Cu-Catalyzed Ring Opening Reaction of 2<i>H</i>‑Azirines with Terminal Alkynes: An Easy Access to 3‑Alkynylated Pyrroles

A highly efficient Cu-catalyzed ring expansion reaction of 2<i>H</i>-azirines with terminal alkynes has been developed. This transformation provides a powerful method for the synthesis of 3-alkynyl polysubstituted pyrroles under mild conditions in good yields. The direct transformation process, specific selectivity, and good tolerance to a variety of substituents make it an alternative approach to the reported protocols