Morphing Natural Product Platensimycin via Heck, Sonogashira, and One-Pot Sonogashira/Cycloaddition Reactions to Produce Antibiotics with In Vivo Activity

Type II fatty acid synthases are promising drug targets against major bacterial pathogens. Platensimycin (PTM) is a potent inhibitor against β-ketoacyl-[acyl carrier protein] synthase II (FabF) and β-ketoacyl-[acyl carrier protein] synthase I (FabB), while the poor pharmacokinetics has prevented its further development. In this work, thirty-two PTM derivatives were rapidly prepared via Heck, Sonogashira, and one-pot Sonogashira/cycloaddition cascade reactions based on the Gram-scale synthesis of 6-iodo PTM (4). About half of the synthesized compounds were approximately equipotent to PTM against the tested Staphylococcus aureus strains. Among them, the representative compounds 4, A4, and B8 exhibited different plasma protein binding affinity or stability in the human hepatic microsome assay and showed improved in vivo efficacy over PTM in a mouse peritonitis model. In addition, A4 was also effective in an S. aureus-infected skin mouse model. Our study not only significantly expands the known PTM derivatives with improved antibacterial activities in vivo, but showcased that C–C cross-coupling reactions are useful tools to functionalize natural product drug leads.