Affiliation: | a GlaxoSmithKline, Cambridge Chemistry Laboratory, Lensfield Road, Cambridge CB2 1EW, UK b Department of Chemisty, Lensfield Road, Cambridge CB2 1EW, UK c OSI Pharmaceuticals, Watlington Road, Cowley, Oxfordshire OX4 6LT, UK d GlaxoSmithKline, Gunnels Wood Road, Stevenage, Hertfordshire SG1 2NY, UK |