Alkynes and Nitrogen Compounds: Useful Substrates for the Synthesis of Pyrazoles

The easy preparation and functionalization of pyrazoles associated with their innumerable biological properties have made this class of N -heterocycles very attractive for the development of new synthetic routes and applications. The cyclization reactions of alkynes and nitrogen compounds represent a powerful tool for the preparation of pyrazoles. This review covers the recent advances in the preparation of pyrazoles by reacting alkynes and nitrogen compounds under transition metal- or metal-free conditions.