In this project, we will develop new chiral transition metal catalysts bearing N-heterocyclic carbene (NHC), cyclic alkyl amino carbenes (CAACs) ligands and other carbene ligands containing a sole axial chirality. In an original and unique manner, the complexes will be prepared from readily available achiral NHC precursors. Thus, the enantiopure complexes will be obtained by preparative chiral HPLC resolution which will provide access to both enantiomers with high optical purity (>99%). The design of the atropisomeric carbenes structures will be supported by DFT calculations which will be performed at an early stage. This project will tackle some fundamental aspects related to chirality including mechanistic aspects of carbene transmetalation, looking to understand the fate of the chiral information during this process. Beyond these fundamental studies, the aim is to create new series of efficient and inexpensive chiral catalysts in order to perform original enantioselective transformations.

As exemplified by the Stryker’s reagent, a phosphine-stabilized hexameric polymetallic copper(I) hydride [(Ph3P)CuH]6 (commercialized by Aldrich) routinely used in stoichiometric or catalytic quantities as a mild and selective reducing agent, Metal-Hydrogen (M-H) bonds occupy an important place in organic synthesis. In this project we intend develop new and original quantum-sized earth-abundant polynuclear metal–hydrides stabilized by carbene ligands for applications in chemoselective transformations of organic substrates.

Following pioneering work by Bertrand in 1988, and the isolation of the first N-heterocyclic carbene (NHC) by Arduengo, the field of stable carbenes has witnessed outstanding breakthroughs and considerable developments. Due to their strong sigma-donating and pi-accepting character, and their simple, yet versatile synthesis, carbenes have successfully challenged the stronghold of phosphines in transition metal catalysis. In recent years, the success of achiral N-heterocyclic carbenes (NHCs) as stable electron-rich neutral ligands has triggered the development of a diversity of chiral NHCs as stereodirecting ancillary ligands for enantioselective transformations. Today, thanks to their modular design and the ease of accessing azolium salt precursors, tailor-made chiral NHCs have proven to be significant tools in asymmetric transformations. Despite these advances, the toolbox of available chiral carbenes still lags behind more classical chiral phosphine ligands. In part, this situation might originate from the seeming inability to capitalise on the rich structural and electronic diversity of stable singlet carbenes. The goal of this project is therefore to prepare new chiral carbene ligands (other than NHCs), in order to extend the still developing family of stable chiral carbenes.