Science of Synthesis: Houben-Weyl Methods of Molecular Transformations Vol. 45a (eBook)

Science of Synthesis – Volume 45a: Monocyclic Arenes, Quasiarenes, and Annulenes 1
Title page 3
Imprint 5
Preface 6
Overview 8
Table of Contents 10
Introduction 26
45.1 Product Class 1: Cyclopropenium Salts, Cyclopropenones and Heteroatom Analogues, and Cyclopropenyl Radicals and Anions 36
45.1.1 Product Subclass 1: Cyclopropenium Salts 37
45.1.1.1 Synthesis of Product Subclass 1 37
45.1.1.1.1 Method 1: Synthesis from Cyclopropenes 37
45.1.1.1.1.1 Variation 1: Hydride Abstraction 37
45.1.1.1.1.2 Variation 2: Protonation 38
45.1.1.1.1.3 Variation 3: Halide Abstraction 39
45.1.1.1.2 Method 2: Synthesis from Halocyclopropanes 42
45.1.1.1.3 Method 3: Synthesis from Cyclopropenones or Their Heteroatom Analogues 42
45.1.1.1.3.1 Variation 1: O-Alkylation and Related Processes 42
45.1.1.1.3.2 Variation 2: Protonation 43
45.1.1.1.3.3 Variation 3: Formation of Dications 44
45.1.1.1.4 Method 4: Transformations of Other Cyclopropenium Salts 45
45.1.1.1.4.1 Variation 1: Friedel--Crafts-Type Reactions 45
45.1.1.1.4.2 Variation 2: Substitution 46
45.1.1.2 Applications of Product Subclass 1 in Organic Synthesis 49
45.1.1.2.1 Method 1: Synthesis of Cyclopropenes 49
45.1.1.2.2 Method 2: Synthesis of Cyclic Compounds 51
45.1.1.2.3 Method 3: Synthesis of Acyclic Compounds 53
45.1.2 Product Subclass 2: Cyclopropenones and Their Heteroatom Analogues 56
45.1.2.1 Synthesis of Product Subclass 2 56
45.1.2.1.1 Method 1: Synthesis from Cyclopropenium Salts 56
45.1.2.2 Applications of Product Subclass 2 in Organic Synthesis 60
45.1.2.2.1 Method 1: Synthesis of Heterocyclic Systems 60
45.1.2.2.1.1 Variation 1: Nitrogen Heterocycles 60
45.1.2.2.1.2 Variation 2: Oxygen Heterocycles 65
45.1.2.2.2 Method 2: Synthesis of Carbocycles 67
45.1.3 Product Subclass 3: Cyclopropenyl Radicals 69
45.1.3.1 Synthesis of Product Subclass 3 69
45.1.4 Product Subclass 4: Cyclopropenyl Anions 69
45.1.4.1 Synthesis of Product Subclass 4 69
45.2 Product Class 2: Cyclobutadienes, Cyclobutenediones, and Squaric Acids 74
45.2.1 Product Subclass 1: Cyclobutadienes 74
45.2.1.1 Synthesis of Product Subclass 1 82
45.2.1.1.1 Method 1: Synthesis by Cycloreversion 82
45.2.1.1.2 Method 2: Synthesis by Decomposition of Cyclopropenyl Diazomethanes 85
45.2.1.1.3 Method 3: Synthesis from Metal--Cyclobutadiene Complexes 87
45.2.1.1.3.1 Variation 1: Using Iron Complexes 87
45.2.1.1.3.2 Variation 2: Using Other Metal Complexes 90
45.2.1.1.4 Method 4: Other Methods 91
45.2.2 Product Subclass 2: Cyclobutenediones 93
45.2.2.1 Synthesis of Product Subclass 2 94
45.2.2.1.1 Method 1: Synthesis from Alkynes 94
45.2.2.1.1.1 Variation 1: By Cycloaddition Reactions 94
45.2.2.1.1.2 Variation 2: Using Transition-Metal Complexes 96
45.2.2.1.2 Method 2: Synthesis from Alkenes 98
45.2.2.1.3 Method 3: Synthesis from Other Cyclobutenediones 100
45.2.2.1.3.1 Variation 1: Friedel--Crafts Reaction of Halocyclobutenediones 100
45.2.2.1.3.2 Variation 2: Reaction of Squaric Acid Derivatives and Carbon Nucleophiles 102
45.2.2.1.3.3 Variation 3: Transition-Metal-Catalyzed Cross-Coupling Reactions 105
45.2.2.1.4 Method 4: Other Methods 107
45.2.3 Product Subclass 3: Squaric Acids and Derivatives 108
45.2.3.1 Synthesis of Product Subclass 3 111
45.2.3.1.1 Method 1: Synthesis of Squaric Acids from Polyhalocyclobutenes and Related Reactions 111
45.2.3.1.2 Method 2: Synthesis of Squarate Esters from Squaric Acids 113
45.2.3.1.3 Method 3: Synthesis via Transesterification and Related Reactions 115
45.2.3.1.4 Method 4: Other Methods 116
45.2.4 Product Subclass 4: Sulfur Analogues of Squaric Acid and Related Compounds 116
45.2.4.1 Synthesis of Product Subclass 4 120
45.2.4.1.1 Method 1: Synthesis from Squarate Esters and Sulfur Nucleophiles, and Related Reactions 120
45.2.4.1.2 Method 2: Synthesis by Alkylation of Thiosquarate Anions 123
45.2.4.1.3 Method 3: Other Methods 124
45.3 Product Class 3: Cyclopentadienyl Anions, Cyclopentadienones, and Heteroatom Analogues 134
45.3.1 Product Subclass 1: Cyclopentadienyl Anions 135
45.3.1.1 Synthesis of Product Subclass 1 135
45.3.1.1.1 Method 1: Direct Deprotonation 135
45.3.1.1.1.1 Variation 1: Using Alkyllithium Reagents 135
45.3.1.1.1.2 Variation 2: Using Metal Hydrides 138
45.3.1.1.1.3 Variation 3: Using Elemental Alkaline Metals 140
45.3.1.1.1.4 Variation 4: Using Alkali Metal Amides 141
45.3.1.1.2 Method 2: Metal Exchange 142
45.3.1.1.3 Method 3: Synthesis from Pentafulvenes 143
45.3.1.1.4 Method 4: Synthesis from Spirocyclopentadienes 147
45.3.1.2 Applications of Product Subclass 1 in Organic Synthesis 148
45.3.1.2.1 Method 1: Synthesis of Metallocenes and Metal Complexes 148
45.3.1.2.2 Method 2: Synthesis of Functionalized Cyclopentadienides 148
45.3.1.2.3 Method 3: Synthesis of Substituted Cyclopentadienes and Indenes 150
45.3.1.2.3.1 Variation 1: Alkylation Reactions 150
45.3.1.2.3.2 Variation 2: Nucleophilic Addition to Carbonyl Compounds 151
45.3.2 Product Subclass 2: Cyclopentadienones and Heteroatom Analogues 154
45.3.2.1 Synthesis of Product Subclass 2 154
45.3.2.1.1 Method 1: Synthesis from Dicarbonyl Compounds 154
45.3.2.1.2 Method 2: Synthesis from Alkynes 158
45.3.2.1.2.1 Variation 1: Insertion of Carbon Monoxide 158
45.3.2.1.2.2 Variation 2: Reaction with Cyclopropenones 160
45.3.2.1.2.3 Variation 3: Reaction with Isocyanates or Isothiocyanates 162
45.3.2.1.3 Method 3: Synthesis from 1,3-Diene-1,4-diyldilithium Compounds 163
45.3.2.1.4 Method 4: Synthesis from Cyclopentenones and Related Compounds 165
45.3.2.1.5 Method 5: Ring-Contraction Methods 166
45.3.2.2 Applications of Product Subclass 2 in Organic Synthesis 168
45.3.2.2.1 Method 1: Formation of Metal Complexes 168
45.3.2.2.2 Method 2: Synthesis of Functionalized Cyclopentadienes 168
45.3.2.2.3 Method 3: Synthesis of Fused Systems 170
45.3.2.2.3.1 Variation 1: Polyaromatic Compounds 170
45.3.2.2.3.2 Variation 2: Polycyclic Compounds 172
45.4 Product Class 4: Benzene and Alkylbenzenes 182
45.4.1 Product Subclass 1: Benzene 182
45.4.1.1 Synthesis of Product Subclass 1 182
45.4.1.1.1 Method 1: Thermal Aromatization of Acetylene 182
45.4.1.1.1.1 Variation 1: Metal-Catalyzed Aromatization of Acetylene 182
45.4.1.1.2 Method 2: Metal-Catalyzed Aromatization of Alkanes 183
45.4.1.1.2.1 Variation 1: Metal-Catalyzed Aromatization of Alcohols 183
45.4.1.1.3 Method 3: Metal-Catalyzed Aromatization of Cycloalkanes 183
45.4.1.1.3.1 Variation 1: Aromatization of Cycloalkenes Using Sonication 183
45.4.2 Product Subclass 2: Monoalkylbenzenes 184
45.4.2.1 Synthesis of Product Subclass 2 184
45.4.2.1.1 Method 1: Friedel--Crafts Alkylation of Arenes 184
45.4.2.1.1.1 Variation 1: Lewis Acid Catalyzed Friedel--Crafts Alkylation of Arenes with Alkyl Halides 184
45.4.2.1.1.2 Variation 2: Brønsted Acid or Base Catalyzed Friedel--Crafts Alkylation of Arenes with Alkyl Halides 186
45.4.2.1.1.3 Variation 3: Photochemical Friedel--Crafts Alkylation of Arenes with Alkyl Halides 186
45.4.2.1.1.4 Variation 4: Friedel--Crafts Alkylation of Arenes with Alcohols 187
45.4.2.1.1.5 Variation 5: Friedel--Crafts Alkylation of Arenes with Alkenes 190
45.4.2.1.1.6 Variation 6: Via Tandem Lewis Acid Catalyzed Halogenation and Friedel--Crafts Alkylation of Alkenes 191
45.4.2.1.1.7 Variation 7: Friedel--Crafts Alkylation of Arenes with Epoxides 191
45.4.2.1.1.8 Variation 8: Friedel--Crafts Alkylation of Arenes with Aldehydes 193
45.4.2.1.1.9 Variation 9: Friedel--Crafts Alkylation of Arenes with Alkyl Methanesulfonates or Trifluoromethanesulfonates 195
45.4.2.1.1.10 Variation 10: Lewis Acid Catalyzed Friedel--Crafts Alkylation of Arenes with .-Alkenyl Silyl Ethers 197
45.4.2.1.1.11 Variation 11: Lewis Acid Catalyzed Friedel--Crafts Alkylation of Arenes with Allylic Acetates 197
45.4.2.1.2 Method 2: Alkylation of Arenes via Cross Coupling of Arenes to Benzyl Ethers 198
45.4.2.1.3 Method 3: Alkylarenes via a Tandem Alkylation--Hydride Reduction Sequence 198
45.4.2.1.3.1 Variation 1: Via Palladium-Catalyzed C--H Activation of Arenes and Coupling with Alkylstannanes 199
45.4.2.1.4 Method 4: Alkylation of Arenes via Suzuki Reaction of Alkylboranes and Related Alkylboron Reagents with Aryl Halides 200
45.4.2.1.4.1 Variation 1: Via Nickel-Catalyzed Cross Coupling 202
45.4.2.1.4.2 Variation 2: Via Organocuprate Coupling to Aryl Trifluoromethanesulfonates 202
45.4.2.1.4.3 Variation 3: Via Kumada-Type Cross Coupling 203
45.4.2.1.4.4 Variation 4: Via Negishi-Type Cross-Coupling Reactions 205
45.4.2.1.4.5 Variation 5: Via Stille-Type Cross-Coupling Reactions 206
45.4.2.1.4.6 Variation 6: Via Hiyama-Type Cross-Coupling Reactions 207
45.4.2.1.5 Method 5: Alkylation of Benzenes through an SNAr Mechanism 208
45.4.2.1.6 Method 6: Alkylation of Benzyl Bromides Using Organocuprates in the Presence of Trialkylboranes 208
45.4.2.1.7 Method 7: Reduction of Alkyl Aryl Ketones Using Hydrazine and a Base under Wolff--Kishner Conditions 209
45.4.2.1.7.1 Variation 1: Microwave Heating under Classic Wolff--Kishner Conditions 210
45.4.2.1.7.2 Variation 2: Wolff--Kishner Reduction of N-(tert-Butyldimethylsilyl)hydrazones 210
45.4.2.1.7.3 Variation 3: Using Tosylhydrazones and Alkylboranes 212
45.4.2.1.7.4 Variation 4: Reduction Using Zinc--Hydrochloric Acid under Clemmensen Conditions 212
45.4.2.1.7.5 Variation 5: Using Phenylphosphines 212
45.4.2.1.7.6 Variation 6: Using Trialkyl Phosphites 213
45.4.2.1.7.7 Variation 7: Using Organosilanes 213
45.4.2.1.7.8 Variation 8: Using Metal Aluminum or Boron Hydrides and a Second Co-reductant 214
45.4.2.1.7.9 Variation 9: Using Selenium under an Atmosphere of Carbon Monoxide 217
45.4.2.1.7.10 Variation 10: Using Hydrogen Gas in the Presence of a Metal Catalyst 217
45.4.2.1.7.11 Variation 11: Using Water or Alcohols as Hydrogen Sources for Reduction in the Presence of a Metal Catalyst 218
45.4.2.1.7.12 Variation 12: Via Tandem Thioketal Formation and Metal Reduction 219
45.4.2.1.7.13 Variation 13: Using Palladium/Carbon as a Catalyst 220
45.4.3 Product Subclass 3: Polyalkylbenzenes 220
45.4.3.1 Synthesis of Product Subclass 3 220
45.4.3.1.1 Method 1: Polyalkylbenzenes via a Directed Carbopalladation Reaction 220
45.4.3.1.2 Method 2: [2 + 2 + 2] Transition-Metal-Catalyzed Cyclotrimerization of Alkynes 220
45.4.3.1.3 Method 3: Nickel-Catalyzed Synthesis of Polyalkylated Phenols 223
45.4.3.1.4 Method 4: [4 + 2] Cyclization of Alkynes with Enynes 223
45.4.3.1.5 Method 5: Tandem Sonogashira--[4 + 2] Benzannulation Protocol of Alkynes with Vinyl Bromides 228
45.4.3.1.6 Method 6: Alkene Metathesis 228
45.5 Product Class 5: Styrenes, Stilbenes, and Other Alk-1-enylbenzenes 234
45.5.1 Synthesis of Product Class 5 234
45.5.1.1 Alkenation of Aldehydes 234
45.5.1.1.1 Method 1: Wittig-Type Reactions 235
45.5.1.1.1.1 Variation 1: The Wittig Reaction 235
45.5.1.1.1.2 Variation 2: The Horner--Wittig Reaction 237
45.5.1.1.1.3 Variation 3: The Horner--Wadsworth--Emmons Reaction 239
45.5.1.1.2 Method 2: The Peterson Reaction 240
45.5.1.1.3 Method 3: The Julia Reaction 241
45.5.1.1.4 Method 4: The Perkin Reaction 242
45.5.1.1.5 Method 5: The Modified Julia Reaction 243
45.5.1.1.6 Method 6: The McMurry Reaction 245
45.5.1.2 Elimination Reactions 246
45.5.1.2.1 Method 1: Elimination of Alcohols 246
45.5.1.2.2 Method 2: Elimination of Alkyl Halides 247
45.5.1.2.3 Method 3: Elimination of 1,2-Dibromides 248
45.5.1.3 Reduction of Alkynes 249
45.5.1.3.1 Method 1: Partial Catalytic Hydrogenation of Alkynes 249
45.5.1.4 Alkene Cross-Metathesis Reactions 251
45.5.1.4.1 Method 1: Using Molybdenum and Ruthenium Carbene Complexes 251
45.5.1.5 Palladium-Catalyzed Cross-Coupling Reactions 252
45.5.1.5.1 Method 1: The Mizoroki--Heck Reaction 252
45.5.1.5.1.1 Variation 1: Aryl Halides as Electrophiles 253
45.5.1.5.1.2 Variation 2: Arenediazonium Salts as Electrophiles 257
45.5.1.5.1.3 Variation 3: Decarbonylative Heck Reaction 259
45.5.1.5.1.4 Variation 4: Desulfonylative Heck Reaction 261
45.5.1.5.2 Method 2: The Suzuki--Miyaura Reaction 262
45.5.1.5.3 Method 3: The Hiyama Reaction 264
45.5.1.5.4 Method 4: The Kosugi--Migita--Stille Reaction 265
45.5.1.5.5 Method 5: The Negishi Reaction 267
45.5.1.5.6 Method 6: The Kumada--Tamao--Corriu Reaction 268
45.5.1.5.7 Method 7: Organoindium Cross-Coupling Reactions 269
45.6 Product Class 6: Annulated Benzenes (1H-Cyclopropabenzenes, 1,2-Dihydrocyclobutabenzenes, Indanes, and Indenes) 278
45.6.1 Product Subclass 1: 1H-Cyclopropabenzenes 278
45.6.1.1 Synthesis of Product Subclass 1 278
45.6.1.1.1 Method 1: Photolysis of 3H-Pyrazoles 278
45.6.1.1.2 Method 2: Aromatization Reactions 279
45.6.1.1.3 Method 3: Synthesis from Other Cyclopropabenzenes 280
45.6.1.1.4 Method 4: Direct Formation of the Cyclopropane Ring 282
45.6.1.1.5 Method 5: Synthesis of Silicon, Germanium, and Boron Analogues of Cyclopropabenzene 283
45.6.1.2 Applications of Product Subclass 1 in Organic Synthesis 284
45.6.1.2.1 Method 1: Synthesis of Carbon-Containing Aromatic Compounds 284
45.6.1.2.2 Method 2: Synthesis of Heterocyclic Compounds 286
45.6.2 Product Subclass 2: 1,2-Dihydrocyclobutabenzenes 288
45.6.2.1 Synthesis of Product Subclass 2 288
45.6.2.1.1 Method 1: Synthesis from Cycloproparenes 288
45.6.2.1.2 Method 2: Synthesis from 2H-Pyran-2-ones 289
45.6.2.1.3 Method 3: Photochemical Reactions 290
45.6.2.1.4 Method 4: Synthesis from Benzyne Derivatives 292
45.6.2.1.5 Method 5: Other Annulation Reactions 295
45.6.2.1.6 Method 6: Synthesis from Metallocyclopentadienes 303
45.6.2.2 Applications of Product Subclass 2 in Organic Synthesis 305
45.6.2.2.1 Method 1: Synthesis of Aromatic Compounds 305
45.6.2.2.1.1 Variation 1: Synthesis of Substituted Benzenes 305
45.6.2.2.1.2 Variation 2: Synthesis of Condensed Systems 305
45.6.2.2.2 Method 2: Synthesis of Heterocyclic Compounds 310
45.6.2.2.3 Method 3: Synthesis of Steroid Derivatives 312
45.6.3 Product Subclass 3: Indanes 314
45.6.3.1 Synthesis of Product Subclass 3 314
45.6.3.1.1 Method 1: Friedel--Crafts Cyclization 314
45.6.3.1.2 Method 2: Nazarov Cyclizations 316
45.6.3.1.3 Method 3: Metal-Mediated Cyclization Reactions 317
45.6.3.1.3.1 Variation 1: Palladium-Catalyzed Cyclization (Heck Reaction) 317
45.6.3.1.3.2 Variation 2: Rhodium-Catalyzed Cyclization 321
45.6.3.1.4 Method 4: Electrochemical Cyclization 324
45.6.3.1.5 Method 5: Ring-Contraction Reactions 325
45.6.3.1.6 Method 6: Multicomponent Reactions 327
45.6.3.1.7 Method 7: Cycloaddition Reactions 329
45.6.3.2 Applications of Product Subclass 3 in Organic Synthesis 330
45.6.3.2.1 Method 1: Indanes as Ligands in Organometallic Complexes 330
45.6.3.2.2 Method 2: Synthesis of Heterocyclic Systems 331
45.6.4 Product Subclass 4: Indenes 332
45.6.4.1 Synthesis of Product Subclass 4 332
45.6.4.1.1 Method 1: Friedel--Crafts Annulations 332
45.6.4.1.2 Method 2: Metal-Catalyzed Annulation Reactions 336
45.6.4.1.2.1 Variation 1: Palladium-Catalyzed Annulation 336
45.6.4.1.2.2 Variation 2: Nickel-Catalyzed Annulation 339
45.6.4.1.2.3 Variation 3: Ruthenium-Catalyzed Annulation 340
45.6.4.1.2.4 Variation 4: Rhodium-Catalyzed Annulation 341
45.6.4.1.2.5 Variation 5: Rhenium-Catalyzed Annulation 343
45.6.4.1.2.6 Variation 6: Cobalt-Catalyzed Annulation 343
45.6.4.1.2.7 Variation 7: Gold-Catalyzed Annulation 344
45.6.4.1.2.8 Variation 8: Platinum-Catalyzed Annulation 345
45.6.4.2 Applications of Product Subclass 4 in Organic Synthesis 345
45.6.4.2.1 Method 1: Synthesis of Fused Indanes and Related Compounds 345
45.6.4.2.2 Method 2: Synthesis of Heterocyclic Systems 346
45.7 Product Class 7: Cycloheptatrienylium (Tropylium) Salts, Tropones, Tropolones, and Heteroatom Analogues 354
45.7.1 Product Subclass 1: Cycloheptatrienylium (Tropylium) Salts 355
45.7.1.1 Synthesis of Product Subclass 1 355
45.7.1.1.1 Method 1: Ring Enlargement of Benzene Derivatives 355
45.7.1.1.2 Method 2: Aryl-Substituted Tropylium Ions by Arylation of the Parent Ion 357
45.7.1.1.3 Method 3: Oxidation of Cycloheptatrienes with Nitrosyl Tetrafluoroborate 358
45.7.1.1.4 Method 4: Tropylium Salts by Alkylation of Tropones and Tropothiones 359
45.7.1.1.5 Method 5: Formation of Silatropylium Ions 360
45.7.1.1.6 Method 6: Formation of Azatropylium (Azepinium) Ions 361
45.7.2 Product Subclass 2: Tropones 362
45.7.2.1 Synthesis of Product Subclass 2 362
45.7.2.1.1 Syntheses by [6 + 1] Combinations 362
45.7.2.1.1.1 Method 1: Synthesis from Phenols by Dihalocarbene Addition 362
45.7.2.1.1.1.1 Variation 1: Reduction of (Dihalomethyl)cyclohexadienones with Polymer-Bound Dibutyltin Hydride 364
45.7.2.1.1.2 Method 2: Annulated Tropones by Intramolecular Oxidative Coupling of Phenols 366
45.7.2.1.1.3 Method 3: 2,3-Dichloro-5,6-dicyanobenzo-1,4-quinone Oxidation of Spirocyclic Naphthalen-2-ones 367
45.7.2.1.1.4 Method 4: Synthesis from Dihalocarbene Adducts of Cyclohexadienes 367
45.7.2.1.1.4.1 Variation 1: Chlorocarbene Addition to Silyl Enol Ethers 368
45.7.2.1.1.5 Method 5: Tropones via Halotropylium Ions as Reactive Intermediates 369
45.7.2.1.1.6 Method 6: Tropones from [4 + 2] Cycloaddition of Benzo-1,2-quinones and Arylalkynes 371
45.7.2.1.2 Syntheses by [5 + 2] Combinations 372
45.7.2.1.2.1 Method 1: cine Substitution of exo-7-Chlorobicyclo[3.2.0]hept-2-en-6-one 373
45.7.2.1.2.2 Method 2: Light-Induced Synthesis of 3- and 4-Alkyltropones 374
45.7.2.1.3 Syntheses by [4 + 3] Combinations 375
45.7.2.1.3.1 Method 1: Rearrangement of 8-Oxabicyclo[3.2.1]oct-6-en-3-ones with Trimethylsilyl Trifluoromethanesulfonate and Triethylamine 375
45.7.2.1.3.1.1 Variation 1: Cycloaddition of Furans and 1,1,3,3-Tetrachloro-2-oxidopropenylium Cation 376
45.7.2.1.3.1.2 Variation 2: 2,7-Dichlorotropones from [3 + 4] Cycloaddition of Buta-1,3-dienes and 1,1,3,3-Tetrachloro-2-oxidopropenylium Cation 378
45.7.2.1.3.2 Method 2: 3-Aminotropones from an N-tert-Butoxycarbonyl-Protected Furan-2-amine 379
45.7.2.1.3.3 Method 3: Cyclopropanation of Buta-1,3-diene with Ethyl 3-Diazopyruvate 380
45.7.2.1.3.4 Method 4: Cyclopropanation of Buta-1,3-dienes with Vinylcarbenes Followed by Cope Rearrangement 381
45.7.2.1.3.5 Method 5: [4 + 2] Cycloadditions with 4,8-Dioxaspiro[2.5]oct-1-ene 384
45.7.2.1.3.6 Method 6: Reaction of Functionalized Buta-1,3-dienes and Tetrachlorocyclopropene 386
45.7.2.1.4 Heteroanologues of Tropones 386
45.7.2.1.4.1 Method 1: Oxidation of a 3H-Azepine 387
45.7.3 Product Subclass 3: Tropolones 388
45.7.3.1 Synthesis of Product Subclass 3 389
45.7.3.1.1 Syntheses by [6 + 1] Combinations 389
45.7.3.1.1.1 Method 1: Rearrangement of 7-Halobicyclo[4.1.0]heptanediones 389
45.7.3.1.1.2 Method 2: Photooxygenation of Ethyl 4,5-Dioxymethylenecyclohepta-2,4,6-trienecarboxylate 391
45.7.3.1.1.3 Method 3: ß-Tropolones from o-Quinones and Triphenylbismuthonium 2-Oxoalkalides 392
45.7.3.1.1.4 Method 4: ß-Tropolones from o-Quinones and 2-Methylquinolines 393
45.7.3.1.2 Syntheses by [5 + 2] Combinations 394
45.7.3.1.2.1 Method 1: Base-Catalyzed Rearrangement of 7,7-Dichloro-4-isopropylidenebicyclo[3.2.0]hept-2-en-6-ones 394
45.7.3.1.2.2 Method 2: Best Route to .-Tropolone 395
45.7.3.1.2.3 Method 3: Pyrylium 3-Oxides as a New Tool for a-Tropolone Synthesis 396
45.7.3.1.3 Syntheses by [4 + 3] Combinations 397
45.7.3.1.3.1 Method 1: Cyclopropanation of 2-Methoxy-Substituted Buta-1,3-diene Ketals 397
45.7.3.1.3.1.1 Variation 1: ß-Tropolone Methyl Ethers from Cyclopropanation of 3-Methoxy-Substituted Buta-1,3-diene Ketals 398
45.7.3.1.3.2 Method 2: [3 + 4] Cycloaddition of a Methoxy-2-oxidopropenylium Cation with Furans 399
45.7.3.1.3.3 Method 3: a-Tropolones by Hydroxylation of 8-Oxabicyclo[3.2.1]oct-6-en-3-ones 400
45.7.3.1.3.4 Method 4: ß-Tropolone Formation on Basic Cleavage of 2,2-Dimethoxy-8-oxabicyclo[3.2.1]oct-6-en-3-ones 401
45.7.3.1.4 Heteroanalogues of Tropolones 402
45.8 Product Class 8: Cyclooctatetraenes 408
45.8.1 Synthesis of Product Subclass 8 409
45.8.1.1 Method 1: Cyclization of Octatetraenes 409
45.8.1.2 Method 2: Copper-Mediated Cyclotetramerization of Ethenes 409
45.8.1.3 Method 3: Metal-Mediated Cyclodimerization of Butadienes 410
45.8.1.3.1 Variation 1: Copper-Mediated Homocoupling 410
45.8.1.3.2 Variation 2: Copper-Mediated Cross Coupling 412
45.8.1.3.3 Variation 3: Nickel-Mediated Homocoupling 413
45.8.1.3.4 Variation 4: Nickel-Mediated Cross Coupling 413
45.8.1.4 Method 4: Reduction of Cyclooctadienes and Cyclooctatrienes Followed by Oxidation of the Resultant Dianion 414
45.8.1.5 Method 5: Dehydrohalogenation of Annulated Cyclooctatrienes and Cyclooctadienes 415
45.8.1.6 Method 6: Removal of Acidic Protons 416
45.8.1.7 Method 7: Decarbonylation and Decarboxylation 416
45.8.1.8 Method 8: Wittig Reaction 418
45.8.1.9 Method 9: Extrusion of Oxygen 418
45.8.1.10 Method 10: Extrusion of Sulfur Dioxide 418
45.8.1.11 Method 11: Nickel-Catalyzed Cyclotetramerization of Alkynes 419
45.8.1.12 Method 12: Isomerization of Cyclooctatetraene Valence Isomers 421
45.8.1.12.1 Variation 1: Isomerization of Bicyclo[4.2.0]octatrienes 421
45.8.1.12.2 Variation 2: Isomerization of Tricyclo[4.2.0.02,5]octa-3,7-dienes 423
45.8.1.12.3 Variation 3: Isomerization of Semibullvalenes 423
45.8.1.12.4 Variation 4: Isomerization of Cubanes 424
45.8.1.12.5 Variation 5: Photolysis of Barrelene 424
45.8.1.13 Method 13: Base-Catalyzed Rearrangement of Cycloocta-1,5-diyne 424
45.8.1.14 Method 14: Ring Expansion by Carbene Rearrangement 425
45.8.1.15 Method 15: Synthesis with Retention of the Cyclooctatetraene Ring by Halogenation of Cyclooctatetraene 425
45.8.1.16 Method 16: Synthesis with Retention of the Cyclooctatetraene Ring by Functionalization of Bromocyclooctatetraene 426
45.8.1.16.1 Variation 1: Metalation Reactions 426
45.8.1.16.2 Variation 2: Dehydrobromination Reactions 427
45.8.1.16.3 Variation 3: Cross-Coupling Reactions 428
45.9 Product Class 9: Nine-Membered and Higher Annulenes and Related Ions 432
45.9.1 Product Subclass 1: Annulenes and Related Ions 432
45.9.1.1 Synthesis of Product Subclass 1 432
45.9.1.1.1 Method 1: Halogenation Followed by Dehydrohalogenation 432
45.9.1.1.2 Method 2: Corey--Winter Alkene Synthesis 433
45.9.1.1.3 Method 3: Wittig Reaction 434
45.9.1.1.4 Method 4: McMurry Coupling 434
45.9.1.1.5 Method 5: Reductive Elimination of Chlorine 435
45.9.1.1.6 Method 6: Hydrogenation of Dehydroannulenes 435
45.9.1.1.7 Method 7: Valence Isomerization 437
45.9.1.1.8 Method 8: Reductive Methylation of Octalene Dianion 439
45.9.1.1.9 Method 9: Prototropic Rearrangement 439
45.9.1.1.10 Method 10: Substitution of Annulene Rings 440
45.9.2 Product Subclass 2: Methano[n]annulenes and Related Ions 441
45.9.2.1 Synthesis of Product Subclass 2 441
45.9.2.1.1 Method 1: Electrocyclization Followed by Dehydrohalogenation 441
45.9.2.1.2 Method 2: Dehydrogenation of Dihydro- or Tetrahydro[n]annulenes and Tetrahydropyrenes 441
45.9.2.1.3 Method 3: Dihydropyrenes by Elimination of Dimethyl Sulfide 442
45.9.2.1.4 Method 4: Dehydration of Allylic Alcohols 443
45.9.2.1.5 Method 5: Elimination of Methanol 443
45.9.2.1.6 Method 6: Dehydrohalogenation 443
45.9.2.1.7 Method 7: Sulfur Elimination 444
45.9.2.1.8 Method 8: McMurry Coupling 444
45.9.2.1.9 Method 9: Diels--Alder Reactions of Cyclopropabenzene 445
45.9.2.1.10 Method 10: Cycloaddition of Acetylene Followed by C--C Bond Cleavage 445
45.9.2.1.11 Method 11: Reductive Addition to Dienones 446
45.9.2.1.12 Method 12: Electrophilic Substitution of Annulene Rings 446
45.9.2.1.13 Method 13: Substitution via Organometallic Species 447
45.9.2.1.14 Method 14: Decarbonylation of Dialdehydes 448
45.9.2.1.15 Method 15: Functionalization of Annulenes via Annulynes 448
45.9.2.1.16 Method 16: Functionalization of Annulenes via Homocoupling 449
45.9.2.1.17 Method 17: Functionalization via Cross Coupling 449
45.10 Product Class 10: Fulvenes 454
45.10.1 Product Subclass 1: Triafulvenes 455
45.10.1.1 Synthesis of Product Subclass 1 455
45.10.1.1.1 Method 1: Synthesis from Cyclopropenones 455
45.10.1.1.1.1 Variation 1: Condensation Reactions with Active Methylene Compounds Initiated by Acetic Anhydride 455
45.10.1.1.1.2 Variation 2: Wittig and Peterson Alkenation Reactions 456
45.10.1.1.1.3 Variation 3: Condensation Reactions with Ketenes 457
45.10.1.1.1.4 Variation 4: Reaction of Cyclopropenethione with Tetracyanoethene Oxide 457
45.10.1.1.2 Method 2: Synthesis from Cyclopropenylium Salts 458
45.10.1.1.2.1 Variation 1: Proton Abstraction from Substituted Cyclopropenylium Salts 458
45.10.1.1.2.2 Variation 2: Reaction of Heterosubstituted Cyclopropenylium Salts with Active Methylene Compounds 459
45.10.1.1.3 Method 3: Synthesis from Substituted Methylenecyclopropanes by Elimination 460
45.10.1.1.4 Method 4: Carbene Reactions of Cyclopropenylidenes 461
45.10.1.1.5 Method 5: Synthesis of Benzotriafulvenes by Peterson Alkenation 462
45.10.2 Product Subclass 2: Triafulvalenes 463
45.10.2.1 Synthesis of Product Subclass 2 463
45.10.2.1.1 Method 1: Synthesis of Dibenzotriafulvalenes by Carbene Dimerization 463
45.10.2.1.2 Method 2: Synthesis of Naphthotriafulvalenes by Peterson Alkenation 464
45.10.3 Product Subclass 3: Pentatriafulvalenes 464
45.10.3.1 Synthesis of Product Subclass 3 465
45.10.3.1.1 Method 1: Synthesis from Cyclopropenones 465
45.10.3.1.1.1 Variation 1: Condensation Reactions with Cyclopentadiene Derivatives Initiated by Acetic Anhydride 465
45.10.3.1.1.2 Variation 2: Condensation Reactions with Substituted Cyclopentadienes 466
45.10.3.1.2 Method 2: Synthesis from Cyclopropenylium Salts 466
45.10.3.1.2.1 Variation 1: Proton Abstraction from Substituted Cyclopropenylium Salts 466
45.10.3.1.2.2 Variation 2: Condensation Reactions of Heterosubstituted Cyclopropenylium Salts 467
45.10.3.1.3 Method 3: Condensation Reactions of Dichlorocyclopropene Derivatives 469
45.10.3.1.4 Method 4: Synthesis of Benzopentatriafulvalenes by Peterson Alkenation 469
45.10.4 Product Subclass 4: Heptatriafulvalenes 470
45.10.4.1 Synthesis of Product Subclass 4 470
45.10.4.1.1 Method 1: Synthesis of Benzoheptatriafulvalenes by Peterson Alkenation 470
45.10.5 Product Subclass 5: Pentafulvenes 470
45.10.5.1 Synthesis of Product Subclass 5 471
45.10.5.1.1 Method 1: Reactions of Cyclopentadienes with Aldehydes or Ketones 471
45.10.5.1.1.1 Variation 1: Condensation Reactions Initiated by Strong Bases 471
45.10.5.1.1.2 Variation 2: Condensation Reactions Initiated by Secondary Amines 472
45.10.5.1.1.3 Variation 3: Condensation Reactions of Cyclopentadienide Ions with Ketones 473
45.10.5.1.2 Method 2: Reactions of Sodium Cyclopentadienide with 1-Haloalkyl Acetates 474
45.10.5.1.3 Method 3: Reactions of Cyclopentadienes with Carboxylic Acid Derivatives 475
45.10.5.1.3.1 Variation 1: Reaction with a Vilsmeier Reagent 475
45.10.5.1.3.2 Variation 2: Condensation Reactions with O-Alkylated Amides 475
45.10.5.1.3.3 Variation 3: Condensation Reactions with S-Alkylated Thioamides 476
45.10.5.1.3.4 Variation 4: Condensation Reactions with Iminium Salts 477
45.10.5.1.4 Method 4: Reactions of Cyclopentadienes with Triheteromethyl Cations 478
45.10.5.1.4.1 Variation 1: Condensation Reactions with O-Alkylated Urea Derivatives 478
45.10.5.1.4.2 Variation 2: Condensation Reactions with S-Methylated Thiourea Derivatives 478
45.10.5.1.5 Method 5: Metal-Catalyzed Cyclization Reactions 479
45.10.5.1.5.1 Variation 1: Trimerization of Alkynes 479
45.10.5.1.5.2 Variation 2: Cyclization Reactions of Alkynes and Vinyl Halides 479
45.10.6 Product Subclass 6: Pentafulvalenes 480
45.10.6.1 Synthesis of Product Subclass 6 480
45.10.6.1.1 Method 1: Oxidative Coupling of Cyclopentadienides 480
45.10.6.1.2 Method 2: Synthesis from Cyclopentadienones 481
45.10.6.1.2.1 Variation 1: Condensation Reactions with Cyclopentadienides 482
45.10.6.1.2.2 Variation 2: Peterson Alkenation 483
45.10.6.1.3 Method 3: Reductive Coupling of 5,5-Dihalocyclopentadienes 483
45.10.7 Product Subclass 7: Heptapentafulvalenes 484
45.10.7.1 Synthesis of Product Subclass 7 484
45.10.7.1.1 Method 1: Reactions of Cyclopentadienides with Tropylium Salts 484
45.10.7.1.1.1 Variation 1: Coupling of Cyclopentadienides with Tropylium Salts 485
45.10.7.1.1.2 Variation 2: Reactions of Cyclopentadienides with Acetoxytropylium Salts 485
45.10.7.1.2 Method 2: Reactions of Cyclopentadienes with Tropones 486
45.10.7.1.3 Method 3: Synthesis from Cycloheptatrienylpentafulvenes by Hydrogen Migration 487
45.10.8 Product Subclass 8: Heptafulvenes 487
45.10.8.1 Synthesis of Product Subclass 8 488
45.10.8.1.1 Method 1: Synthesis from Tropones 488
45.10.8.1.1.1 Variation 1: Condensation Reactions with Active Methylene Compounds Initiated by Acetic Anhydride 488
45.10.8.1.1.2 Variation 2: Reaction with Grignard Reagents 489
45.10.8.1.1.3 Variation 3: Condensation Reactions with Ketenes 490
45.10.8.1.1.4 Variation 4: Reaction of Cycloheptatrienethiones with Tetracyanoethene 491
45.10.8.1.2 Method 2: Synthesis from Tropylium Salts 491
45.10.8.1.2.1 Variation 1: Proton Abstraction from Alkyl-Substituted Tropylium Salts 491
45.10.8.1.2.2 Variation 2: Condensation Reactions with Active Methylene Compounds 493
45.10.8.1.2.3 Variation 3: Reactions with Bromomalononitrile 494
45.10.8.1.3 Method 3: Synthesis from Heterosubstituted Tropylium Salts 494
45.10.8.1.3.1 Variation 1: Reaction of an Alkoxytropylium Salt with an Active Methylene Compound 494
45.10.8.1.3.2 Variation 2: Reaction of an Acetoxytropylium Salt with a Lithium Reagent 495
45.10.8.1.4 Method 4: Enolization of Acylcycloheptatrienes 495
45.10.8.1.5 Method 5: Synthesis by Hofmann Elimination 496
45.10.8.1.6 Method 6: Synthesis from Heptafulvenone 497
45.10.8.1.6.1 Variation 1: Reactions of Heptafulvenone with Carbonyl Compounds 497
45.10.8.1.6.2 Variation 2: Reactions of Heptafulvenone with Thioketones 498
45.10.9 Product Subclass 9: Heptafulvalenes 498
45.10.9.1 Synthesis of Product Subclass 9 499
45.10.9.1.1 Method 1: Dimerization of Cycloheptatrienylidenes 499
45.10.9.1.1.1 Variation 1: Heptafulvalenes from the Sodium Salts of Tropone Tosylhydrazones 499
45.10.9.1.1.2 Variation 2: Dehydrochlorination of Chlorocycloheptatrienes 500
45.10.9.1.1.3 Variation 3: Rearrangement of Phenylcarbenes 500
45.10.9.1.2 Method 2: Reductive Coupling of 7,7-Dichlorocycloheptatrienes 501
45.10.9.1.3 Method 3: Reactions of Heptafulvenone with Tropone Derivatives 502
45.11 Product Class 11: Dimethylenecyclobutenes and Quinodimethanes 508
45.11.1 Product Subclass 1: Dimethylenecyclobutenes 508
45.11.1.1 Synthesis of Product Subclass 1 509
45.11.1.1.1 Method 1: [3,3]-Sigmatropic Rearrangements and Electrocyclic Reactions 509
45.11.1.1.1.1 Variation 1: Thermolysis of Hexa-1,5-diynes 509
45.11.1.1.1.2 Variation 2: Thermolysis of Substituted Diallenes 510
45.11.1.1.1.3 Variation 3: Dimerization of Species Generated In Situ from Propenes, Propadienes, or Propynes 510
45.11.1.1.2 Method 2: Synthesis from Cyclobutenes 512
45.11.1.1.2.1 Variation 1: By the Formation of exo-Double Bonds via Hofmann Elimination 512
45.11.1.1.2.2 Variation 2: By Wittig Reaction 512
45.11.1.1.2.3 Variation 3: By Dehydrochlorination 513
45.11.1.1.2.4 Variation 4: By Substitution of Carbanionic Species Generated from 1,2-Dimethyl-3,4-dimethylenecyclobutene 513
45.11.2 Product Subclass 2: Quinodimethanes 514
45.11.2.1 Synthesis of Product Subclass 2 515
45.11.2.1.1 Method 1: o-Quinodimethanes by Thermal Reactions 515
45.11.2.1.1.1 Variation 1: Ring Opening of Benzannulated Cyclobutenes 515
45.11.2.1.1.2 Variation 2: Elimination of Sulfur Dioxide from Sulfones 518
45.11.2.1.1.3 Variation 3: Elimination of Sulfur Dioxide from Sultines 519
45.11.2.1.1.4 Variation 4: Elimination of Carbon Dioxide from 5,8-Dihydro-7H-1,3-dioxolo[4,5-g][2]benzopyran-7-one 519
45.11.2.1.1.5 Variation 5: Elimination of Hydrogen Chloride from 1-Methyl-2-(trichloromethyl)benzenes 519
45.11.2.1.2 Method 2: o-Quinodimethanes by 1,4-Elimination Reactions of 1,2-Dialkylbenzenes Containing Leaving Groups Bonded to the Alkyl Substituents 520
45.11.2.1.2.1 Variation 1: Using Metals as Reducing Agents 520
45.11.2.1.2.2 Variation 2: Anion-Induced 1,4-Eliminations 521
45.11.2.1.2.3 Variation 3: Hofmann Elimination of N,N,N-Trimethyl(10-methyl-9-phenanthryl)methanaminium Chloride 523
45.11.2.1.2.4 Variation 4: Proton-Induced 1,4-Eliminations 524
45.11.2.1.3 Method 3: o-Quinodimethanes by Addition/Elimination Reactions 524
45.11.2.1.4 Method 4: o-Quinodimethanes by Photochemical Reactions 525
45.11.2.1.4.1 Variation 1: Photochemically Induced 1,5-Shifts 525
45.11.2.1.4.2 Variation 2: Photochemically Induced Eliminations 526
45.11.2.1.5 Method 5: o-Quinodimethanes by Cathodic Reduction and Anodic Oxidation of 1,2-Dialkylbenzenes 527
45.11.2.1.6 Method 6: o-Quinodimethanes by Palladium(0)/Samarium(II) Iodide Induced Intramolecular Cyclization 528
45.11.2.1.7 Method 7: p-Quinodimethanes by Pyrolysis of 1,4-Dialkylbenzenes and Their Derivatives 528
45.11.2.1.8 Method 8: p-Quinodimethanes by Methylenation of Naphtho-1,4-quinone or Anthra-9,10-quinone 529
45.12 Product Class 12: Radialenes 532
45.12.1 Product Subclass 1: [3]Radialenes 533
45.12.1.1 Synthesis of Product Subclass 1 533
45.12.1.1.1 Method 1: Synthesis by Substitution Reactions 533
45.12.1.1.1.1 Variation 1: Aromatic Substitution Reactions 533
45.12.1.1.1.2 Variation 2: Nucleophilic Substitution Reactions 537
45.12.1.1.2 Method 2: Synthesis by Elimination Reactions 540
45.12.1.1.2.1 Variation 1: E2 Elimination of Hydrogen Halides 540
45.12.1.1.2.2 Variation 2: Elimination of Trimethylamine (Hofmann Elimination) 541
45.12.1.1.3 Method 3: Synthesis by Addition Reactions 541
45.12.1.1.3.1 Variation 1: Addition of Methylenecarbenes 541
45.12.1.1.3.2 Variation 2: Addition and Oligomerization of Transition Metal Carbenoids 542
45.12.1.1.4 Method 4: Synthesis by Cyclization Reactions 543
45.12.1.1.4.1 Variation 1: Synthesis by Ring Closure with Transition Metals 544
45.12.2 Product Subclass 2: [4]Radialenes 544
45.12.2.1 Synthesis of Product Subclass 2 544
45.12.2.1.1 Method 1: Synthesis by Elimination Reactions 544
45.12.2.1.1.1 Variation 1: E2 Elimination of Hydrogen Halides and Pyrolysis of Hofmann Bases 545
45.12.2.1.1.2 Variation 2: 1,4-Dehalogenation, Reductive Dehydroxylation, and Retro-Diels--Alder Reaction 547
45.12.2.1.2 Method 2: Synthesis by Dimerization Reactions 548
45.12.2.1.2.1 Variation 1: Thermal and Photochemical Dimerization Reactions 549
45.12.2.1.2.2 Variation 2: Transition-Metal-Mediated Dimerization and Oligomerization Reactions 552
45.12.3 Product Subclass 3: [5]Radialenes 561
45.12.3.1 Synthesis of Product Subclass 3 561
45.12.3.1.1 Method 1: Transition-Metal-Mediated Oligomerization Reactions 561
45.12.3.1.2 Method 2: Addition--Elimination Reactions of [5]Radialenones 562
45.12.4 Product Subclass 4: [6]Radialenes 564
45.12.4.1 Synthesis of Product Subclass 4 564
45.12.4.1.1 Method 1: Synthesis by Reductive Elimination Reactions 564
45.12.4.1.2 Method 2: Synthesis by Elimination or Isomerization Reactions at High Temperature 565
45.12.4.1.3 Method 3: Transition-Metal-Mediated Oligomerization Reactions 566
45.12.5 Product Subclass 5: Expanded Radialenes 567
45.12.5.1 Synthesis of Product Subclass 5 567
Keyword Index 572
Author Index 604
Abbreviations 632