ASYMMETRIC CATALYSIS - COMPARISON OF THE ENANTIOSELECTION OF RHODIUM-CATALYZED INTRAMOLECULAR HYDROSILATION AND HYDROACYLATION

The previously reported observation that 4-pentenals bearing either a tertiary group or acyl or ester substituents at the 4-position gave very high ee's for hydroacylation using the [Rh(S-binap)(solvent)(2)](+) catalyst suggested that the same catalyst might give high ee's for intramolecular hydrosilation of similarly substituted allylic alkoxides bound to diaryl- or dialkylsilanes. Although the chemical yields and ee's are dependent on the solvent used and on the olefin and silicon substituents, there are combinations of these parameters which lead to high ee's for hydrosilation of substrates bearing these substituents,