1. Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, Centre for New Antivirals and Antineoplastics, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, CZ-16610 Prague 6, Czech Republic, Department of Biochemistry and Molecular Biology, Penn State College of Medicine, 500 University Drive, Hershey, Pennsylvania 17033, Institut für Organische Chemie, Johann Wolfgang Goethe Universität, Marie Curie Strasse 11, D-60439...