1. Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, Florida 32611, Institute of Chemistry of Romanian Academy, M. Viteazul 24, Timisoara 300223, Romania, Institute of Chemistry, Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086, Estonia, and MolCode Ltd., Soola 8, Tartu 51013, Estonia