1. GlaxoSmithKline Pharmaceuticals, Department of Synthetic Chemistry, 709 Swedeland Road, King of Prussia, Pennsylvania 19406, U.S.A., Department of Analytical Sciences, 709 Swedeland Road, King of Prussia, Pennsylvania 19406, U.S.A., and Department of Environmental Research, 801 Riverside Road, King of Prussia, Pennsylvania 19406, U.S.A.