Organocatalytic Asymmetric Synthesis of Spirooxindole Embedded Oxazolidines.

The first organocatalytic asymmetric synthesis of spirooxindole embedded oxazolidines has been developed via a domino reaction involving hemiaminal formation, followed by an unprecedented aza-Michael reaction between isatin derived N-Boc ketimines and γ-hydroxy enones. A quinine derived bifunctional squaramide catalyst was found to be efficient for this reaction, and the products were obtained in good diastereoselectivity and with high enantioselectivity.