Transition metal complexes bearing atropisomeric saturated NHC ligands

Mariia Savchuk (1) , Lucas Bocquin (1) , Muriel Albalat (1) , Marion Jean (1) , Nicolas Vanthuyne (1) , Paola Nava (1) , Stéphane Humbel (1) , Damien Hérault (1) , Hervé Clavier (1)

1 ISM2 - Institut des Sciences Moléculaires de Marseille

From achiral imidazolinium salts, chiral transition metal complexes containing an N-heterocyclic carbene (NHC) ligand were prepared (metal = palladium, copper, silver, gold, rhodium). Axial chirality in these complexes results from the formation of the metal-carbene bond leading to the restriction of rotation of dissymmetric N-aryl substituents about the C–N bond. When these complexes exhibited a sufficient configurational stability, a resolution by chiral high-performance liquid chromatography (HPLC) on preparative scale enabled isolation of enantiomers with excellent enantiopurities (>99% ee) and good yields. A study of the enantiomerization barriers revealed the effect of the backbone nature as well as the type of transition metal on its values. Nevertheless, the evaluation of palladium-based complexes in asymmetric intramolecular α-arylation of amides demonstrated that the ability to induce an enantioselectivity cannot be correlated to the configurational stability of the precatalysts.

Domaines: Chimie de coordination

Mariia Savchuk, Lucas Bocquin, Muriel Albalat, Marion Jean, Nicolas Vanthuyne, et al.. Transition metal complexes bearing atropisomeric saturated NHC ligands. Chirality, 2022, 34 (1), pp.13-26. ⟨10.1002/chir.23378⟩. ⟨hal-03500191⟩