Structures and absolute configurations of carpetimycins A and B.

Carpetimycins A and B, two new i3-lactam antibiotics related to thienamycin'), epithienamycins2), olivanic acids'-5) and PS-50, were found in the culture filtrate of Streptomyces sp. KC-6643. These antibiotics have strong activity against Gram-positive and Gram-negative bacteria including (3-lactamase producing strains. Although the carbapenem antibiotics have been reported to be unstable substances, carpetimycins A and B are more stable than olivanic acids. In a previous paper'), we presented the isolation, characterization, biological properties and structures of these antibiotics. In this paper, we describe the structure elucidation including stereochemistry of carpetimycins A and B on the basis of chemical studies and X-ray analysis.