Ag-Catalyzed Asymmetric 1,3-Dipolar Cycloaddition of N-2,2,2-Trifluoroethylisatin Ketimines with Conjugated Exocyclic Double Bonds: Access to Pyrrolidines with Four Consecutive Stereocenters Including Two Adjacent Spiro-Quaternary Centers

Ag-catalyzed enantioselective 1,3-dipolar cycloaddition of N-2,2,2-trifluoroethylisatin ketimines with conjugated exocyclic double bonds including alpha-alkylidene succinimides and aurone derivatives was developed for the first time. Using a catalyst system consisting of a ferrocenyl P,N-ligand and AgNO2, the reaction provides a facile method for the construction of chiral pyrrolidines bearing four consecutive stereocenters and two adjacent spiro-quaternary chiral centers, as well as offers a direct route to structurally diverse enantioenriched CF3-containing 3,2 '-pyrrolidinyl spirooxindole derivatives.