From Prochiral N‑Heterocyclic Carbenes to Optically Pure Metal Complexes: New Opportunities in Asymmetric Catalysis

• Published in: Journal of the American Chemical Society Vol. 142; no. 1; pp. 93 - 98
• Main Authors: Kong, Lingyu, Morvan, Jennifer, Pichon, Delphine, Jean, Marion, Albalat, Muriel, Vives, Thomas, Colombel-Rouen, Sophie, Giorgi, Michel, Dorcet, Vincent, Roisnel, Thierry, Crévisy, Christophe, Nuel, Didier, Nava, Paola, Humbel, Stéphane, Vanthuyne, Nicolas, Mauduit, Marc, Clavier, Hervé
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 08.01.2020
• Subjects: Catalysis; Chemical Sciences; Coordination chemistry
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.9b12698

Well-defined optically pure transition metal (TM) complexes bearing C 1- and C 2-symmetric N-heterocyclic carbene (NHC) ligands were prepared from prochiral NHC precursors. As predicted by DFT calculations, our strategy capitalizes on the formation of a metal-carbene bond which induces an axis of chirality. Configurationally stable atropisomers of various NHC-containing TM complexes were isolated by preparative HPLC on a chiral stationary phase in good yields and excellent optical purities (up to 99.5% ee). The carbene transfer from an optically pure Cu complex to a gold or palladium center reveals, for the first time, a full stereo­retentivity, supporting the hypothesis of an associative mechanism for the transmetalation. The potential of these new chiral TM complexes was illustrated in asymmetric catalysis with up to 98% ee.