Enantioselective synthesis of pyrazolone α-aminonitrile derivatives via an organocatalytic Strecker reaction

A new organocatalytic enantioselective Strecker reaction of pyrazolone-derived ketimine electrophiles has been developed. Using pseudo-enantiomeric squaramide catalysts the nucleophilic 1,2-addition of trimethylsilyl cyanide to the ketimines efficiently provides a direct entry to both enantiomers of pyrazolone alpha-aminonitrile derivatives at will in good yields and high enantioselectivities for a wide variety of substrates.