PENICILLINS AND CEPHALOSPORINS AND THEIR PRODUCTION

摘要

.beta.-Lactams of the formula and pharmaceutically acceptable nontoxic salts thereof wherein A is hydrogen or alkyl of 1 to 4 carbon atoms; B is phenyl, methylphenyl, chlorophenyl, hydroxyphenyl or cyclohexa-1,4-dien-1-yl; R is a moiety of the formula or wherein E is hydrogen, -OH or -O-CO-CH3; and ? constitutes a center of chirality; are produced which exhibit antibiotic activity. These .beta.-lactams exhibit a substantially greater antibacterial action, especially against Enterobacterisceae than known .beta.-lactams.