Organocatalytic Asymmetric Synthesis of Aza-Spirooxindoles via Michael/Friedel-Crafts Cascade Reaction of 1,3-Nitroenynes and 3-Pyrrolyloxindoles.

An asymmetric [3+3] cyclization of nitroenynes and 3-pyrrolyloxindoles has been realized with a chiral bifunctional squaramide catalyst. This Michael/Friedel-Crafts cascade strategy provides a facile and efficient access to enantioenriched polycyclic aza-spirooxindoles with 32-95% isolated yields and excellent stereocontrol under mild reaction conditions.