Sequential 1,3-Dipole Cycloaddition of Nitrile Imines with Alkenyl Isoxazoles and Aromatization: A One-Pot Access to 1,3,4-Triarylpyrazoles

摘要

A novel one-pot two-step process for the preparation of 1,3,4-triarylpyrazoles is disclosed. This process involves a 1,3-dipolar cycloaddition reaction of alkenyl isoxazoles with nitrile imines generated in situ, followed by SnCl2-promoted aromatization/elimination reaction to give a range of 1,3,4-triarylpyrazoles in a fully regioselective manner. This protocol features mild reaction conditions, easily available raw materials, and excellent regioselectivity.