Enantioselective Construction of Spirooxindole-Fused Cyclopentanes.

The present study reports an asymmetric organocatalytic cascade reaction of oxindole derivates with α,β-unsaturated aldehydes efficiently catalyzed by simple chiral secondary amine. Spirooxindole-fused cyclopentanes were produced in excellent isolated yields (up to 98%) with excellent enantiopurities (up to 99% ee) and moderate to high diastereoselectivities. The synthetic utility of the protocol was exemplified on a set of additional transformations of the corresponding spiro compounds. In addition, a study showing the promising biological activity of selected enantioenriched products was accomplished.