A novel 1 beta-methylcarbapenem antibiotic, S-4661 synthesis and structure-activity relationships of 2-(5-substituted pyrrolidin-3-ylthio)-1 beta-methylcarbapenems

The synthesis and biological activity of(1R,5S,6S)-2-[(3S,5S)-5-substituted pyrrolidin-3-ylthio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylic acids are described. These compounds exhibit potent antibacterial activity against a wide range of both Gram-positive and Gram-negative bacteria including Pseudomonas aeruginosa. Of these new carbapenems, (1R,5S,6S)-2-[(3S,5S)-5-sulfamoylaminomethyl pyrrolidin-3-ylthio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylic acid (S-4661) showed the most potent and well balanced activity and was selected as a candidate for further evaluation.