1. Faculty of Chemistry and Pharmacy, University of Innsbruck, Innrain 52c, A-6020 Innsbruck, Austria
2. Department of Pharmaceutical Chemistry, Philipps University Marburg, Marbacher Weg 6, D-35032 Marburg, Germany
3. Boehringer Ingelheim Pharma GmbH & Co. KG, Birkendorfer Strasse 65, D-88397 Biberach/Riss, Germany