In this review, a comparison between the Lewis acid catalysed and organocatalysed 1,3-dipolar cycloaddition is presented with special focus on the enantioselective synthesis of five-membered hetero- or carbocyclic systems, is described. These reactions exhibit very interesting features, but the most important one is the generation of up to four stereogenic centres in only one reaction step.
asymmetric catalysis; cycloadditions; Lewis acids; organocatalysts
