Enantioselective Synthesis of Multisubstituted Spirocyclopentane Oxindoles Enabled by Pd/Chiral Rh(III) Complex Synergistic Catalysis.

An asymmetric [3 + 2]-cycloaddition reaction of α,β-unsaturated 2-acyl imidazoles with spirovinylcyclopropanyl-2-oxindoles catalyzed synergistically by an achiral palladium(0) catalyst and a chiral-at-metal rhodium(III) complex has been developed. A series of biologically important 3-spirocyclopentane-2-oxindoles with four contiguous stereocenters were synthesized in high yields (up to 99%) with excellent stereoselectivities (up to 99% ee, 20:1 dr).