Amination of <i>N</i>-Aryl Prolinol via Ring Expansion and Contraction: Application to the Chiral Ligand for the Catalytic Asymmetric Reaction

Chiral diaminophosphines 4 were prepared from (S)-prolinol-derived aminophosphine oxide 5 by bromination with ring expansion followed by amination with ring contraction and reduction, using trichlorosilane. In the presence of 4 as a ligand, palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate (11) with a dialkyl malonate−BSA−LiOAc system was successfully carried out with good enantioselectivities (up to 98% ee).