Studies on monocyclic beta-lactam antibiotics. IV. Synthesis and antibacterial activity of (3S,4R)-3-[2-(2-aminothiazol-4-yl)-(Z)-2-(O-substituted oxyimino)acetamido]-4-methyl-1- (1H-tetrazol-5-yl)-2-azetidinones.

The synthesis and in vitro activity of the 3-(O-substituted oxyiminoacetamido)-2-azetidinones (IV) possessing a tetrazole moiety at N-1 position are described. The introduction of lipophilic functions into the oxyimino moiety gave in some good activity against staphylococci, but decreased activity against Gram-negative bacteria. In contrast, the introduction of hydrophilic functions such as carboxycyclobutane resulted in strong activity against Gram-negative bacteria including Pseudomonas aeruginosa, and no or very small activity against the staphylococci.