Cu and Pd complexes of N-heterocyclic carbenes : catalytic applications as single and dual systems

Abstract

Nowadays, the requirement to design highly valuable compounds is undoubtedly one of the major challenges in the field of organic and organometallic chemistry. The use of the versatile and efficient N-heterocyclic carbenes (NHCs) combined with transition metals represents a key feature in modern organometallic chemistry and homogeneous catalysis. In the course of this thesis, the straightforward design and synthesis of a library of Pd(0) bearing NHC ligands was achieved. Their catalytic performances (Chapter 1) and their phosphorescence properties in solution (Chapter 2) were disclosed. Currently, cross-couplings are some of the most important types of reaction in palladium catalysis. The formation of highly hindered biaryls substrates is one of the main requirements in cross-coupling chemistry. The design and synthesis of a palladium dimer bearing a bulky NHC ligand can fulfil this proposal (Chapter 4). The development of new classes of ligands is a topic of interest. For this reason, normal, abnormal, remote and mesoionic N-heterocyclic carbenes copper complexes were investigated and their reactivity compared in the [3+2] cycloaddition of azides and alkynes (Chapter 7). Air and moisture stable Cu(I)-NHC species have also been compared to their silver analogues for the alkynylation of ketones (Chapter 9). The different reactivity of the two latter organometallic species (Cu and Ag) with ethyldiazoacetate reagent via the formation of carbenes or C-H activated product is presented in Chapter 8. Recently, the development of a bimetallic catalytic system is strongly considered and has high impact. For this reason, two dual catalytic transformations (Pd-NHC and Cu-NHC) were studied for the C-H arylation (Chapter 5) and the synthesis of substituted alkenes products via a relay or cooperative mechanisms (Chapter 6). The isolation of intermediates and mechanistic studies were examined in each of these studies.