List of Contributors XI
Preface XV

1 Synthesis of Dendralenes 1
Nicholas J. Green,Mehmet F. Saglam, andMichael S. Sherburn
1.1 Introduction 1
1.2 Multibond Forming Processes 2
1.2.1 Double Alkenylation Reactions 2
1.2.2 Double Alkenation Reactions 4
1.2.3 Other Multibond Forming Processes 10
1.3 Solo-Bond-Forming Reactions 15
1.3.1 C1–C2 Alkenation Reactions 15
1.3.2 C2–C3 Alkenylation Reactions 17
1.3.3 C3–C3? Alkenation Reactions 25
1.4 Dendralenes from Dendralenes 28
1.5 Functional Group Interconversion Reactions 31
1.6 Concluding Remarks 32
References 32

2 The Diene-Transmissive Hetero-Diels–Alder Reaction 39
Takao Saito and Noriki Kutsumura
2.1 Introduction 39
2.2 DTHDA Reaction of Heterotrienes 41
2.2.1 DTHDA Reaction of Thiatrienes 41
2.2.2 DTHDA Reaction of Oxatrienes 42
2.2.3 DTHDA Reaction of Azatrienes 46
2.2.4 DTHDA Reaction of Dioxatrienes as Masked Oxathiatrienes and
Oxazatrienes 51
2.3 DTHDA Reaction with Heterodienophiles 52
References 56

3 The Nazarov Cyclization of Cross-Conjugated Ketones 59
Louis Barriault and MathieuMorin
3.1 Introduction 59
3.2 Mechanism 59
3.3 Substituent Effects 60
3.3.1 ?-Substituents 60
3.3.1.1 Steric Hindrance 60
3.3.1.2 Electron-Donating Substituents 61
3.3.1.3 Electron-Withdrawing Substituents 62
3.3.2 ?-Substituents 63
3.3.2.1 Steric Hindrance 63
3.3.2.2 Electron-Donating Substituents 65
3.3.3 Torquoselectivity 65
3.3.3.1 Silyl Groups as Traceless Substituents 66
3.3.3.2 Allenyl Alkenyl Ketones 67
3.3.3.3 Chirality Transfer 68
3.3.3.4 Catalysis of the Nazarov Reaction 69
3.4 Interrupted Nazarov Reactions 73
3.4.1 Cascade Cyclizations 73
3.4.2 [3+2]- and [4+3]Cycloadditions of the Oxyallyl Cation 74
3.4.3 Intermolecular Trapping of the Nazarov Intermediate 75
References 78

4 [n]Radialenes 79
GerhardMaas
4.1 Introduction 79
4.2 Syntheses and Reactivity 80
4.2.1 [3]Radialenes 81
4.2.2 [4]Radialenes 89
4.2.3 [5]Radialenes 97
4.2.4 [6]Radialenes 98
4.2.5 Higher [n]Radialenes and Radialene Substructures in Polycyclic
Conjugated ?-Systems 105
4.3 Structural and Bonding Properties 107
References 111

5 Oxocarbons, Pseudo-oxocarbons, and Squaraines 117
Vanessa E. de Oliveira, Renata Diniz, Fl?via C.Machado, and Luiz Fernando
C. de Oliveira
5.1 Introduction 117
5.2 Oxocarbons and Coordination Chemistry 121
5.3 Pseudo-oxocarbons 128
5.3.1 Squaraines 132
5.4 Conclusion and Outlook 139
References 139

6 Recent Developments in Fulvene and Heterofulvene
Chemistry 145
Takeshi Kawase and Hiroyuki Kurata
6.1 Introduction 145
6.2 Triafulvenes 148
6.2.1 Benzotriafulvene and Related Compounds 149
6.2.1.1 Synthesis 149
6.2.1.2 Reactions of Benzotriafulvenes 149
6.2.2 Triafulvalene and Related Compounds 150
6.2.2.1 Synthesis of Benzotriafulvalenes 150
6.2.2.2 Triafulvalenes 151
6.2.2.3 Cyclic Bicalicenes 151
6.2.3 Heterotriafulvenes 152
6.2.3.1 Cyclopropenones (CPNs) 152
6.2.3.2 Reaction of CPNs and Related Compounds 154
6.2.3.3 Cyclopropenone Imides (Azatriafulvenes) 159
6.2.3.4 The Other Heterotriafulvenes 159
6.3 Pentafulvenes and Related Compounds 162
6.3.1 Pentafulvenes 162
6.3.1.1 Synthesis of Pentafulvenes 162
6.3.1.2 Reactions of Pentafulvenes 175
6.3.2 Pentafulvalenes 179
6.3.2.1 Synthesis of Symmetric Benzofulvalenes 179
6.3.2.2 Synthesis of Asymmetric Benzofulvalenes 182
6.3.3 Synthesis of Pentafulvenes as Functional Dyes 183
6.3.3.1 6,6-Dicyanofulvenes 183
6.3.3.2 1,3-Dithiafulvalenes 186
6.3.4 Fused Ring Systems Involving Pentafulvene Moieties 187
6.3.4.1 Dibenzopentalenes 191
6.3.4.2 Indacenes 196
6.3.4.3 Heterocyclic Systems 198
6.3.4.4 Carbaporphyrinoids 201
6.3.4.5 Reactions of Fulvalenes for the Construction of Fullerene
Fragments 202
6.3.5 Cyclopentadienones (Oxapentafulvene) 205
6.3.5.1 Synthesis of CPDN 207
6.3.5.2 Reaction of CPDNs 219
6.3.6 Heterofulvenes 222
6.3.6.1 Azafulvenes 222
6.3.6.2 Silafulvene 223
6.3.6.3 Phosphafulvene 224
6.4 Heptafulvenes 225
6.4.1 Synthesis of Heptafulvenes 226
6.4.1.1 Synthesis of Dihydroazulene/Vinylheptafulvene (DHA/VHF)
Systems 226
6.4.1.2 Reaction of 2H-Cyclohepta[b]furan-2-one Derivatives 228
6.4.2 Heteroheptafulvenes 233
6.4.2.1 Thiatropone (Tropothione) 233
6.4.2.2 Azaheptafulvenes 234
6.5 Other Fulvenes 235
References 236

7 Constructing Molecular Complexity and Diversity by Cycloaddition
Reactions of Fulvenes 249
Bor-Cherng Hong
7.1 Introduction 249
7.2 Reactions of Pentafulvenes 250
7.2.1 [2+2]Cycloadditions 250
7.2.2 [2+3]Cycloadditions 251
7.2.3 [2+4]Cycloadditions 253
7.2.4 [2+8]Cycloadditions 258
7.2.5 [4+2]Cycloadditions 258
7.2.6 [4+3]Cycloadditions 266
7.2.7 [6+2]Cycloadditions 267
7.2.8 [6+3]Cycloadditions 269
7.2.9 [6+4]Cycloadditions 277
7.2.10 Miscellaneous Reactions 280
7.3 Reactions of Heptafulvenes 280
7.4 Reactions of Triafulvenes 284
7.5 Conclusions 296
Acknowledgments 296
References 296

8 Cross-Conjugation and Electronic Structure in TTF Analogs 301
Masashi Hasegawa and YohjiMisaki
8.1 Introduction 301
8.2 Dendralene-Type TTF Analogs and Related Compounds 302
8.2.1 [n]Dendralenes (n=3,4) with DT Units 302
8.2.2 Analogs of DT [n]Dendralenes 305
8.2.3 Thienylene-Inserted DT[n] Dendralenes and Related
Compounds 307
8.2.4 Tris-Fused TTF Analogs Possessing [3]Dendralene Moieties 313
8.3 Radialene-Type TTF Analogs (DT-Substituted Radialenes) 314
8.3.1 [4]- and [6]Radialenes with DT Rings 315
8.3.2 [5]Radialene with DT Rings 317
8.3.3 Extended [5]radialenes 320
8.4 Cross-Conjugated TTFs and Related Compounds Linked by
?-Systems 323
8.4.1 TTFs in Cross-Conjugated Systems 323
8.4.2 Acetylene-Extended Tetrathiafulvalenes in Cross-Conjugated
Systems 326
8.4.3 Acetylene-Extended Radialenes and Dendralenes 328
8.4.4 Cross-Conjugated Systems in Acetylene-Extended Radiaannulene
Frameworks 329
References 333

9 Cross-Conjugation in Expanded Systems 337
Christian Richard Parker and Mogens Br?ndsted Nielsen
9.1 Introduction 337
9.2 Tetrathiafulvalene and Dithiafulvene 338
9.2.1 Oligomers by Dithiafulvene Oxidation 339
9.2.2 Anthraquinone-Extended Tetrathiafulvalenes 339
9.3 Communication between Two Identical Redox Centers 340
9.3.1 Organic Redox Centers 342
9.3.2 Organometallic Redox Centers 344
9.3.3 Expanded Radiaannulenes and Radialenes 346
9.4 Cross-Conjugation and Optical Properties 349
9.4.1 Nitrophenolates 350
9.4.2 Other Donor–Acceptor Systems 351
9.4.3 Extended Tetrathiafulvalenes and Dithiafulvene-Dendralenes 352
9.4.4 Synthesis of Dithiafulvene-Dendralene Oligomers by Cascade
Reactions 353
9.4.5 Photoinduced Charge Separation in a Donor–Acceptor System 354
9.5 Conjugation and Molecular Electronics 355
9.5.1 Theoretical Comparison of Conduction Pathways 355
9.5.2 Meta- versus Para-Anchoring 356
9.5.3 The Dithienylethene Photoswitch 357
9.5.4 Hydroquinone–Quinone Redox Switch 357
9.5.5 Oligo(phenyleneethynylene)-Tetrathiafulvalene Cruciform Redox
Switch 358
9.6 Conclusions 359
References 361

10 Transition Metal Complexes of Cross-Conjugated ? Systems 365
Holger Butensch?on
10.1 Introduction 365
10.2 Trimethylenemethane Complexes 365
10.3 Fulvene Complexes 372
10.4 Fulvalene Complexes 380
10.5 Azulene Complexes 385
10.6 Pentalene and Acepentalene Complexes 387
10.7 Various Complexes 389
References 391

11 Cross-Conjugation and Quantum Interference 397
Gemma C. Solomon
11.1 Introduction 397
11.2 Molecular Electron Transport 398
11.3 The Transport Properties of Cross-Conjugated Molecules 401
11.4 Understanding and Predicting Interference 405
11.5 More than Topology 409
11.6 Conclusions 410
References 411

12 Cross-Conjugation in Synthesis 413
Christopher G. Newton andMichael S. Sherburn
12.1 The Rapid Generation of Structural Complexity 413
12.2 Diene-Transmissive Diels–Alder Reactions 413
12.3 [3]Dendralenes 416
12.3.1 Classification 416
12.3.2 Acyclic [3]Dendralenes 417
12.3.3 Cyclic [3]Dendralenes 422
12.4 Higher Dendralenes 428
12.5 Applications 433
12.6 The Radialenes 435
12.7 Concluding Remarks 440
References 441
Author Index 445
Subject Index 451