Optically Pure C1-Symmetric Cyclic(alkyl)(amino)carbene Ruthenium-Complexes for Asymmetric Olefin Metathesis

An expedient access to the first optically pure ruthenium complexes containing C1-symmetric cyclic (alkyl)(amino)carbene (CAAC) ligands is reported. They demonstrate excellent catalytic performances in asymmetric olefin metathesis with high enantioselectivities (up to 92% ee).
Optically Pure C1-Symmetric Cyclic(alkyl)(amino)carbene (CAAC) Ruthenium-Complexes for Asymmetric Olefin Metathesis

An expedient access to a range of optically pure, well-defined, ruthenium complexes containing chiral CAAC ligands was developed. It relies on an efficient resolution of their racemic mixture via chiral prepHPLC on chiral-stationary phase. This process allowed for the isolation of air-stable (+) and (–)-enantiomers in good to nearly quantitative yields and excellent optically purity (ranging from >98 to >99.5%). Using these catalysts, excellent performances were observed in asymmetric ring-opening cross-metathesis (AROCM) with high enantioselectivities (up to 92% ee). Preliminary mechanistic insights provided by DFT models highlight the origin of the enantioselectivity. Moreover, a promising 50% ee was reached in the more challenging asymmetric cross-metathesis (ACM), one of the highest selectivity reported so far. This novel approach paves the way for the development of more sophisticated CAAC transition-metal complexes and should create new opportunities in asymmetric catalysis.

Those original works were done through a collaborative project involving researchers from the Rennes Institute of Chemical Sciences (CNRS/ENSC Rennes/Université de Rennes 1/INSA Rennes), the University of California San Diego (UMI CNRS), the Aix-Marseille university and the King Abdullah University of Science and Technology (KAUST).

Contacts

  • Marc Mauduit, Univ Rennes, CNRS, ISCR - UMR 6226, F-35000 Rennes, France
  • Guy Bertrand & Rodolphe Jazzar, Université de Californie à San Diego (UMI CNRS 3555)

Emails: guybertrandatucsd [dot] edu; rjazzaratucsd [dot] edu; marc [dot] mauduitatensc-rennes [dot] fr

Reference

Jennifer Morvan, François Vermersch, Ziyun Zhang, Laura Falivene, Thomas Vives, Vincent Dorcet, Thierry Roisnel, Christophe Crévisy, Luigi Cavallo, Nicolas Vanthuyne, Guy Bertrand, Rodolphe Jazzar and Marc Mauduit
Journal of the American Chemical Society, 2020, 142, 19895-19901 https://dx.doi.org/10.1021/jacs.0c10705

 

Published December 11, 2020