Hydrosilylation Catalysts

Hydrosilylation Catalysts

Author: Angewandte Chemie International Edition

Aaron Sadow and colleagues, Iowa State University, Ames, USA, have developed new organocerium compounds for catalytic hydrosilylation chemistry. Complexes containing cerium–carbon σ-bonds have properties such as high thermal sensitivity, highly polar bonds, and high reactivity toward oxygen-containing species, which makes the synthesis of homoleptic organocerium compounds challenging.

The ligand tris(dimethylsilyl)methyl can be easily transmetalated with cerium triiodide to give the isolable Ce{C(SiHMe2)3}3. This species reacts with the Lewis acid B(C6F5)3 by β-H abstraction to give the zwitterionic hydridoborato bis(alkyl)cerium species Ce{C(SiHMe2)3}2HB(C6F5)3.

The synthesized zwitterionic species serves as a precatalyst for the hydrosilylation of acrylates with secondary silanes to give α-silyl esters with more than 2,000 turnovers. The catalyst is highly active and, e.g., gives full conversion of methyl acrylate and PhMeSiH2 with 0.05 mol% catalyst within 5 minutes. The team suggests that other ancillary ligands could be used for controlling the enantioselectivity of the reactions.


 

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