A practical synthesis of 3-[(1R)-1-t-butyldimethylsilyloxyethyl]-4-[(2R)-4-halo-3-oxo-2-butyl]azetidinone, a versatile intermediate for carbapenem antibiotics

A key intermediate for 2-(functionalized-methyl)-1-β-methylcarbapenems, 3-[(1R)-1-t-butyldimethylsilyloxyethyl]-4-[(2R)-4-halo-3-oxo-2-butyl]azetidinone, was prepared efficiently from a commercially available carboxylic acid in 3 steps.