Enantioselective Construction of Multi-Nitrogen-Containing Spirocycles: Asymmetric [3+2] Annulation of 4-Isothiocyanato Pyrazolones with Azodicarboxylates

The 4-isothiocyanato pyrazolones were exploited as a class of efficient synthon for the construction of triazoline derivatives via asymmetric [3+2] annulation of 4-isothiocyanato pyrazolones with azodicarboxylates, providing a wide range of structurally diverse multi-nitrogen-containing spirocycles in excellent yields (up to 97%) with excellent enantioselectives (up to 97% ee).