Chiral-Boron Complex-Catalyzed Asymmetric [3 + 2] Cycloaddition of 2'-Hydroxychalcones with N -2,2,2-Trifluoroethylisatin Ketimines.

A highly efficient asymmetric [3 + 2] cycloaddition reaction of 2'-hydroxychalcones with N -2,2,2-trifluoroethylisatin ketimines catalyzed by a ( R )-3,3'-I 2 -BINOL-boron complex was developed. A broad range of 3,2'-pyrrolidinyl spirooxindole derivatives bearing a CF 3 -substituted pyrrolidine moiety with four contiguous stereocenters was prepared in high yields with excellent diastereo- and enantioselectivities (up to >20:1 dr and >99% ee). This protocol had the characteristics of mild reaction conditions, high efficiency, and excellent stereocontrol.