Synthesis of σ-Heterocyclic Iron Complexes Based on [3+3] Cycloaddition to 1,3-Dipolar Reagents

Treatment of iron complex (η⁵-C₅H₅)Fe(CO)₂CH₂C≡CPh 1 with nitrogen-containing 1,3-dipolar reagents (nitrile oxides and azomethine ylide) yields six-membered σ-heterocyclic iron complexes, due to cycloaddition and subsequent 1,2-migration of the (η⁵–C₅H₅)₂Fe (CO) group.