1. Department of Chemistry University of Sheffield Sheffield S3 7HF UK
2. Integrated Drug discovery R&D Sanofi Aventis (Deutschland) GmbH Industriepark Höchst 65926 Frankfurt am Main Germany
3. Present address: Department of Medicinal Chemistry Research and Early Development Respiratory & Immunology BioPharmaceuticals R&D AstraZeneca Pepparedsleden 1 43183 Mölndal Sweden
4. Functional Molecules & Polymers Institute of Chemical and Engineering Sciences A*STAR, Biopolis Singapore Singapore