1. University of Bremen, Institute for Organic and Analytical Chemistry, Leobener Strasse 7, D-28359 Bremen, Germany
2. University of Bremen, MAPEX Center for Materials and Processes, Bibliothekstraße 1, D-28359 Bremen, Germany
3. Kiel University, Otto-Diels-Institute for Organic Chemistry, Otto-Hahn-Platz 4, D-24098 Kiel, Germany