1. Department of Pharmacy Pharmaceutical and Medicinal Chemistry Saarland University Campus C2 3 66123 Saarbrücken Germany
2. Institute of Organic Chemistry Technische Universität Braunschweig Hagenring 30 38106 Braunschweig Germany
3. Department of Chemistry and Molecular Biology Division of Organic and Medicinal Chemistry University of Gothenburg Kemigården 4 412 96 Göteborg Sweden