Rubrolides A, D, P, T, U: Total Syntheses and Antibacterial Evaluation of Highly Brominated Marine Natural Products

Rubrolides are marine natural products with numerous biological activities. Over the last few decades, more than 20 members of this natural product class have been isolated, but their mode of action remains unknown. All compounds share a furanone core structure with β‐aryl and γ‐benzylidene substituents. The highly brominated rubrolides T, U, and an analog of rubrolide U are synthesized for the first time. Furthermore, the developed method enables the synthesis of natural rubrolides A, D, and P as pure Z ‐isomers. The synthetic approach employs a Suzuki‐Miyaura cross‐coupling reaction with a dibrominated aromatic boronic species as the key step, followed by a vinylogous Aldol condensation to introduce the second aromatic substituent. The synthesized compounds are biologically tested and show outstanding antibiofilm activity for Stenotrophomonas maltophilia , Bacillus subtilis , and Staphylococcus aureus. All synthesized compounds shows only negligible effects at GABA A receptors, suggesting that they are unlikely to exert neurotoxic effects at a concentration of 10 µM.