Recent Developments on 1,3-Dipolar Cycloaddition Reactions by Catalysis in Green Solvents

The use of eco-compatible synthetic procedures in organic reactions and, in particular, in 1,3-dipolar cycloaddition reactions, has recently received a great deal of attention and considerable progress has been achieved in this area in the last years. This review summarizes the approaches currently employed to synthesize heterocyclic compounds by catalyzed 1,3-dipolar cycloadditions in green solvents in the last six years. Our choice to do a selection of the literature from 2014 to 2019 was made considering the absence of a recent review about this period, to our knowledge. Several examples to construct heterocycles by 1,3-dipolar cycloadditions will be discussed in this work subdivided in function of the most important class of non-conventional and green solvents, i.e., ionic liquids (ILs), deep eutectic solvents (DES), and water.