Enantioselective Amination of ß-Keto Esters Catalyzed by Chiral Calcium Phosphates.

ABSTRACT

A catalytic enantioselective amination of ß-keto esters using (S)-BINOL chiral calcium phosphate has been developed. The reaction produces chiral α-amino-ß-keto ester derivatives in most cases with moderate to excellent enantioselectivities (up to 99 %) and good yields (up to 99 %). This mild synthetic method highlights a low catalyst loading and high catalytic efficiency. When the substrate backbone was changed to 1-tetralone-derived ß-keto esters, unexpectedly high yields of selective redox products were obtained. The practicality of the reaction was realized by a scale-up without any significant loss in the enantioselectivity and yield. Chiral calcium phosphate was successfully recovered and reused for four runs, indicating its stability and high catalytic activity.