Synthesis of beta,gamma-unsaturated lactams via a magnesium iodide promoted ring expansion of secondary methylenecyclopropyl amides.

A novel and efficient route to exo-beta,gamma-unsaturated lactams from substituted and non-substituted secondary methylenecyclopropyl amides is reported. Subsequent modification of the resulting exo-beta,gamma-unsaturated lactams provides access to several pharmaceutically relevant scaffolds. [reaction: see text].