1. Department of Organic Chemistry, Charles University in Prague, Hlavova 8, 12843 Prague 2, Czech Republic, http://www.orgchem.cz/roithova
2. Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, WI 53706‐1322, USA
3. Institut für Chemie, Elektrochemie und Galvanotechnik, Technische Universität Ilmenau, Weimarer Straße 25, 98693 Ilmenau, Germany
4. Institute of Organic Chemistry and Biochemistry, Flemingovo nám. 2, 16610 Prague 6, Czech Republic