Abstract:
Cycloaddition/annulation reactions remain the most attractive methods for the synthesis of five membered heterocyclic ring systems. Among the three possible strategies for [3 + 2] cycloaddition, this review focuses on 1,3-carbon donor–acceptor (C3, D–A) cycloaddition/annulation reactions with imines to synthesize pyrrolidines. The formal [3 + 2] cycloaddition, which includes the in situ 1,3-carbon D–A precursor generation through metal catalysis, Lewis acid catalysis and organocatalysis approaches is highlighted. The scope and limitations of this strategy along with its applications in the synthesis of natural product alkaloids reported during the last decade are outlined.