1. Department of Chemistry, University of Warsaw, Pasteura 1, 02 093 Warsaw, Poland, Center for Heterocyclic Compounds, University of Florida, Gainesville, Florida 32611, University of Erlangen-Nürnberg, Henkestrasse 42, D-91054 Erlangen, Germany, Computational Chemistry Annex, University of Georgia, Athens, Georgia 30602-2525