Asymmetric Activation of tropos Ligands in the Strecker Reaction

Significance

The catalytic asymmetric Strecker reaction is an important reaction in the synthesis of chiral amino acids. The authors report on a highly selective catalytic method for the cyanation of N-tosyl-protected aldimines and ketimines which yield tertiary or quaternary α-amino nitriles in high yields and ee. The key is the use of a flexible biphenol ligand in combination with a readily available chiral modifier. The atropos ligand is influenced by the chiral modifier and directs the ligand to the most stable conformation, which then defines the enantiodiscrimination of the catalytic center.