KCO-Promoted Formal [3+3]-Cycloaddition of -Unsubstituted Isatin ,-Cyclic Azomethine Imine 1,3-Dipoles with Knoevenagel Adducts.

The synthesis of dicyclic spiropyridazine oxoindole derivatives by using [3+3]-cycloaddition of -unsubstituted isatin ,'-cyclic azomethine imine 1,3-dipoles was reported. The products bearing two consecutive stereocenters, including spiroquaternary stereocenters in one ring structure, can be effectively obtained in moderate to excellent yields (20-93%) and low to moderate diastereoselectivities (1:9-10:1 dr). The synthesized compounds (>35 examples) were characterized by single-crystal XRD, FTIR, NMR, and mass spectral analysis.