Zinc Catalysis: Applications in Organic Synthesis

Zinc can be an interesting and attractive alternative to precious metals as catalysts due to good abundance, low costs, biological relevance and low toxicity. For this reason, research in the field of zinc catalysis has tremendously grown over the last years leading to numerous interesting applications in organic synthesis.

Filling the gap in the market for comprehensive coverage of this hot topic, this unique and timely book is written by international experts who adopt a sustainable approach here.

Chapters include information on synthesis, physical properties, coordination and biochemistry of zinc complexes, but with the primary focus being on applications in organic transformations, i.e. the reduction of unsaturated compounds, oxidation reactions, polymerizations, C–O and C–N bond cleavage reactions, Friedel–Crafts reaction, hydroamination as well as C–C, C–N, C–O bond formation reactions. Aimed at stimulating further research and discussion in the field of zinc catalysis, this is a valuable reference for professionals in academia and industry!

List of Contributors XI

1 Introduction: Zinc Catalysts for Organic Transformations 1
Stephan Enthaler and Xiao–Feng Wu

References 3

2 Zinc–Catalyzed Reductions of Unsaturated Compounds 5
Yuehui Li, Kathrin Junge, and Matthias Beller

2.1 Introduction 5

2.2 Hydrosilylation of Unsaturated Compounds 5

2.2.1 Nonchiral Hydrosilylation of Carbonyl Bonds 6

2.2.2 Asymmetric Hydrosilylation of C=O Bonds 14

2.2.3 Zinc–Catalyzed Hydrosilylation of C=N and Other Multiple Bonds 19

2.3 Hydrogenation 25

2.4 Transfer Hydrogenation of Unsaturated Compounds 28

2.5 Concluding Remarks 29

References 29

3 Zinc–Catalyzed Oxidation Reactions 33
Liang–Qiu Lu and Xiao–Feng Wu

3.1 Introduction 33

3.2 Oxidative Transformation of Alkenes 34

3.3 Oxidative Transformation of Aldehydes 38

3.4 Oxidative Transformation of C X Bonds (X=O, N, and S) 42

3.5 Oxidative Functionalization of sp3 C H Bonds 49

3.6 Other Oxidative Reactions with Redox–Active Ligands 50

3.7 Summary and Outlook 53

References 53

4 Zinc–Catalyzed Friedel Crafts Reactions 57
Yonghai Hui, Lili Lin, Xiaohua Liu, and Xiaoming Feng

4.1 Introduction 57

4.2 Friedel Crafts Acylation 58

4.3 Friedel Crafts Alkylations 59

4.3.1 Racemic Friedel Crafts Alkylation 60

4.3.2 Asymmetric Friedel Crafts Alkylations 64

4.4 Conclusions 80

References 80

5 Zinc–Catalyzed Hydroamination Reactions 83
Tianshu Li, Jelena Wiecko, and Peter W. Roesky

5.1 Introduction 83

5.2 Inorganic Zinc Salts as Catalysts 85

5.3 Aminotroponiminate Zinc Complexes as Catalysts 93

5.3.1 Aminotroponiminate Zinc Complex as a Hydroamination Catalyst 93

5.3.2 Modifications of Aminotroponiminate Zinc Complexes 95

5.3.3 Aminotroponiminate Zinc Complex Immobilized on Mesoporous Silica 101

5.4 Other Zinc Organometallic Compounds as Catalysts 104

5.4.1 Other Zn N Complexes 104

5.4.2 ZnEt2, [Cp 2 Zn2], and [Cp 2Zn] as Hydroamination Precatalysts 110

5.5 Double Metal Cyanide Catalysts 114

5.6 Summary 115

References 115

6 Zinc–Catalyzed C C Bond Formation 119
Rubén Vicente

6.1 Introduction 119

6.2 Zinc–Catalyzed Aldol–Type Reactions 120

6.2.1 Zinc–Catalyzed Aldol and Mukaiyama–Aldol Reactions 120

6.2.2 Zinc–Catalyzed Michael Addition Reactions 123

6.2.3 Zinc–Catalyzed Henry and Aza–Henry Reactions 126

6.2.4 Zinc–Catalyzed Mannich–Type Reactions 127

6.3 Zinc–Catalyzed Cycloaddition Reactions 127

6.4 Zinc–Catalyzed Addition of Organometallic Reagents to Carbonyl and Related Compounds 129

6.4.1 Alkylation Reactions with Grignard Reagents 129

6.4.2 Allylation, Propargylation, and Allenylation Reactions with Organometallic Reagents 130

6.4.3 Catalytic Acetylide Addition Reactions 132

6.5 Zinc–Catalyzed Cross–Coupling Reactions 133

6.6 Radical Reactions Involving Catalytic Amounts of Zinc 134

6.7 Zinc–Catalyzed Reactions through Alkyne Activation 135

6.8 Zinc–Catalyzed Cyclopropanation Reactions 139

6.9 Other Zinc–Catalyzed Reactions 141

6.10 Summary and Outlook 142

References 143

7 Zinc–Catalyzed C N and C O Bond Formation Reactions 149
Luis A. López and Jesús González

7.1 Introduction 149

7.2 Zinc–Catalyzed C N Bond Formation Reactions 150

7.2.1 Zinc–Catalyzed Hydroamination Reactions and Related Processes 150

7.2.2 Zinc–Catalyzed Reactions of Carbonyl Compounds or Carboxylic Acid Derivatives with Amines and Related Compounds 156

7.2.3 Zinc–Catalyzed Reactions Involving Azides and Diazocompounds 159

7.2.4 Zinc–Catalyzed –N–Functionalization of C–H Bonds 162

7.2.5 Zinc–Catalyzed C N Bond–Forming Reactions Involving the Cleavage of Cyclopropanes and Epoxides 163

7.3 Zinc–Catalyzed C O Bond Formation Reactions 164

7.3.1 Zinc–Catalyzed C O Bond Formation Involving Intramolecular Cyclization 164

7.3.2 Zinc–Catalyzed Transesterifications and Amide Cleavages 167

7.3.3 Zinc–Catalyzed Michael Addition/Cyclization Sequence 171

7.3.4 Zinc–Catalyzed Hetero–Diels Alder Reactions of Aldehydes and Functionalized Dienes 171

7.3.5 Zinc–Catalyzed Multicomponent Reactions 172

7.4 Summary and Conclusion 174

References 175

8 Zinc–Catalyzed Transformation of Carbon Dioxide 179
Stefan Kissling, Peter T. Altenbuchner, Teemu Niemi, Timo Repo, and Bernhard Rieger

8.1 Introduction 179

8.2 Zinc Catalysts for the Copolymerization of Epoxides and CO2 181

8.2.1 Mechanistic Aspects of CO2/Epoxide Copolymerization 181

8.2.2 Heterogeneous Catalysts 182

8.2.3 Homogeneous Catalysts 185

8.2.4 Functional Polycarbonates 194

8.3 Zinc–Catalyzed Synthesis of Cyclic Carbonates Utilizing Carbon Dioxide as a Chemical Feedstock 196

8.3.1 Cyclic Carbonates from Cycloaddition of CO2 to Epoxides 196

8.3.2 Cyclization of Carbon Dioxide and Diols 200

8.4 Summary 201

References 202

9 Zinc–Catalyzed Depolymerization Reactions 207
Stephan Enthaler

9.1 Introduction 207

9.2 Zinc–Catalyzed Depolymerization of Polyethers 208

9.3 Zinc–Catalyzed Depolymerization of Polyesters 212

9.4 Zinc–Catalyzed Depolymerization of Silicones 214

9.5 Summary 215

References 215

10 Applications of Zinc–Promoted Reaction in Total Synthesis 219
Hui Liu and Xuefeng Jiang

10.1 Introduction 219

10.2 Zinc–Promoted Reactions without Ligands 219

10.2.1 Zinc–Catalyzed Reactions 219

10.2.2 Zinc–Mediated Reactions 224

10.3 Zinc–Mediated Reactions with Ligands 243

10.3.1 Zinc–Catalyzed Reactions 243

10.3.2 Zinc–Mediated Reactions 252

10.4 Other Zinc–Promoted Reactions 262

References 271

11 Application of Organozinc Reagents in Oxidative Coupling Reactions 275
Aiwen Lei, Zhiliang Huang, and Dong Liu

11.1 Introduction 275

11.1.1 Oxidative Coupling 276

11.1.2 Organozinc Reagents 277

11.1.3 Preparation of Organozinc Reagents 277

11.1.4 Organozinc Halides 280

11.2 Oxidative Coupling between Zinc Reagents and C(sp) Nucleophiles 283

11.3 Oxidative Coupling between Organozinc Reagents and C(sp2) Nucleophiles 287

11.3.1 C(sp2)–M Compounds as Nucleophiles 287

11.3.2 C(sp2)–H Compounds as Nucleophiles 289

11.4 Oxidative Coupling between Organozinc Reagents and C(sp3) Nucleophiles 292

11.4.1 Oxidative Coupling between Organozinc Reagents and C(sp3)–Organometallic Reagents 292

11.4.2 Oxidative Coupling between Organozinc Reagents and C(sp3)–H Compounds 295

11.5 Oxidative Coupling between Organozinc Reagents and Heteroatom Nucleophiles 296

11.5.1 C N Bond Formation 296

11.5.2 C O Bond Formation 298

11.6 Conclusion 299

References 299

Index 303

Stephan Enthaler is the leader of a young researcher′s group in the field of homogeneous catalysis at the Technical University Berlin, Germany. He studied chemistry at the University of Rostock (Germany) and obtained his PhD from the Leibniz–Institute for Catalysis at the University of Rostock under the supervision of Prof. M. Beller. Afterwards he moved to MIT (Massachusetts Institute of Technology, Cambridge, USA) for postdoctoral studies with a fellowship of the DFG (Deutsche Forschungsgemeinschaft). In 2009, he returned to Germany to the Technical University Berlin to work within the Cluster of Excellence "Unifying Concepts in Catalysis" (UniCat). His research interests are focused on the development of homogeneous catalysts for organic transformations.

Xiao–Feng Wu leads a junior research group at Zhejiang Sci–Tech University (China) and Leibniz–Institute for Catalysis in Rostock (Germany). He studied chemistry at Zhejiang Sci–Tech University, where he obtained his bachelor′s degree in science in 2007. In the same year, he went to Université de Rennes 1 (France) to work with Prof. C. Darcel. He obtained his master′s degree there in 2009 and then joined the group of Prof. M. Beller at the Leibniz–Institute for Catalysis in Rostock, where he completed his PhD thesis in 2012. His research interests include carbonylation reactions, heterocycle synthesis, and the catalytic application of cheap metals.