Enantioselective Rh(I)-Catalyzed Addition of Arylboronic Acids to Cyclic Ketimines

A method for the
enantioselective synthesis of chiral α-tertiary
amines via Rh-catalyzed 1,2-addition of arylboronic acids to cyclic
ketimines is described. The products are efficiently accessed in good
yields and excellent enantioselectivities using a commercially available
chiral ligand. The reaction scope includes vinyl, aryl, and heteroarylboronic
acids with yields ranging from 40% to 99% and enantiomeric excesses
from 88% to 99%. Conversion of an addition product into an α,α-diaryl-substituted
amino acid is also demonstrated.