Biomimetic Synthesis of Cyanogramides B and C.

Marinacarboline E and cyanogramides B and C from the marine-derived bacterium have been synthesized. The key step is the Baeyer-Villiger oxidation of marinacarboline E to a ketene aminal via O → N acetyl migration, followed by addition of water or MeOH. Replacing the phenylethyl by a styryl side chain afforded dehydromarinacarboline E that was oxidized to a tetracyclic aminal.