1. Department of Chemistry, SmithKline Beecham S.p.A., Via Zambeletti, 20021 Baranzate, Milano, Italy, Department of Pulmonary Pharmacology, SmithKline Beecham Pharmaceuticals, 709 Swedeland Road, King of Prussia, Pennsylvania 19406-0939, and Department of Neurology Research, SmithKline Beecham Pharmaceuticals, New Frontiers Science Park, Third Avenue, Harlow, Essex, England CM19 5AW