Enantioselective catalytic hydrosilylation of propiophenone with a simple combination of a cationic iridium complex and a chiral azolium salt

This study aims to propose a simple procedure for the development of enantioselective hydrosilylation of a ketone using catalytic amounts of [Ir(cod)2]BF4 and chiral azolium salt. Previously, catalytic asymmetric hydrosilylation reactions have used well-defined metal-N-heterocyclic carbene (NHC) complexes. The proposed method offers an important advantage of avoiding preparation of NHC-metal species. Several reaction parameters including the amount of reductant, solvent, catalyst loading, and ligand structure were evaluated. In addition, the investigation of the reaction progress as a function of time revealed that an iridium species, which was generated after 5 h of reaction time, catalyzed the stereoselective reduction with almost perfect facial selection of the ketone. An attempt to obtain a catalytic active species from the reaction of [Ir(cod)2]BF4 and chiral azolium salt has been made. The newly obtained iridium species promoted the hydrosilylation of a ketone with high yield and enantioselectivity.Graphical abstract
Source: Journal of Organometallic Chemistry - Category: Chemistry Source Type: research