Ligand Design in Metal Chemistry

Mark Stradiotto, Department of Chemistry, Dalhousie University, CanadaRylan Lundgren, Department of Chemistry, University of Alberta, CanadaBoth professors have a well-established track-record of working in the field of organometallic ligand design and catalysis, and have published extensively on the subjects of metal-catalyzed cross-coupling, novel transition-metal bond activation, and asymmetric catalysis. They are co-inventors of the now commercialized DalPhos ligand family and have broad experience of the  field of ligand design. Professor Stradiotto has worked in the field of organometallic chemistry for the past fourteen years. Professor Lundgren earned his PhD under the supervision of Prof Stradiotto at Dalhousie University in 2010. Following a PDF at MIT and Caltech with Prof. Greg Fu, Rylan accepted a faculty position at the University of Alberta (Canada).

• List of Contributors xiiForeword by Stephen L. Buchwald xivForeword by David Milstein xviPreface xvii1 Key Concepts in Ligand Design: An Introduction 1Rylan J. Lundgren and Mark Stradiotto1.1 Introduction 11.2 Covalent bond classification and elementary bonding concepts 21.3 Reactive versus ancillary ligands 41.4 Strong‐ and weak‐field ligands 41.5 Trans effect 61.6 Tolman electronic parameter 61.7 Pearson acid base concept 81.8 Multidenticity, ligand bite angle, and hemilability 81.9 Quantifying ligand steric properties 101.10 Cooperative and redox non‐innocent ligands 121.11 Conclusion 12References 132 Catalyst Structure and Cis–Trans Selectivity in Ruthenium‐based Olefin Metathesis 15Brendan L. Quigley and Robert H. Grubbs2.1 Introduction 152.2 Metathesis reactions and mechanism 172.2.1 Types of metathesis reactions 172.2.2 Mechanism of Ru‐catalyzed olefin metathesis 192.2.3 Metallacycle geometry 192.2.4 Influencing syn–anti preference of metallacycles 222.3 Catalyst structure and E/Z selectivity 242.3.1 Trends in key catalysts 242.3.2 Catalysts with unsymmetrical NHCs 262.3.3 Catalysts with alternative NHC ligands 292.3.4 Variation of the anionic ligands 312.4 Z‐selective Ru‐based metathesis catalysts 332.4.1 Thiophenolate‐based Z‐selective catalysts 332.4.2 Dithiolate‐based Z‐selective catalysts 342.5 Cyclometallated Z‐selective metathesis catalysts 362.5.1 Initial discovery 362.5.2 Model for selectivity 372.5.3 Variation of the anionic ligand 382.5.4 Variation of the aryl group 402.5.5 Variation of the cyclometallated NHC substituent 412.5.6 Reactivity of cyclometallated Z‐selective catalysts 422.6 Conclusions and future outlook 42References 433 Ligands for Iridium‐catalyzed Asymmetric Hydrogenation of Challenging Substrates 46Marc‐André Müller and Andreas Pfaltz3.1 Asymmetric hydrogenation 463.2 Iridium catalysts based on heterobidentate ligands 493.3 Mechanistic studies and derivation of a model for the enantioselective step 573.4 Conclusion 63References 644 Spiro Ligands for Asymmetric Catalysis 66Shou‐Fei Zhu and Qi‐Lin Zhou4.1 Development of chiral spiro ligands 664.2 Asymmetric hydrogenation 734.2.1 Rh‐catalyzed hydrogenation of enamides 734.2.2 Rh‐ or Ir‐catalyzed hydrogenation of enamines 734.2.3 Ir‐catalyzed hydrogenation of α,β‐unsaturated carboxylic acids 754.2.4 Ir‐catalyzed hydrogenation of olefins directed by the carboxy group 784.2.5 Ir‐catalyzed hydrogenation of conjugate ketones 794.2.6 Ir‐catalyzed hydrogenation of ketones 804.2.7 Ru‐catalyzed hydrogenation of racemic 2‐substituted aldehydes via dynamic kinetic resolution 814.2.8 Ru‐catalyzed hydrogenation of racemic 2‐substituted ketones via DKR 824.2.9 Ir‐catalyzed hydrogenation of imines 844.3 Carbon–carbon bond‐forming reactions 854.3.1 Ni‐catalyzed hydrovinylation of olefins 854.3.2 Rh‐catalyzed hydroacylation 854.3.3 Rh‐catalyzed arylation of carbonyl compounds and imines 864.3.4 Pd‐catalyzed umpolung allylation reactions of aldehydes, ketones, and imines 874.3.5 Ni‐catalyzed three‐component coupling reaction 874.3.6 Au‐catalyzed Mannich reactions of azlactones 894.3.7 Rh‐catalyzed hydrosilylation/cyclization reaction 894.3.8 Au‐catalyzed [2 + 2] cycloaddition 904.3.9 Au‐catalyzed cyclopropanation 914.3.10 Pd‐catalyzed Heck reactions 914.4 Carbon–heteroatom bond‐forming reactions 914.4.1 Cu‐catalyzed N─H bond insertion reactions 914.4.2 Cu‐, Fe‐, or Pd‐catalzyed O─H insertion reactions 934.4.3 Cu‐catalyzed S─H, Si─H and B─H insertion reactions 954.4.4 Pd‐catalyzed allylic amination 954.4.5 Pd‐catalyzed allylic cyclization reactions with allenes 974.4.6 Pd‐catalyzed alkene carboamination reactions 984.5 Conclusion 98References 985 Application of Sterically Demanding Phosphine Ligands in Palladium‐Catalyzed Cross‐Coupling leading to C(sp2)─E Bond Formation (E = NH2 , OH, and F) 104Mark Stradiotto and Rylan J. Lundgren5.1 Introduction 1045.1.1 General mechanistic overview and ancillary ligand design considerations 1055.1.2 Reactivity challenges 1075.2 Palladium‐catalyzed selective monoarylation of ammonia 1085.2.1 Initial development 1095.2.2 Applications in heterocycle synthesis 1105.2.3 Application of Buchwald palladacycles and imidazole‐derived monophosphines 1125.2.4 Heterobidentate κ2‐P,N ligands: chemoselectivity and room temperature reactions 1155.2.5 Summary 1175.3 Palladium‐catalyzed selective hydroxylation of (hetero)aryl halides 1175.3.1 Initial development 1185.3.2 Application of alternative ligand classes 1205.3.3 Summary 1225.4 Palladium‐catalyzed nucleophilic fluorination of (hetero)aryl (pseudo)halides 1235.4.1 Development of palladium‐catalyzed C(sp2)─F coupling employing (hetero)aryl triflates 1245.4.2 Discovery of biaryl monophosphine ancillary ligand modification 1255.4.3 Extending reactivity to (hetero)aryl bromides and iodides 1275.4.4 Summary 1285.5 Conclusions and outlook 129Acknowledgments 130References 1316 Pd‐N‐Heterocyclic Carbene Complexes in Cross‐Coupling Applications 134Jennifer Lyn Farmer, Matthew Pompeo, and Michael G. Organ6.1 Introduction 1346.2 N‐heterocyclic carbenes as ligands for catalysis 1356.3 The relationship between N‐heterocyclic carbene structure and reactivity 1366.3.1 Steric parameters of NHC ligands 1366.3.2 Electronic parameters of NHC ligands 1386.3.3 Tuning the electronic properties of NHC ligands 1396.4 Cross‐coupling reactions leading to C─C bonds that proceed through transmetalation 1406.5 Kumada–Tamao–Corriu 1416.6 Suzuki–Miyaura 1486.6.1 The formation of tetra‐ortho‐substituted (hetero)biaryl compounds 1496.6.2 Enantioselective Suzuki–Miyaura coupling 1536.6.3 Formation of sp3─sp3 or sp2 ─sp3 bonds 1566.6.4 The formation of (poly)heteroaryl compounds 1586.7 Negishi coupling 1636.7.1 Mechanistic studies: investigating the role of additives and the nature of the active transmetalating species 1666.7.2 Selective cross‐coupling of secondary organozinc reagents 1686.8 Conclusion 170References 1717 Redox Non‐innocent Ligands: Reactivity and Catalysis 176Bas de Bruin, Pauline Gualco, and Nanda D. Paul7.1 Introduction 1767.2 Strategy I. Redox non‐innocent ligands used to modify the Lewis acid–base properties of the metal 1797.3 Strategy II. Redox non‐innocent ligands as electron reservoirs 1817.4 Strategy III. Cooperative ligand‐centered reactivity based on redox active ligands 1927.5 Strategy IV. Cooperative substrate‐centered radical‐type reactivity based on redox non‐innocent substrates 1957.6 Conclusion 200References 2018 Ligands for Iron‐based Homogeneous Catalysts for the Asymmetric Hydrogenation of Ketones and Imines 205Demyan E. Prokopchuk, Samantha A. M. Smith, and Robert H. Morris8.1 Introduction: from ligands for ruthenium to ligands for iron 2058.1.1 Ligand design elements in precious metal homogeneous catalysts for asymmetric direct hydrogenation and asymmetric transfer hydrogenation 2058.1.2 Effective ligands for iron‐catalyzed ketone and imine reduction 2128.1.3 Ligand design elements for iron catalysts 2138.2 First generation iron catalysts with symmetrical [6.5.6]‐P‐N‐N‐P ligands 2168.2.1 Synthetic routes to ADH and ATH iron catalysts 2178.2.2 Catalyst properties and mechanism of reaction 2188.3 Second generation iron catalysts with symmetrical [5.5.5]‐P‐N‐N‐P ligands 2208.3.1 Synthesis of second generation ATH catalysts 2208.3.2 Asymmetric transfer hydrogenation catalytic properties and mechanism 2228.3.3 Substrate scope 2268.4 Third generation iron catalysts with unsymmetrical [5.5.5]‐P‐NH‐N‐Pʹ ligands 2278.4.1 Synthesis of bis(tridentate)iron complexes and P‐NH‐NH2 ligands 2278.4.2 Template‐assisted synthesis of iron P‐NH‐N‐Pʹ complexes 2288.4.3 Selected catalytic properties 2298.4.4 Mechanism 2308.5 Conclusions 231Acknowledgments 232References 2329 Ambiphilic Ligands: Unusual Coordination and Reactivity Arising from Lewis Acid Moieties 237Ghenwa Bouhadir and Didier Bourissou9.1 Introduction 2379.2 Design and structure of ambiphilic ligands 2389.3 Coordination of ambiphilic ligands 2429.3.1 Complexes featuring a pendant Lewis acid 2429.3.2 Bridging coordination involving M → Lewis acid interactions 2439.3.3 Bridging coordination of M─X bonds 2489.3.4 Ionization of M─X bonds 2509.4 Reactivity of metallic complexes deriving from ambiphilic ligands 2519.4.1 Lewis acid enhancement effect in Si─Si and C─C coupling reactions 2519.4.2 Hydrogenation, hydrogen transfer and hydrosilylation reactions assisted by boranes 2559.4.3 Activation/functionalization of N2 and CO 2629.5 Conclusions and outlook 264References 26610 Ligand Design in Enantioselective Ring‐opening Polymerization of Lactide 270Kimberly M. Osten, Dinesh C. Aluthge, and Parisa Mehrkhodavandi10.1 Introduction 27010.1.1 Tacticity in PLA 27110.1.2 Metal catalysts for the ROP of lactide 27210.1.3 Ligand design in the enantioselective polymerization of racemic lactide 27410.2 Indium and zinc complexes bearing chiral diaminophenolate ligands 29210.2.1 Zinc catalysts supported by chiral diaminophenolate ligands 29210.2.2 The first indium catalyst for lactide polymerization 29410.2.3 Polymerization of cyclic esters with first generation catalyst 29510.2.4 Ligand modifications 29610.3 Dinuclear indium complexes bearing chiral salen‐type ligands 29710.3.1 Chiral indium salen complexes 29710.3.2 Polymerization studies 29710.4 Conclusions and future directions 301References 30211 Modern Applications of Trispyrazolylborate Ligands in Coinage Metal Catalysis 308Ana Caballero, M. Mar Díaz‐Requejo, Manuel R. Fructos, Juan Urbano, and Pedro J. Pérez11.1 Introduction 30811.2 Trispyrazolylborate ligands: main features 31011.3 Catalytic Systems Based on TpXMl Complexes (M = Cu, Ag) 31111.3.1 Carbene addition reactions 31211.3.2 Carbene insertion reactions 31411.3.3 Nitrene addition reactions 31911.3.4 Nitrene insertion reactions 32111.3.5 Oxo transfer reactions 32211.3.6 Atom transfer radical reactions 32411.4 Conclusions 326Acknowledgments 326References 32712 Ligand Design in Modern Lanthanide Chemistry 330David P. Mills and Stephen T. Liddle12.1 Introduction and scope of the review 33012.2 C‐donor ligands 33312.2.1 Silylalkyls 33312.2.2 Terphenyls 33512.2.3 Substituted cyclopentadienyls 33612.2.4 Constrained geometry cyclopentadienyls 33812.2.5 Benzene complexes 34012.2.6 Zerovalent arenes 34212.2.7 Tethered N‐heterocyclic carbenes 34312.3 N‐donor ligands 34412.3.1 Hexamethyldisilazide 34412.3.2 Substituted trispyrazolylborates 34712.3.3 Silyl‐substituted triamidoamine, [N(CH2Ch2NSiMe2But)3]3– 34812.3.4 NacNac, {N(Dipp)C(Me)CHC(Me)N(Dipp)}− 34912.4 P‐donor ligands 34912.4.1 Phospholides 34912.5 Multiple bonds 35012.5.1 Ln═CR2 35012.5.2 Ln ═ NR 35412.5.3 Ln ═ O 35512.6 Conclusions 356Notes 357References 35713 Tight Bite Angle N,O‐Chelates. Amidates, Ureates and Beyond 364Scott A. Ryken, Philippa R. Payne, and Laurel L. Schafer13.1 Introduction 36413.1.1 N,O‐Proligands 36613.1.2 Preparing metal complexes 36713.2 Applications in reactivity and catalysis 37713.2.1 Polymerizations 37713.2.2 Hydrofunctionalization 38513.3 Conclusions 400References 401Index 406

"Catalysis underpins both modern industrial and academic chemistry, improving reaction sustainability, shaping reaction selectivity and facilitating fundamentally new reaction pathways. While the focus is often on the showpiece metals themselves, the ligands are the true shapers of this reactivity. Stradiotto and Lundgren have curated a collection that certainly celebrates ligands across a wide array of applications. At over 400 pages across 13 chapters written by world leaders in catalysis and ligand design, the book is a modern resource for those working in the area. The book opens with a chapter detailing the underlying key concepts that feature throughout the rest of the book. This is likely the only chapter which would serve the undergraduate student – but as a stand-alone chapter would indeed provide a strong additional resource for final year students on a catalysis and/or coordination chemistry course. From there, each chapter captures a specific vignette of relevance to the authors. The overall book is by no means comprehensive in coverage, but it neither intends to be or indeed should be. Instead, it permits the reader to learn about specific topics in the key authors voice, and from a unified perspective of the ligand design... The book, as a secondary impact, also helps to showcase the important contribution Canadian researchers have made to catalysis and ligand design, with 6 of the 13 chapters written by authors at Canadian universities. In closing, the collection of articles found in Ligand Design in Metal Chemistry is certainly worthy of a book shelf spot for those working in the field of ligand design in catalysis. As the content of the book is necessarily focussed, this reviewer recommends a thorough read through the table of contents to ensure that chapters of particular interest are complemented by those that will introduce the reader to new areas." (AOC, Feb 2017)