Synthesis of Five-MemberedN,N,N- andN,N,N,N-Heterocyclic Compounds: Applications of Microwaves

The development of new strategies for the synthesis of small-sized heterocycles has remained a highly attractive but challenging proposition. An overview of the application of microwave irradiation to the synthesis of five-membered heterocyclic compounds containing three and four nitrogen atoms is presented, focusing on the developments in the past 5–10 years. This contribution covers the literature concerning the total synthesis of N,N,N- and N,N,N,N-heterocycles. The literature data are summarized based on the size and type of cycles.