Sustainable catalytic processes

Hydroelementations of heterocycles catalysed with cobalt hydrides. 

In recent years, in contrast to the literature on cobalt-catalysed cross-couplings and the use of cobalt salts combined with reductants, MP has focused on simple, well-defined cobalt hydride complexes with inexpensive ligands. The use of these complexes has the advantage of generating little waste, and of being effective with a low catalytic load. These catalysts have proven to be competitive with noble metals in the field of C-H activation as well as B-H, Si-H bond activation in hydroelementation processes. MP and MB have recently shown that these cobalt hydrides with phosphine ligands were able to catalyse the reduction of imines and N-heteroarenes such as quinolines and pyridines. A quinoline reduction/functionalisation sequence, allowing the introduction of a borane that can be post-functionalised, was thus developed. In the future, new syntheses of highly functionalized quinolines and pyridines, which may exhibit biological activities, will be envisaged, initially targeting tetrahydroquinolines. An extension to aza-helicenes will also be studied in order to develop a new method for helicene functionalization. Finally, the cobalt complexes used in this approach have easily exchangeable phosphine ligands, which makes an enantioselective approach possible. The application of this method to biosourced quinolines (from lignin depolymerisation products) will be considered. Of course, as already done previously, for each new process developed, mechanistic studies via classical spectroscopic (NMR, IR, Mass – coll. IPCM) and theoretical (DFT – coll. IPCM and international) tools will be undertaken.

Hydrogenation and dehydrogenation 

We also want to develop new LOHCs (Liquid Organic Hydrogen Carriers) for hydrogen transport, such as 1,x-diaminoalkanes/1,x-dinitrilealkanes. Indeed, these diamine/dinitrile couples have several advantages. They have a high gravimetric hydrogen content and a high volumetric hydrogen storage capacity. They are well known and already used in large quantities in the textile industry and this industry is developing several bio-based approaches to these synthons. We propose to develop catalytic systems based on 3d transition metals (Co, Ni, and Fe). We want to use only systems that are easy, accessible (no expensive and delicate synthesis), scalable (synthesis easily transposed from one system to another), and recyclable.  We will first work on two established systems, already developed by the consortium, based on well-defined cobalt complexes (homogeneous approach) and mono-disperse cobalt nanoparticles (nanocatalytic approach). 

Cationic organoacid catalysts. 

Many important transformations in organic chemistry involve cationic intermediates where the nature of the associated anion is crucial to control reactivity and selectivities. A new project, funded by the Emergence SU programme and led by GL, focuses on the development of cationic Brønsted organoacids associated with very weakly coordinating anions for applications in the synthesis of (poly)cyclic compounds. At present, the protonation of very weak bases with acids conjugated with such anions still represents a real challenge that GL proposes to overcome by using in situ generated superacid carbocations. Using this methodology, new classes of cationic organoacids with very high acidities will be prepared and studied in detail. These new charged organic species will then be considered in catalysis for the activation of non-polar functions such as unactivated C-C multiple bonds, which are beyond the reach of most commonly used neutral organic acids. In this context, efforts will be made to develop the catalytic and stereoselective hydrofunctionalisation of non-activated olefins, which represents a simple, atom- and step-saving, but challenging approach to molecular complexity.