Enantioselective Hydrocyanation of Aldehydes Catalyzed by [Li{Ru(phgly)₂(binap)}]X (X = Cl, Br)

Novel bimetallic complexes [Li{Ru[(S)-phgly]2[(S)-binap]}]X (X = Cl, Br) are readily synthesized by mixing Ru[(S)-phgly]2[(S)-binap] and LiX. A single-crystal X-ray analysis reveals the structure. These bimetallic complexes efficiently catalyze asymmetric hydrocyanation of aldehydes with a substrate-to-catalyst molar ratio of 500−2000 at −78 to −60 °C. A range of aromatic, heteroaromatic, and α,β-unsaturated aldehydes as well as a tert-alkyl aldehyde is converted to the cyanohydrins in high enantiomeric excess (up to 99%).