Synthesis of Chlorinated Bicyclic C-Fused Tetrahydrofuro[3,2-<i>c</i>]azetidin-2-ones

Some bicyclic C-fused chlorinated tetrahydrofuro[3,2-c]azetidin-2-ones were prepared by a fairly general route involving Staudinger reaction of allylic/propargylic imidates with dichloroketene followed by highly diastereoselective CuCl/PMDETA-catalyzed 5-exo-trig/dig chlorine atom transfer radical cyclization. An oxepan-fused β-lactam was also prepared similarly by 7-endo-trig cyclization. Synthetic application of the side chain chlorine atom of the products was demonstrated by its substitution in one of the products with azide followed by azide−alkyne click reaction with phenylacetylene to obtain a 1,2,3-triazolyltetrahydrofuro[3,2-c]azetidin-2-one.