Additions of Oxindoles to Nitroolefins: An Entry to Pyrrolidinoindolines

Significance

The authors report a Michael addition of oxindoles to aromatic, heteroaromatic, and aliphatic nitroolefins catalyzed by bifunctional Takemoto-type catalyst 1. The reaction provided oxindoles bearing a chiral quaternary center at C3 in good yield and good to excellent diastereomeric and enantiomeric ratios. Furthermore, the synthetic utility of the method was illustrated by the synthesis of the pyrrolidinoindoline (+)-esermeth­ole, which is an intermediate in the synthesis of (+)-physostigmine.