Palladium(II)-Catalysed Oxidation of Alkenes

Abstract

This review provides a summary of recent developments in the palladium(II)-catalysed oxidation of alkenes, focusing largely on reactions which lead to the formation of new carbon–oxygen or carbon–nitrogen bonds. Three classes of reaction are covered: i) oxidations proceeding via allylic C–H bond cleavage and formation of a π-allyl complex; ii) Wacker-type oxidations proceeding via nucleopalladation followed by β-hydride elimination; and iii) 1,2-difunctionalisation of alkenes proceeding via nucleopalladation followed by functionalisation of the resulting σ-alkylpalladium(II) intermediate. The mechanisms are discussed alongside the scope and limitations of each reaction. 1 Introduction 1.1 Background 1.2 Oxidation Pathways 1.3 Observation of Reaction Intermediates 2 Allylic Oxidation 2.1 Background 2.2 Allylic Oxygenation 2.3 Allylic Amination 2.4 Allylic Functionalisation with Other Nucleophiles 3 The Wacker Oxidation 3.1 Background 3.2 Variation of the Co-Oxidant 3.3 Direct Oxygen-Coupled Wacker Oxidations 3.4 Aldehyde-Selective Wacker Oxidations 3.5 Wacker Oxidation of Internal Alkenes 3.6 Aza-Wacker Oxidations 4 Intermolecular 1,2-Difunctionalisation of Alkenes 4.1 Introduction 4.2 Oxyhalogenation Reactions 4.3 Dioxygenation Reactions 4.4 Oxycarbonylation Reactions 4.5 Aminohalogenation Reactions 4.6 Diamination Reactions 4.7 Aminooxygenation Reactions 4.8 Aminocarbonylation Reactions 5 Summary and Conclusions