Studies on beta-lactam antibiotics. II. Synthesis and antibacterial activity of cephalosporins with substituted 1,3-dithietane directly attached to the C-3 position.

Preparation of cephalosporins bearing a 1,3-dithietane ring attached to the C-3 position using intramolecular rearrangement are described. The diastereoisomers (6a-I and 6a-II) were separated by silica gel column chromatography. These 3-[4-(carbamoyl carboxymethylene)-1,3-dithietane-2-yl]cephems showed comparable activity against Gram-negative bacteria to that of ceftazidime.