Nocardicin A, a new monocyclic beta-lactam antibiotic II. Structure determination of nocardicins A and B

The structures of nocardicins A and B, novel monocyclic beta-lactam antibiotics produced by a strain of Nocardia, have been established as 1 and 2, respectively, on the basis of spectroscopic and chemical evidence. They are the first examples of monocyclic beta-lactam antibiotics possessing relatively high antimicrobial activity, and are stereochemically and biologically related to penicillins and cephalosporins.