Iron(II) Halide Promoted Cyclization of Cyclic 2‑Enynamides: Stereoselective Synthesis of Halogenated Bicyclic γ‑Lactams

A simple and mild process was developed for the highly stereoselective synthesis of halogenated bicyclic [4.3.0] and [3.3.0] γ-lactams, possessing four stereocenters, from easily available cyclic 2-enynamides. The reaction required only an inexpensive iron­(II) halide under dry air and was tolerant of aryl, heteroaryl, and alkyl groups at the alkyne terminus.