Catalytic [4+2] Cyclization of α,β‐Unsaturated Acyl Chlorides with 3‐Alkylenyloxindoles: Highly Diastereo‐ and Enantioselective Synthesis of Spirocarbocyclic Oxindoles

Cinchona alkaloids were used as Lewis base catalysts in the title reaction. The [4+2] cyclization of α,β-unsaturated acyl chlorides with electron-deficient alkenes derived from oxindole gave the corresponding spirocarbocyclic oxindoles.