Dr Guillaume Lefèvre

Chimie ParisTech

"One E-H bond, two metals: synergy between Fe and main-group cations in catalysis (E = B, C, Si, Ge)"

Iron catalysis is of high interest in a context of green and sustainable chemistry, owing to the low cost and toxicity of this metal. However, in numerous catalytic processes, the reactive iron species are usually air- and moisture-sensitive, thermally unstable, making their characterization and monitoring rather difficult. The generation of such species is moreover classically performed in literature by reduction of a stable Fe(II) or Fe(III) precursor with a reductant associated with a main-group cation (e.g. RMgX, R₂Zn, KC₈, Na(hmds),…).

Using mechanistically-driven approaches, our group recently demonstrated that a synergy between iron catalysts and those main-group cations (Mg^II, Zn^II, Li^I, Na^I, …) had a crucial impact on the nature of the in situ generated iron active species, and can lead to the development of various catalytic patterns, using the same iron precursor. The example of C–H bond functionalization will be discussed: depending on the nature of the main-group additives, cross-coupling involving C–H pro-nucleophiles, reductive dehydrocoupling with B–H substrates, of Hydrogen Isotopic Exchange (HIE) leading to the D-labelling of B–H bonds can be achieved (Scheme 1).

Scheme 1

The application of this bimetallic synergy to the reactivity of non-innocent (N,N^•–)₂Fe^II complexes ((N,N) = phen-type ligands) active in [2+2+2] cycloadditions and alkyne hydroelementations (addition of Si–H and Ge–H bonds) will also be discussed.

Recent references of our group on this topic
- Zhurkin, F.; Parisot, W.; Lefèvre, G.; Adv. Synth. Cat. 2024, in press, 10.1002/adsc.202301340, A solely-Fe-catalyzed Sonogashira-type coupling of non-activated secondary alkyl iodides with terminal alkynes.
- Wowk, V.; Bauer, A. K.; Radovic, A.; Chamoreau, L.-M.; Neidig, M. L.; Lefèvre, G. JACS Au 2024, accepted, doi.org/10.1021/jacsau.3c00649, Divergent Fe-mediated C-H activation paths driven by alkali cations.
- Féo, M.; Djebbar, F.; Zhurkin, F.; Binet, L.; Touati, N.; Leech, M. C.; Lam, K.; Brémond, E.; Lefèvre, G. J. Organomet. Chem. 2023, 999, 122796, Ligand dynamics and reactivity of a non-innocent homoleptic iron complex (N,N)₂Fe stabilized by phen-type ligands.
- Féo, M.; Bakas, N. J.; Radovic, A.; Parisot, W.; Clisson, A.; Chamoreau, L.-M.; Haddad, M.; Ratovelomanana-Vidal, V.; Neidig, M. L.; Lefèvre, G. ACS Catal. 2023, 13, 4882–4893, Thermally Stable Redox Noninnocent Bathocuproine-Iron Complex for Cycloaddition Reactions.
- Wowk, V.; Lefèvre, G. Dalton Trans. 2022, 51, 10674-10680. Perspective Article. The crucial and multifaceted roles of main-group cations and their salts in iron-mediated cross-couplings.