Asymmetric addition of trimethylsilyl cyanide to aldehydes catalysed by chiral (salen)TiIV complexes

The asymmetric addition of trimethylsilyl cyanide to a range of aldehydes is catalysed by the titanium(IV) complexes of chiral salen derivatives 3–6. The enantiomeric excess of the resulting cyanohydrins is predominantly dependent upon the structure of the aldehyde, with electron-rich aromatic aldehydes giving best results. Electron-deficient aromatic aldehydes give cyanohydrins with low enantiomeric excesses, whilst ketones fail to react.