Affiliation: | a School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK b F. Hoffmann-LaRoche AG, Discovery Chemistry, Pharmaceuticals Division, Bldg. 92-6.88, 4070 Basel, Switzerland c Roche Products Limited, 40 Broadwater Road, Welwyn Garden City, Herts AL7 3AY, UK |