1. School of Chemistry, Main Building, Cardiff University, Park Place, Cardiff, CF10 3AT, U.K., GlaxoSmithKline Medicines Research Centre, Stevenage, Hertfordshire, SG1 2NY, U.K., and WestCHEM, Department of Pure and Applied Chemistry, Thomas Graham Building, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, U.K.