A highly stereoselective synthesis of cis-and trans-3-alkoxy-3-phenyl/benzylthioazetidin-2- ones is described. The reaction of α-chlorosulfide-β-lactams with various alcohols catalyzed by a Lewis acid such as ZnCl2 in the presence of molecular sieves (3–4Å) leads to cis-3- alkoxy-3-phenyl/benzylthio-β-lactams whereas treatment of potassium 2-alkoxy-2- phenylthioethanoate with appropriate Schiff's base using POCl3 in the presence of ...
