AM1 study of structure-activity relationships in bicyclic aza-β-lactams

Abstract AM1 calculations on bicyclic aza-β-lactams 4 (1,3-diazetidin-2-ones) are carried out to investigate the effect of ring size (five versus six), position of olefin ( Δ 2 versus Δ 3 ), and electronegative atom (oxygen) in the tethered non-β-lactam ring on the structure of diazetidinone. The results are discussed in terms of structural trends related to β-lactamase and transpeptidase inactivation capability. The biological activity of novel aza-β-lactams 4 is comparable to that of β-lactams 3 .