1. Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, P.O. Box 11720, Gainesville, Florida 32611-7200, Department of Chemistry, University of Tartu, 2 Jakobi Str., Tartu, Estonia, and Department of Chemistry and Center for Green Manufacturing, The University of Alabama, P.O. Box 870336, Tuscaloosa, Alabama 35487-0336