Enantioselective catalytic addition of HCN to ketoimines. Catalytic synthesis of quaternary amino acids.

[formula: see text] Highly enantioselective addition of HCN to ketoimines has been achieved for the first time using readily accessible and recyclable Schiff base catalysts. Essentially quantitative isolated yield and enantioselectivity of up to 95% ee was obtained. Furthermore, some of the Strecker adducts could be recrystallized in high recovery, yielding optically pure materials. Conversion of the alpha-aminonitrile adducts to the corresponding alpha-quaternary alpha-amino acids was effected in high yield by a formylation/hydrolysis sequence.