An Organocatalytic Cascade Strategy for the Enantioselective Construction of Spirocyclopentane Bioxindoles Containing Three Contiguous Stereocenters and Two Spiro Quaternary Centers

A rapid and efficient organocatalytic cascade sequence for the direct construction of spirocyclopentane bioxindoles has been carried out by using a chiral squaramide catalyst in the presence of a base. This process constitutes a powerful approach to the preparation of biologically important bispirooxindoles in high enantioselectivities (see scheme).