Cyclopropanes in Organic Synthesis

Preface ix

Part I Reactivity and availability 1

Introduction, 1

Reference, 2

1 Structure and Reactivity of the Cyclopropane Species 3

1.1 Geometry and Bonding, 3

1.2 Energy, 4

1.3 Spectra, 5

1.4 Cyclopropyl Cations, 5

1.5 Cyclopropyl Anions, 6

1.6 Cyclopropyl Radicals, 7

1.7 Cyclopropylidenes, 7

1.8 Cyclopropylcarbinyl Cations, 8

1.9 Cyclopropylcarbinyl Anions, 8

1.10 Cyclopropylcarbinyl Radicals, 10

1.11 Cyclopropylcarbenes, 10

1.12 Conclusion, 11

References, 13

2 Ring Cleavage Reactions 15

2.1 Cyclopropyl Activation, 16

2.1.1 Halogen, Oxy, and Sulfur Substituted Cyclopropanes, 16

2.1.2 Alkylidenecyclopropanes, 19

2.2 Cyclopropylcarbinyl Activation, 23

2.2.1 Halogeno, Oxy, Acyl and Metallomethyl Cyclopropanes, 23

2.2.2 Alkylidenecyclopropanes, 27

2.2.3 Vinyl and Ethynyl Cyclopropanes, 29

2.2.4 1,2?]Divinylcyclopropanes, 33

2.2.5 Acceptor Cyclopropanes, 35

2.2.6 Donor Cyclopropanes, 38

2.2.7 Donor-Acceptor Cyclopropanes, 43

2.3 Conclusion, 48

References, 49

3 Synthesis of Cyclopropanes 57

3.1 1,3?]Cyclization Reactions, 57

3.1.1 Cyclizations with Cleavage of Two Single Bonds, 58

3.1.2 Cyclizations with Cleavage of One Double Bond and One Single Bond, 59

3.1.3 Cyclizations with Cleavage of Two Double Bonds, 62

3.2 [2 + 1] Cyclization Reactions, 65

3.2.1 Cycloaddition of Carbene Equivalents to Olefins, 66

3.2.2 Coupling of 1,1?]Carbodianion and 1,2?]Carbodication Equivalents, 79

3.2.3 Coupling of 1,1?]Carbodication and 1,2?]Carbodianion Equivalents, 83

3.3 Addition Reactions to the Double Bond of Cyclopropenes, 88

3.4 Interconversion of Cyclopropanes, 90

3.5 Conclusion, 90

References, 90

Part Ii Synthetic Application 99

Introduction, 99

References, 100

4 Triangulation Retrosynthetic Analysis 103

4.1 Retrosynthetic Triangulation, 103

4.2 Conclusion, 108

References, 108

5 Acyclic Compounds 109

5.1 Formation of Carbon Substituents, 109

5.1.1 Nonactivated Cyclopropane Precursors, 109

5.1.2 Cyclopropylcarbinyl Activated Precursors, 112

5.1.3 Cooperatively Activated Precursors, 138

5.2 Formation of Olefin Groups, 139

5.2.1 Cyclopropylcarbinyl Activated Precursors, 139

5.2.2 Cyclopropyl Activated Precursors, 142

5.2.3 Fragmentation of the Cyclopropane Precursors, 146

5.2.4 Cooperatively Activated Cyclopropane Precursors, 147

5.3 Formation of Carbonyl Groups, 151

5.3.1 Cyclopropylcarbinyl Precursors, 151

5.3.2 Cooperatively Activated Precursors, 156

5.4 Retrosynthetic Account, 162

References, 163

6 Cyclobutane Derivatives 167

6.1 Grandisol Syntheses, 167

6.2 Cyclobutane Synthetic Intermediates, 169

6.3 Retrosynthetic Account, 183

References, 184

7 Cyclopentanes 187

7.1 Vinylcyclopropane-Cyclopentene Rearrangement, 187

7.1.1 Cyclopropylcarbinyl Activated Precursors, 187

7.1.2 Cooperatively Activated Precursors, 188

7.2 Cycloaddition Reactions, 221

7.2.1 Cyclopropylcarbinyl Activated Precursors, 221

7.2.2 Cooperatively Activated Precursors, 221

7.3 Modification of Substituents, 223

7.3.1 N onactivated Cyclopropane Precursors, 223

7.3.2 Cyclopropylcarbinyl Activated Precursors, 224

7.3.3 Cooperatively Activated Precursors, 231

7.3.4 Fragmentation Reactions, 245

7.4 Retrosynthetic Account, 246

References, 246

8 Cyclohexanes 251

8.1 Intramolecular Cyclization Reactions, 251

8.2 Cycloaddition Reactions, 255

8.3 Modification of Substituents, 269

8.3.1 Cyclopropylcarbinyl Activated Precursors, 269

8.3.2 Cyclopropyl Activated Precursors, 275

8.3.3 Cooperatively Activated Precursors, 277

8.4 Retrosynthetic Account, 282

References, 283

9 Cycloheptanes 285

9.1 Divinylcyclopropane-Cycloheptadiene Rearrangement, 285

9.2 Cycloaddition Reactions, 315

9.3 Modification of Substituents, 318

9.3.1 Nonactivated Cyclopropane Precursors, 318

9.3.2 Cyclopropylcarbinyl Activated Precursors, 318

9.3.3 Cyclopropyl Activated Precursors, 323

9.3.4 Cooperatively Activated Precursors, 325

9.4 Retrosynthetic Account, 329

References, 330

10 Cyclooctanes and Larger Carbocycles 333

10.1 Cycloaddition Reactions, 333

10.2 Modification of Substituents, 334

10.2.1 Cyclopropylcarbinyl Activated Precursors, 334

10.2.2 Cyclopropyl Activated Precursors, 338

10.3 Retrosynthetic Account, 340

References, 340

11 Heterocyclic Compounds 341

11.1 Intramolecular Cyclization Reactions, 341

11.1.1 Nonactivated Cyclopropane Precursors, 341

11.1.2 Cyclopropylcarbinyl Activated Precursors, 342

11.1.3 Cyclopropyl Activated Precursors, 378

11.1.4 Cooperatively Activated Precursors, 380

11.2 Cycloaddition Reactions, 387

11.2.1 Cyclopropylcarbinyl Activated Precursors, 387

11.2.2 Cooperatively Activated Precursors, 390

11.3 Modification of Substituents, 400

11.3.1 Cyclopropylcarbinyl Activated Substrates, 400

11.3.2 Cyclopropyl Activated Substrates, 402

11.3.3 Cooperatively Activated Substrates, 402

11.4 Retrosynthetic Account, 409

References, 410

CONCLUSION 415

AUTHOR Index 417