1. Department of Chemistry, University of California, Riverside, California 92521-0403, Institut für Organische Chemie der Universität Erlangen-Nürnberg, Henkestrasse 42, 91054 Erlangen, Germany, Department of Chemistry, The University of Auckland, Private Bag, Auckland, New Zealand, 92521-0403, and School of Chemistry, University of Sydney, NSW 2006, Australia