Preface ........................................................ XV
List of Contributors ......................................... XVII
Part One Alkene Reductions
1 Reduction of Functionalized Alkenes .......................... 3
Jean-Pierre Genet
1.1 Introduction ............................................ 3
1.2 Asymmetric Hydrogenation of Dehydroamino Acids .......... 4
1.2.1 Rh-Catalyzed Reactions ........................... 4
1.2.1.1 Hydrogenation with Chiral
Bisphosphine Ligands .................... 4
1.2.1.2 Mechanism of the Asymmetric
Hydrogenation with Rhodium Catalysts .... 8
1.2.1.3 Rh-Catalyzed Hydrogenation with
Monophosphoms Ligands ................... 9
1.2.2 Ruthenium- and Iridium-Catalyzed Reactions ...... 10
1.2.2.1 Ruthenium .............................. 10
1.2.2.2 Mechanism of the Ruthenium-Catalyzed
Asymmetric Hydrogenation ............... 12
1.2.2.3 Iridium ................................ 13
1.3 Simple Enamides ........................................ 13
1.4 Hydrogenation of β-(Acylamino) Acrylates ............... 16
1.5 Hydrogenation of Unsaturated Carboxylic Acids and
Esters ................................................. 18
1.5.1 Mechanistic Aspects of the Ru-(BINAP)-
Catalyzed Hydrogenation of Carboxylic Acids ..... 21
1.6 Hydrogenation of Unsaturated Esters, Lactones,
Amides and Ketones ..................................... 22
1.7 Hydrogenation of Unsaturated Alcohols .................. 25
1.7.1 Diastereoselective Hydrogenation with Rh and
Ir Catalysts .................................... 25
1.7.2 Enantioselective Hydrogenation with Chiral Ru
and Ir Catalysts ................................ 26
1.8 Synthesis of Pharmaceutical Intermediates .............. 28
1.9 Conclusion ............................................. 32
2 Hydrogenation of Unfunctionalized Alkenes ................... 39
Jarle S. Diesen and Pher G. Andersson
2.1 Introduction ........................................... 39
2.2 Iridium Catalysis ...................................... 39
2.2.1 Catalysts ....................................... 41
2.2.1.1 Ligands ................................ 41
2.2.1.2 Anion .................................. 41
2.2.2 Substrates ...................................... 44
2.2.3 Mechanism ....................................... 52
2.3 Ruthenium and Rhodium Catalysis ........................ 53
2.4 Chiral Metallocene Catalysts ........................... 57
2.4.1 Titanium and Zirconium Systems .................. 57
2.4.2 Lanthanide Systems .............................. 60
2.5 Conclusion ............................................. 62
3 The Development and Application of Rhodium-Catalyzed
Hydroboration of Alkenes .................................... 65
Anthony G. Coyne and Patrick J. Guiry
3.1 Introduction ........................................... 65
3.2 Mechanism .............................................. 66
3.3 Selectivity of Metal-Catalyzed Hydroboration ........... 67
3.3.1 Regioselectivity ................................ 67
3.3.2 Stereoselectivity ............................... 69
3.3.2.1 Chiral P,P Ligands ..................... 69
3.3.2.2 Chiral P,N Ligands ..................... 74
3.4 Recent Applications in Synthesis ....................... 82
3.5 Conclusion ............................................. 84
4 Alkene Reduction: Hydrosilylation ........................... 87
Penelope A. Mayes and Patrick Perlmutter
4.1 Introduction ........................................... 87
4.2 Isolated Alkenes ....................................... 87
4.2.1 Palladium ....................................... 87
4.2.1.1 Aromatic Alkenes ....................... 87
4.2.1.2 Nonaromatic Alkenes .................... 93
4.2.2 Metals Other Than Palladium ..................... 94
4.3 Conjugated Alkenes ..................................... 95
4.3.1 Acyclic 1,3-Dienes .............................. 95
4.3.2 Cyclic 1,3-Dienes ............................... 98
4.3.3 Enynes .......................................... 98
4.4 α,β-Unsaturated Systems ................................ 99
4.4.1 Copper .......................................... 99
4.4.2 Tandem Processes ............................... 102
4.5 Conclusions ........................................... 103
Part Two Carbonyl Reactions
5 Carbonyl Hydrogenation ..................................... 109
Christian Hedberg
5.1 Introduction .......................................... 109
5.2 Asymmetric Hydrogenation of Activated Ketones and
β-Keto Esters ......................................... 109
5.2.1 α-Keto Ester Hydrogenation ..................... 112
5.2.2 1,3-Diketones .................................. 112
5.2.3 Hydrogenation of β-Keto Ester Analogues ........ 114
5.2.4 Mechanism ...................................... 115
5.2.5 Catalyst Preparation ........................... 117
5.2.6 Dynamic Kinetic Resolution (DKR) of β-Keto
Esters ......................................... 118
5.3 Ketone Hydrogenation .................................. 120
5.3.1 Mechanism ...................................... 121
5.3.2 Aryl Alkyl Ketones ............................. 124
5.3.3 Dialkyl Ketones ................................ 127
5.3.4 Diaryl and Aryl Heteroaryl Ketones ............. 127
5.3.5 Phosphine-free Hydrogenation of Alkyl Aryl
Ketones ........................................ 128
5.3.6 α,β-Unsaturated Ketones ........................ 132
6 Reduction of Carbonyl Compounds by Hydrogen Transfer ....... 135
Serafino Gladioli and Rossana Taras
6.1 Introduction .......................................... 135
6.2 Historical Overview ................................... 135
6.3 General Background .................................... 136
6.4 Hydrogen Donors ....................................... 137
6.5 Catalysts ............................................. 138
6.6 Mechanisms ............................................ 139
6.7 Ligands ............................................... 143
6.8 Substrates ............................................ 148
6.8.1 Ketones ........................................ 148
6.8.2 Functionalized Carbonyl Compounds .............. 150
6.8.3 Aldehydes ...................................... 151
6.8.4 Conjugated Carbonyl Compounds .................. 152
7 Carbonyl Hydroboration ..................................... 159
Noriyoshi Aral and Takeshi Ohkuma
7.1 Introduction .......................................... 159
7.2 Recent Topics in Diastereoselective Reduction ......... 159
7.3 Enantioselective Reduction ............................ 163
7.3.1 Reagents (Introduction) ........................ 163
7.3.2 Simple Ketones ................................. 167
7.3.2.1 Aromatic Ketones ...................... 167
7.3.2.2 Aliphatic Ketones ..................... 168
7.3.3 α,β-Unsaturated Ketones ........................ 169
7.3.4 α-Hetero Substituted Ketones ................... 171
7.3.5 Keto Esters .................................... 171
7.3.6 Diketones ...................................... 173
7.4 Synthetic Applications ................................ 173
7.4.1 Reduction of Chiral Ketones with Chiral
Reducing Agents ................................ 173
7.4.2 Application to Natural Product Synthesis ....... 175
8 Diverse Modes of Silane Activation for
the Hydrosilylation of Carbonyl Compounds .................. 183
Sebastian Rendler and Martin Oestreich
8.1 Introduction .......................................... 183
8.2 Metal-Catalyzed Hydrosilylations ...................... 185
8.2.1 Silane Activation by Oxidative Addition ........ 185
8.2.2 Silane Activation by a-Bond Metathesis ......... 188
8.2.3 Silane Activation by High-valent Oxo
Complexes ...................................... 193
8.3 Transition-metal-free Hydrosilylations ................ 197
8.3.1 Bransted Acid-promoted Hydrosilylations ........ 197
8.3.2 Lewis Acid-catalyzed Hydrosilylations .......... 198
8.3.3 Lewis Base-catalyzed Hydrosilylations .......... 200
8.4 Closing Remarks ....................................... 202
9 Enzyme-catalyzed Reduction of Carbonyl Compounds ........... 209
Kaoru Nakamura and Tomoko Matsuda
9.1 Introduction .......................................... 209
9.1.1 Differences between Chemical and Biological
Reductions ..................................... 209
9.1.1.1 Selectivity ........................... 209
9.1.1.2 Safety of the Reaction ................ 210
9.1.1.3 Natural Catalysts ..................... 210
9.1.1.4 Catalyst Preparation .................. 210
9.1.1.5 Large-scale Synthesis and Space-Time
Yield ................................. 210
9.1.2 Reaction Mechanism ............................. 211
9.2 Hydrogen Sources ...................................... 211
9.2.1 Alcohol as a Hydrogen Source for Reduction ..... 212
9.2.2 Sugars as Hydrogen Sources for Reduction ....... 212
9.2.3 Formate as a Hydrogen Source for Reduction ..... 213
9.2.4 Molecular Hydrogen as a Hydrogen Source for
Reduction ...................................... 213
9.2.5 Light Energy as a Hydrogen Source for
Reduction ...................................... 214
9.2.6 Electric Power as a Hydrogen Source for
Reduction ...................................... 214
9.3 Methodology for Stereochemical Control ................ 215
9.3.1 Screening of Biocatalysts ...................... 215
9.3.2 Modification of Biocatalysts by Genetic
Methods ........................................ 216
9.3.2.1 Engineered Yeast ...................... 216
9.3.2.2 Overexpression ........................ 217
9.3.2.3 Modification of Biocatalysts:
Directed Evolution .................... 218
9.3.3 Modification of Substrates ..................... 218
9.3.4 Modification of Reaction Conditions ............ 219
9.3.4.1 Acetone Treatment of the Cell ......... 219
9.3.4.2 Selective Inhibitors .................. 220
9.4 Medium Engineering .................................... 221
9.4.1 Organic Solvent ................................ 221
9.4.1.1 Water-soluble Organic Solvent ......... 221
9.4.1.2 Aqueous-Organic Two-Phase Reaction .... 221
9.4.2 Use of Hydrophobic Resin ....................... 222
9.4.3 Supercritical Carbon Dioxide ................... 223
9.4.4 Ionic Liquid ................................... 224
9.5 Synthetic Applications ................................ 225
9.5.1 Reduction of Aldehydes ......................... 225
9.5.2 Reduction of Ketones ........................... 225
9.5.3 Dynamic Kinetic Resolution and
Deracemization ................................. 227
9.5.3.1 Dynamic Kinetic Resolution ............ 227
9.5.3.2 Deracemization through Oxidation
and Reduction ......................... 230
9.6 Conclusions ........................................... 231
Part Three Imino Reductions
10 Imine Hydrogenation ........................................ 237
Carmen Claver and Elena Fernández
10.1 Recent Advances in the Asymmetric Hydrogenation of
Imines ................................................ 237
10.1.1 Iridium Catalysts .............................. 238
10.1.1.1 Iridium / P-P Ligands ................. 238
10.1.1.2 Iridium / Phosphine-Phosphite
Ligands ............................... 241
10.1.1.3 Iridium / Diphoshite, Diphosphinite
and Phosphinite-Phosphite Ligands ..... 241
10.1.1.4 Iridium / P,N-Ligands ................. 243
10.1.1.5 Iridium / N-Ligands ................... 245
10.1.1.6 Other Iridium / Phosphorous
Systems ............................... 246
10.1.2 Rhodium and Palladium Catalysts ................ 247
10.1.3 Ruthenium Catalysts ............................ 248
10.1.4 Titanium and Zirconium Catalysts ............... 248
10.1.5 Gold Catalysts ................................. 249
10.2 Green Approaches ...................................... 249
10.2.1 Aqueous-Organic Two-Phase Solvent Systems ...... 249
10.2.2 Catalyst Immobilization on Insoluble
Materials ...................................... 252
10.2.3 Carbon Dioxide / Ionic Liquid Media ............ 255
10.3 Mechanistic Insights .................................. 257
10.3.1 Homolytic and Heterolytic H2-Metal
Activation ..................................... 258
10.3.2 H-/H+ Transfer to the Imine in the Inner or
Outer Coordination Sphere ...................... 259
10.3.3 Neutral or Ionic Mechanisms .................... 261
10.3.4 Ligand-assisted Mechanisms ..................... 264
10.3.5 Enantiodifferentiation Steps ................... 264
11 Imino Reductions by Transfer Hydrogenation ................. 271
Martin Wills
11.1 History and Background ................................ 271
11.2 Mechanisms of C=N Bond Reduction by Transfer
Hydrogenation ......................................... 271
11.3 Asymmetric Reduction of C—N Bonds: Catalysts,
Mechanisms and Results ................................ 273
11.3.1 Organometallic Catalysts Based on Ru, Rh,
and Ir ......................................... 273
11.3.1.1 Mechanistic Discussion ................ 278
11.3.2 Asymmetric Reductive Aminations Using
Ammonium Formate to Give the Primary Amine
Directly (the Leuchart-Wallach Reaction) ....... 279
11.3.3 MPV Type Reductions ............................ 280
11.3.4 Carbene-based Catalysts ........................ 281
11.3.5 Organocatalytic Methods ........................ 281
11.4 Specific Synthetic Applications ....................... 283
11.4.1 Sultams ........................................ 283
11.4.2 Tetrahydroisoquinolines and Tetrahydro-
(3-carbolines .................................. 285
11.5 Conclusion ............................................ 291
12 Hydroboration and Diboration of Imines ..................... 297
Stephen A. Westcott and R. Thomas Baker
12.1 Introduction .......................................... 297
12.2 Uncatalyzed Reactions ................................. 298
12.2.1 Imines ......................................... 298
12.2.2 Diimines ....................................... 303
12.2.3 Tosylhydrazones ................................ 304
12.2.4 Nitriles ....................................... 305
12.3 Catalyzed Reactions ................................... 307
12.3.1 Transition Metals .............................. 310
12.4 Conclusions ...................................... 312
13 Hydrosilylation of imines .................................. 321
Olivier Riant
13.1 Introduction .......................................... 321
13.2 Rh, Ir, Ru Based Catalysts ............................ 322
13.3 Titanium-based Catalysts .............................. 324
13.4 Zinc-, Copper-, and Rhenium-based Catalysts ........... 328
13.5 Lanthanide-based Catalysts ............................ 330
13.6 Tin-based Catalysts ................................... 331
13.7 Chiral Lewis Bases as Catalysts ....................... 333
13.8 Miscellaneous Methods ................................. 334
13.9 Conclusion ............................................ 335
Part Four Miscellaneous Reductions
14 Alkene and Imino Reductions by Organocatalysis ............. 341
Hans Adolfsson
14.1 Introduction .......................................... 341
14.2 Reducing Agents ....................................... 342
14.2.1 N-Heterocyclic Hydrogen Donors ................. 342
14.2.2 Silanes ........................................ 343
14.3 Alkene Reduction ...................................... 343
14.3.1 Alkene Reduction by Transfer Hydrogenation
of α,β-Unsaturated Aldehydes and Ketones ....... 344
14.3.2 Alkene Reduction in Organocatalytic Tandem
Processes ...................................... 348
14.4 Imine Reductions ...................................... 351
14.4.1 Enantioselective Reductions of Ketimines
Using Trichlorosilane as Reducing Agent ........ 351
14.4.2 Enantioselective Reductions of Ketimines
Using Hantzsch Esters as Reducing Agents ....... 354
14.4.3 Organocatalytic Reductive Amination of
Aldehydes and Ketones .......................... 357
14.5 Concluding Remarks .................................... 358
15 Alkyne Reductions .......................................... 363
Ian J. Munslow
15.1 Introduction .......................................... 363
15.2 Hydrogenation ......................................... 363
15.2.1 Semi-hydrogenation ............................. 364
15.3 Hydroboration ......................................... 366
15.3.1 Catalysis ...................................... 368
15.3.1.1 Palladium .................................... 368
15.3.1.2 Rhodium ...................................... 368
15.3.1.3 Zirconium .................................... 370
15.3.1.4 Titanium ..................................... 371
15.3.2 Mechanism ...................................... 371
15.4 Hydrosilylation ....................................... 373
15.4.1 Terminal Alkynes ............................... 374
15.4.2 Internal Alkynes ............................... 378
15.4.3 Mechanism ...................................... 381
15.5 Conclusions ........................................... 382
16 Metal-Catalyzed Reductive Aldol Coupling ................... 387
Susan A. Gamer and Michael J. Krische
16.1 Introduction-Reductive Generation of Enolates from
Enones ................................................ 387
16.2 The Reductive Aldol Reaction .......................... 389
16.2.1 Rhodium ........................................ 390
16.2.2 Cobalt ......................................... 398
16.2.3 Iridium ........................................ 401
16.2.4 Ruthenium ...................................... 401
16.2.5 Palladium ...................................... 403
16.2.6 Copper ......................................... 403
16.2.7 Nickel ......................................... 406
16.2.8 Indium ......................................... 407
16.3 Conclusion ............................................ 408
17 Dissolving Metals .......................................... 419
Miguel Yus and Francisco Foubelo
17.1 Introduction .......................................... 419
17.2 Reduction of Compounds with C=X Bonds ................. 420
17.2.1 Reduction of Carbonyl Compounds ................ 420
17.2.2 Reduction of Imines ............................ 422
17.3 Reduction of Carboxylic Acids and Their
Derivatives ........................................... 423
17.4 Reduction of functional groups bearing N, О and S ..... 424
17.4.1 Reduction of Sulfoxides ........................ 424
17.4.2 Reduction of Nitro Compounds ................... 425
17.4.3 Reduction of Compounds with N-X Bonds
(X = N, O, S) .................................. 425
17.5 Reduction of C=C and C=C Bonds ........................ 426
17.5.1 Reduction of C=C Bonds ......................... 426
17.5.2 Reduction of C≡C Bonds ......................... 430
17.6 Partial Reduction of Aromatic and Heteroaromatic
Rings ................................................. 431
17.6.1 The Birch Reduction of Aromatic Compounds ...... 431
17.6.2 Partial Reduction of Heteroaromatic Rings ...... 433
17.7 Reduction of Compounds with C—X Bonds ................. 434
17.7.1 Reduction of α-Functionalized Carbonyl
Compounds ...................................... 434
17.7.2 Reduction of C-Hal to C-H Bonds ................ 435
17.7.3 Reduction of C-O to C-H Bonds .................. 436
17.7.4 Reduction of C-N to C-H Bonds .................. 438
17.7.5 Reduction of C-S to C-H Bonds .................. 439
17.7.6 Reduction of C-C to C-H Bonds .................. 440
18 Hydrometallation of Unsaturated Compounds .................. 447
Usein M. Dzhemilev and Askhat С Ibragimov
18.1 Introduction .......................................... 447
18.2 Thermal Hydroalumination .............................. 448
18.2.1 Alkenes ........................................ 448
18.2.2 Dienes (Unconjugated) .......................... 452
18.2.3 Dienes (Conjugated) ............................ 454
18.2.4 Alkynes ........................................ 456
18.3 Catalytic Hydroalumination ............................ 456
18.3.1 Alkenes ........................................ 456
18.3.2 Dienes ......................................... 467
18.3.3 Alkynes ........................................ 467
18.4 Catalytic Hydromagnesiation ........................... 472
18.4.1 Alkenes ........................................ 472
18.4.2 Dienes ......................................... 475
18.4.3 Alkynes ........................................ 479
18.5 Summary ............................................... 482
Index ......................................................... 491
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