CNRS
Centro de Investigación, Examinar oportunidades similares
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Centro de Investigación, Examinar oportunidades similares
-Synthesis of various chiral CAAC ligand precursors (iminium salts)
-Synthesis of various chiral CAAC-based Ru-complexes
-Evaluation in asymmetric ring-closing metathesis (ARCM) and cross-metathesis (ACM)
-Synthesis of enantioenriched relevant building blocks
In a few decades, olefin metathesis has rapidly become one of the most efficient synthetic tools in organic chemistry, thanks to the development of efficient, well-defined, air stable and easy to handle N-heterocyclic carbenes (NHCs) ruthenium-arylidene complexes with high tolerance towards many organic functions. Asymmetric version of this tool was also investigated with a slew of Ru-complexes featuring chiral NHCs with varying successes in ring-opening cross-metathesis (AROCM) and ring-closing metathesis (ARCM). In 2007, a new class of carbenes namely cyclic (alkyl)(amino) carbenes (CAACs) arose as a contender to NHCs's as ligands for olefin metathesis catalysts. Since then, CAAC-Ru complexes demonstrated remarkable catalytic performances in a number of metathesis transformations. Despite these achievements there is still no report dealing with CAAC ligands in asymmetric metathesis. On this concern, we recently developed an expedient access to a range of optically pure, well-defined Ru-complexes containing chiral CAACs. 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 nearly quantitative yields and excellent optically purity (>98%). Using these catalysts, excellent performances were observed in AROCM with high enantioselectivities (up to 92% ee).
During this Post-doc position, the researcher will synthesize a library of unprecedented optically pure CAAC-Ru complexes. These new catalysts will be subsequently evaluated in asymmetric ring-closing metathesis (ARCM) and cross-metathesis (ACM) targeting synthesis of original chiral building blocks for agrochemical industry and perfumery.
Organometallics: Materials and Catalysis (OMC) TEAM located at ENSC of Rennes
Supervisor : Dr. Marc MAUDUIT
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