1. Institute for Organic Chemistry & Chemical Biology, Center of Biomolecular Magnetic Resonance, Johann Wolfgang Goethe University, Max-von-Laue-Straße 7, D-60439 Frankfurt am Main, Germany
2. LGCR/Department of Parallel Synthesis & Natural Product Sciences, Sanofi-Aventis Deutschland GmbH, Industriepark Hoechst, Bldg. H811, D-65926 Frankfurt am Main, Germany.