Ruthenium catalysts polymer-immobilised catalyst

Scheme 2.32 Synthesis of syn -amide alcohol with polymer-immobilised ruthenium catalyst.

The triethoxysilane endgroup had to be introduced as the respective isocyanate and was then used to attach the polymer on the silicon support. In a final step, the NHC are formed and the ruthenium precursor loaded onto the polymer. Only 13% of the imidazolium sites are attached to ruthenium. The formation of this polymer supported Grubbs catalyst is doubtless a synthetic masterpiece, however, immobilisation of the Grubbs catalyst was achieved in a far less complicated manner only a few years later by a far simpler method by Fiirstner and coworkers [244]. 

The use of polymer-stabilised colloidal platinum clusters (containing cinchoni-dine) in acetic acid provides up to 97.6% ee in the reduction of methyl pyruvate (MeCOCOzMe). Polyvinylpyrrohdine is used as the polymer, and the particle size is small. The use of nanoparticles as a support for catalysts is an attractive concept owing to the large surface areas of these materials. However, such supported catalysts of this type are often difficult to recover. Hu and coworkers have achieved the immobilisation of ruthenium(phosphine)( 1,2-diamine) catalysts onto... 

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