General and highly efficient synthesis of 2-alkylideneazetidines and beta-lactams via copper-catalyzed intramolecular N-vinylation.

[Structure: see text] N-Tosyl-3-halo-3-butenylamines underwent efficient Ullmann-type coupling with the catalysis of CuI/N,N'-dimethylethylenediamine to afford 2-alkylideneazetidines, which could be readily converted to the corresponding beta-lactams by oxidation with O3.