1. School of
Chemistry and Biochemistry, Georgia Institute of Technology, 910 Atlantic Drive,
Atlanta, Georgia 30332, United States
2. School of Biology, Georgia Institute of Technology, 310 Ferst Drive, Atlanta,
Georgia 30332, United States
3. Department of Chemistry, University of Massachusetts, 710 North Pleasant Street,
Amherst, Massachusetts 01003, United States
4. Organisch-Chemisches Institut, Ruprecht-Karls Universität Heidelberg, Im Neuenheimer
Feld 270, 69120 Heidelberg, Federal Republic of Germany