Iron-catalyzed regioselective reductive cyclotrimerization of alkynyl bromides to 1,2,4-substituted arenes and D ₃ -arenes

Herein, we report an iron-catalyzed regioselective reductive cyclotrimerization of alkynyl bromides for the synthesis of 1,2,4-substituted arenes and D₃-arenes, enabled by using MeOH and CD₃OD as proton sources, respectively. A series of 1,2,4-substituted arenes and D₃-arenes bearing various functional groups were successfully obtained in good yields with excellent regioselectivities. Preliminary mechanistic studies suggested that the terminal alkyne generated <i>in situ</i> may act as an intermediate in this cyclotrimerization process.