Carbon–carbon bond formation at the C-4 position of an azetidin-2-one ring by intermolecular radical coupling reactions: a route to tribactams

Abstract
The β-lactam 4 was linked to the enones 8–10 using a radical reaction mediated by tri-n-butyltin hydride to give the 2,6-disubstituted cyclohexanones 11–16, respectively: 13 was converted into the protected tribactam 18 in two steps.