1. PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
2. Dipartimento di Scienze Chimiche, University of Camerino, Via S. Agostino 1, 62032 Camerino, Italy
3. Latvian Institute of Organic Synthesis, Aizkraukles iela 21, Riga LV-1006, Latvia