1. Contribution from the School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom, Department of Chemistry, University of Exeter, Stocker Road, Exeter EX4 4QD, United Kingdom, and Medicinal Chemistry Department, AstraZeneca R&D Charnwood, Bakewell Road, Loughborough LE11 5RH, United Kingdom