1. Department of Chemistry The Scripps Research Institute 10550 North Torrey Pines Road La Jolla CA 92037 USA
2. NSF/NASA Center for Chemical Evolution Atlanta GA 30332 USA
3. Department of Chemistry and Biology University of Salerno Via Giovanni Paolo II, 132 84084 Fisciano, Salerno Italy
4. Department of Medicinal Chemistry, Institute for Medical Research KU Leuven Herestraat, 49 Leuven 3000 Belgium