Facile transformation of 3,4-disubstituted 2-azetidinones to chiral 5,6-dihydro-2-pyridones

Chiral 5,6-disubstituted-5,6-dihydro-2(1H)-pyridones were prepared efficiently from readily accessible 3,4-disubstituted-2-azetidinones having preadjusted substituents and stereochemistry through the reductive ring opening of 2-azetidinones followed by Z-selective installation of acetate moiety and re-cyclization to 2-pyridones.