Electronic structures of cephalosporins and penicillins. 15. Inductive effect of the 3-position side chain in cephalosporins.

Induction appears to be the primary means by which the side chain at position 3 of the cephem nucleus influences the chemical reactivity of the beta-lactam ring. In vitro antibacterial activity data suggest that when the cephalosporin is in the active site of the target bacterial enzymes, the presence of a leaving group in the side chain can promote inhibition.