A novel approach to racemic and enantiopure nonconventional fused bi- and tricyclic β-lactams hasbeen developed by using regio- and stereocontrolled intramolecular free radical reactions in monocyclic2-azetidinone-tethered allenynes and haloallenes. The access to allene cyclization precursors was achievedby metal-mediated carbonyl allenylation of appropriately substituted 4-oxoazetidine-2-carbaldehydes inan aqueous environment. The tin-promoted radical cyclizations of allene-β-lactams are totally regioselectivefor the central allenic carbon, providing bi- and tricyclic β-lactams containing a seven-membered ring.