'Ligand-free-like' CuCl-catalyzed atom transfer radical cyclization of N-substituted N-allyl polychloroamides to γ-lactams.

Atom transfer radical cyclization (ATRC) of N-alkyl N-allyl dichloroamides to γ-lactams, catalyzed by 'naked' CuCl, worked efficiently in DMF, whereas, when the same dichloroamides were N-sulfonylated, DMF needed to be replaced by acetonitrile. The outcome of the cycloisomerization with N-substituted N-allyl trichloroacetamides was less affected by solvent choice, although for an effective reaction to occur, the solvent had to dissolve the cuprous salt. Catalyst loading ranged between 5 and 20 mol%