Sequential 1,3-dipole Cycloaddition of Nitrile Imines with Alkenyl Isoxazoles and Aromatization：A one-pot access to 1,3,4-Triarylpyrazoles

A novel one-pot two-step process for the preparation of 1,3,4-triarylpyrazoles was disclosed. This process involved a sequential 1,3-dipole cycloaddition reaction of in situ generated nitrile imines with alkenyl isoxazoles and SnCl2-promoted aromatization/elimination reaction, offering a collection of 1,3,4-triarylpyrazoles in a fully regioselective manner. This protocol featured mild reaction conditions, easily available raw materials and excellent regioselectivity.