K2CO3-Promoted Formal [3+3]-Cycloaddition of N-Unsubstituted Isatin N,N′-Cyclic Azomethine Imine 1,3-Dipoles with Knoevenagel Adducts

The synthesis of dicyclic spiropyridazine oxoindole derivatives by using [3+3]-cycloaddition of N-unsubstituted isatin N,N '-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.

Automated summary

The synthesis of dicyclic spiropyridazine oxoindole derivatives by [3+3]-cycloaddition reaction of N-unsubstituted isatin N,N'-cyclic azomethine imine 1,3-dipoles was successfully achieved. The products, having two consecutive stereocenters including spiroquaternary stereocenters in one ring structure, were obtained in moderate to excellent yields (20-93%) and low to moderate diastereoselectivities (1:9-10:1 dr). The synthesized compounds were thoroughly characterized using various spectroscopic techniques.