Organometallic Catalysis: Concepts and Applications of Palladium Chemistry in Modern Organic Synthesis

Transcription

1 Giovanni Poli Organometallic Catalysis: Concepts and Applications of Palladium Chemistry in Modern Organic Synthesis MeO 2 C Br OAc MeO 2 C H H O Ph N O Ph N H In the photo: The pyramids of Giza, Cairo, Egypt

2 Organometallic Catalysis: Concepts and Applications of Palladium Chemistry in Modern Organic Synthesis 1 The Transition Metal-Ligand bond: an introduction 1.1 Preface (suggested readings) 1.2 Formal oxidation state, d n configuration, oxidation number, coordinative unsaturation 1.3 Hapticity and electron count 1.4 The crystal field approach Octahedral geometry The spectrochemical series Tetrahedral geometry Square planar geometry 1.5 The molecular orbital theory 1.6 The ligand field theory The σ-bonding The π-bonding 1.7 Electronic structure vs geometry at the metal 1.8 Valence electron count in transition metal complexes 1.9 Common ligands in transition-metal complexes Phosphines σ-donation and π-backdonation Tolman s cone angle The bite angle Carbon monoxide CO vibration as internal probe N-Heterocyclic carbenes Fischer-type carbene ligands Schrock-type carbene ligands Ru carbenes Formal electron count and typical usage and/or reactivity of TM carbenes

3 2 The Elementary Steps in TM Catalysis 2.1 Ligand substitution e - Associative processes e - Disssociative processes Nucleophilic attack on coordinated ligands 2.2 Oxidative addition The formal transformation Non-polar substrates: 3-center mechanism Definition of agostic Polar substrates Halides Other examples From Pd(II) to Pd(IV) 2.3 Reductive elimination 2.4 Oxidative coupling 2.5 Transmetalation 2.6 Migratory insertion 2.7 Dehydrometalation (β H-elimination) 3 The catalytic chemistry of palladium (0): [Pd(0) Pd(II) Pd(0)] 3.1 Generation of Pd(0) from Pd(II) complexes 3.2 Pd(0) sources 3.3 Syn carbopalladations: The Mizoroki-Heck reaction Mechanism, reaction conditions Ligandless conditions Halides and pseudohalides Regioselectivity Allylic alcohols as alkenes Intramolecular versions, asymmetric versions Halo-dienes Asymmetric versions Palladium-ene cyclizations Decabopalladation (β-carbon elimination) Cleavage of yclopropylcarbinyl- and cyclopropyl-palladium complexes

4 Dehydropalladation versus decarbopalladation Arylative fragmentation 3.4 η 3-Allyl Palladium Chemistry Polarization of allyl-complexes Fluxionality of η 3 -allyl complexes Generation of η 3 -allyl complexes Reactions of η 3 -allyl complexes Non-stabilized nucleophiles Stabilized carbon nucleophiles (the Tsuji-Trost reaction) Base-free conditions Regioselectivity and the memory effect Oxygen nucleophiles Nitrogen nucleophiles Terminal vs central attack Enantioselective allylic alkylations Types of enantiodiscrimination Oxazoline ligands Trost ligands Interaction between η3-allyl Pd-complexes and allenes Cyclization of 1,3-dienyl allenes 3.5 Additions toy[pd(ii)]x-activated alkenes and alkynes (Y = C, N, O) Non-catalytic PdX 2 mediated processes The Balme-Goré coupling The Wolfe carboetherification Indole aminopalladation 4 The catalytic chemistry of palladium (II): 4.1 Non-organometallic Pd(II) sources 4.2 Addition of Nucleophiles to Alkenes: General Reactivity 4.3 Oxidative processes [Pd(II) Pd(0)] anti heteropalladations Hydroxypalladation (Wacker process) Alkoxypalladation Acetoxypalladation Allylic acetoxylation

5 Aminopalladation ,4-Chloroacetoxylation and 1,4-diacetoxylation Oxidative carbocyclization of allenes Oxidative carbocyclization of indoles Oxidative Mizoroki-Heck Coupling 4.4 Non-oxidative processes [Pd(II) that stays Pd(II)] Palladations followed by deoxypalladations Amino- and acetoxy-palladation Cycloisomerization processes ,6-en-ynes The hydridopalladium mechanism The oxidative mechanism ,3 versus 1,4 diene products Asymmetric versions Palladium enolates 5 Cyclopalladations and Oxidative Additions to R[Pd(II)]R 5.1 Orthometalation 5.2 The Catellani Reaction 6 Sequential Pd-catalyzed Reactions and Synthetic Applications 6.1 Kaneda / Sonogashira, Kaneda / Suzuki 6.2 Allylic alkylation / Pauson Khand 6.3 Sequential carbopalladations Zip closures 6.4 Suzuki / Mizoroki-Heck 6.5 Carbopalladation / oxypalladation 6.6 Palladium-ene / carbopalladation 6.7 N-arylation / aryl-aryl coupling 6.8 Allylation / Mizoroki-Heck 6.9 The synthesis of N-acetyl clavicipitic acid methyl ester 6.10 The synthesis of strychnine

6 Suggested Bibliographic References for Consultation M. Bochmann, Organometallics 1, Complexes with Transition Metal-Carbon σ-bonds, Oxford University Press, Oxford, 1992 L. S. Hegedus, Transition Metals in the Synthesis of Complex Organic Molecules, University Science Books, Sausalito, California, USA, 1999 M. Schlosser Ed. Organometallics in Synthesis: A Manual, J. Wiley & Sons, 2002 F. Mathey, A. Sevin, Chimie Moleculaire des Eléméments de Transition, Les éditions de l École Polytechnique, 2000 J. Tsuji, Palladium Reagents and Catalysts, J. Wiley & Sons, 2004 J. M. Campagne; D. Prim, Les Complexes de Palladium en Synthèse Organique, CNRS ed J. Tsuj Ed., Palladium in Organic Synthesis, Springer, 2005 E-I Negishi Ed. Handbook of Organopalladium Chemistry for Organic Synthesis, J. Wiley & Sons, 2002 C. Elschenbroich, Organometllics, Wiley-VH, Weinheim, 2005 E. C. Constable, Metals and Ligand Reactivity, VCH, Weinheim, 1996 R. Toreki, Organometallic Hypertext Book,

7 Preface to the course This course is the fruit of the assembling of several years of teaching notes at the University Pierre et Marie Curie - Paris 6. Indeed, most of the subjects dealt with are presently incorporated into a Master M2 course (MC 504), wherein I teach. Handwritten at the beginning, I timidly started transposing this material into an electronic version a few years ago. Far from being satisfactory to me, this work may represent a useful source of information for undergraduate students desiring to improve their knowledge in organometallic catalysis and more specifically in palladium chemistry, and for teachers wishing to integrate their own notes. The reader will soon realise that this work is far from being comprehensive, some important topics being absent. A reason of these holes is historical and is due to the fact that some relevant topics (absent in this work) are extensively and adequately treated by other colleagues in the same Faculty. Nonetheless, I will try in the future to enrich the files, possible new entries being inter alia: diallyl palladium derivatives, palladium catalyzed oxidations, and cross-couplings. I am deeply indebted to colleagues and students who patiently went through the proofs, helping me to considerably minimize my errors. Thus, many thanks to Claire Kammerer, Guillaume Prestat, Sylvain Roland, David Lopes, and Carlo Mealli for proofreading! Of course, some errors and inaccuracies will inevitably stick somewhere in the files. I apologize in advance for those. All people who will take the time to signal me oversights or suggestions for possible improvements will be of course very much welcomed. Finally, feel free to print, distribute and forward this course to friends and colleagues all over the web! I will be only glad. Giovanni Poli Université Pierre et Marie Curie 5 February 2007 Prof. Giovanni Poli Université Pierre et Marie Curie - Paris 6, Laboratoire de Chimie Organique (UMR CNRS 7611), Institut de Chimie Moléculaire (FR 2769), case 183, 4 place Jussieu, F Paris cedex 05, France. : +33 (0) : +33(0) : giovanni.poli@upmc.fr