Stereoselective synthesis of 2-azetidinones as cholesterol-absorption inhibitors

The synthesis of two 2-azetidinones possessing powerful cholesterol- absorption inhibition properties has been accomplished by a short and highly stereoselective reaction sequence. The key step is the condensation of the titanium enolate of the easily prepared 2-pyridylthioester (R)-11 with imine 6 which affords the desired β-lactam intermediate in the correct relative and absolute configuration. Conversion to the pharmacologically active compounds is readily accomplished by simple functional group manipulation. (C) 2000 Elsevier Science Ltd.