Bidentate N-Heterocyclic Carbene Ligands Incorporating Oxazoline Units

Bidentate N-Heterocycllc Carbene Ligands Incorporating Oxazoline Units [Pg.327]

Whereas, for example, the asymmetric hydrosilylation of 2-naphthyl methyl ketone with this catalyst was carried out with 99% yield and 91% ee, the enan-tioselectivities for most aryl alkyl ketones were found to be slightly below those of the most efficient phosphane-based systems. However, the system was found to be exceptionally selective in the hydrosilylation of unsymmetrical dialkyl ketones (Table 15.5), which are difficult substrates [58]. The selectivity for the reduction of prochiral dialkyl ketones was comparable or even superior to the best previously reported for prochiral nonaromatic ketones. [Pg.330]

Whereas cyclopropyl methyl ketone was hydrosilylated with an enantioselec-tivity of 81% ee, the increase of the steric demand of one of the alkyl groups led to improved enantiomeric excesses, reaching 95% ee in the case of terf-butyl methyl ketone. Linear-chain n-alkyl methyl ketones, which are particularly challenging substrates, were reduced with good asymmetric induction, such as in the case of 2-octanone (79% ee) and even 2-butanone (65% ee) [58]. [Pg.330]

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