Isolation, biosynthesis and chemical modifications of Rubterolones A-F: rare tropolone alkaloids from Actinomadura sp 5-2

Huijuan Guo, René Benndorf, Daniel Leichnitz, Jonathan L. Klassen, John Vollmers, Helmar Görls, Matthias Steinacker, Christiane Weigel, Hans-Martin Dahse, Anne-Kristin Kaster, Z. Wilhelm de Beer, Michael Thomas-Poulsen, Christine Beemelmanns