Recent Advances on Epoxide‐ and Aziridine‐Based [3+2] Annulations

[3+2] Annulations are a powerful method for the synthesis of five‐membered heterocyclic compounds. The annulations have concerted cycloaddition and formal (stepwise) cycloaddition reaction pathways. In addition to the well‐established O‐centered and N‐centered ylides, epoxides and aziridines could serve as synthetic equivalent of 1,3‐dipoles for [3+2] annulation with dipolarophiles for making functionalized tetrahydrofuran, pyrrolidine, and associated compounds. This review article covers recent development on epoxide‐ and aziridine‐based [3+2] annulation reactions. The reactions are classified based on the ring opening conditions, including acid/base catalysis, organocatalysis, and transitional‐metal catalysis.