Preparation and antibacterial activity of delta 1-thienamycin

delta 1-Thienamycin (2), a double-bond isomer of thienamycin, was prepared by isomerizing N-[[(p-nitrobenzyl)oxy]-carbonyl]thienamycin p-nitrobenzyl ester (5b) with DBU in Me2SO followed by hydrogenolysis of the protecting groups. When evaluated in a disc-diffusion antibacterial assay, delta 1-thienamycin was found to be essentially devoid of activity. The lack of antibacterial activity was ascribed to a chemically less reactive beta-lactam amide bond than that found in thienamycin.