Co(III)-Based Catalysts with Chiral Cyclopentadienyl Ligands

Co(III)-Based Catalysts with Chiral Cyclopentadienyl Ligands

Author: ChemistryViews.org

Enantioselective C–H functionalizations usually require precious-metal catalysts with chiral ligands. Using the more abundant 3d transition metals could make such reactions more cost-effective and sustainable. However, this is still challenging.

Nicolai Cramer and colleagues, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland, have developed a cobalt(III)-based catalyst with a chiral cyclopentadienyl-type ligand (pictured). The catalyst can promote enantioselective C–H functionalizations. The team prepared the complex from the cyclopentadienyl ligand and Co2(CO)8 under a CO atmosphere, followed by an oxidation using iodine.

The catalyst was used for the enantioselective synthesis of dihydroisoquinolones from N-chlorobenzamides and different alkenes. The team used a catalyst loading of 5 mol%, together with silver triflate as an additive and cesium pivalate as a base in hexafluoroisopropanol (HFIP) as a solvent. The desired products were obtained in good yields and with excellent enantio- and regioselectivities (up to > 99:1 er).


 

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