Base Catalyzed Abnormal [3 + 2]-Cycloaddition between Isatin N,N'-Cyclic Azomethine Imine 1,3-Dipole and 3-Methyleneoxindole for the One-Step Construction of Tetracyclic Bispirooxindoles.

An abnormal [3 + 2]-cycloaddition and highly effective and convenient one-step preparation of tetracyclic bispirooxindoles containing two all-carbon quaternary spirocenters from isatin N,N'-cyclic azomethine imine 1,3-dipole and 3-methyleneoxindole in the presence of catalytic organic base has been disclosed. A variety of bispirooxindoles bearing a dinitrogen heterocycle with four adjacent cycles have been obtained in excellent yields (up to 95%) and diastereoselectivities (>99:1) under mild conditions.