STUDIES ON BETA-LACTAM ANTIBIOTICS .4. AN IMPROVED SYNTHESIS OF 3-(ISOTHIAZOLYLTHIOMETHYL)CEPHALOSPORINS AND ITS APPLICATION TO NEW DERIVATIVES

An improved synthesis and in vitro activity of cephalosporins with a ( 4-carboxy-3-hydroxy-5-isothiazolyl)thiomethyl group at the 3-position and its application to the preparation of new derivatives are describe d. These compounds showed excellent activity against Gram-negative bac teria including beta-lactamase producing strains. Among them, 2f was t he most interesting because of its broad spectrum of antibacterial act ivity, including Gram-positive bacteria, and its outstanding inhibitor y potency against Pseudomonas aeruginosa.