General Approach for the Stereocontrolled Construction of the β‐Lactam Ring in Amino Acid‐Derived 4‐Alkyl‐4‐carboxy‐2‐azetidinones.

Abstract

The first general approach toward the asymmetric synthesis of 4-alkyl-4-carboxy-2-azetidinones derived from amino acids is described. The stereoselective construction of the β-lactam ring was achieved through base-mediated intramolecular cyclization of the corresponding Nα-chloroacetyl derivatives bearing (+)- or (−)-10-(N,N-dicyclohexylsulfamoyl)isoborneol as chiral auxiliary (ee up to 82%).