Zirconium-Catalyzed Enantioselective [3+2] Cycloaddition of Hydrazones to Olefins Leading to Optically Active Pyrazolidine, Pyrazoline, and 1,3-Diamine Derivatives

Asymmetric [3+2] cycloaddition of hydrazones to external olefins has been successfully conducted in high yields with high enantioselectivities using a chiral zirconium catalyst. These reactions open ways to synthetically and biologically important pyrazoline, pyrazolidine, and 1,3-diamine derivatives. Further, several experiments suggested that the reactions proceeded via concerted pathways.