Total synthesis and biological evaluation of (-)-atrop-abyssomicin C

Enantioselective synthesis of a marine antibiotic (-)-atrop-abyssomicin C was accomplished in 21 steps, in 1.8% overall yield (4%, based on the recovered starting material). The key steps of the synthesis are the formation of the functionalized cyclohexane core by an organocatalyzed Tsuji-Trost reaction, the formation of a tricyclic spirotetronate unit by a gold-catalyzed reaction sequence and the highly efficient eleven-membered ring closure by a Nozaki-Hiyama-Kishi reaction. Biological tests showed all abyssomicin derivatives to possess strong antibacterial activity against methicillin resistant S. aureus strains; however, they also proved to be cytotoxic, both to malignant and to normal somatic cells.