Asymmetric Diastereoselective Synthesis of Spirocyclopropane Derivatives of Oxindole

A new asymmetric organocatalytic synthesis of spirocyclopropane oxindoles has been developed. The method is based on the Michael addition of N-Boc-protected 3-chlorooxindole to unsaturated 1,4-dicarbonyl compounds, affording trans-substituted spirocyclopropane oxindole derivatives in high diastereo- and enantioselectivity.