1. Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, v.v.i. Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
2. Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße, 35032 Marburg, Germany
3. Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia