systems present a new route to cyclic compounds as an alternative to more traditional methods employed in classical organic chemistry. The synthesis of cyclic structures based on acetylene systems has important applications in the formation of nanostructures, naturally occurring compounds and chemosensory materials for the design of nonlinear optics, electronic and photonic devices.

Alkynes in Cycloadditions presents a modern review of regioselective synthesis of aromatic and non-aromatic carbocyclic and heterocyclic ring systems based primarily on [2+2+2] and [4+2] cycloadditions, and other reactions of acetylenic units including enediynes and enyne-allenes.

Topics covered include:

• New strategies for the formation of aromatic and polynuclear hydrocarbons based on (Z)-hex-3-en-1,5-diyne and (Z)-hepta-1,2,4-triene-6-yne blocks.
• One-step synthesis of benzene derivatives, β-substituted naphthalenes and acenes by the cycloaromatization of enediynes and enyne-allenes by Bergman, Myers-Saito and Shmittel.
• Mechanisms of cycloaromatization resulting in the formation of fulvene and indene systems.
• Heterocyclization involving enyne-carbodiimides.
• New achievements in classical cycloaddition reactions such as the Diels-Alder condensation with acetylenic dienophiles and [2+2] cycloadditions with acetylene components

Alkynes in Cycloadditions presents a comprehensive summary of the literature on methods for the synthesis of ring systems from acetylenes for academic researchers working in the fields of organic synthesis, physical organic chemistry, organometallic chemistry, catalysis, materials science, nanomaterials and biochemistry.

Professor Irina A. Maretina, St Petersburg State Institute of Technology, St. Petersburg, Russia. Irina Maretrina is a well-known name in the field of acetylene chemistry. Her research focuses on the chemistry of alkynes, in particular diacetylenes and the synthesis and reactivity of unsaturated heteroatomic compounds, including nitrogen-containing heterocyclic compounds.

Professor Boris I. Ionin (Translator), St Petersburg State Institute of Technology, Department of Organic Chemistry, St Petersburg, Russia. Boris Ionin is a renowned organic chemist specializing in acetylene and phosphorus chemistry, and nuclear magnetic resonance. He is an Editorial Board member for the Russian Journal of General Chemistry and Editor for the English translation of this journal.

John C. Tebby (Consulting Editor), Emeritus Professor FRSC DSc, former Head of Chemistry, Staffordshire University.

Preface xi

Acknowledgment xiii

Biography xv

1 Introduction 1

2 Regioselective Syntheses of Polysubstituted Benzenes Catalyzed by Transition Metal Complexes 5

2.1 Reactions of [2+2+2] Cycloaddition of Acetylene Units 5

2.1.1 Reactions of Alkynes with Metallocyclopentadiene as an Intermediate 5

2.1.2 Intra-intermolecular [2+2+2] Cycloaddition of Alkynes 6

2.2 Stereochemical Aspect of The Problem of Intermolecular Reactions of Diynes with Monoalkynes 18

2.2.1 Strategy of Enantioselective [2+2+2] Cycloaddition 18

2.2.2 Intramolecular [2+2+2] Reactions of Triynes 22

2.3 Heteroatom Bound to the Triple Bond 28

2.3.1 Nitrogen-Containing Substrates 28

2.3.1 [2+2+2] Cycloadditions of Alkynes to Nitriles: Synthesis of Pyridines 29

2.4 Heterohelicens. Asymmetric Syntheses 34

2.4.1 Oxygen-Containing Helicens 34

2.4.2 Nitrogen-Containing Helicens. Helical Dications 36

2.5 Aromatic Rings with Boron and Silicon Substituents 38

2.6 [2+2+2] Cycloaddition Reactions of 1-Alkynylphosphines and Their Derivatives 40

2.7 Intramolecular [2+2+2] Cycloaddition of Diynes to Alkenes 45

2.7.1 Allene as an Alkene Component 45

2.7.2 Formation of Polycyclic Cyclohexadienes by Ru-catalyzed Cascade Reactions of

1,6-Diynes and Alkenes 46

2.7.3 Stereochemical Aspects of the Reaction of Diynes with Alkenes 50

2.7.4 Hetero-[2+2+2] Cycloaddition of Alkynes to Compounds with a Multiple Carbon–Heteroatom Bond 51

2.8 Polysubstituted Benzenes. Reactions of [4+2]

Cycloaddition and Other Approaches 53

2.8.1 Reactions of Conjugated Enynes 53

2.8.2 Acceleration of Pd-catalyzed [4+2]-Benzannulation in the Reaction of Enynes and Diynes in the Presence of Lewis Acids and Bronsted Bases 59

2.9 Combined Reactions 63

2.9.1 Formal [4+2+2] Cycloaddition of 1,6-Diynes to 1,3-Dienes Catalyzed by Ru: Formation of Cyclooctatrienes and Vinylcyclohexadienes 64

2.9.2 Eight-Membered Ring Systems Formation by [4+2+2] Annulation 66

2.9.3 AuBr3 (AlCl3)- and Cu(OTf)2-Catalyzed [4+2] Cycloaddition of Alkynyl- and Alkenyl-Enynones and Enynals: An Approach to Functionalized Polycyclic Hydrocarbons 69

2.10 Construction of Polycyclic Systems 71

2.10.1 The Strategy of Synthesis of Steroid Systems by the Co-catalyzed [2+2+2] Cycloaddition of Nonconjugated Enyne-Allenes and Enediynes 72

2.10.2 Cobalt(I)-Mediated [2+2+2] Cyclization of Allene-Diynes: A Diastereoselective Approach to 11-aryl Steroid Core. 11-Aryl-substituted Steroid Systems by Co-catalyzed [2+2+2] Cyclization of Allene-Diynes 74

2.10.3 Synthesis of (3S)-hydroxyandrosta-5,7-diene-17-ones via Intramolecular Cobalt-Mediated [2+2+2] Cycloaddition 77

2.10.4 Intramolecular Cycloaddition of Nonconjugated Enediynes of a Higher Order as a Route to Functionalized Condensed Polycyclic Systems 79

2.10.5 A Strategy for the Synthesis of Aromatic Molecular-Bowl Hydrocarbons 85

2.10.6 A Route to Archimedenes: Total Synthesis of C3h-symmetric [7]phenylenes 93

2.10.7 Polycyclic Azaheterocycles 96

3 Radical Cycloaromatization of Systems Containing (Z)-3-hexene-1,5-diynes and (Z)-1,2,4-heptatrien-6-ynes and Related Heteroatomic Blocks 107

3.1 The Historical Aspect of the Chemistry of Enediynes, Enyne-Allenes and Enyne-Cumulenes 107

3.1.1 Anticancer Enediyne Antibiotics 108

3.2 Routes to the Cycloaromatization of Enediyne and Enyne-Allene Systems. Bergman and Myers–Saito Cyclization 113

3.2.1 Generation of Free Radicals by (Z)-3-hexene-1,5-diynes and (Z)-1,2,4-heptatrien-6-ynes 113

3.2.2 Thermal Cyclization 114

3.2.3 Photochemical Cyclization 122

3.2.4 Catalytic Cyclization 128

3.3 Cycloaromatization by C1–C5, C2–C7 and C2–C6 (Myers–Saito and Schmittel) Routes to Indeno-Fused Structures 135

3.3.1 Thermal C1–C5 Radical Cyclization of Enediynes 135

3.3.2 The Limitations of the Cycloaromatization Reactions 136

3.3.3 Thermal and Photochemical C2–C6 Cyclization of Enyne-Allenes: Switching the

Regioselectivity from C2–C7 (Myers–Saito) to C2–C6 (Schmittel) Cyclization Mode 138

3.3.4 Practical Aspects of the Syntheses Based on Enyne-Allenes 141

3.4 External Initiation of the Enediyne Cycloaromatization 157

3.4.1 Cycloaromatization Initiated by External Radicals 157

3.4.2 Ionic Activation of Cyclization of Enediynes 166

3.4.3 Other Types of Cyclization 174

3.5 Features of Cycloaromatization of Heteroatomic Enediynes 179

3.5.1 Trigger Mechanisms for the Cycloaromatization of Enediynes 179

3.5.2 Nitrogen-Containing Enediynes 185

3.5.3 Metal-Induced Bergman Cycloaromatization 208

3.5.4 Sulfur-Containing Enediynes 218

3.6 Cycloaromatization of Hetero-Systems 223

3.6.1 Enyne-Heteroallene and Enyne-(hetero)cumulenes 223

3.6.2 Features of Dienyne Cyclizations 225

4 Selected Cycloaddition and Heterocyclization Reactions with Unusual Acetylenic and Allenic Starting Compounds 233

4.1 Cycloaddition and Heterocyclization Reactions of Acetylenic Compounds with Electron-Withdrawing Substituents 233

4.2 Diels–Alder [4+2] Cycloaddition: Acetylenes as Dienophiles 235

4.3 Formation of Cyclobutene Derivatives by [2+2]-Cycloaddition 237

4.4 [2+2] Cyclization of Some 1,3-Butadienes Produced from Acetylenic Alcohols of Propargyl Type 243

4.5 Heterocyclization of Electron-Deficient Acetylenes with Nucleophilic Reagents 245

5 Concluding Remarks 249

Index

The New copy of this book will include any supplemental materials advertised. Please check the title of the book to determine if it should include any access cards, study guides, lab manuals, CDs, etc.

The Used, Rental and eBook copies of this book are not guaranteed to include any supplemental materials. Typically, only the book itself is included. This is true even if the title states it includes any access cards, study guides, lab manuals, CDs, etc.