1,4-Bis-(4-methoxyphenyl)azetidin-2,3-dione has been prepared and used as a synthon for the stereoselective synthesis of C-3-alkyl/aryl azetidin-2-ones. Some of these are well known for their cholesterol absorption inhibitor activity. A regioselective Grignard reaction at a keto-group followed by highly stereoselective removal of the hydroxyl group via reductive removal of the xanthate ester is a key step in this synthesis. Base-induced isomerization of cis-azetidin-2-ones to the thermodynamically stable trans-isomer was also studied.
azetidin-2,3-diones - azetidin-2-ones - β-lactam - Grignard reaction - tributyltin hydride