1. Department of Chemistry, Oxford University, Mansfield Road, Oxford, OX1 3TA (UK), Fax: (+44)‐1865‐275674 http://www.chem.ox.ac.uk/researchguide/cjschofield.html
2. Current address: Georg‐August‐University Göttingen, Department of Chemistry, Institute of Organic and Biomolecular Chemistry, Göttingen (Germany)
3. Henry Wellcome Building for Molecular Physiology, Department of Clinical Medicine, University of Oxford (UK)