1. Department of Chemistry, The Robert Robinson Laboratories, University of Liverpool, Liverpool L69 7ZD, U.K., Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool L69 3GE, U.K., Liverpool School of Tropical Medicine, University of Liverpool, Liverpool L69 3GE, U.K., UFC Ltd., Synergy House, Guildhall Close, Manchester Science Park, Manchester M15 6SY, U.K., and Department of Chemistry, School of Arts and Sciences, The Johns Hopkins University, Baltimore, Maryland 21218